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Explanation of Environmental Contaminant Data Tables

Listing a contaminant in the data tables that follow does not mean that it will cause adversehealth effects from exposures. Instead, the list indicates which contaminants will be furtherevaluated in the public health assessment.

The data tables include the following abbreviations:
CREG = Cancer Risk Evaluation Guide
EMEG = Environmental Media Evaluation Guide
PMCLG = Proposed Maximum Contaminant Level Goal
ppm = parts per million
mg/kg/day = milligrams per kilogram per day
µg/m3 = micrograms per cubic meter of air
RfD = Reference Dose
CMRL = Chronic Minimal Risk Level
IMRL = Intermediate Minimal Risk Level
FREQ>CV = the number of times a concentration exceeded the comparison value compared to the number of times it was analyzed.

Sources of Data

    Sources of those tables are references 7 and 11.

    Samples were collected in 1988 - 1989.


ppm ppmSource
Arsenic*2.3j - 18.40.6EMEG14/14
Barium144 - 3170140Rfd14/14
Beryllium*ND - [0.94]0.16CREG10/14
CadmiumND - 36.1j0.4EMEG9/14
Chromium7.2 - 45310EMEG10/14
Lead98.5 - 1870jNone**N/A
Manganese*88.6 - 387200Rfd4/14
MercuryND - 4.01.6Rfd1/14
Vanadium*[3.1] - 22.514Rfd2/14
Bis(2-ethylhexyl) phthalateND - [1300]j40Rfd2/13
Di-n-butyl-phthalateND - 480j200Rfd1/13
PentachlorophenolND - [91]5.8CREG2/13
PCB:Aroclor-1260ND - 1.6j0.09CREG3/13
Total ChlordaneND -[4.000]j0.5CREG2/13
Heptachlor epoxideND0.08CREG0/5
j- the associated numerical value is an estimated quantity because quality control criteria werenot met. However, presence of the material is reliable.

[] - the associated numerical value is an estimated quantity because the amount detected isbelow the contract required detection limit (CRDL). Presence of the material is reliable.

* the concentration range is within background for soils in the Salt Lake City area (42).

** There are no MRLs, Rfds, or cancer slope factors. Whenever lead is found at a site, it isfurther evaluated because of lead's well-documented ability to cause health effects in childrenat low concentrations.

The Contract Required Detection Limit (CRDL) of 4.7-11.3 ppm antimony is above acomparison value of 0.8 ppm based on Rfd. The CRDL of selenium is sometimes above thecomparison value.



ppb ppbSource
ArsenicND - 30.910EMEG1/5
LeadND - [2.0]0.0PMCLG1/5
Vinyl chloride *ND - 270.02CREG1/5
Benzene *ND - 121.21CREG1/5
[] - the associated numerical value is an estimated quantity because the amountdetected is below the contract required detection limit (CRDL). Presence of thematerial is reliable.

The Contract Required Detection Limit of 3.3 ppb thallium is above a comparisonvalue of 0.4 ppb, based on the Life Time Health Advisory.

* Sampling location PC-MW-07

Contaminants not exceeding comparison values were not listed.



Arsenic*4.0 - 21.50.6EMEG9/9
Barium111 - 4480140Rfd8/9
Beryllium*ND - [0.95]0.16CREG8/9
CadmiumND - 4.70.4EMEG8/9
Chromium7.9 - 38.40.4EMEG8/9
Lead31.7j - 552jNone**N/A
Manganese187 - 713200Rfd8/9
MercuryND - 0.491.6Rfd0/9
Vanadium*11.6 - 28.714Rfd7/9
Bis(2-ethylhexyl) phthalateND - 0.84j40Rfd0/8
Di-n-butyl-phthalateND - 1.5j200Rfd0/8
Pentachloro-phenolND - [0.73]j5.8CREG0/8
PCB: Aroclor-1260ND - 1.2j0.09CREG4/9
Total ChlordaneND - 3.30.5CREG1/13
DieldrinND - 0.14j0.04CREG1/9
Heptachlor epoxideND - 1.10.08CREG2/9
j - the associated numerical value is an estimated quantity because quality controlcriteria were not met. However, presence of the material is reliable.

[] - the associated numerical value is an estimated quantity because the amount detectedis below the contract required detection limit (CRDL). Presence of the material isreliable.

* the concentration range is within background for soils in the Salt Lake City area (42).

