ATSDR uses several types of medium-specific screening values to assist in selecting the contaminants that will be evaluated for public health significance. For this assessment, the specific screening values include Environmental Media Evaluation Guides (EMEGs), Cancer Risk Evaluation Guides (CREGs), and Reference Dose Media Evaluation Guides (RMEGs). EMEGs are media-specific estimates that pose a minimal risk to humans. They are based on ATSDR's minimal risk levels (MRLs) or EPA's reference doses (RfDs). The RfD is an estimate of daily human exposure to a contaminant for a lifetime below which (non-cancer) health effects are unlikely to occur (12). CREGs are estimated contaminant concentrations that are based on one excess cancer for a million persons exposed over a lifetime and are calculated from EPA's cancer slope factors. RMEGs are calculated from EPA's Reference Doses and are based on their estimates of the daily exposure to a contaminant that is unlikely to cause adverse health effects.

APPENDIX C

ENVIRONMENTAL EXPOSURE PATHWAYS

TABLES 1 - 3

APPENDIX D

COMPARISON OF ESTIMATED EXPOSURE DOSE
TO HEALTH GUIDELINES

TABLES 1 - 2

Appendix D, Table 1 - Results of Comparison of Estimated Exposure Dose to Health Guidelines for Persons Exposed to On-Site Contaminants at the ICG Iselin Railroad Yard National Priorities List Site, Jackson, Madison County, Tennessee
Contaminant	Pathway Medium	Health Guideline (mg/kg/day)			Cancer Class
		Value	Source	Exceeded by Estimated Exposure Dose
2-Hexanone	Surface Soil Surface Water		Unknown
2-Methylnaphthalene	Surface Soil		Unknown
4-Methyl-2-pentanone	Surface Water		Unknown
Naphthalene	Surface Soil		Unknown
Carbazole	Surface Soil		None
Dibenzofuran	Surface Soil		Unknown
Dieldrin	Surface Soil Sediment	0.00005	MRL	NO NO	B2
carcinogenic PAHs	Surface Soil Sediment	0.1	aMRL	NO NO	B2
Aluminum	Sediment		Unknown
Antimony	Surface Soil Sediment	0.0004	RfD	NO
Arsenic	Surface Soil Sediment	0.0003	MRL	NO NO	A
Cadmium	Surface Soil Sediment	0.0007	MRL	NO NO	B1
Chromium	Surface Soil Sediment	0.005	RfD	NO NO	A
Copper	Surface Soil Sediment		None
Iron	Sediment		Unknown
Lead	Surface Soil Sediment		None		B2
Manganese	Surface Water Sediment	0.005	RfD None	NO
Mercury	Sediment	0.002	iMRL	NO

Appendix D, Table 2 - Results of Comparison of Estimated Exposure Dose to Health Guidelines for Persons Exposed to Off-Site Contaminants At and Near the ICG Iselin Railroad Yard National Priorities List Site, Jackson, Madison County, Tennessee
Contaminant	Pathway Medium	Health Guideline (mg/kg/day)			Cancer Class
		Value	Source	Exceeded by Estimated Exposure Dose
Tetrachloroethene	Municipal Well Water	0.01	RfD	NO	B2
Aluminum	Sediments Terrace Area Soils		Unknown
Antimony	Terrace Area Soils	0.0004	RfD	NO
Arsenic	Sediments Terrace Area Soils	0.0003	MRL	NO NO	A
Barium	Sediments Terrace Area Soils	0.07	RfD	NO NO
Copper	Sediments		None
Iron	Sediments Terrace Area Soils		Unknown
Lead	Sediments Terrace Area Soils		None		B2
Manganese	Surface Water Sediments Terrace Area Soils	0.005	RfD None None	NO
Vanadium	Sediments Terrace Area Soils	0.0003	iMRL	NO NO
Unknown = Health guideline not available aMRL = ATSDR's acute Minimal Risk Level MRL = ATSDR's Minimal Risk Level RfD = EPA's Reference Dose iMRL = ATSDR's intermediate Minimal Risk Level * = Health guideline for Benzo(a)pyrene None = Health guideline not available

APPENDIX E

RESPONSE TO PUBLIC COMMENTS

The data from the Supplemental Remedial Investigation (RI) Report, submitted on May 17, 1996, need to incorporated into this document.

