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Comments from Howard University

Submitted by: Cynthia Warrick, R.Ph., Ph.D.; Howard University; 3/27/00

1) The community adjacent to the Defense Depot Memphis Tennessee (DDMT) is very concerned about health effects that may be related to past, present, and future exposure from hazardous substances migrating from the DDMT site. Residents have documented increased adverse health effects, diseases, and mortalities in their community that they perceive are in some way related to activities on the site. They have increased fear and anxiety that more serious problems might occur when the excavation of the site takes place for proposed remedial action. They are also concerned that unknowing citizens will be placed on a site that has not been cleaned up to residential levels, especially in light of the health disparities in minority and poor communities that make them more sensitive to pollution effects than the majority population.


ATSDR has never been able to obtain from DDMT area residents any of that documentation of increased adverse health effects. We hope that Howard University will be able to obtain it and share that information with ATSDR.

Regarding the fear that people might be allowed to use an improperly cleaned up location on DDMT, the Depot is working with the community members of the RAB to insure that this does not happen.

2) Department of Health and Human Services (DHHS) has reported that minorities suffer from cancer, cardiovascular disease, diabetes, and HIV-AIDS at more than double the rate of the US white population. Additionally, many minorities have not been immunized properly. Minority residents, with already compromised immune systems, are probably more sensitive to environmental toxicants, than those populations with intact immune systems and proper nutrition. Of course, research will need to done to prove this statement, but precautionary action in light of current data should be adopted.


ATSDR has always insured that its evaluation procedures include special consideration of minority and other sensitive populations.

3) Only limited sampling of the site has taken place and no off-site sampling has been done. According to the health assessment, on page 13 it says, "No sampling of sediment was done on Dunn Field." However, on page 15, 1st sentence: "Only limited sampling of surface soil has been done at Dunn Field." Additionally, the most recent sampling took place in 1995 with comprehensive sampling results not available yet. It would be more appropriate to release the health assessment once an evaluation of the comprehensive sampling of Dunn field has taken place.


Very extensive sampling of the DDMT Main Facility was done and it was evaluated in the public comment release of the public health assessment. Extensive sampling of Dunn Field has now been done and is evaluated in this document. ATSDR's evaluation of these data were provided to Howard University in February 2000.

4) On page 16, the fact that only adult exposure doses were calculated and not children is confusing. Because children are living off-site and the numerous schools in the near-by community, where children are outside more often than adults, not calculating possible exposure doses for sensitive populations is a problem.


In response to this concern, both adult and child exposure doses were calculated and evaluated in this version of the public health assessment.

5) Off-site sampling needs to be undertaken to determine if there are exposure pathways not only for PAHs, but also for arsenic and dieldrin. According to Priority Health Conditions, all three of these substances have been found to cause adverse reproductive outcomes, of which the community has documented to occur at abnormally high rates.


In its proposal for an exposure investigation in the DDMT area, ATSDR indicated that arsenic and dieldrin would be included in the chemicals tested.

6) It appears to be controversial if in one part of the health assessment, only limited or no sampling of surface soil has been done; and on page 17, it is proposed that doses are too low to cause health effects. Without comprehensive sampling data, how can these conclusions be made? It is also problematic to release a health assessment with "the possible exception of the Rozelle neighborhood". It is recommended that on-site and off-site sampling be done prior to release of the final health assessment and that the community residents be allowed to participate in the sampling plan development.


Most of this concern has been addressed now that extensive sampling data are available for Dunn Field and were evaluated in this document. The release of the final public health assessment will not be delayed until the completion of ATSDR's proposed exposure investigation because ATSDR's documents and conclusions are always open to revision whenever new data become available. ATSDR is already working with DDMT-CCC and Howard University in finalizing its proposed DDMT area exposure investigation. As of November 9, 2000, ATSDR has been unable to reach agreement with Howard University and DDMT-CCC about the proposed ATSDR exposure investigation. Most of the locations originally proposed for sampling by ATSDR are included in sampling that EPA is scheduled to conduct in December 2000. The locations that EPA plans on sampling are the Rozelle area near Dunn Field, drainage ditches near the Southeast corner of the Main Facility, and the Tarrent Branch.

7) On page 23, it states that ATSDR staff observed children playing in a drainage ditch between Ball and Ketchum roads. Isn't this a current exposure pathway for children especially following a storm or other weather event where soil and runoff could be contaminated? Were residents queried on how often the children play in the ditch? During rain? Etc. . .


Yes, this could be an exposure pathway if contaminant levels are great enough. The data for the results for the sampling points on the DDMT about 50 feet away from where children could have been exposed do not indicate a problem. The levels for arsenic were 1 ppm, for dieldrin 0.2 ppm, and for lead 7.7 ppm. ATSDR proposed sampling of this location to specifically identify what the concentrations are.

8) Surface water contamination questions from page 25.

Section (1) - When were the industrial pipes and lined ditches installed?
Section (2-3) - Is monitoring data available for Nonconnah Creek?
Section (4) - Were residents near Tarrent Branch asked about the second open ditch from DDMT?
Section (5) - When was Cane Creek concrete-lined?


Section (1) question - We were unable to identify when the pipes and lined ditches installed.
Section (2-3) question - Monitoring data are available and ATSDR has provided Howard University with what it had in its files.
Section (4) question - Residents near Tarrent Branch were not asked about the second open ditch because ATSDR would not have been able to evaluate the situation since no environmental sampling data on this ditch are available.
Section (5) question - Based on engineering plans found in the City of Memphis files, it was about 1973 which is when Hamilton High opened.

9) ATSDR estimates that about 500 - 3,000 persons could have had regular contact with surface water from DDMT, and that a small child might reasonably travel 500 feet, the distance to a ditch. Thus, children should be accounted for in the exposure calculations.


Both adult and child exposure doses were calculated and evaluated in this document.

10) What contaminants were tested for in the Allen Well Field? When?


As required by the Safe Drinking Water Act, the wells from the Allen Well Field are tested for about 130 contaminants at least once a year.

11) Why are arsenic and iron levels high in the area around DDMT? Were these possible exposures calculated for risks to children?


The arsenic and iron levels are not high based on the typical levels for the Memphis area. The child exposure doses for arsenic and iron were calculated and evaluated and found not be health hazard given the likely exposure scenarios and the toxicity of these chemicals.

12) What is the basis for this statement on page 29? "Most surface water and sediment sampling locations from the area around DDMT receive little or no water from DDMT."


This conclusion is based on a comparison of the drainage from DDMT with the sampling locations.

13) Were residents polled concerning surface water flow from the site following storm events, floods, etc.?


No, they were not polled.

14) On page 41, community residents expressed concern for possible cumulative effects from mixtures of chemicals at DDMT. Have studies been made to determine possible cumulative effects on sensitive populations, etc.?


ATSDR has considerable interest in this topic and the studies it has sponsored have tried to address the issue of sensitive populations.

15) On page 44, the health assessment documents that possible health effects to children was taken into consideration, however, there is no information throughout the report to indicate this.


In evaluating the possible health impact of contaminants on the DDMT Main Facility, exposure of children was considered. In this document, child exposure doses were calculated for all the exposure situations evaluated.

Comments from Depot Redevelopment Corporation
of Memphis and Shelby County

Submitted by Jim Covington, Depot Redevelopment Corporation; 3/9/00

1) Dunn Field: The report indicates (p. 15) that "The soil and surface water sampling of Dunn Field is not adequate for public health purposes because it focused on suspected contamination source areas and only a few location were tested." The results of recent comprehensive sampling of Dunn Field will, the report indicates, make a definitive answer possible. We forward to seeing those results in the final version of the PHA.


These data are included in this document.

2) Evaluation of Residential Areas Around DDMT: The report is inconclusive (p. 20-23) in regard to the potential risk from contamination along drainage ditches in three areas - the Rozelle neighborhood, the neighborhood south of the SE corner of the Depot, and residential properties along Tarrent Branch which flows from the west end of the Depot. We understand that the potential risk will be clarified by further testing which will be reflected in the final PHA.


This information will be included in the final PHA if the exposure investigation has been completed by then. The sampling of the surface water drainage areas proposed in ATSDR's exposure investigation is now going to be conducted by EPA, probably in October 2000. EPA will release the results of their sampling to the public and will report them to the Memphis Depot Restoration Advisory Board (RAB).

3) Toxicological Evaluation: The report acknowledges the potential for elevated cancer risk from soil contact due to PAH contamination (p. 78 - 79) in three specific areas of the Depot. We understand that, on two of the three sites (between Buildings 689 and 690 and on the south side of Building 249), encapsulation of any residual contamination will result from planned redevelopment activities (pavement for employee parking). If the sampling west of Building 629 warrants, the Depot Redevelopment Corporation should be advised to design a method of encapsulation for that site into planned improvements.


Further evaluation of this situation indicates that it is not a public health hazard.

4) Public Health Actions and Recommendations: Efforts to improve diagnostic methods within the medical community related to potential health risks associated with the Depot or any other site, which the report indicates ATSDR intends, should be extended to all appropriate treatment facilities in the community. The planned action (p. 45) suggests that such assistance will be limited to "the existing HRSA clinic in Memphis". Former Depot employees intended to benefit from this effort are dispersed throughout the City and County.


The efforts of ATSDR's Office of Urban Affairs will include this aspect.

Comments from Tennessee Department of Environment
and Conservation (TDEC) Division of Superfund (DSF)

Submitted by Jordan English, TDEC/DSF; 3/7/00

1) TDEC, DSF is uncertain what future actions, reports, or assessments may be taken/generated as a result of the soil sampling program planned for the Rozelle neighborhood. Please clarify whether a report from this investigation will be generated or whether there will simply be an addendum to this document provided.


If this sampling is done, a report will be generated and distributed to area residents, and the various local, state, and federal agencies with DDMT. If this sampling is completed before the public health assessment is completed, then a summary of the sampling results will be included in that document.

2) There are several references through the document alluding to primarily 3 surface water drainages. The maps however show 4. The drainage which exits the facility near Custer St. is apparently the drainage that is excluded. This ditch drains a significant portion of the Main Installation to the north, including the DRMO yard. Please correct all references to 3 drainages, including the Conclusions section.