** A comparison value cannot be calculated for lead because there are no MRLs, Rfds,or cancer slope factors. Whenever lead is found at a site, it is further evaluated because of lead's well-documented ability to cause health effects in children at lowconcentrations in the environment.

The Contract Required Detection Limit of 4.8- 5.6 ppm antimony is above acomparison value of 0.8 ppm based on Rfd. The CRDL of selenium is sometimesabove the comparison value.



BenzeneND - 18j
off-site air
BenzeneND - 25j
on-site air
j- the associated numerical value is an estimated quantity because quality controlcriteria were not met. However, presence of the material is reliable.



ppb ppb mg/kg/day Source
none exceeding comparison values in three monitoring wells
The Contract Required Detection Limit of 3.3 ppb thallium is above a comparison value of 0.4 ppb based on LTHA.



Surface SoilP/E* and othersSurface soil On-site Soil,
IngestionChildren inresidencesimmediately east andsouth of P/E,particularly if pica.

Adults to a lesserextent

Ambient AirP/E and othersAir- general airquality may be poordue to industries. On Site, Off SiteInhalationAll workers andresidents in thegeneral vicinity ofP/E.PrimarilyPast

* P/E = Petrochem/EkoTek

Table 7.

Surface WaterP/E*WaterOn site near RRor pastcontainmentoverflows. Ponded water.Skin ContactIngestion
Possibly adjacentresidents E ofP/E.
GroundwaterP/EWaterMunicipal orprivate well useIngestionSalt Lake CityResidentsFuture
Worker WasteMaterialP/EWaste MaterialWaste PilesSkin Contact
Soil GasP/ESoilWaste Piles, on-and off- site soilsInhalationRemedialWorkersFuture

* P/E = Petrochem/EkoTek


Exposed Populations and PotentiallyExposed PopulationsAffected by a Completed or Potential Exposure Pathway* For:
LocationApprox.No. of PersonsHeavy Metals ex. Pb, Cr, ArChlorinated SolventsPCB'sPhthalatesPesticidesBenzene and other volatileorganics
Residents and Workersfrom NearbyHomes andBusinessesBoth on-and off-siteexposureUnknownSoil
Soil-limitedSoilNot exposedSoilAir
Site Workers<100 Soil

* potential exposure pathways are shown in italics
GW = groundwater



Arsenicsoil0.0003Rfd1children and pica children
Bariumsoil0.07Rfdchildren and pica children
Cadmiumsoil0.0002CMRLpica children2
Chromiumsoil0.005Rfdpica children2

Manganesesoil0.1Rfdpica children2
Mercurysoil0.0008IMRLpica children2
Vanadiumsoil0.003IMRL4pica children2
Polychlorinated biphenyls(PCBs)soil0.000005CMRL5children and pica children
Chlordanesoil0.0006CMRLpica children2
Dieldrinsoil0.00005CMRLpica children2
Heptachlor epoxidesoil0.000013Rfdchildren and pica children
Bis(2-ethylhexyl) phthalatesoil0.02Rfdchildren and pica children
Di-n-butyl-phthalatesoil0.1Rfdpica children
Pentachlorophenolsoil0.03Rfdpica children

Explanation of Table 9

1 - Rfd is reference dose.

2 - Pica children are assumed to ingest five grams of soil per day.

3 - Currently, there are no health guidelines available for lead in soil. Whenever lead is found ata site, it is further evaluated because of lead's well-documented ability to cause health effects inchildren at low concentrations in the environment.

4 - IMRL is intermediate minimal risk level.

5 - CMRL is chronic minimal risk level.

Calculation of Exposure Doses for Soil Ingestion

The exposure doses for soil ingestion were calculated in the following manner. The maximumconcentration for a contaminant was multiplied by the soil ingestion rate for adults, 0.0001kg/day; children, 0.0002 kg/day, or pica children, 0.005 kg/day. (The habit of ingesting largeamounts of soil is called pica.) This product was divided by the average weight for an adult, 70kg (154 pounds) or for a child, 10 kg (22 pounds). These calculations assume that there isfrequent daily exposure to soil contaminated at the maximum level. A qualitative summary ofthese results can be found in Table 9, Appendix C.