This information has already been incorporated into the document (Reference #5).

Please change the name of the Site from "ICG Iselin Railroad Yard" to "Iselin Rail Yard Site." ICG (Illinois Central Gulf Railroad Company) was only one of several companies to operate at the Site, and ICG has been reorganized and no longer operates under this name. The facility has been known as the "Iselin Site" since it began operations in the early 1900s.

ATSDR uses the name the site was given when proposed for the NPL (as stated in the Federal Register).

Page vi, fourth paragraph, second sentence. Ecological sampling was conducted during the Phase II Remedial Investigation to assess if adverse conditions existed at the Site.

The sentence has been amended to showed that it refers to human biological data.

Page vi, fourth paragraph, last sentence. Please delete this sentence. Additional air sampling was conducted at the site during Phase II of the Remedial Investigation. The additional air sampling is presented in the Supplemental RI Report for the Iselin Rail Yard Site dated May 1996.

The paragraph has been rephrased. Because historical air data are not available, past exposure to air contaminants (if any), could not be quantified or qualified. It cannot be determined if any of the contaminants of concern in the contaminated soil, surface water, and sediments pose a threat via inhalation exposure because recent air sampling data is limited.

Page vi, fifth paragraph, second sentence. Please delete aluminum, copper, and phosphorous from this sentence. These constituents are not suspected to be carcinogenic in humans.

Aluminum has not been classified for carcinogenicity. No studies were located regarding cancer in humans or animals following chronic exposure via ingestion of or dermal contact with aluminum or its compounds. The studies regarding cancer following inhalation exposure to aluminum or its compounds were inconclusive due to the addition of other variables which could have contributed to the development of the carcinogenic effect. The available information has not shown that aluminum is a potential carcinogen.

Copper was deleted from the sentence.

Phosphorous is not classifiable as to carcinogenicity due to lack of human and animal data.

Page vi, last paragraph, second sentence. Ground water levels were measured from all on-Site and off-Site ground water monitoring wells on August 19, 1996. A water table configuration map was generated from this data and submitted to TDEC-DSF in September 1996. The natural direction of ground water flow at the Site is well defined, and information available from JUD should enable ATSDR to assess the influences on ground water flow at the Site from pumping the JUD wells.

This information had not been made available to ATSDR at the time that the public comment version of this document was written. ATSDR will attempt to retrieve this information. Thank you for making us aware of its existence.

Page 2, first paragraph, last sentence. Please clarify that the operations that ceased producing wastewater in 1986 were limited to railroad activities.

This has been reflected in the document.

Page 2, last paragraph, first sentence. Following this sentence, please add the following sentence: Field work performed by RMT, Inc., for the Phase II Remedial Investigation continued through December 1995.

The historical data is given chronologically. Your comment is already in the document. See the last paragraph of the Site Description and History section.

Page 3, last paragraph, first sentence. Why are racial demographics of neighboring residents relevant to a health study? Please delete reference to racial percentage.

The public health assessment as defined by ATSDR is not a health study. Demographic data is required in ATSDR public health assessments. It is one of the elements ATSDR is required to address under Section 104(i)(6)(A) of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980, as amended [42 U.S.C. 9604(i)(6)(A)].

Page 4, third paragraph, first sentence. The JUD south well field is not down-gradient of the Site. Ground water flow is to the south-southwest. The JUD south well field is west and northwest of the Site.

"Down-gradient" was removed from the sentence.

Page 4, third paragraph, second sentence. Is the number of wells stated (10) all of the JUD wells or just the number of wells in the JUD south well field? It may be helpful to provide data on the number of wells in both the JUD south and north well fields.

The JUD south well field consists of 13 wells.

Page 4, fourth paragraph, fourth sentence. The sentence "Local ground water flow is toward the JUD south well field" is not correct.

That statement was removed from the document.

Page 4, fourth paragraph, last sentence. The Supplemental RI and other information available from JUD should enable ATSDR to assess whether pumping the wells in the South Well Field influences ground water flow at the Site.