While there are four surface water drainages with their origin at DDMT, ATSDR considers only three as potential human exposure pathways and has identified them as such in the public health assessment. There appears to be only limited human contact with the drainage identified by TDEC.

3) Page 7 - TDEC/DSF was unaware that the mustard agent was drained into a vat of bleach. It was our understanding that the mustard agent was drained into a pit containing bleach.


Thanks for bringing this to our attention. The document has been revised to change vat to pit.

4) Page 7 - The last sentence of the 5th paragraph is confusing. The Allen Well Field is a primary source of drinking water.


Thanks, the document has been revised to incorporate your suggestion.

5) Page 22 - The introductory paragraph/sentence on this page is contradictory to the second sentence in the next paragraph. If exposure is ongoing then might and may are inappropriate words to use in the introduction. The wording is awkward and contradictory. Please clarify.


Thanks for bringing this to our attention. Might and may have been replaced by could to insure consistency in meaning.

6) Page 27 - The fourth paragraph refers to the span dome that collapsed. It was located near the western boundary of the Main Facility.


Thanks, the "is" has been replaced by "was".

7) Page 41 - Sufficient/appropriate sampling should occur to document that dieldrin or other chemicals are correctly attributed to the Depot. Just because there are any chemicals present on the adjacent properties doesn't mean that they necessarily migrated from the Depot.


ATSDR Exposure Investigations, especially those involving environmental sampling, are designed to identify exposure to site contaminants. The protocol of the exposure investigation ATSDR is proposing to do in the DDMT area was devised to do that by taking a sample just over the DDMT property line then moving progressively further away. Contamination would be considered site-related only if the sampling results show a clear "trail" away from the site.

8) Pages 67-68 - Interpretation of these tables need further explanation. What is the cancer risk at the Health Guideline concentration? How does this compare to the estimated exposures as described? What was the benchmark used for contaminants with no Health Guideline criteria?


As explained in the text before these two tables, a health guideline is for noncancerous health effects. Cancer risk is a separate calculation using the cancer slope factor for that chemical. Some chemicals like benzo(a)pyrene have a cancer slope factor but no health guideline. Others have health guidelines but no cancer slope factor even though they are carcinogens.

Comments from the Department of Defense

Submitted by Jan B. Reitman, Defense Logistics Agency; 3/30/00

General Comments

1) The quality of this document is substantially below the quality of documents submitted by the DHAC's Federal Facilities Branch for the following reasons:

  • The document is largely judgmental without providing the supporting information and analysis needed to evaluate the conclusions.

  • The supporting information and analysis is always included in other DOD documents. Past contaminant data has been missing at other DOD sites, however those documents contain a qualitative or quantitative analysis examining potential risks. The risk analysis includes examination of operations to see if there were any changes from past to current operations; this was not conducted in this document. Conservative exposure assumptions are made in the other documents with an analysis of the risk.


Every statement in the public health assessment is supported by appropriate references. The evaluation done in this document follows the policy and procedures established by ATSDR. It was reviewed by the Director and Assistant Director for Science of the Division of Health Assessment and Consultation. It was found to have followed that guidance. The risk analysis of past operations is sometimes used in ATSDR's PHA, but only if those analyses can result in a valid estimation of exposure. ATSDR did not identify those data for DDMT but would be willing to evaluate them if they do exist. The issue of the analysis of past operations is discussed in more detail starting on page 179.

2) The report did not include concepts of "exposure," "release," and "dose" clearly. Sometimes they are confusing. Release and exposure are used interchangeably in some cases, while they often are different from each other. A release does not always result in an exposure. So also, dose is proportional to the amount of contact with the contaminated area. For example, children play in the ditch does not necessarily mean they are exposed, unless it is clear that they were wet, and played in the unlined ditches, and sediments and surface water got on to their body. In the event they contacted water and sediment, how much area of the skin was in contact, and how often and for what duration all play a role in determining the dose, which in turn determines the risk or hazard. Excessive importance was given to the offsite drainage ditches, without establishing whether there is significant onsite contamination is being released to these water bodies from the Depot. The available data indicate that offsite releases are not occurring, therefore exposures to the ditches are not important.


This document complies with the public health assessment process described in the ATSDR Public Health Guidance Manual, other relevant ATSDR policies and procedures, and the legislation by which ATSDR was created and health assessments mandated.

3) Concepts of complete migration and exposure pathways are not clearly presented. It is not clear that there is a complete pathway for transport of onsite soils to offsite receptors. Runoff is channeled through storm drains and flooding is not common for this area. Onsite soils are for the most part stabilized through grassy cover or gravel. The aerosol pathway is possible, however as presented in the draft Dunn Field Remedial Investigation Report, maximum VOC concentrations in surface soil did not result in unacceptable risk for this pathway. Thus such statements where offsite soils may be contaminated by onsite soils contamination should be carefully evaluated prior to including in this PHA. Contaminant fate and transport based on site history, aging of the contaminants and changes in the nature of contamination with time, were not presented.


The extensive process described by the commenter is not part of the typical public health assessment. This sort of evaluation would included in a public health assessment whenever it would enhance and support the document's conclusions. This sort of evaluation is typically found in EPA Baseline Risk Assessments.

4) Please be consistent with capitalization of Main Facility. Pages 4, 25, 27 and 32 provide examples where capitalization is inconsistent.


Thanks, the document has been revised to insure that Main Facility is capitalized consistently.

5) Appears to be confusion between the Sediment Sampling Program conducted by USASSDC (reference 57) and the Background Sampling Program conducted by CH2M Hill (no reference). Both occurred in 1995. Sediment Sampling Program was specific to Depot storm water drains. Background Sampling Program was specific to areas where Depot operations would not have had an impact. There is mention of 22 sample locations in connection with both these programs when in fact the Background sampling report included 22 sample locations. Please be specific to the appropriate sampling program. Also, the 1995 Sediment Sampling Program was not technically part of the RI Sampling Program. The Sediment Sampling Program was specifically initiated due to public concerns about the storm drains. The RI sampling plans did not include the sampling that was accomplished by the Sediment Sampling Program. Also, the document speaks of a "DDMT area" sampling program. Was this the Background Sampling Program? If so, be specific and include the Background Sampling Program Report as a reference. See pages: 13, 17, 22, and 29.


ATSDR has found that there is often confusion among lay and technical people about the meaning of "background". Because of comments by reviewers within ATSDR about this issue the term "area sampling" was used instead of "background". ATSDR received only the data files for the Background Sampling Program and not the actual report.

6) This PHA did not include latest data in its entirety (e.g., soil gas survey data in Dunn field to locate soil sampling locations, and all the soil, sediment and surface water data from Dunn Field, immuno-assay data along the railroad tracks used for highest PAH sample location selection). Dunn Field investigations included exploratory surveys to include highest soil gas emission areas from which soil samples were collected from surface and subsurface. This latest investigation approach and sampling results were not included in this PHA. Therefore, conclusion leading to insufficient data for Dunn Field (Page 14) is mis-representing the site understanding.


ATSDR did not receive the data from the extensive sampling of Dunn Field until the document was ready for public comment release so it was not possible to incorporate those data in the document. However, ATSDR did know in a qualitative sense what the results were with the exception of the soil gas or immuno-assay data. These new data only reinforced the conclusions already made about Dunn Field. These data were reviewed in this document.

7) The "Background Study" was not referenced in the report. At the end of the report, it was identified as a study carried out to identify how-wide DDMT operations influenced the area. This was not the purpose of the background report, but rather it was conducted to establish urban background conditions around the Depot, following EPA and TDEC guidance.


Nowhere in the PHA is the "Background Study" identified as a study carried out to identify how-wide DDMT operations influenced the area. ATSDR never received a copy of nor knew of this study so it is difficult to cite it or reference it. In the PHA it is stated that, "Low concentrations of chemicals are in soil, sediment, and surface water from the area around DDMT. Available data indicate that DDMT is not a major source for these chemicals." This is ATSDR's interpretation of these data.

8) TDEC's name is Tennessee Department of Environment and Conservation, not Tennessee Department of Environmental Conservation. See pages: 12, 39, 42, and 45.


Thanks, it has been corrected in this document.

9) There are several instances where footnotes are used to provide where/how information was obtained. In most instances, there is a trip report of the same date that should contain the information being referenced. Should use the reference and not a footnote. See pages: 11, 16, 17, 23, 26, 28, 32, 37, 39, 41, and 42.


This document was edited by a professional editor and was found to comply with ATSDR's guidance for its documents.

10) The summary italicized statements are often confusing and misleading. They are alarming in that they discuss exposure pathways without including the public health analysis. The summaries are often not supported by the accompanying text.


This style is an effective way to communicate with an audience with a wide range of technical expertise and specific knowledge about a site. It was found to be acceptable to the health educators, editors, and senior technical staff who reviewed the document.

11) Remedial actions conducted so far should be included as part of the site history, including soil excavations in the residential areas, and active groundwater remediation in the Dunn Field area.


This information is included in this document.

12) The locations of the neighborhoods are not shown on any of the figures. Without this information, it makes review of this PHA difficult.


Figure 5 has been revised to include this information.

13) In general contamination trends, what was detected, whether it is related to the Depot operations, and what type of contamination may be expected versus detected was not discussed. The interpretation of the data as it relates to the site operations is missing from this PHA. For example, PAHs were detected along the railroad tracks and roadways. Dieldrin was mostly found in the grass strips and Golf Course, and may have been from historical pesticide applications. No mustard bomb related chemicals were reported in the site media.


It was not possible for ATSDR to consider these interpretations in the December 1999 release of the public health assessment since it did not receive the documents on which they are based until June 2000. They were considered in this document.

14) Surface water drainage ditches are dry for most of the year across the Depot, with only exception being in the northwest area of the Dunn Field. Ponds in the Golf Course contain water throughout the year. The surface water data reported for most of the drainage ditches is from rain events. Additionally most of the surface runoff is collected through storm-water drainage system through out the depot. Figure 5 implies a free offsite flow from surface runoff, however the flow is only through an enclosed drainage system. Also, exposure pathways are incomplete for most of these ditches because of lack of flow.