Calculation of Risk of Carcinogenic Effects

Carcinogenic risk from soil ingestion was calculated through the following. The maximumconcentration of a contaminant was multiplied by the soil ingestion rate for adults of 0.0001kg/day, then this result is divided by the average adult body weight of 70 kg. This product ismultiplied by the EPA's Cancer Slope Factor for the contaminant. The result represents themaximum risk for cancer after 70 years of exposure to the maximum concentration of thecontaminant. Cancer slope factors were available for beryllium, PCB, chlordane, dieldrin, bis(2-ethylhexyl)phthalate, di-n-butyl-phthalate, pentachlorophenol, and heptachlor epoxide (20).

The actual risk of cancer is probably lower than the calculated number. The method used tocalculate EPA's Cancer Slope Factor assumes that high dose animal data can be used to estimatethe risk for low dose exposures in humans (17). The method also assumes that there is no safelevel for exposure (18). There is little experimental evidence to confirm or refute those twoassumptions. Lastly, the method computes the 95% upper bound for the risk, rather the averagerisk, which results in there being a very good chance that the risk is actually lower, perhapsseveral orders of magnitude (19).


Figure 1
Figure 1.

Figure 2
Figure 2.

Figure 3
Figure 3.



The Petrochem Public Health Assessment was available for public review and comment fromNovember 10, 1992 through December 8, 1992. The Public Comment Period was announced inlocal newspapers; the resident and business owners in the Swedetown area were notified byletter. Copies of the public health assessment were made available for review at the Rose ParkBranch Library, the Non-Fiction Reference Section of the Salt Lake City Public Library, and theUtah Department of Environmental Quality. In addition, the public health assessment was sentto seven persons or organizations who requested copies. Comments were received from oneperson, EPA, and UDEQ.

Comments and responses are summarized below. The comment letters can be requested fromATSDR through the Freedom of Information Act.

ATSDR appreciates your skepticism. Our conclusions are only valid for the limited data weevaluated for Swedetown residential area and were not intended to mean that the site is safe. The data are inadequate for such a determination. To better identify the possible health threat,ATSDR recommends that additional sampling of the residential area be done.

However, the soil sampling data were adequate, though barely so, for evaluating healthimplications for this media. This lead to the conclusion that the maximum levels of arsenic,cadmium, and barium in residential soil might result in adverse health effects in some children. The statement in the Recommendations that people may have been exposed is based on theseconclusions.

The response to question 1 in the Community Health Concerns Evaluation section is notcontradictory. It is based on a specific question posed by a business owner. The question waswhether employees would suffer long-term effects from the short-term acute illnesses theyexperienced from emissions from the plant while it was in operation. It was reported that thoseillnesses were experienced several times a year for 10 years and that symptoms were mild andrecovery was rapid. Given this specific exposure scenario, long-term effects are unlikely. However, given another scenario, such as daily low level exposures, it is not possible to excludethe possibility of long-term effects.

The commenter states that "It may be ATSDR's belief that long-term health effects are unlikely;UDEQ does not share in this confidence in the presence of all the uncertainties." ATSDRresponse to question 1 relates only to the question and exposure scenario posed by the businessowner. As stated previously, the possibility of long-term effects from other exposure situationscan not be eliminated.

ATSDR does not consider this approach contradictory. Environmental data often are adequatefor one media but not for an entire site. ATSDR has a responsibility to make health evaluationsfor any media where the data is adequate, even though, as is the case with Petrochem, the sourceof contamination is uncertain.

As far as what biological indicators would indicate exposure to site-related contaminants afterfour years of inactivity, this would be any indicator for which exposure is still occurring. Thetype and extent of off-site movement of site contaminants and the possibility of exposure to them,hopefully, will be answered by the Remedial Investigation.

The biological indicator testing and the other public health actions, if needed, can be done by theState of Utah, either using their or ATSDR funds, as available, or by ATSDR. The State of Utahhas already begun to address the community concerns about cancer.

