PUBLIC HEALTH ASSESSMENT
USA DEFENSE DEPOT MEMPHIS
MEMPHIS, SHELBY COUNTY, TENNESSEE
APPENDIX A - PARAMETERS TESTED IN THE SCREENING, 1989
AND 1995-1998 REMEDIAL, BACKGROUND,
AND BRAC SAMPLING PROGRAMS
Parameters Tested in the Screening Sites, 1989 and 1995-1998 Remedial,
Background, and BRAC Sampling Programs23
2-fluorobiphenyl - ss
2-fluorophenol - ss
2,4-dichlorophenylacetic acid - ss
2,4,6-tribromophenol - ss
benzyl butyl phthalate
bromofluorobenzene - SS
butyl benzyl phthalate
decachlorobiphenyl - ss
fluorobenzene gamma BHC (lindane)
methyl isobutyl ketone
methyl ethyl ketone (2-butanone)
PCB-1016 (arochlor 1016)
PCB-1221 (arochlor 1221)
PCB-1232 (arochlor 1232)
PCB-1242 (arochlor 1242)
PCB-1248 (arochlor 1248)
PCB-1254 (arochlor 1254)
PCB-1260 (arochlor 1260)
tert-butyl methyl ether
tetrachloro-m-xylene - ss
total fuel hydrocarbon, gasoline
total organic carbon (soil/water)
APPENDIX B - EXPLANATION OF EVALUATION PROCESS
In evaluating these data, ATSDR used comparison values to determine which chemicals to examine more closely. Comparison values are health-based thresholds below which no known or anticipated adverse human health effects occur. Comparison values can be based on cancer or non-cancer health effects. Non-cancer levels are based on the lowest (i.e., most toxic) valid toxicologic study for a chemical and the assumption that a small child (22 lbs.) is exposed every day. Cancer levels are the media concentrations at which there would be a one in a million excess cancer risk for an adult eating contaminated soil every day for 70 years. For chemicals for which both cancer and non-cancer numbers exist, the more toxic (i.e., lower) level is used. A description of the comparison values used in this evaluation can be found in Appendix C. Exceeding a comparison value does not mean that health effects will occur, just that more evaluation is needed.
Further evaluation focuses on identifying which chemicals and exposure situations are likely to be a health hazard. The first step is the calculation of child and adult exposure doses, as described in Appendix D. These are then compared with an appropriate health guideline for a chemical. An exposure dose is the amount of chemical ingested daily per unit of body weight. Health guidelines are the amount of chemical per unit of body weight where health effects very likely do not occur, based on investigations of human exposures to the chemical, or, if human data don't exist or are not valid, of animal experiments. Most health guidelines are based on animal data. The results of these calculations are presented in Tables D1 and D2 starting on page 67. Any exposure situation, where the exposure dose is lower than a health guideline, is eliminated from further evaluation.
The next step in the evaluation process is determining whether the worst case exposure situations used in earlier calculations need to be revised to better fit the actual situation. For example, both Dunn Field and the DDMT Main Facility have reportedly been fenced and guarded since the Depot opened. Except for the area near the 8 base housing units, small children could not have experienced health effects due to exposure to contaminants on-site because they could not enter the site. Thus, exposure situations involving small children (1-2 years old) were dropped from further evaluation except for those that include the base housing area on Main Facility. Likewise, exposure situations for adults on Dunn Field would assume that exposure is less frequent than for adults on the Main Facility because it appears that no one spent every work day on Dunn Field.
The last evaluation step is the comparison of these revised exposure doses with known
toxicological values for the chemical of concern. This would include the no observed and
lowest observed adverse health effects levels (NOAEL & LOAEL) identified in ATSDR
Toxicological Profiles. If the chemical of concern is a carcinogen, the cancer risk is
recalculated using the revised exposure dose. These comparisons are the basis for stating
whether the exposure might be a health hazard.
APPENDIX C - EXPLANATION OF COMPARISON VALUES
Health Comparison Values (CVs) are the contaminant concentrations found in a specific media (air, soil, or water) and used to select contaminants for further evaluation. The CVs used in this document are listed below.