Statement removed from the document.

Page 6, last paragraph, first sentence. Please explain that Tables 1 through 13 in Appendix B list all carcinogens regardless of whether comparison levels were exceeded.

Carcinogens whose maximum concentration exceeded the CREG and those which are known carcinogens but do not have a CREG are included in the tables of Appendix B.

Page 7, first paragraph, first sentence (continuation from page 6). This sentence states that it is prudent to compare concentrations of organic and inorganic constituents detected in surface soils, subsurface soils, and sediments to background or normal soil/sediment levels. Where is this comparison presented in the assessment? In addition, surface soil samples collected during the Remedial Investigation at the Site were collected from both 0-6 inches and 0-3 inches. Soil samples collected from both of these intervals meet the US EPA criteria for a surficial soil sample.

Unlike the risk assessment conducted by EPA which is quantitative, the ATSDR public health assessment is a qualitative document. Most public health assessments mention the rationale for preparing the document, however, the exact numbers and calculations are not always included. The comparison was made but the numbers were not included in the public health assessment.

ATSDR defines surface soil as soil samples taken from the top 0-3 inches of soil. For the purpose of this public health assessment any soil sample taken at the depth of 0-6 inches is called unspecific soil and those samples taken at a depth greater than six inches is called sub-surface soil.

Page 7, third paragraph, second sentence. Please replace the word "access" with "assess."

Document reflects the change.

Page 7, forth paragraph,, second sentence. Arsenic and manganese are naturally occurring compounds in the soils at the Site.

A sentence acknowledging this fact was added to the paragraph.

Page 7, fifth paragraph, second sentence. Please replace the sentence "The direct push technology advances a water sampling device directly into the soil to a selected depth without the need to drill boreholes and without making drill cuttings." with the following sentence: The direct push technology advances a water sampling device through the soil to a selected depth below the water table without drilling a borehole or generating drill cuttings.

Paragraph modified to reflect this change.

Page 8, second paragraph, third and fourth sentences. Not all of the samples collected at the average depth of 30-feet below land surface or greater detected 1,1-dichloroethene, trichloroethene, and vinyl chloride. The location of the highest concentration of VOCs detected in the ground water samples were located on the east side of the Site, up-gradient from the potential source areas at the Site and down-gradient from the landfill adjacent to the Site.

The paragraph was modified to reflect this change.

Page 8, third paragraph, first sentence. For the purpose of the Remedial Investigation, (following the TDEC-DSF approved Work Plan), surface soil samples were collected from 0-6 inches and 0-3 inches. Soil samples collected from both of these intervals meet the US EPA criteria for a surficial soil sample.

A paragraph was added to the unspecific soil subsection to reflect the samples that were taken in December 1995.

Page 9, second paragraph, seventh sentence. Please provide an explanation of why chromium is assumed to be hexavalent.

This is a very conservative approach which will allow for the greatest protection of public health.

Page 9, second paragraph, last sentence. Please provide an explanation of why all detected carcinogenic PAHs were compared to ATSDR's screening value for benzo(a)pyrene.

The paragraph was modified. All carcinogenic PAHs were converted to their relative potency to benzo(a)pyrene.

Page 9, last paragraph, first sentence. Please replace the word "are" with "were." Air samples collected on that day only show what was present at the time of the sampling.

Document reflects this change.

Page 11, second paragraph, third and fourth sentence. The wastewater treatment facility is inoperative. It does not receive any process water from the Site. The majority of the rail tie pile is covered with soil. Additional air sampling was conducted at the Site during Phase II of the Remedial Investigation. The additional air sampling is presented in the Supplemental RI Report for the Iselin Rail Yard Site dated May 1996.

The air sampling did not cover the area of the rail tie pile/dump and the wastewater treatment facility.

Page 11, Section 1, Ground Water. Please include a discussion describing the TDEC ground water investigation at the former landfill located up-gradient of the Site. Volatile Organic Compounds (VOCs) have been detected in the ground water monitoring wells installed by TDEC up-gradient of the Site at the adjacent landfill, and the VOCs have been determined to be migrating onto the Iselin Rail Yard Site.