The document clearly states in several locations that water flow in most of these ditches is only occasional. Figure 5 shows the location of the drainage ditches and in no way indicates whether flow is occasional or constant.

Specific Comments

15) The Public Health Assessment: A Note of Explanation: Again, in this brief narrative prior to Foreword, there should be a recollection that a PHA was conducted in 1995 and that this is a follow on study. The narrative should also briefly explain why this follow-on document is needed.


This section is a "boiler plate" that is inserted into every public health assessment by staff in the Program Evaluation, Records, and Information Services Branch. As such the "boiler plate" does not include any reference to a specific site situation.

16) A Note of Explanation: Second paragraph, first and second sentences: Was this document, either in its entirety or some portion thereof, previously released to other groups? Did these other groups consist of private citizens? Were changes affected on the document due to input from these other groups? If so, change this paragraph to reflect what was done. Technically, this document has already been somewhat reviewed by the public.


Again, this section is a "boiler plate" that is inserted into every public health assessment by staff in the Program Evaluation, Records, and Information Services Branch.

17) Foreword, Exposure paragraph, last sentence: Does ATSDR routinely collect additional information when it is needed? If ATSDR doesn't collect additional samples, who does?


As mandated by Congress, ATSDR does recommend additional environmental sampling in its PHAs whenever it concludes that such sampling is necessary to fill gaps in the data necessary to properly evaluate the site. These recommendations are directed to the agency responsible for the site. For non-federal sites it would be EPA or the State. For federal sites, it would be the federal agency responsible for the site.

18) Page 3, para 1 - This paragraph lacks description of DoD property (DDMT) and can be perceived that since 1942, a mile radius of DDMT has been nearly an all African-American community. Based on a review of the historic documents, this is not a true perception nor relevant (for this report). Recommend the first paragraph be changed to read:

  • The former Defense Distribution Depot Memphis, Tennessee (DDMT), contains 642 acres and is located in the southern portion of the City of Memphis, Tennessee, about 2.5 miles north-northwest of the Memphis International Airport and about 5 miles southeast of the Mississippi River. DDMT is a Department of Defense (DoD) facility operated by the Defense Logistics Agency (DLA) with the actual property owners being Department of the Army. DDMT was created in 1942 for the Army Quartermaster Corps. The primary mission of DDMT has been to store; ship and receipt military supply items. On October 14, 1992, the Environmental Protection Agency (EPA) placed DDMT on the National Priorities List (NPL) based on a numeric ranking called the Hazardous Ranking System that determines the level of potential risk of a site to human health or the environment. In 1995, DDMT was place on the Base Closure and Realignment Commission (BRAC) list for closure and was officially closed on September 27, 1997
  • .


This is the summary of the document and, as such, the additional information suggested by the commenter is not necessary.

19) Page 3, para 2, last sentence. This statement is confusing, particularly in a summary section. How large are these PAH contaminated areas? Can a worker spend entire day in each area? If this is hypothetical, then it should be clearly stated so. Most of the PAHs onsite are under gravel covers, near railroad ties, and rarely exposed for direct exposure. There are no known workers spending time exclusively in the PAH contaminated areas. Therefore the statement should include 'if exposure were to occur.' In relative risk terms exposures to workers, if they were to occur, will be lower than exposure to other workers such as persons laying the roads (asphalt has higher PAHs).


This statement on PAHs is has been deleted from this document due to further evaluation of this exposure scenario.

20) Page 3, para 3, third sentence: Is the ditch from the west side of the main installation Tarrent Branch, or does that ditch feed Tarrent Branch? Also, recommend changefrom "Data are lacking"to "Data is lacking."


It is Tarrent Branch. In public health/biological literature, the word "data" is almost always considered to be plural so the appropriate verb is "are" rather than "is."

21) Page 3, para 3. Most of the ditches are dry, with only one ditch being an exception. The continuous flow ditch located north and northwest of Dunn Field also receives runoff from areas other than Dunn Field. While exposure pathway could be complete for the drainage ditches, as offsite public has access, the release from Dunn Field is not confirmed. Constituents detected are similar to those within Main Installation and general perimeter conditions, and urban background conditions. The information included in this summary is not conclusive.


A summary is not intended to be conclusive or comprehensive.

22) Page 3, 3rd full paragraph, last two sentences - The report does not acknowledge the offsite groundwater contamination west of the southwest corner of the Depot. Although the concentrations of VOCs are significantly less than those west of Dunn Field, they are still above MCL and require consideration for remedial action as discussed in the draft Main Installation Feasibility Study.


The draft Main Installation Feasibility Study was not provided to ATSDR. However, based on a request by one of the members of the Memphis RAB, ATSDR has included information on this groundwater contamination on page 28 of this version of the public health assessment.

23) Page 3, para 4. The short-term air-borne exposure needs to be explained. What are the five elements of the pathway? Later in the document, it states this occurred once.


This sentence has been revised in this document to include the phrase "at least once" to make this clearer.

24) Page 3, para 4,- This first sentence differs from the statement on page 27, para 3. Which is correct? Did airborne exposure definitely occur or "probably" occur? If the statements in the main part of the document are correct, then the summary should be consistent with those statements. The statement "In the past accidental releases may have occurred", does not mean exposures have occurred. Contaminants may have never reached past property boundary. There are no known exposures.


The statement in the Summary on long-term air exposures has been replaced by "Little indication exists in the data available to ATSDR that long-term exposure to site contaminants of all or most of the residents around DDMT occurred via the air." This is taken from the discussion of the air pathway on page 27.

25) Page 3, para 5, single sentence. The statement implies there are no concerns for long-term. Is there a possibility for short-term exposures to this indirect pathway?


Long-term has been deleted from this sentence.

26) Page 3, para 6: While the thoughts on reevaluating the 1995 PHA, examining the cancer data, and the commitment to review additional environmental data seem to be within the purview of a PHA, it is unclear why the Greater Memphis Environmental Justice Workgroup, the enhancement of depot area health care facilities, and the health education are included here. While these are each worthwhile efforts, they do not seem to belong within this document according to the Foreword. Please either explain the relevance or remove these inappropriate references.


The inclusion of these references in the public health assessment was requested by Dr. Rueben Warren, the Associate Administrator for Urban Affairs as a way to document these public health activities. The request was accepted by Rear Admiral Robert Williams, the Director of the Division of Health Assessment and Consultation.

27) Page 4, para 1, last line. DOD has repeatedly asked that the word "revisit" not be used in conjunction with this assessment. The agreed upon language (per November 1998 meeting between ATSDR and DLA) for this document was a "Site Review and Update". Change "revisit" to "review and update". See also Page 12, Para 1, line 3.


The health assessor, John Crellin, was not aware of this agreement. This document has been revised to delete "revisit."

28) Page 4, para 2, last sentence: Please verify that no one has reviewed some portion of this document before the release of the document in December 1999.


Portions of the community health concerns section were shared with DDMT-CCC, DDMT, and others in October 1998. Preliminary drafts of the contaminant maps and tables were provided to DDMT and CH2MHILL in 1998. Those portions of the documents that directly supported the conclusions of the document were sent to Dr. Kathleen Buchi of DOD in June 1999. The community health concerns section was provided to DDMT - CCC in July 1999 to respond to a complaint that community concerns were not being addressed in the document. No one outside of ATSDR saw or reviewed the whole document before its release for public comment in December 1999.

29) Page 4, para 3: Please add that ordnance to include explosive bombs, chemical warfare weapons, biological warfare weapons, and nuclear weapons was never stored or distributed from the site. The only exception to this is the small arms munitions used by the facility security force. This is a concern the DoD staff has heard from the public in the past.


This suggestion has been incorporated into this document.

30) Page 4, para 3 - Suggest including figure 3 from the 1995 report to show the overall site location.


Figure 1 has been revised to include a small map identifying DDMT location within Shelby County.

31) Page 4, para 3 - Add a sentence to help readers understand the origins of the depot: "Located on land previously farmed for cotton, the depot was constructed to meet the needs of the Army early in WWII."


Reference to the cotton field has been inserted but the other information is not germane to the purpose of this PHA.

32) Page 4, para 4, sentence 2 - Replace "and such" with more descriptive terms like "tires, wooden pallets, repair parts, and other supplies" (insert the appropriate descriptions). "Drums of chemicals" were also stored in the open storage areas. The only "medical waste disposal" at the Depot that records indicate is incineration or burial of expired-shelf life items. The term "medical waste" may be confused with biohazardous waste. Please specify what "medical waste" includes or means.


"Disposal of medical items" has been substituted for "medical waste disposal" in this document.

33) Page 4, para 5. To minimize confusion, add a sentence defining the term chemical warfare materials after the first sentence and move the sentence beginning "Most of this storage…" to the end of the paragraph.


This paragraph is adequate as written.

34) Page 6, Figures 2 and 3: The northern most drainage off of the west side of Dunn field appear to cross Rozelle. I do not believe that is correct unless the drainage is within a enclosed storm sewer. If that is the case and there is little to no opportunity for exposure to the public, why is it indicated on the two figures? Please also refer to the attached information from the 1995 PHA that states there are two unlined ditches running from the western side of Dunn Field through the Rozelle neighborhood. Please verify these drainage pathways.


This ditch does run under Rozelle street in a pipe. However, during the rest of its course through the Rozelle area it is an open unlined ditch that anyone in the Rozelle area could easily and regularly access. The 1995 PHA is incorrect as there are three ditches coming off Dunn Field in the Rozelle area.

35) Page 6, Figure 2: The key symbol for "Tracks where 1946 Mustard bomb Train" does not match the actual symbol on the figure. There also is no symbol in the key for housing/residential.


These problems have been corrected in this PHA.

36) Page 6, Figure 2: The terms "Toxic Materials" and "Toxics Recovery" associated with Buildings 835 and 865 are not technically accurate. Not all hazardous materials are toxic (compressed oxygen, for example), and these two buildings stored/recovered a variety of hazardous materials. The building identified as the "Span Dome Site" is now Building 925. After the span dome collapsed, it was not rebuilt. Suggest inserting either "former" or "spill" into that identifier.