Environmental Media Evaluation Guides (EMEGs) are estimated contaminant concentrations in a media where no chance exists for non-carcinogenic health effects to occur. The EMEG is derived from U.S. Agency for Toxic Substances and Disease Registry's (ATSDR) minimal risk level (MRL).
Remedial Media Evaluation Guides (RMEGs) are estimated contaminant concentrations in a media where no chance exists for non-carcinogenic health effects to occur. The RMEG is derived from U.S. Environmental Protection Agency's (EPA) reference dose (RfD).
Cancer Risk Evaluation Guides (CREGs) are estimated contaminant concentrations that would be expected to cause no more than one additional excess cancer in a million persons exposed over a lifetime. CREGs are calculated from EPA's cancer slope factors (CSF).
Risk-Based Concentrations (RBCs) are the estimated contaminant concentrations in which no chance exists for carcinogenic or noncarcinogenic health effects. The RBCs used in this public health assessment were derived using provisional reference doses or cancer slope factors calculated by toxicologists of EPA's Region III (92).
EPA Action Levels (EPA ALs) are the estimated contaminant concentrations in water of which additional evaluation is needed to determine whether action is required to eliminate or reduce exposure. Action levels can be based on mathematical models.
EPA Soil Screening Levels (EPA SSL) are estimated contaminant concentrations in soil at which additional evaluation is needed to determine if action is required to eliminate or reduce exposure.
APPENDIX D - CALCULATION OF ESTIMATED EXPOSURE DOSES
Calculation of Exposure Dose from Ingestion of Contaminated Soil
The exposure doses for ingestion of contaminated soil were calculated in the following manner. The maximum or mean concentration for a chemical in DDMT soil was multiplied by the soil ingestion rate for adults, 0.0001 Kg/day, or the rate for children, 0.0002 Kg/day. This product was divided by the average weight for an adult, 70 Kg (154 pounds), or for a small child, 10 Kg (22 pounds). For adults, we assumed that only DDMT workers could have been exposed. Thus, exposure could have occurred 5 times a week rather than 7, which resulted in the exposure dose being adjusted by a factor of 5/7ths (0.7). Exposure doses for children were calculated only for exposure situations near the 8 base housing units on the Eastern edge of the main facility. Children, especially small children, could not likely be exposed elsewhere on the DDMT Main Facility and Dunn Field because they reportedly have always been fenced and guarded. Those calculations assume frequent daily exposure to soil contaminated at the specified level. The results of the actual calculations are recorded in Tables D1 - D2 on the following pages.
Calculation of Risk of Carcinogenic Effects
Carcinogenic risks from the ingestion of soil were calculated using the following procedure. The adult exposure doses for ingestion of soil were calculated as described previously, then multiplied by the EPA's Cancer Slope Factor (CSF) for that chemical (93). This result was multiplied by 0.4 because maximum exposure length of 30 years was assumed rather than the 70 years assumed for the CSF. This is because we concluded that only workers could be exposed. Results of the calculation of carcinogenic risk from exposure can be found on Tables D1 and D2 on the following pages.
The actual risk of cancer is probably lower than the calculated number. The method used to
calculate EPA's Cancer Slope Factor assumes that high dose animal data can be used to
estimate the risk for low dose exposures in humans (94). The method also assumes that there
is no safe level for exposure (95). Little experimental evidence exists to confirm or refute
those two assumptions. Lastly, the method computes the 95% upper bound for the risk, rather
than the average risk, which results in there being a very good chance that the risk is actually
lower, perhaps several orders of magnitude (96). One order of magnitude is 10 times greater
or lower than the original number, two orders of magnitude are 100 times, and three orders are 1,000 times.