COMMENT: In general it appears that the population of Swedetown is too small to besignificant to most of your formulas. The surface samples are only expected to give youpreliminary evidence. So I am skeptical that your results claim that is no threat to human healthexcept for Pica kids.
RESPONSE: Except for health outcome data, the evaluations in the public health assessment arenot dependent on population size. However, the toxicological evaluations are very dependent onthe quality and quantity of the environmental sampling data. Because of the overall inadequacyof the environmental data for this site, ATSDR could not determine whether the site represents ahealth hazard and made recommendations to fill the data gaps.
COMMENT: One wonders if this site is not a serious threat, how can so many millions of dollars be spent on it's behalf?
RESPONSE: As stated above, the environmental data are inadequate for determining whether the Petrochem site is currently a health hazard. This site was a health hazard in the past, whichis why it was closed and the worst areas of contamination removed. Any remaining areas ofcontamination on site and any contaminants that moved off-site should be identified during theremedial investigation and then cleaned up.
COMMENT: In order to place the previous investigations/results in their proper context, ATSDRshould include in the Summary section a brief description of the Superfund process, and wherethe Petrochem/Ekotek site stands in that process. It should also be pointed out that earlierinvestigations were not intended to be comprehensive and that the information found lacking inthe earlier stages will be addressed during the upcoming Remedial Investigation for the site.
RESPONSE: These are very good suggestions. The Background section of the public healthassessment will be revised to include information on the Superfund process. A brief mention willalso be made in the Summary. The purpose of earlier environmental investigations and that a RIwill be done will be mentioned in the Environmental Contamination and Other Hazards section.
COMMENT: Page 1, paragraph and Page 2, paragraph 2. The last sentences should be changedto state "the site was added to the National Priorities List in October 1992."
RESPONSE: Thanks for this new information. The public health assessment will be revisedaccordingly.
COMMENT: Page 3, paragraph 4. The second sentence should read "Since then security hasbeen provided on a drive-by basis.
RESPONSE: The public health assessment has been revised to reflect this change.
COMMENT: The following is an example of contradictory statements within the public healthassessment. In the Summary, page 1, paragraph 2, it is stated that the "ambient air pathwaycannot be fully evaluated for health implications because of the lack of monitoring during plantoperations." In the Recommendations, page 27, it is stated that "...people may have been exposedto contaminants at levels that may cause illness or disease..." However, in the response toCommunity Health Concerns Evaluation, page 23, question 1, an evaluation of health implicationis made in spite of the lack of air monitoring data and potential exposure to contaminants whichmay have caused illness or disease. It may be ATSDR's belief that long-term health effects areunlikely; the Utah's Department of Environmental Quality (UDEQ) does not share in thisconfidence in the presence of all the uncertainties.
RESPONSE: These statements are not contradictory. In a public health assessment, ATSDRevaluates the possible health impact of the entire site, and the environmental data for eachmedia. For Petrochem, the site was determined to be an indeterminate public health hazardbecause data were inadequate. Likewise, the environmental data for the air pathway wereinadequate for a full evaluation.
COMMENT:The following is another example of contradictory statements within the publichealth assessment. Page 1, paragraph 5 states the following: "...the extent and sources of off-sitecontamination of the residential soil and ground water are unknown.", and, "...there are manyestimates in the data obtained which are inadequate for determining public health implications." Yet earlier in paragraph 3 of the Summary section, the statement is made that "...maximumconcentrations of other soil contaminants (other than arsenic and barium) were not a healthconcern. Such a statement cannot be made if the data reviewed is inadequate for determiningpublic health implications.
RESPONSE: As stated earlier, ATSDR evaluates the possible health impact of the entire site,and the environmental data for each media. For Petrochem, the site was determined to be anindeterminate public health hazard because of the inadequacy of the data. However, the soilsampling data were adequate, though barely so, for evaluating health implications for thismedia.
COMMENT: The following is a third example of contradictory statements within the publichealth assessment. The Summary, page 1 and in the Conclusions, page 25, states that the siterepresents "an indeterminate public health hazard because the environmental data reviewed areinadequate for fully assessing the possible impact of this site on public health" and "extent of off-site groundwater and soil contamination has not been determined." Even though insufficient dataexists to assess the impact on public health, the authors encourage the residents to eat thevegetables out of their gardens, acknowledging that "small amounts of contaminants may be onor in the vegetables", and permitting the children to play in the dirt. Because of the uncertaintiessurrounding this site until further testing is done, UDEQ does not agree with ATSDR's responseto questions 4 and 5 on page 24.
RESPONSE: As with the other two examples given by the commenter of contradictions, theproblem is whether the entire site is being evaluated or a specific media. The soil data areadequate to make the responses to questions 4 (permitting children to play in the dirt) and 5(stating that vegetables are safe to eat).
COMMENT: It was stated in UDEQ's previous comments on the Initial Release for the HealthAssessment that despite the title, Possible Health Consequences of the Exposure Doses (page17), no health consequences are noted. What are the symptoms of exposure to the contaminantsof concern? The description of the possible health effects from exposure to barium was better inthe Initial Release HA than in the current HA.
RESPONSE: Possible health consequences (i.e., that adverse health effects may occur) are notedfor arsenic, barium, and cadmium. The listing of possible symptoms is an uncertain exercisewhen animal data are being used to predict whether human health effects will occur. Since mostof the discussions of possible health consequences were based on animal data, it was decided tobe consistent for all the discussions and not list possible symptoms.
COMMENT: The typical/natural levels for inorganics referred to in the report are based on atable summarizing "background" soil samples from approximately 23 pre-remedial SiteInvestigations in the Salt Lake City area (reference #42). This summary has its limitations andwas not intended to represent actual background conditions for the Salt Lake area. Indeed, thevariability in the concentrations for most of the compounds indicate that a much larger samplesize would be required in order to determine representative background concentrations. Conclusions such as the one made for arsenic concentrations (page 17, paragraph 4, firstsentence) based on reference #42 should be changed accordingly.
RESPONSE: The data from the 23 pre-remedial Site Investigations was given to ATSDR byUDEQ as "background data." UDEQ stated in their comments on the initial release of thePetrochem Public Health Assessment, "The levels of arsenic found in residential soils are atbackground levels for the Salt Lake Valley." The data appear to be adequate for the purposethey are used for in the document. "Naturally occurring" in the first sentence of paragraph 4 onpage 17 has been deleted.
COMMENT: Page 27, paragraphs 4 and 5. What biological indicators of exposure arerecommended by HARP? Petrochem has been inactive for over 4 years; what biologicalindicator proposed will determine ambient exposure to site-related contaminants after 4 years ofinactivity? Who will conduct this testing? Who will be responsible for conducting the healthstatistics review and community health investigation to community concerns about cancer?
RESPONSE: The biological indicators of exposure recommended by HARP would be thoseappropriate for the known exposures (i.e., metals in soil). It is not known whether theseexposures are site-related.
COMMENT: Overall the document is difficult to understand. There are numerous discrepanciesand contradictions that remain that should be addressed in a general re-write of this document. The authors should recognize that their audience is the general public and provide an adequatelevel of explanation, making sure that the discussions in the text supports theirconclusions/recommendations. Discussions, such as the one on page 17 regarding arsenic, leavethe reader with more questions than answers. Sections such as this need to be re-written in clearconcise language.
RESPONSE: Many of the general concerns mentioned have already been addressed in earlierresponses. The three specific examples of contradictions given, are not contradictions. Noexamples of discrepancies were given, so a response can not be made.