Paragraph modified.

Page 11, last paragraph, seventh sentence. Delete the Seventh Sentence. See the Supplemental RI for additional data.

The Supplemental RI was used to make the indicated determination.

Page 12, fifth paragraph, second sentence. It should not be stated that the samples were contaminated unless the levels measured are significantly greater than average concentrations for these metals in the region. Also, please delete the word "heavy" in this sentence. Not all of the metals listed are heavy metals.

The levels of the indicated metals were above normal background so only change to the statement was deletion of "heavy".

Page 15, second paragraph, second sentence. Please state if there is evidence that children younger than six years old have played at the Site.

This information is based on conversations with local residents during the ATSDR public availability sessions. At the time of the ATSDR site visit, children were not observed playing on the site.

Page 15, third paragraph, first sentence. Please add the word "possibly" between "site" and "were." There is no historical air analysis available showing that exposure to constituents in air actually occurred by nearby residents or persons on Site.

In addition, there is no evidence to show that nearby residents or persons on the Site were not exposed to constituents in the air. It is quite likely that during the time the site was in full operation, workers and others were exposed to airborne constituents. It is also quite likely that some of these airborne constituents traveled beyond the Site's boundary.

"Likely" was inserted instead of "possibly".

Page 15, third paragraph, fifth sentence. Please change the word "release" to "released."

Document reflects this change.

Page 15, third paragraph, eighth sentence. Constituents that are not Site-related should not be discussed in this assessment. As stated under "Pathways Analysis" on page 14,, "...the possible environmental exposure pathways are evaluated to help determine whether individuals have been, are being, or will be exposed to site-related contaminants." The first element required in this analysis is that the contaminant of concern is possibly related to the Site.

In the sentence to which you refer, the sources are on-site exposure points, releases, and activities which may have contributed to airborne releases.

Document not modified.

Page 15, last paragraph, first sentence. There is no known "on-site waterbodies" associated with the Site.

Based upon the documents reviewed by ATSDR, portions of Jones Creek and the Unnamed Intermittent Tributary are on the site. It is possible that children while trespassing upon the site at the very least waded in these waterbodies.

Page 16, second paragraph. It is not appropriate to discuss contamination that is not related to the Iselin Site in this assessment. Please delete this entire paragraph.

The soils in the area of the school are discussed because the concentration of some of the contaminants exceeded ATSDR environmental screening values. Since the school houses a headstart program, the participants are considered to be a highly susceptible population.

Document not modified.

Page 16, third paragraph, second sentence. New ground water sampling data presented in the Supplemental RI should assist in making this determination.

Document has been modified.

Page 17, first paragraph, last sentence. Please replace "potable purposes" with "a primary water supply." Potable purposes would most likely exclude dermal contact. Also, please state that TDEC-DSF would not allow a water supply well to be installed at the Site.

Document reflects these changes.

Page 17, last paragraph, second sentence. Please replace the sentence "Contaminants from the site may enter the aquifer and therefore be transported to nearby wells" with the following: Contaminants from the Site may enter this aquifer, and therefore be transported to the nearby wells.

Modification made.

Page 18, first paragraph. Please state that PCE has never been detected in the ground water at the Site. Also, if the PCE is not thought to be Site-related, exposure to PCE through the JUD distribution system should not be mentioned in this assessment.

The municipal wells are discussed in this document because a concern had been raised about VOCs in the water. Recently available data seems to support the statement that the site is not responsible for the VOC contamination in the wells.

Page 20, Exposure Dose Estimation. Where are the calculated exposure doses presented in the report? Also, example calculation for each exposure pathway would be beneficial to include in the assessment for the benefit of the public who may not be familiar with these calculations.

The public health assessment is a qualitative document, therefore, those calculations are not included in most of the documents. The general formula for oral exposure was included in this document and summary tables to show the results of the comparison of the estimated exposure doses to health guidelines are presented in Appendix D.

Page 20, Exposure Dose Formula. What method was used to calculate the contaminant concentration for use in the exposure dose (ED) calculation?

As stated in the text, the maximum concentration of the contaminant found in the specified medium of the specified pathway was used.

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