|Table D1 - Estimated Exposure
Doses and Cancer Risk for Dunn Field Soil Contaminants
Compared to Health Guidelines for Ingestion1
|Contaminant||Maximum Level in parts per million (ppm)||Estimated Adult Exposure Doses in mg/kg/day*||Health Guideline in mg/kg/day*||Source of Guideline||Cancer Risk|
|Arsenic||35||0.00004||0.0003||MRL2||2 in 100,0003|
|Alpha-chlordane||1.5||0.000002||0.0003||MRL2||1 in 1,000,0004|
|Dieldrin||0.5||0.000001||0.00005||MRL2||1 in 100,0003|
|Benzo(a)pyrene5||68||0.00007||none||none||2 in 10,0006|
|* mg/kg/day = milligrams/kilogram/day
1 An explanation of how these exposure doses and cancer risk were calculated can be found in the preceding page. No health guidelines are available for lead, benzo(a)anthracene, benzo(b)fluoranthene, indeno(1,2,3-c,d)pyrene, benzo(k)fluoranthene, and dibenz(a,h)anthracene.
2 MRL = ATSDR's minimal risk level. For more information on the MRL for arsenic or alpha- chlordane, see the arsenic or chlordane toxicological profiles.
3 Maximum additional lifetime risk of cancer per 100,000 individuals.
4 Maximum additional lifetime risk of cancer per 1,000,000 individuals.
5 Maximum additional lifetime risk of cancer per 10,000 individuals.
|Table D2 - Estimated Exposure
Doses and Cancer Risk for Soil Contaminants
Compared to Health Guidelines for Ingestion1
|Contaminant||Level in Parts per Million (ppm)||Estimated Adult Exposure Doses in mg/kg/day*||Health Guideline in mg/kg/day*||Source of Guideline||Cancer Risk|
|Maximum Arsenic Level||84||0.0001||0.0003||MRL2||2 in 10,0003|
|Mean Arsenic Level||15.7||0.00002||0.0003||MRL2||3 in 100,004|
|Maximum Benzo(a)Pyrene||450||0.00007||none||none||5 in 1,0005|
|Mean Benzo(a)Pyrene Level||6.6||0.000009||none||none||7 in 100,004|
|Maximum Beryllium Level||2||0.000003||0.002||RfD6||1 in 100,0004|
|Mean Beryllium Level||0.3||0.0000004||0.002||RfD6||2 in 1,000,0007|
|Maximum Dieldrin Level||10||0.00001||0.00005||MRL2||2 in 100,0004|
|Mean Dieldrin Level||0.5||0.0000007||0.00005||MRL2||1 in 1,000,0007|
|Maximum DDT Level||59||0.00008||0.0005||RfD6||3 in 100,0004|
|Mean DDT Level||0.8||0.0000008||0.0005||RfD6||0.4 in 1,000,0007|
|* mg/kg/day = milligrams/kilogram/day
1 An explanation of how these exposure doses and cancer risk were calculated can be found in the preceding page. No health guidelines are available for lead, benzo(a)anthracene, benzo(b)fluoranthene, indeno(1,2,3-c,d)pyrene, and dibenz(a,h)anthracene.
2 MRL = ATSDR's minimal risk level.
3 Maximum additional lifetime risk of cancer per 10,000 individuals.
4 Maximum additional lifetime risk of cancer per 100,000 individuals.
5 Maximum additional lifetime risk of cancer per 1,000 individuals.
6 RfD = EPA's reference dose.
7 Maximum additional lifetime risk of cancer per 1,000,000 individuals.
APPENDIX E - CONTAMINANT TABLES FOR
THE DEFENSE DEPOT - MEMPHIS, TENNESSEE
|Contaminant||Range in Soil
|Dunn Field Mean in mg/kg||Background Mean in mg/kg||Samples > DL2||Samples >CV3||CV in mg/kg||CV Source4|
|Beryllium||ND - 1.2||0.8||0.2||11/12||11/05||0.2/3006||CREG/RMEG|
|Benzo(a)pyrene||ND - 4.1||1.0||0.9||11/12||7||0.1||CREG|
|Benzo(b)fluoranthene||0.1 -4.9||1.5||0.9||12/12||7||0.9||EPA SSL|
|Dibenz(a,h)anthracene||ND - 0.5||0.2||0.8||7/12||6||0.09||EPA SSL|
|Benzo(a)anthracene||0.07 - 3.8||0.9||0.9||12/12||3||0.9||EPA SSL|
|Indeno(1,2,3-c,d)pyrene||ND - 3.2||0.8||0.8||9/12||2||0.9||EPA SSL|
|* The source of these data is the 1990 RI
(3), and the 1995 sediment sampling data provided directly to ATSDR by DDMT.