Every effort has been made to write public health assessments that can be useful, informative,and understandable to the general public. The document was reviewed by technical experts,professional editors, and administrators within ATSDR. In addition, the residents, businessowners, and others have been communicated with regularly throughout the development of thepublic health assessment. Suggestions for improving the readability of the public healthassessment (in general) are welcomed. Please send recommendations to: Director, Division ofHealth Assessment and Consultation, ATSDR, Mail Stop E-32, 1600 Clifton Road, Atlanta, GA 30333.

COMMENT: Summary/3: The list of soil contaminants should be prefaced with a statement thatthis list is based upon existing sampling, and should not be presented as a complete list. EPAmust repeat the comment it made on 31 August 1992 in a review letter for an earlier draft of thisreport. While a great deal of information is known about the now-removed primary sources ofcontamination at the Site, relatively little is known about the remaining contamination of the Sitesoils and ground water. Even less is known concerning the potential pathways for contaminationto migrate from the Site, and the exposure pathways which may affect off-site receptors. Theseinformation needs are the primary purpose for conducting a Remedial Investigation andFeasibility Study (RI/FS), which is now underway.
RESPONSE: The list of contaminants in the soil exposure pathway in the Summary is notdescribed as being complete or incomplete. The sources of the sampling data are described inthe Environmental Contamination and Other Hazards section (page 7, paragraph 1) and thelimitations of those data are mentioned numerous times in the public health assessment,especially paragraph 5 of the summary.
COMMENT: Summary/5: ATSDR recommends that EPA and UDEQ better characterize off-siteground water and soil contamination. This implies that off-site contamination exists, and that itis the result of Site activities. During the RI, pathways for contamination to migrate from theSite will be investigated. However, the Site is located in an industrial area, and there are manypotential sources of off-site contamination other than the Petrochem Site. Off-site soilcontamination is especially difficult to attribute to a particular source. Unless off-sitecontamination can be scientifically attributed to the Site, EPA has no authority with respect to theSite to address such contamination. Therefore, ATSDR's recommendation should be modified.
RESPONSE: ATSDR is required by the Superfund Amendments and Reauthorization Act of 1986(SARA) to release a public health assessment on a site within one year after a site is proposedfor the National Priorities List (NPL). This often means that the public health assessment has tobe written before comprehensive environmental sampling such as found in an RI is conducted. The Petrochem Preliminary Public Health Assessment is identified as "Preliminary" because ofthe lack of those comprehensive data. For Petrochem, the site was determined to be anindeterminate public health hazard because of the inadequacy of most of the data. However, thesoil sampling data were adequate, though barely so, for evaluating health implications for thismedia.