The labels for these buildings came from maps provided by DDMT.

37) Page 7, para 3 - Replace the parenthetical explanation of the stockpile material with a standalone and accurate description of the purpose of the material. Please delete "agents" as it may be confused with the chemical warfare agents mentioned in the previous and following sentences. Bauxite (aluminum ore- Al 2 O 3 . nH2O with ferric oxide and silica impurities)and Fluorspar (metal smelting flux- primarily Ca F2) are NOT used in the manufacture of chemical warfare materiel or chemical agent. However, the bauxite and fluorspar ore piles do not exist at the Depot anymore.


This paragraph has been revised as suggested.

38) Page 7, para 4 - Several related comments as follows:

  • Sentence 5 is misleading. Replace it with a description of how the bombs were detoxified according to the standard operating procedures required and approved at the time, noting that supertropical lime solution (strong bleach) is the material used today to detoxify mustard agent.

  • Please indicate whether the "attempt" of detoxifying the mustard was successful. A statement to this effect is in the Archives Search Report.

  • The second line reads "In 1946, German mustard bombs, being transported by rail through the Memphis area, were found to be leaking (5). The train was brought to the DDMT Main Facility where the leaking bombs were unloaded and the train decontaminated". This statement doesn't explain where the Mustard Bombs were heading and/or why they were taken to DDMT. Recommend change to " In 1946, German mustard bombs that were being transported by rail from Mobile Alabama through Memphis Tennessee in route to Pine Bluff Arkansas, were discovered to be leaking while at the Memphis Station (5). Since DDMT was the nearest military installation, the train was routed to DDMT where the leaking bombs were unloaded and the train, to include train-rails, were decontaminated by trained specialist from Aberdeen Maryland."


The chemical warfare materials cleanup on Dunn Field that began in June 2000 suggests that the paragraph is adequate as written.

39) Page 7, para 5, Several related comments as follows:

1. The main solvent in the subsurface of Dunn Field (solvent disposal/burial area) is 1,1,2,2-tetrachloroethane.

2. Please change the wording of the second sentence to "This, along with potential private offsite sources, resulted in extensive contamination…….." The BRAC Cleanup Team has evidence that there may be a non-federal government contributor to the plume to the north of Dunn field.

3. Please check the 30-40 below surface statement for the fluvial aquifer. Across Dunn Field, the fluvial aquifer starts about 60 - 80 ft below ground surface rather than 30-40. The saturated thickness of the fluvial aquifer averages about 10-20 ft thick across Dunn Field.

4. No mention is made that the fluvial is not the aquifer used for potable uses by the City of Memphis. Also, per comments by USGS, "Fluvial Aquifer" should not be capitalized.

5. Please indicate that the wells in the Allen Well Field draw water from the Memphis Sand aquifer, not the fluvial aquifer.

6. Although the flow of the fluvial aquifer is essentially to the west, flow patterns in the contaminated portion of the fluvial aquifer do not correspond to most of the mapped locations around the Depot. Commentator would propose phrasing the final sentence of this paragraph as: "The contaminated groundwater may eventually reach the vicinity of the Allen Well Field, which is used by the City of Memphis as a secondary source of drinking water."

7. Check the Allen well field use by the City of Memphis as a secondary water source. The commentator believed it was a primary source.

8. Regarding the first sentence, this sentence can be perceived that DDMT violated environmental statues by burying chemical in Dunn Field. Recommend change to"At the time when DDMT buried chemicals at Dunn Field, there were no environmental requirements to have an impermeable (i.e., liquids can't flow through) liners and caps as now required."

9. DoD has found in the Dunn Field Remedial Investigation, lead and arsenic concentrations are not elevated in the pumped groundwater and are therefore sampling artifacts rather than environmental contamination.

10. Lead (maximum concentration was 21 mg/kg) and arsenic (maximum concentration was 17 mg/kg) in the subsurface (burial activity) were similar to background concentrations. This paragraph as written is confusing because it seems to mix subsurface soils with groundwater.

[11] The last sentence is misleading, as the details in the report are contrary (on Page 27 first paragraph).


The suggestions 1-7, 9, and 10 are accepted and the appropriate revisions have made. The rest of the suggestions are not germane to the document.

40) Page 7, para 6, Please add at the end of second sentence migration pathway 'possibility.'


This paragraph is acceptable as written.

41) Page 8, Figure 3, comments: 1) The ore piles no longer exist, therefore should be identified as former ore piles. 2) The Mustard Bomb Debris locations should be identified as suspected or reported, as they are confirmed locations. 3) The acid burial area could not be confirmed. 4) The latest Dunn Field investigations indicated presence of solvents in larger area than that reported in this figure. Either, make this figure represent current conditions or indicate in the title that it represent historical conditions only. Additionally, the road that connects Kyle to Rozelle, Menager, does not cross the railroad tracks to the west of Rozelle. The road simply makes a ninety degree turn south to Rozelle. Also, the symbol for the railroad track is not used on the map. In fact, the rail as indicated on the north side of Dunn Field is incorrect.


The suggested revisions have been made.

42) Page 9, Figure 4: In the percentage African-Americans figure, the gray "Greater than 0-50% African American" key is incorrect. It should be "Less than 50%…"


Thanks for catching this mistake. It has been corrected.

43) Page 10, para 3 - The specific communications referenced do not include installation press releases, etc. These should be specifically identified just as the newspaper articles are, unless only the press was telling the story. Also, the newspaper articles referenced do not include information on a "1998 hazardous waste incident." Unsure what the "1998 hazardous waste incident" involved. The subjects of the three articles dated 1998 include: research on toxicity related to reuse of the property, a survey regarding depot neighbor's concerns, and past military residue. No mention of a "1998 hazardous waste incident." Please delete this. Also, although the newspaper article cited may have speculated on a connection, clean monitoring and pumping wells between the contaminated Allen Well field pumping well and the Dunn Field plume provide evidence that the Allen Well field contamination is not from the Depot.


The 1998 hazardous waste incident was the problem with the vials and is reference 28 - Military residue from past is concern for today. The mention of "hazardous waste" has been deleted.

44) Page 12, para 4 - Add at the end a description of what the last two subgroups are doing, since the first three are described.


These two sub-groups are no longer functioning so no description is needed.

45) Page 13, 2nd full paragraph -- The data sources cited do not include the ongoing (since 1996) groundwater sampling at Dunn Field and the Main Installation, although this information for the Main Installation was provided to ATSDR in the Main Installation dataset. Second, the RI investigation for Dunn Field is not cited here. Surface and subsurface soil, sediment, and surface water analytical data from samples across Dunn Field was provided to Dr. John Crellin/ATSDR on 21 December 1999. This dataset is the basis of the ongoing Remedial Investigation and Risk Assessment at Dunn Field. Dr. Crellin had asked for the information approximately three weeks earlier. At the time of his request we had not completed validation of the Storage Area samples and gave Dr. Crellin the option of receiving a partial dataset at that time or waiting for a full dataset. Dr. Crellin requested the full dataset when it was ready. Subsequent clarification regarding sample points and station identifications were provided to Dr. Crellin on 14 January 2000. Review of communications indicate that there may have been some lingering uncertainty by ATSDR on the location of a couple of samples, but the database was useable.


Because groundwater was considered an eliminated exposure pathway, the groundwater data were not evaluated. ATSDR did not request nor was it provided the groundwater data for the Main Facility. The groundwater data for Dunn Field were provided without being requested. These data were not evaluated in this document because this pathway was eliminated. The extensive data on surface soil, surface water, and sediment recently made available for Dunn Field are evaluated in this public health assessment.

46) Page 14, 2nd paragraph: The Corps did not conduct the sampling, they provided oversight to contractors who collected the samples and performed the analysis. Should make that distinction.


This sentence has been revised to substitute "is responsible for conducting" for "conducts."

47) Page 14, para 6 - The format for placing the conclusions in italics at the beginning of a section is confusing. Suggest inserting "Conclusion summary:" at the beginning of the paragraph, or moving the conclusion to the end of the section.


The author has found that these summary paragraphs are an effective way to help the lay person understand the document. ATSDR public health assessments are supposed to be written with multiple audiences as targets.

48) Page 14, Para 6, line 1. The sentence states that the sampling is not adequate. What is this not adequate for -- public health evaluation? A public health evaluation was completed on the following pages.


The extensive data provided on Dunn Field since the public comment release and its evaluation in this document makes this comment moot.

49) Page 15 - For consistency, the headings for para 1, 3 and 4 should be reworded to parallel those on pages 17-18. For example, use "Sediment Sampling" instead of "Sediment."


Thanks, this suggested revision has been made.

50) Page 15, Sediment paragraph: Since the paragraph indicates the "chemical detected included . . . PAH groups," should indicate what group the benzo, dibenz and indeno compounds are in.


Identifying these compounds as PAHs in this paragraph would not enhance the information communicated in this paragraph so no changes will be made.

51) Page 15, Para 5. This paragraph 5 seems inconsistent with paragraph 4. There were surface water and sediment sampling results available (USASSDC, Jan. 96) outside the depot fence line from all major drainage's leaving the depot property and surface soil sampling results (CH2M Hill, May 98) also from outside the fence line. The statement that these are inadequate for a public health assessment lacks reasoning that explains why the data is inadequate. The stated reason for the inadequacy of the data is poor. Please explain the data inadequacy in more detail. Regardless, there is now much more data for Dunn Field that is available for use in this report.


These paragraphs were accurate when written but are now moot as is this comment due to the new Dunn Field data that are evaluated in this document.

52) Page 16, Para 1: Please ensure that conclusions were based on assessment of at least that available data which could significantly impact results. Sufficient analytical data to statistically assess health impacts of soil and surface water contamination at Dunn Field does exist and should be included in evaluation of data.


As described in comment 45, these data were not provided to ATSDR until December 21, 1999 which was after the official release date for the public comment release of this public health assessment. These data are evaluated in this document.

53) Page 16, Soil Contaminants, 1st paragraph: Please reference Depot Layout map No. 11-44 dated 1944 regarding the fence at the Depot. This map is available for review at the Memphis Depot Caretaker and a copy is attached (See Attachment 1 on next page). This is the source of the statement regarding fences at the Depot. A map is a better reference than limited historical knowledge.