There is a legend for this table following Table E7.
Table E2 - Contaminants Detected in Dunn Field Surface Water*
|Contaminant||Range in Water in mg/L7||Samples > DL2||Samples > CV3||CV in mg/L**||CV Source4|
|Acetone||0.002 - 0.02||3/3||0||10||RMEG|
|Barium||0.06 - 0.09||3/3||0||70||RMEG|
|Benzoic Acid||ND - 0.003||1/3||0||4,000||RMEG|
|Bis(2-ethylhexyl)phthalate||ND - 0.01||1/3||0||0.3/206||CREG/RMEG|
|Cadmium||ND - 0.006||1/3||0||0.2||EMEG|
|Copper||ND - 0.02||2/3||0||130||EPA Action Level|
|Dieldrin||ND - 0.0001||2/3||0||0.0002/0.056||CREG/EMEG|
|Lead||ND - 0.04||1/3||0||1.5||EPA Action Level|
|Methylene Chloride||ND - 0.001||1/3||0||0.5/606||CREG/EMEG|
|Nitrosodiphenylamine||ND - 0.005||1/3||0||0.7||CREG|
|Zinc||0.06 - 0.1||3/3||0||300||EMEG|
|* The source of these data is the 1990 RI
(3), and the 1995 sediment sampling data provided directly to ATSDR by DDMT.
** These comparison values are multiplied by 100 because it is assumed that daily ingestion of surface water for a small child is 10 milliliters (ml) rather than the 1 liter (1,000 ml) used for drinking tap water.
There is a legend for this table following Table E7.
Table E3 - Surface Soil Contaminants above a Comparison Value
|Contaminant||Range in mg/kg1||Samples > DL2||Samples > CV3||CV in mg/kg||CV Source4|
|Alpha-chlordane||ND - 4||50/243||5/15||0.5/36||CREG/RMEG|
|Antimony||ND - 2,420||114/323||8||20||RMEG|
|Arsenic||ND - 101||352/361||351/705||0.5/206||CREG/EMEG|
|Barium||6 - 7,300||158/158||3||4000||RMEG|
|Benzo(a)anthracene||ND - 970||167/352||59||0.9||EPA SSL|
|Benzo(a)pyrene||ND - 450||164/349||121||0.1||CREG|
|Benzo(b)fluoranthene||ND - 540||174/359||59||0.9||EPA SSL|
|Benzo(k)fluoranthene||ND - 450||151/338||23||9||EPA SSL|
|Beryllium||ND - 2||162/319||142/05||0.2/3006||CREG/RMEG|
|Beta BHC||ND - 2.5||11/168||2||0.4||CREG|
|Bis(2-ethylhexyl) phthalate||ND - 250||45/110||1/05||50/1,0006||CREG/RMEG|
|Cadmium||ND - 159||187/347||6||10||EMEG|
|Chlordane||ND - 1.2||9/66||1/05||0.5/306||CREG/EMEG|
|Chromium||5 - 16,200||370/370||17||300||RMEG|
|Chrysene||ND - 620||178/357||2||88||EPA SSL|
|Copper||ND - 28,500||370/372||2||3,100||HEAST|
|DDD||ND - 3.6||116/316||1||3||CREG|
|DDE||ND - 39||187/333||9||2||CREG|
|DDT||ND - 59||205/334||15/15||2/306||CREG/RMEG|
|Dibenz(a,h)anthracene||ND - 160||21/334||15||0.09||EPA SSL|
|Dieldrin||ND - 10||180/324||125/95||0.04/36||CREG/EMEG|
|Gamma-chlordane||ND - 4||60/310||7/05||0.5/306||CREG/EMEG|
|Heptachlor||ND - 1.1||3/159||1/05||0.2/306||CREG/RMEG|
|Heptachlor epoxide||ND - 0.3||4/161||2/05||0.08/0.76||CREG/EMEG|
|Indeno(1,2,3-c,d)pyrene||ND - 310||132/302||48||0.9||EPA SSL|
|Iron||1,360 - 242,000||108/108||18||23,000||HEAST|
|Lead||ND - 17,500||371/372||42||400||EPA SSL|
|PCB-1254 (Arochlor 1254)||ND - 10||2/114||1||1||RMEG|
|PCB-1260 (Arochlor 1260)||ND - 18||11/166||7||0.4||CREG|