ATSDR has a responsibility to make health evaluations for any media where the data isadequate, even though, as is the case with Petrochem, the source of soil contamination isuncertain. The recommendation for further characterization was made to help determine therole of the site, if any, in contributing to off-site contamination. In addition, ATSDR has aresponsibility to recommend further sampling that would quantify possible human exposures,even if those exposures are not site-related.

Recommendation 2 in the Recommendations section was written with those two goals in mind. Sampling at the perimeter of the site, as recommended, is a common way of identifying whethercontaminants have moved off-site. As documented in the public health assessment, there is goodanecdotal evidence that contaminants have been moved off-site to the west. Additional samplingin the residential area of Swedetown is needed to better quantify the contaminant levels and thehealth risk. The source of those contaminants is uncertain.

The commenter raises a concern about EPA's lack of authority to perform sampling not relatedto the site. It has been the experience of ATSDR that EPA or state environmental agenciesusually have the authority and responsibility, though not always the funding, to performenvironmental sampling when the source is uncertain. Recommendation 2 identifies the need foradditional sampling but in no way obligates any agency to perform that sampling. SARAmandates that ATSDR identify additional sampling needs in the public health assessment.

ATSDR will be contacting EPA and the Utah Department of Environmental Quality (UDEQ)before this document goes final to identify whether they can commit to perform any of therecommended sampling. Commitments to implement or actual implementation of any of therecommendations by ATSDR, EPA, UDEQ, or other agencies will be placed in a Public HealthActions section.