Thanks for providing this information. It is used as reference in this document.

54) Page 17, para 3 and page 20-21 - The format for placing the conclusions in italics at the beginning of a section is confusing. Suggest inserting "Conclusion summary:" at the beginning of the paragraph, or moving the conclusion to the end of the section.


The author has found that these summary paragraphs are an effective way to help the lay person understand the document. ATSDR public health assessments are supposed to be written with multiple audiences as targets.

ATTACHMENT 1 - provided as part of comment 53

Attachment 1
Attachment 1a.

Attachment 2
Attachment 1b.

55) Page 17, para 4 & supporting information in the appendix (77-78). This conclusion is misleading. When referring to page 77, the cancer (PAHs) evaluation that occurred used exposure assumptions - 70 year, 7-days a week. These assumptions are unrealistic for a potential exposure occurring at an industrial complex, which is less than 60 years old. The evaluation should have been done using 5-day a week and no more than a 40-year exposure (most people retire before 40 years), that would reduce the cancer risk. To further state that it is unclear that anyone may have experienced this exposure scenario is an unrealistic statement. The likelihood of someone working in the soil at the cited buildings every day 7-days a week for 70-years is highly improbable. Page 42 states that in order for a cancer risk one would have to work in the soil, not just walk over it. This section implies that all one needs to do is walk over the area to have the increased risk. What was the likelihood of foot traffic over the suspect area? Page 66 indicates that the cancer risk was calculated using a 5-day exposure. Was the cancer rate determined differently for PAHs? If so why? For consistency and accuracy, it is suggested that parallel logic or documentation be used.


These exposure situations are no longer considered a health risk based on a further evaluation of the data for these contaminants. This document has been revised to reflect this.

56) Page 17, Results of Environmental Sampling, 1st paragraph: Was under the impression that ATSDR was provided sampling data from the 1998 remedial investigation sampling. No "remedial investigation" sampling occurred in 1995, only background sampling at areas that should not have been impacted by Depot operations and the sediment sampling that was not technically part of the RI sampling effort and was not specified in the RI sampling plans. The current RI report references the sediment sampling report as a separate sampling event not related to the RI sampling effort.


We are both incorrect. A check of the RI data provided to ATSDR by DDMT identifies sample collection dates in 1997. This document has been revised to reflect this date.

57) Page 20, Sediment paragraph: In previous portions of the document, the term PAHs is defined as polycyclic aromatic hydrocarbons, as opposed to this definition - polynuclear aromatic hydrocarbons. Please be consistent.


Thanks for identifying this mistake. A revision has been made.

58) Page 20, para 4. The conclusions do not appear to be supported by the text. Page 20, para 2 & 3 state sediment and surface water do not represent a public health hazard, page 17 states that even with daily exposure, health effects are very unlikely, and page 15 states that no further evaluation of surface water is necessary, yet this paragraph implies that there is a problem in the Rozelle neighborhood. Why? If there is not a problem with exposure from Dunn Field, or the Main Facility, where is the contamination supposedly originating?


The meaning of this comment is very unclear. The conclusion in paragraph 4 that contaminants from DDMT do not currently represent a public health hazard is supported by the sampling data. There is a possible data gap for the Rozelle neighborhood which ATSDR is proposing to fill. ATSDR agrees that the likelihood of finding contamination is small. However, ATSDR believes that it is a prudent public health practice to provide the residents of this neighborhood assurance that there is no contamination.

59) Page 21, para 2. DOD does not concur with the conclusion that an evaluation of exposure from 1942 to 1989 is not possible. This evaluation was completed in the PUBLIC HEALTH ASSESSMENT, USA DEFENSE DEPOT MEMPHIS, MEMPHIS, SHELBY COUNTY, TENNESSEE, CERCLIS NO. TN4210020570, November 8, 1995 Prepared by: The Agency for Toxic Substances and Disease Registry Division of Health Assessment and Consultation (see attached excerpt on next page, Attachment 2). Similar evaluations have been made in other PHAs. As previously stated, when past data has been considered in the past, an attempt to evaluate the public health concerns is made based on current information and information about the processes conducted at the base. There seems to be no attempt to make this evaluation in this assessment based on the same information available during the preparation of the cited PHA.


This document complies with the public health assessment process described in the ATSDR Public Health Guidance Manual, other relevant ATSDR policies and procedures, and the legislation by which ATSDR was created and health assessments mandated.

Specifically, the public health assessment process is driven by data, especially environmental sampling data. The extensive environmental sampling done since 1995 strongly supports the conclusions of this document.

The modeling or evaluation of industrial processes can provide data useful in the public health assessment or risk assessment process. An example would be a smelter where knowledge of the composition of the ores fed into the smelter and the operation specifications could permit fairly accurate predictions of what was emitted from the smelter stack. However, DDMT had no industrial processes for which modeling can be done.

As a military supply, storage, and maintenance facility, contamination could have occurred through leaks and accidental spills. The potential for this can be evaluated through examination of reports on the handling and impact of toxic substances at DDMT. However, according to the 1990 RI, these reports go back only to the 1960s so it is not possible to evaluate the potential for releases for the 20 years the Depot existed before that time (3). The 1982 Installation assessment identified a number of problems with the way toxic substances were handled at DDMT (7). This indicates that releases could have occurred and, at least in the case of the pentachlorophenol dipping vat, did occur. Additional support for the potential for past releases of toxic substances comes from the statements made by former DDMT workers at the Memphis RAB meetings.

The environmental sampling done at DDMT since 1989 did not identify any extensive areas of contamination. This indicates that there were no significant releases of the chemicals that persist in the environment such as arsenic, lead, chlordane, and many others. However, these data can't be used to make a similar statement about those chemicals that do not persist in the environment such as the volatile organic compounds. It is not possible to prove or disprove that significant spills of these compounds occurred.

Does all this prove that there was a health hazard in the past as asserted by DDMT-CCC? No, but as discussed above, there are insufficient qualitative or quantitative to prove that wasn't one, especially prior to the 1960s. The statement in this document that there are insufficient information to state whether a health hazard existed is the only reasonable conclusion, given the available data.

ATTACHMENT 2: referred to in comment 59

Please note that the following information is extracted directly out of the PUBLIC HEALTH ASSESSMENT, USA DEFENSE DEPOT MEMPHIS, MEMPHIS, SHELBY COUNTY, TENNESSEE, CERCLIS NO. TN4210020570, November 8, 1995 Prepared by: The Agency for Toxic Substances and Disease Registry Division of Health Assessment and Consultation, pp 16-18:

Drainage Ditches

Other surface water pathways that need to be evaluated are the ditches that drain from the site. These ditches are also possible routes for contamination to reach the waters and sediment of Cane and Nonconnah Creeks. According to RI information, several ditches or streams drain from DDMT to Cane or Nonconnah Creeks. These are shown in Figure 6 (1).

An open, concrete-lined channel runs north from Dunn Field into Cane Creek. Two unlined ditches run west from Dunn Field through the Rozelle Street area. During a February 1995 site visit by ATSDR, these were both observed to contain relatively small volumes of water. Tarrant Branch runs west from the Main Facility, eventually entering Nonconnah Creek to the south. Drainage ditches run from the Golf Course Pond and Lake Danielson south, entering Nonconnah Creek. An unnamed ditch runs east from the Main Installation to the storm sewer system. Each of the ditches except Tarrant Branch are dry for at least part of the year (2).

Since there is little chance that people would drink water from the drainage ditches in any significant quantity, the only possible exposure concern would be dermal exposure (contact with the skin). There are few studies on dermal exposures of people to low levels of these chemicals. However, in general, this is much less likely to be a health problem than exposure by drinking the contaminated water. This is because these chemicals are not as easily absorbed into the body through the skin as they would be if they are taken in by drinking water.

Because the most likely exposure would be from walking beside or wading in the ditches, the most likely contact with the chemicals would be a person's feet and possibly hands. These are the parts of the body that are the least able to absorb contaminants (18). Also, it is important to remember that for exposure to a low level of contamination to be a problem, the exposure has to occur frequently (generally daily) over a long period of time (many years) (18).

Sixteen drainage ditch samples were collected for the 1990 RI (2). These samples were collected onsite, from each of the ditches that drained from DDMT to offsite. The contaminants found in these samples are listed in Table 2. With the exception of the pesticides DDT and DDE, the VOC bis(2-ethylhexyl)phthalate (DEHP), and the PAHs fluoranthene and pyrene, levels were lower than EPA drinking water standards. For the contaminants found in these ditches, dermal exposure is therefore not a public health concern.

DDT and DDE do not enter the body through the skin very easily, so that exposure to these chemicals in the small amounts present in the southern onsite drainage ditches is not likely to be a public health problem (19). DEHP is not easily absorbed through the skin, particularly in small amounts, such as are present in these onsite ditches (20). The amount of DEHP present also does not present a public health threat.

If enough fluoranthene and pyrene are present, dermal exposure can result in a noticeable skin irritation. However, neither chemical is believed to cause cancer or other long-term problems (16). These contaminants are not present at levels that would be considered health threats. Based on the low levels present, and the limited possibility of contact, it is not likely that these PAHs present a health threat.

There is currently no information available on contamination in the ditches on western side of Dunn Field. Surface water contamination is not likely to be a problem in ditches draining Dunn Field since, for the most part, the contamination is buried below the surface, and is not likely to affect rainwater runoff. Also, any rainwater soaking into Dunn Field would percolate downward to the water table, which is about 40 feet below ground surface in the DDMT area. It is highly improbable that rainwater percolating into Dunn Field could move laterally off Dunn Field to get into the drainage ditches. The ditches themselves will be "recharged" by groundwater within 10 to 20 feet of their streambanks and would not be affected by groundwater contaminants under Dunn Field.