|Thallium||ND - 42||3/222||1||5.5||HEAST|
|Zinc||9 - 28,200||378/378||3||20,000||EMEG|
Table E4 - Contaminants in Sediment Samples above a Comparison Value
|Contaminant||Range in mg/kg1||Samples > DL2||Samples >CV3||CV in mg/kg||CV Source4|
|Arsenic||ND - 14||25/37||25/05||0.5/206||CREG/EMEG|
|Antimony||ND - 56.7||4/37||1||20||RMEG|
|Benzo(a)anthracene||ND - 2.1||22/37||5||0.9||EPA SSL|
|Benzo(b)fluoranthene||ND - 2.3||24/37||5||0.9||EPA SSL|
|Benzo(k)fluoranthene||ND - 25||21/37||1||9||EPA SSL|
|Benzo(a)pyrene||ND - 2||24/37||18||0.1||CREG|
|Beryllium||ND - 0.6||31/39||19/05||0.2/3006||CREG/RMEG|
|Cadmium||ND - 168||14/37||1||10||EMEG|
|Chromium||9 - 3,400||37/37||1||300||RMEG|
|DDT||ND - 2.9||16/37||1/05||2/306||CREG/RMEG|
|Dibenz(a,h)anthracene||ND - 0.3||4/37||2||0.09||EPA SSL|
|Gamma-chlordane||ND - 0.7||7/18||1/05||0.5/306||CREG/EMEG|
|Iron||ND - 49,300||19/29||1||23,000||HEAST|
|Lead||ND - 7,640||31/37||2||400||EPA SSL|
|Total polynuclear aromatic hydrocarbons||ND - 16.5||7/11||4||0.1||CREG*|
|* This is the CREG for benzo(a)pyrene.
There is a legend for this table after Table E7.
|Contaminant||Range in Water in mg/L7||Samples > DL2||Samples > CV3||CV in mg/L*||CV Source4|
|Arsenic||ND - 0.08||24/43||24/05||0.002/0.36||CREG/EMEG|
|Dieldrin||ND - 0.0004||18/51||2/05||0.0002/0.056||CREG/EMEG|
|* These comparison values are multiplied by
100 because it is assumed that daily ingestion of surface water for a small
child is 10 milliliters (ml) rather than the 1 liter (1,000 ml) used for
drinking tap water.
The legend for this table follows Table E7.
Table E6 - Contaminants in Background Sediment above a Comparison Value
|Contaminant||Range in Sediment (mg/kg)1||Samples > DL2||Samples > CV3||CV in mg/kg||CV Source4|
|Arsenic||ND - 11.1||18/22||18/05||0.5/206||CREG/EMEG|
|Beryllium||ND - 0.8||6/22||6/05||0.2/3006||CREG/RMEG|
|Benzo(a)pyrene||ND - 2.5||7/22||3||0.1||CREG|
|Benzo(b)fluoranthene||ND - 2.6||7/22||2||0.9||EPA SSL|
|Benzo(a)anthracene||ND - 2.9||6/22||2||0.9||EPA SSL|
|Dibenz(a,h)anthracene||ND - 0.7||2/22||2||0.09||EPA SSL|
|Iron||3,330 - 30,700||22/22||1||23,000||HEAST|
|Indeno(1,2,3-c,d)pyrene||ND - 1.7||7/22||1||0.9||EPA SSL|
|Alpha-chlordane||ND - 2.4||5/22||1/05||0.5/36||CREG/RMEG|
|Gamma-chlordane||ND - 2||5/22||1/05||0.5/306||CREG/EMEG|
|Cadmium||ND - 38||4/22||1||10||EMEG|
|The legend for this table can be found after Table E7.|
Table E7 - Contaminants in Background Surface Water above a Comparison Value
|Contaminant||Range in Surface Water (mg/L)7||Samples > DL2||Samples > CV3||CV in mg/L*||CV Source4|
|Arsenic||ND - 0.01||13/22||13/05||0.002/0.36||CREG/EMEG|
|* Comparison values for drinking water were
multiplied by 100 because it was assumed that daily ingestion of surface
water for a child was 10 ml rather than the 1,000 ml used for drinking tap
The legend for this table can be found after this table.