COMMENT: Page 2/paragraph 2: The Site was added to the National Priorities List on October14, 1992.
RESPONSE: The public health assessment has been revised to include this new information.
COMMENT: Page 9/paragraph 2: With respect to soil gas and off-site contamination, EPA mustrepeat its 31 August 1992 comment. EPA fails to see the relevance of chlorinated solvents beingdiscovered in off-site soil gas. No link, such as a potential pathway, has been made between theSite and these off-site gases. In addition, ATSDR states that the presence of off-site soil gasindicates that off-site groundwater needs to be characterized further. This implies without ascientific basis that the Site has contaminated both off-site soil gas and off-site ground water. This entire paragraph should be deleted.
RESPONSE: This commenter stated earlier that, "...relatively little is known about theremaining contamination of the Site soils and ground water. Even less is known concerning thepotential pathways for contamination to migrate from the Site, and the exposure pathways whichmay affect off-site receptors. These information needs are the primary purpose for conducting aRemedial Investigation and Feasibility Study (RI/FS)..." The recommendation to furthercharacterize off-site groundwater is one of the ways to fill those information needs. The findingof chlorinated solvents in soil gas off-site demonstrates the need for further characterizationsince chlorinated solvents have been found on site. Sampling such as done during an RI willlikely indicate whether there is a link.
COMMENT: Page 11/paragraph 2: Regarding the soil pathway with respect to off-site soil, EPAmust firmly repeat its 31 August 1992 comment. As described above in Comment No. 2,relatively little is known about on-site contamination. Until the RI/FS is thoroughly underwayand on-site characterization has been completed, any speculation relating off-site soilcontamination to the Site will remain inconclusive. Contaminants have been found in off-sitesoil, some of which are also found in on-site soil. However, given the industrial nature of thearea, one cannot automatically attribute this contamination to the Site, as this report implies. Therefore, ATSDR should revise its conclusion of a completed exposure pathway with relationto off-site soils. While off-site contamination does exist, within the context of this report thedetermination of a completed exposure pathway implies the source of contamination is thePetrochem Site. In addition, the comment may well prove unnecessary. However, if the RI/FSdata indicates that this off-site sampling is indeed necessary, EPA shall ensure that a thoroughsampling investigation is conducted to protect the nearby community and environment. Thisissue of off-site soil should be revised not only in this paragraph, but in all similar paragraphsthroughout the document.
RESPONSE: The second sentence of this paragraph has been deleted to help clarify this issue. However, as described on pages 10-11 of the public health assessment, ATSDR considers anexposure pathway complete when there is good evidence of human exposure. The source of thecontaminants does not have to be ascertained for an exposure pathway to be consideredcomplete. ATSDR mentions throughout the document the possible contribution of other sourcesto soil contamination off-site.
COMMENT: Page 12/paragraph 5: EPA strongly objects to the conclusion of soil gas as apotential exposure pathway. ATSDR agreed in a 19 October 1992 letter to EPA with EPA'scomment that until the source of off-site soil gases is identified, no link can be made between thegases and the Site. ATSDR should delete this conclusion, not only in this paragraph, but also inall similar text throughout the document.
RESPONSE: Similar to completed pathways, the source of contamination need not be known forATSDR to consider a potential exposure pathway to exist.
COMMENT: Page 17/paragraph 1: ATSDR discusses possible health consequences resultingfrom exposure to off-site contaminated soil. As described above in Comments No. 2 and 5, thereare several potential sources for off-site soil contaminants other than the Petrochem Site. However, this paragraph implies that exposure to this off-site soil can be attributed to Petrochem. This paragraph should be revised, and also any similar paragraphs in the text.
RESPONSE: The fourth sentence of this paragraph has been revised as follows to remove thisimplication.
    Thus they may not be indicative of the consequences of ingesting soil from other areas inSwedetown near the Petrochem site because the levels aremay be either lower or unknown.
COMMENT: Page 26/Recommendation 2: ATSDR states that the soil of adjacent businessesand residences and the nearby Swedetown residences should be sampled. This recommendationshould be deleted. ATSDR agreed in a 19 October 1992 letter with EPA's original comment thatcharacterization, including comprehensive sampling, of off-site residential soil, ground water andair is premature and may well prove to be unnecessary.
RESPONSE: ATSDR agreed with the original comment and deleted the sentence quoted. Theoriginal comment was "Your statements in paragraph 4 of the Summary that 'off-site residentialsoil, groundwater, and air need (emphasis added) further characterization includingcomprehensive sampling' are premature and may well prove to be unnecessary." We did notmean to indicate that further characterization was unnecessary. As described in an earlierresponse, ATSDR has a responsibility to make such recommendations.
COMMENT: Page 27/Recommendation 3: ATSDR recommends that ambient air be monitorednear locations where surface soil gas contaminants are identified. As described above inComment No. 6, EPA and ATSDR have previously agreed that any off-site air sampling ispremature.
RESPONSE: ATSDR did not intend its response to a comment on a specific sentence in theSummary section of the Initial Release to include other parts of the document. We apologize forany misunderstanding that may have occurred.

Recommendation 3 is another of the information needs identified by the commenter that can beaddressed in an RI.


1. The National Toxicology Program in its Annual Report on Carcinogens classifies a chemicalas a "known human carcinogen" based on sufficient human data. Its classification of a chemicalas being "reasonablely anticipated to be a carcinogen" is based on limited human or sufficientanimal data.

2. IARC defines a class 1 carcinogen as a substance which studies in humans indicate a causalrelationship between the agent and human cancer. Class 2 carcinogens are those reasonablyanticipated to be carcinogens. For a 2A classification, there is limited evidence ofcarcinogenicity from human studies which indicate that a causal interpretation is credible, but notconclusive. A classification of 2B indicates that there is sufficient evidence of carcinogenicityfrom studies in experimental animals.

3. In EPA's classification scheme, a chemical is considered a class A or human carcinogen basedon sufficient evidence from studies of humans. A substance is considered class B1 if there islimited evidence from human studies. B2 is used when evidence for carcinogenicity isinadequate or non-existent based on human studies, but sufficient based on animal studies.

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  16. P
  17. Q
  18. R
  19. S
  20. T
  21. U
  22. V
  23. W
  24. X
  25. Y
  26. Z
  27. #