Additionally, VOCs and metals are the contaminants buried at Dunn Field. VOCs were found at elevated levels in the groundwater samples. Several metals were also detected at elevated levels. Table 1 shows these contaminants. In general, if VOCs had been present at one time in surface soil, they do not remain in surface soils for any length of time and therefore would not be present to be carried in rainwater runoff into the ditches. Also, VOCs are not easily absorbed through the skin in amounts large enough to be a problem, particularly when amounts are as low as could possibly be present in the drainage ditches (23,24,25,26,27,28,29).

The metals found in the groundwater samples at Dunn Field are also not generally a problem in terms of contact with the skin. This is especially true when these metals are in water and are present in such small amounts (30,31,32,33,34).

In summary, it is unlikely that hazardous waste buried in Dunn Field is carried offsite by rainfall runoff. It is not likely that surface water would be contaminated as much as groundwater.

The actual contamination of surface water in the ditches has not been determined. Additional ditch water sampling planned for DDMT will provide information on any contaminants present. However, using the assumptions made above, it is unlikely that skin contact with the ditch water (or sediment) is harmful.


60) Page 21, Para 4, Line 3: The sentence beginning "Long term air exposures…" should be more completely prefaced by a discussion of contaminants, pathways, and receptors in preceding sections. Sampling discussions on page 20 could include an explanation of transfer of constituents to air. The discussion of Health Consequences beginning on page 20 should clarify what matrix (such as air) is the probable route of exposure.


These are summary paragraphs and they are followed by more comprehensive discussions. These discussions do not include some of the information suggested by the commenter because it was not considered germane to the public health assessment.

61) Page 21, para 8- page 22. What contact is ATSDR assuming that occurs with surface water and sediment? Is the exposure considered oral or dermal? Why is the contact considered daily? What are the activities the neighbors are engaged in that are causing the daily contact? What analysis was completed to determine risks?


As indicated in Figures 3 and 5, there is a ditch running through the middle of the neighborhood and between two houses. Anyone walking between the houses could contact the sediment or water depending on whether there is water flowing. Since these ditches are usually dry, children could crawl or play in the sediment.

62) Page 22, 4th paragraph: Were the 22 samples part of the background sampling or the sediment sampling? Should provide document reference number from reference section.


As indicated earlier, these 22 samples were from what DDMT identified as background samples but which in this document are identified as area samples to avoid confusion over what is mean by background. The source of these data was identified in footnotes earlier in the public health assessment. They can't be formally referenced since DOD did not provide ATSDR with their Background Report.

63) Page 22, Paragraph 5, offsite migration is stated to be occurring for the Dunn Field. There is no concrete evidence for this. Observed chemicals in the ditches could be from pesticide applications directly on to the ditches to prevent insects/mosquitoes. The runoff from roads is more likely than the contaminated sites within Dunn Field. Also, exposures to surface water and sediment are limited to feet and palms, due to shallow water levels. Concrete lined ditches do not have sediment accumulation; therefore sediment exposures are limited only to the unlined ditches.


It is doubtful that the ditches in this area were sprayed with pesticides as these ditches are not a good habitat for mosquitoes. The ditches have water in them only during rain events. The Rozelle area is sloped east to west so any water in the ditches flows through and does not pool up.

64) Page 22, General Comments (2), Where Exposure to DDMT….. :

  • The interpretation of exposure pathway on this page is misleading. Certain facts have to be established prior to exposure evaluations such as, what is the nature of the contamination in these ditches? How much of it is coming from the Dunn Field? For an exposure pathway to be considered as occurring, a source, a migration pathway, and an exposure point has to be present. If observed chemicals are ambient concentrations, none were from the Depot, then the exposure to the Depot constituents are not likely to occur. Therefore exposure pathways are incomplete. If the observed contamination is from possible past pesticide application in the ditches, then they are not truly related to hazardous waste operations within the Depot, as pesticide applications generally follow the suggested use. The only constituents detected in these ditches were low level chlorinated pesticides that were detected at similar concentrations in the 'background' samples, and are not specific to the Depot. Therefore, the exposure pathway analysis included on this page is making more definitive statements implying local residents were exposed to the Depot contaminants, when the contamination is present in ditches throughout urban environment.

  • Also soil contaminated by sediment and surface water from Dunn Field is implied. The scenario under which such contamination can occur is not explained. Flow in these ditches is low therefore overflow is highly unlikely.


The last paragraph in this section has been revised to focus on the lack of sampling.

65) Page 23, 3rd and Last paragraphs, Statement that past exposures are unknown, however overland flow patterns are the same, and exposure receptors are the same. Majority of the chemicals detected is inorganic chemicals, which do not decrease in concentration with time, and are indicators of the past occurrences. The chlorinated pesticides are expected to accumulate in the organic carbon of the sediments with time, therefore are expected to increase in concentration for a time after usage ceases, however are likely to decrease slowly with time. Any other non-persistent compounds are short-lived and are not a chronic exposure concern. There is no obvious offsite release from the Dunn Field (no continuous flow), or direct runoff. Based on these facts, past exposures are not expected to be different from the present exposures. The text should be modified by either including further explanation or these statements should be eliminated from this PHA.


The paragraphs indicated by the commenter have been revised to better describe this conclusion about evaluating past exposures.

66) Page 23, Para 4: The italicized text prefacing the actual evaluation of residential areas around DDMT provides an overview of conclusions reached in subsequent discussions. Perhaps this text (and similar italicized text in other sections) should be included as a regular section of the report as a "Section Overview". Specific statements made in this text are not fully rationalized in the subsequent sections. It is unclear why a portion of the Rozelle neighborhood is an "exception" It should be clarified if this is an exception to the conclusion that no current hazards exist, or an exception that this area was not assessed. This section should more clearly identify what contaminants, pathways, and receptors may be applicable to creating a risk in each of the "exceptions".


We are unable to provide a response to this comment as the content of paragraph 4 on page 23 has no relationship to what is described in this comment. For example, the comment refers to the Rozelle neighborhood while the southeast drainage is the topic of the paragraph referenced.

67) Page 23, Para 4, statement indicates shallow ditches have more potential for overflow. While this is theoretically correct, how often does this happen? If it rarely happens, what types of contaminants are expected to be persistent enough to be concern? For the conditions at the Depot is this scenario expected to be of concern based on low levels of chemicals, absence of known flooding in the operational history and longevity of the chemicals? All these issues need to be addressed at the same time this statement is made, so later on when it is concluded that the Depot does not pose a health concern, the reasons are clearly explained.


Again, we are unable to provide a response because the comment does not match the paragraph referenced.

68) Page 24, Figure 5 - The diagram includes two types of arrows but the legend only includes one. Include both types in the legend.


This problem is corrected in this document.

69) Page 26, First full sentence. Has there been a dye test that confirms flow from DDMT reaching Cane Creek? Does the author mean the nearest continuous flow stream is Cane Creek, and this may receive some flow from the Depot? Are there continuous flow ditches between the Depot and the Cane Creek, or is this expected to occur only during rain events? Further clarification is needed with this statement.


DDMT's 1982 and 1990 reports, and the City of Memphis Drainage Map indicate that water from DDMT flows into Cane Creek (3,7,75). However, we agree that this is sentence is very unclear and it has been revised in this document.

70) Page 26, para 3 - It is unclear how these estimates are made. If the entire population within this area is 30,720, almost 10% are being assumed to live within 500 feet from the Depot boundary (3000) and all are using the ditches. However, it is generally known, youth tend to be playing in the ditches, while adults and younger children are not. Even if 3000 people live within 500 ft from, the depot, only a small percentage of that population are expected to be children between 6-17 years of age, who could be playing in the ditches. Thus, these estimates of persons exposed should be significantly less than what is currently stated. Also, some of these receptors could be in the ditches only once in their lifetime, while others could be there multiple times, and almost none are expected to be there every day. Please revisit the estimates of exposed population and further clarify the intent of this information.


The way these estimates were made is clearly described on page 27 of the document and is a commonly used technique to estimate population numbers.

71) Page 26, para 4 headed "Groundwater" - To avoid confusion, include an interpretive statement at the end such as "There is no risk from this contaminated ground water since no wells draw from it."


There is no need for such a statement here as the lead sentence in the last paragraph of this section states, "Exposure to site contaminants in drinking water does not appear to have been possible."

72) Page 26, last paragraph, and Page 27 first two paragraphs. Groundwater information is oversimplified. Contamination in the Dunn Field has been identified in the shallow aquifer, while Allen Well field wells are greater than 300 feet in depth. Groundwater flow direction is different for Main Installation, where it is through a trough, versus Dunn Field where it flows to the northwest and west. Allen well field is directly west. Groundwater under Dunn Field is being remediated through an active remediation system.


This information has been revised in this document.

73) Page 27, Air, 2nd paragraph: The Span Dome was torn down after the 1985 incident and is no longer located on the western boundary. Suggest changing verb to "was."


This change has been made.

74) Page 27, para 3 - The use of the term 'exposure' should be revisited in this write-up since release to the air does not necessarily result in human exposure. Most of the constituents listed in this paragraph exhibit chemical properties indicating these chemicals dissipate in air within few feet from the release point, thus offsite public exposure is highly unlikely. Also, replace "release to the air" with "the release to the environment." This is more accurate and reflects the same wording used in the description of the same incident on page 40, para 2.


For the purposes of a public health assessment, this paragraph is acceptable as written.

75) Page 28, para 1, last sentence - Because soils along the perimeter are not expected to receive contaminants from onsite soils, the perimeter samples being referenced are assumed to be from the ditch bottoms. The PAHs are much lower in the paint booth area compared to other locations along the railroad tracks. Further explanation is needed for the statement.


The type of media sampled was identified in the first sentence of this paragraph, "This is confirmed by soil sampling data...." The PAH levels around the paint booth are elevated compared to those at the site perimeter, while they are not as high as the concentrations around the railroad tracks.

76) Page 28, para 2 (and the following other text) - While it true that indirect exposures through food chain consumption/accumulation are not likely, the primary reason is lack of exposure due to absence of surface water bodies that can support fish population. All other reasons (e.g., low concentrations) are secondary, as concentration levels play no role in the absence of habitat.


This section has been revised.

77) Page 28, para 4 - The text should read to clearly indicate that this is past use only, as there are no fish in the ponds now, and this is anecdotal information.


This paragraph has been revised to indicate that there are currently no fish in the ponds. The source of the story about fishing in the pond is already identified.

78) Page 28, para 5 - The offsite soil contamination is implied. Historical records of flooding and overflow should be reviewed prior to these statements. Also, with time chemicals are likely to be washed off of surfaces more than they are adhered onto the surfaces by flooding. This is inaccurate prediction and should be thoroughly thought through before presenting in this PHA document. Also, the first sentence is subjective and the commentator disagrees with the statement in so much as the intent is in regards to the Depot. If the "systematic evaluation" of off-site soils is some Memphis/Shelby County Health Department, Tennessee Department of Environment and Conservation, or Environmental Protection agency initiative, then the statement may be correct. The Depot considers it's off-site sampling effort which included background sampling (CH2Hill, May 98) as well as sediment sampling (USASSDC, Jan 96), to constitute systematic sampling.


For the purposes of a public health assessment, this paragraph is acceptable as written.

79) Page 29, para 2 - Provide the document reference number from the reference section that contains information regarding the sampling locations being discussed here. If these locations were part of the background sampling program, then the "local environmental activist" referenced in the note did not assist in selecting sampling locations. ATSDR and the activist assisted with locations for the 1995 sediment sampling program (reference 57).


The source of these data was identified in a footnote on page 29. ATSDR was unable to cite a specific source because this document was not provided. ATSDR has in its files detailed notes taken by Jeffery Kellam that describe the locations where these samples were taken and that the local activist participated in selecting those sites.

80) Page 29, para 3 - The "Background" study was to establish the general background conditions around Shelby County, not to assess influence of DDMT on these areas, as implied in this paragraph.


ATSDR does not state nor intend to imply the purpose of this sampling.

81) Page 31, para 2 - A complete exposure pathway is mentioned in the second sentence. Although a possible complete pathway to the ditches offsite are identified, no such pathways exist for onsite media and the offsite public. Even in ditches, it is not definitive that children playing in these ditches contacted contaminated sediments. There are no contaminants in surface water above naturally occurring levels. Organic chemicals are mostly from sediments. If the children play in the concrete lined ditches no exposures are likely. Thus, there is considerable uncertainty associated with exposure pathways in general, and for the Depot in particular. The text should be revised to eliminate the certainty associated with exposure pathway statements.


ATSDR provided an extensive justification of its conclusion. Based on ATSDR's published guidance, it is the only conclusion that can be made.

82) Page 31, 4th paragraph: Delete period after "women."


This change was made.

83) Page 32, comment response 2: Please reference Depot Layout map No. 11-44 dated 1944 regarding the fence at the Depot.


This change was made.

84) Page 32, first paragraph, and other places where estimated population numbers are included, please revise the number of people potentially exposed based on comment above made on Page 26. Page 34, comment response 5: Should address the drinking water question as in comment response 8.


See our response on page 187 about population estimates. The information in comment response 8 has been added to number 5. Thanks for the suggestion.

85) Page 35, Response to Comment 9. The groundwater underneath Dunn Field is being actively remediated in an attempt to prevent future vertical migration of contamination. This should be indicated in the response.


A mention of this has been included in this document.

86) Page 36, statement 13 - Replace "assessable" with "accessible" to reflect the correct meaning.


Thanks, this was done.

87) Page 37, comment response 14: Should use reference 46 from the reference section instead of the note.


Thanks, this was done.

88) Page 39, comment 21: There is a note symbol (2), but no corresponding footnote.


This has been deleted

89) Page 43, item 4 - This first sentence differs from the statement on page 27, para 3. Which is correct? Did airborne exposure definitely occur or "probably" occur? If the statements in the main part of the document are correct, then the summary should be consistent with those statements.


They probably occurred. The appropriate revision has been made.

90) Page 47, references 8, 9, and 10: These documents were essentially rough drafts of what became and should be referenced: Final Remedial Investigation Sampling Letter Reports, Final Screening Sites Sampling Letter Reports and Revised Final BRAC Sampling Letter Reports.


The documents referenced were what was provided to ATSDR.

91) Page 51, reference 51: Change period after "July 27" to a comma.


Thanks, this was done.

92) Page 70, Table E2 - which included the data used as basis for the statements on exposure includes old data (1990 and 1995), with common laboratory contaminants, indicative lack of data quality evaluation. Chemicals such as acetone and methylene chloride are not expected to last in the surface water therefore, do not represent current site conditions, they are not likely to be site-related, and data quality is questionable. More recent samples did not indicate presence of such volatiles. Chemicals like dieldrin are not expected to be soluble in water, and are likely from suspended sediment material. All these issues need to be resolved prior to exposure considerations. More recent data collected as part of RI is available for the Dunn Field drainage ditch surface water that was not included in this report.


The data referred to were not provided to ATSDR until after the public health assessment when out for public comment. These data are evaluated in this document.

93) Page 75, para 3, last sentence - Is this sampling inadequacy the same one identified elsewhere that can be resolved? See comment for Page 15, para 5 and page 16, above.


This section has been revised to reflect the data on Dunn Field received since the public comment version was released.

94) Page 91-92 - This section is difficult to follow. Figure 5 is helpful in visualizing this section, but this could be improved. The figure currently only shows drainage in open ditches. Adding the locations of referenced drainage in pipes and storm sewers as well would aid in following this major topic in this section.


Figure 5 has been revised.


Thank you for the opportunity to review this draft document. We are pleased that the quality of the document is substantially improved over the first version.

1) Page 5, paragraph 1. Change "revisit" to "review and update" see response to DOD comment, # 27.

RESPONSE - Thanks, I missed this one and have changed it.

2) Page 5, paragraph 4, sentence 4. Based on the placement of the reference to Figure 2, it implies Figure 2 identifies the storage in "open areas", while the figure legend is for all contaminant storage areas. The key on Figure 2 should differentiate between open and other storage areas.

RESPONSE - I moved the reference to Figure 2 to the first sentence to resolve this problem.

3) Page 5, paragraph 5. Delete "substantial amounts of" or define. What is meant by this phrase is unclear. The storage amount is not substantial when compared to other DOD sites whose predominate mission involved chemical warfare-related materials.

RESPONSE - I replaced substantial with a specific mention of the amount of the space that was used.

4) Page 17, table. The table labels are illegible in the dark box.

RESPONSE - Thanks, I have reduced the percent fill to make it lighter.

5) Page 36, paragraph 1. The response discusses a 1982 DOD report, however the reference is to an ATSDR trip report. This is misleading, implying that the DOD report states that management of toxic substances was "marginal". The substances were handled in accordance with the applicable standards at the time.

RESPONSE - Thanks for catching this. I have corrected it.

6) Page 103, 3). Request of copy of referenced survey from ATSDR. Also subject survey should be referenced in this report. (Perhaps this is item 37 in the reference listing?)

RESPONSE - A copy of this survey was already provided to John DeBack. Please ask him for a copy or request directly from Crater Gray of Memphis-Shelby County Health Department.

7) Page 108, 16). Based on the fact that there is a groundwater treatment system (planned or actual), the contamination should never reach the Allen Well Field. This is an important point to make in responding to the individual's concerns.

RESPONSE - I have added the following to this section, "If it operates as designed, the groundwater treatment system that was recently installed at the northwest end of Dunn Field should greatly reduce or eliminate the flow of contaminants and perhaps make this issue moot." .

8) Page 109/110. There is a blank page between p. 109 and p.110. Is this intentional?

RESPONSE - Thanks, that has been corrected.

9) Page 135, 53). The commenter is referring to the DERTF, not DEBRA and Dr. Huganaut is CDR Hughart. The "army" should be "Army" when referring to the actual organization.

RESPONSE - Thanks for providing this information. The appropriate revisions have been made. Joseph Hughart was recently promoted to Captain (O-6).

10) Page 180, 58). The commenter is simply asking ATSDR to identify what they think the potential source of contamination is for the Rozelle area. In the PHA they had stated it was not from the Main Area and not from Dunn Field. If these two areas are not the source, where is the potential source? DOD did not comment on the recommendation for sampling as implied by the response.

RESPONSE - The possible source is contaminants that moved from Dunn Field sometime in the past as indicated on page 23, "Soil, now present in the Rozelle area, may have been contaminated in the past through the overflowing of ditches in this neighborhood. No sampling has been done of the soil around these ditches." The discussion on page 20 is about the health hazard represented by contaminant levels identified in the sampling conducted since 1989. I admit that the chance of this having occurred in quite small but the most concrete way to deal with this issue is to sample these areas as EPA will do in December.

11) Page 180-181 59). DOD simply disagreed that ATSDR has done a thorough review of the potential past exposure in this review and update. DOD does not and did not presuppose a conclusion on that investigation. On page 181 paragraph 2, ATSDR incorrectly assigns an assertion to DOD. The DOD commenter did not assert any conclusion, but simply referenced the previous PHA where ATSDR conducted some evaluation of potential past exposures. On page 13 of this previous PHA, ATSDR states "Contamination at the depot does not pose a health concern to people living on or near the depot, and it did not pose a health hazard in the past." Request the first two sentences of paragraph 2 on page 181 be deleted.

RESPONSE - These two sentences have been deleted.

12) Page 186-187, 66) ATSDR indicated that no response could be provided as the relationship of the content of the comment and the referenced section was not clear. The comment addressed Section - CURRENT CONDITIONS OF SITE, the first paragraph under Subsection - Evaluation of Residential Areas around DDMT. This paragraph begins with, "With the possible exception of the Rozelle neighborhood…" at the bottom of page 20. The subsequent sections where the commenter is looking to find the clarification/rationalization for the initial conclusionary statements run fro page 20 through page 23. In other words, clarify better what is the possible potential problem for Rozelle.

RESPONSE - See the response to number 58.

13) Page 187, 67) ATSDR was unable to provide a response because the comment did not seem to match the referenced paragraph. The comment addressed Section - CURRENT CONDITIONS OF SITE, Subsection - Evaluation of Residential Areas around DDMT, under the heading Where Exposure to DDMT Contaminants in Surface Water could be occurring. It starts with 3) In or near the 4 ditches that flow south from the southeast…. The third full sentence indicates that ditches join and flow to Nonconnah Creek. These ditches are dry most of the time, thus there is no flow, except during rain events. The Nonconnah Creek is more than a mile away.

RESPONSE - In reviewing your original comments and the text you are referring to, I believe the current explanation already provides the justification you are requesting.


ATSDR Plain Language Glossary
of Environmental Health Terms
Revised -15Dec99 (additional revisions by John Crellin)

How a chemical enters a person's blood after the chemical has been swallowed, has come into contact with the skin, or has been breathed in.

Acute Exposure:
Contact with a chemical that happens once or only for a limited period of time. ATSDR defines acute exposures as those that might last up to 14 days.

Additive Effect:
A response to a chemical mixture, or combination of substances, that might be expected if the known effects of individual chemicals, seen at specific doses, were added together.

Adverse Health Effect:
A change in body function or the structures of cells that can lead to disease or health problems.

Antagonistic Effect:
A response to a mixture of chemicals or combination of substances that is less than might be expected if the known effects of individual chemicals, seen at specific doses, were added together.

The Agency for Toxic Substances and Disease Registry. ATSDR is a federal health agency in Atlanta, Georgia that deals with hazardous substance and waste site issues. ATSDR gives people information about harmful chemicals in their environment and tells people how to protect themselves from coming into contact with chemicals.

Background Level:
An average or expected amount of a chemical in a specific environment. Or, amounts of chemicals that occur naturally in a specific environment.

Used in public health, things that humans would eat - including animals, fish and plants.

See Community Assistance Panel.

A group of diseases which occur when cells in the body become abnormal and grow, or multiply, out of control

Any substance shown to cause tumors or cancer in experimental studies.

See Comprehensive Environmental Response, Compensation, and Liability Act.

Chronic Exposure:
A contact with a substance or chemical that happens over a long period of time. ATSDR considers exposures of more than one year to be chronic.

Completed Exposure Pathway:
See Exposure Pathway.

Community Assistance Panel (CAP):
A group of people from the community and health and environmental agencies who work together on issues and problems at hazardous waste sites.

Comparison Value (CVs):
Concentrations or the amount of substances in air, water, food, and soil that are unlikely, upon exposure, to cause adverse health effects. Comparison values are used by health assessors to select which substances and environmental media (air, water, food and soil) need additional evaluation while health concerns or effects are investigated.

Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA):
CERCLA was put into place in 1980. It is also known as Superfund. This act concerns releases of hazardous substances into the environment, and the cleanup of these substances and hazardous waste sites. ATSDR was created by this act and is responsible for looking into the health issues related to hazardous waste sites.

A belief or worry that chemicals in the environment might cause harm to people.

How much or the amount of a substance present in a certain amount of soil, water, air, or food.

See Environmental Contaminant.

Delayed Health Effect:
A disease or injury that happens as a result of exposures that may have occurred far in the past.

Dermal Contact:
A chemical getting onto your skin. (see Route of Exposure).

The amount of a substance to which a person may be exposed, usually on a daily basis. Dose is often explained as "amount of substance(s) per body weight per day".

Dose / Response:
The relationship between the amount of exposure (dose) and the change in body function or health that result.

The amount of time (days, months, years) that a person is exposed to a chemical.

Environmental Contaminant:
A substance (chemical) that gets into a system (person, animal, or the environment) in amounts higher than that found in Background Level, or what would be expected.

Environmental Media:
Usually refers to the air, water, and soil in which chemical of interest are found. Sometimes refers to the plants and animals that are eaten by humans. Environmental Media is the second part of an Exposure Pathway.

U.S. Environmental Protection Agency (EPA):
The federal agency that develops and enforces environmental laws to protect the environment and the public's health.

The study of the different factors that determine how often, in how many people, and in which people will disease occur.

Coming into contact with a chemical substance.(For the three ways people can come in contact with substances, see Route of Exposure.)

Exposure Assessment:
The process of finding the ways people come in contact with chemicals, how often and how long they come in contact with chemicals, and the amounts of chemicals with which they come in contact.

Exposure Pathway:
A description of the way that a chemical moves from its source (where it began) to where and how people can come into contact with (or get exposed to) the chemical.
ATSDR defines an exposure pathway as having 5 parts:
  • Source of Contamination,

  • Environmental Media and Transport Mechanism,

  • Point of Exposure,

  • Route of Exposure; and,

  • Receptor Population.

When all 5 parts of an exposure pathway are present, it is called a Completed Exposure Pathway. Each of these 5 terms is defined in this Glossary.

How often a person is exposed to a chemical over time; for example, every day, once a week, twice a month.

Hazardous Waste:
Substances that have been released or thrown away into the environment and, under certain conditions, could be harmful to people who come into contact with them.

Health Effect:
ATSDR deals only with Adverse Health Effects (see definition in this Glossary).

Indeterminate Public Health Hazard:
The category is used in Public Health Assessment documents for sites where important information is lacking (missing or has not yet been gathered) about site-related chemical exposures.

Swallowing something, as in eating or drinking. It is a way a chemical can enter your body (See Route of Exposure).

Breathing. It is a way a chemical can enter your body (See Route of Exposure).

Lowest Observed Adverse Effect Level. The lowest dose of a chemical in a study, or group of studies, that has caused harmful health effects in people or animals.

See Cancer.

Minimal Risk Level. An estimate of daily human exposure - by a specified route and length of time -- to a dose of chemical that is likely to be without a measurable risk of adverse, noncancerous effects. An MRL should not be used as a predictor of adverse health effects.

The National Priorities List. (Which is part of Superfund.) A list kept by the U.S. Environmental Protection Agency (EPA) of the most serious, uncontrolled or abandoned hazardous waste sites in the country. An NPL site needs to be cleaned up or is being looked at to see if people can be exposed to chemicals from the site.

No Observed Adverse Effect Level. The highest dose of a chemical in a study, or group of studies, that did not cause harmful health effects in people or animals.

No Apparent Public Health Hazard:
The category is used in ATSDR's Public Health Assessment documents for sites where exposure to site-related chemicals may have occurred in the past or is still occurring but the exposures are not at levels expected to cause adverse health effects.

No Public Health Hazard:
The category is used in ATSDR's Public Health Assessment documents for sites where there is evidence of an absence of exposure to site-related chemicals.

Public Health Assessment. A report or document that looks at chemicals at a hazardous waste site and tells if people could be harmed from coming into contact with those chemicals. The PHA also tells if possible further public health actions are needed.

A line or column of air or water containing chemicals moving from the source to areas further away. A plume can be a column or clouds of smoke from a chimney or contaminated underground water sources or contaminated surface water (such as lakes, ponds and streams).

Point of Exposure:
The place where someone can come into contact with a contaminated environmental medium (air, water, food or soil). For examples:
the area of a playground that has contaminated dirt, a contaminated spring used for drinking water, the location where fruits or vegetables are grown in contaminated soil, or the backyard area where someone might breathe contaminated air.

A group of people living in a certain area; or the number of people in a certain area.

Potentially Responsible Party. A company, government or person that is responsible for causing the pollution at a hazardous waste site. PRP's are expected to help pay for the clean up of a site.

Public Health Assessment(s):
See PHA.

Public Health Hazard:
The category is used in PHAs for sites that have certain physical features or evidence of chronic, site-related chemical exposure that could result in adverse health effects.

Public Health Hazard Criteria:
PHA categories given to a site which tell whether people could be harmed by conditions present at the site. Each are defined in the Glossary. The categories are:
  • Urgent Public Health Hazard

  • Public Health Hazard

  • Indeterminate Public Health Hazard

  • No Apparent Public Health Hazard

  • No Public Health Hazard

Receptor Population:
People who live or work in the path of one or more chemicals, and who could come into contact with them (See Exposure Pathway).

Reference Dose (RfD):
An estimate, with safety factors (see safety factor) built in, of the daily, life-time exposure of human populations to a possible hazard that is not likely to cause harm to the person.

Route of Exposure:
The way a chemical can get into a person's body. There are three exposure routes:
- breathing (also called inhalation),
- eating or drinking (also called ingestion), and
- or getting something on the skin (also called dermal contact).

Safety Factor:
Also called Uncertainty Factor. When scientists don't have enough information to decide if an exposure will cause harm to people, they use "safety factors" and formulas in place of the information that is not known. These factors and formulas can help determine the amount of a chemical that is not likely to cause harm to people.

The Superfund Amendments and Reauthorization Act in 1986 amended CERCLA and expanded the health-related responsibilities of ATSDR. CERCLA and SARA direct ATSDR to look into the health effects from chemical exposures at hazardous waste sites.

Sample Size:
The number of people that are needed for a health study.

A small number of people chosen from a larger population (See Population).

Source (of Contamination):
The place where a chemical comes from, such as a landfill, pond, creek, incinerator, tank, or drum. Contaminant source is the first part of an Exposure Pathway.

Special Populations:
People who may be more sensitive to chemical exposures because of certain factors such as age, a disease they already have, occupation, sex, or certain behaviors (like cigarette smoking). Children, pregnant women, and older people are often considered special populations.

A branch of the math process of collecting, looking at, and summarizing data or information.

Superfund Site:
See NPL.

A way to collect information or data from a group of people (population). Surveys can be done by phone, mail, or in person. ATSDR cannot do surveys of more than nine people without approval from the U.S. Department of Health and Human Services.

Synergistic effect:
A health effect from an exposure to more than one chemical, where one of the chemicals worsens the effect of another chemical. The combined effect of the chemicals acting together are greater than the effects of the chemicals acting by themselves.

Harmful. Any substance or chemical can be toxic at a certain dose (amount). The dose is what determines the potential harm of a chemical and whether it would cause someone to get sick.

The study of the harmful effects of chemicals on humans or animals.

Abnormal growth of tissue or cells that have formed a lump or mass.

Uncertainty Factor:
See Safety Factor.

Urgent Public Health Hazard:
This category is used in ATSDR's Public Health Assessment documents for sites that have certain physical features or evidence of short-term (less than 1 year), site-related chemical exposure that could result in adverse health effects and require quick intervention to stop people from being exposed.

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