Footnotes for Tables E1 - E7
1 - mg/kg = milligrams of chemical per kilogram of soil. mg/kg = parts per million (ppm)
2 - DL = detection limit
3 - CV = comparison value. See Appendix C for an explanation of comparison values.
4 - These comparison values are described in Appendix C starting on page 64.
5 - The samples above a CREG are the first number and those above an EMEG or RMEG is the second.
6 - The first number is a CREG and the second is an EMEG or RMEG.
7 - mg/l = milligrams of chemical per liter of water.
APPENDIX F - TOXICOLOGICAL EVALUATION
This appendix is a detailed chemical-by-chemical evaluation of the possible health consequences of exposure to DDMT contaminants. These evaluations are summarized on pages 16 and 18.
Possible Health Consequences of Chemicals found on Dunn Field
When a sample concentration exceeded a CV, the maximum level of that chemical was used to calculate an exposure dose, which was then compared with an appropriate health guideline.
Of the 9 chemicals in soil with concentrations above CVs, three - arsenic, alpha-chlordane, and dieldrin, had health guidelines for non-carcinogenic health effects. There were health guidelines to identify cancer risk for arsenic, alpha-chlordane, benzo(a)pyrene, and dieldrin (58,77,97,98). Table D1 on page 67 contains the results for these four chemicals. Only adult exposure doses were calculated because access of small children to Dunn Field contaminants appears very unlikely because Dunn Field is and has always been fenced. A qualitative evaluation of the possibility of health consequences was done for the 5 chemicals (benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, dibenz(a,h)anthracene, and indeno(1,2,3-c,d)pyrene) for which there were no health guidelines. As indicated above, the conclusions on these 6 chemicals are applicable only to the locations sampled and not to all of Dunn Field because of inadequate number and extent of sampling.
As indicated on Table D1, health effects due to arsenic in 5 Dunn Field soil samples are not likely to occur because the concentrations are too low even when workers were assumed to be exposed 5 days a week for 30 years.
As indicated on Table D1, health effects due to alpha-chlordane in 5 Dunn Field soil samples are not likely to occur because known concentrations are too low even when workers were assumed to be exposed 5 days a week for 30 years.
As indicated on Table D1, health effects due to dieldrin in 5 Dunn Field soil samples are not likely to occur because known concentrations are too low even when workers were assumed to be exposed 5 days a week for 30 years.
Six of the substances in Dunn Field soil found above comparison values are members of the chemical group, polycyclic aromatic hydrocarbons [PAHs] (58). These six are benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene, dibenz(a,h)anthracene, and indeno(1,2,3-c,d)pyrene. EPA's guidance for the quantitative risk assessment of PAHs was used to identify maximum cancer risk for the 6 PAHs (99). This was done because the other 5 PAHs do not have health guidelines. The additional maximum excess cancer risk for each of the six PAHs is moderate (about 1-2 in 10,000) if someone was exposed 5 days a week for 30 years. The cumulative maximum excess risk for same length of exposure to all six PAHs is elevated (1 in 1,000).
However, although cancer risk is elevated, the actual chance of anyone being harmed is very low or non-existent because regular long-term exposure of any individual was unlikely. This conclusion is based on that fact that all PAH concentrations above background from Dunn Field came from one location. The PAH levels at the other 3 locations were 0.2 PPM or lower and are within the PAH levels of 0.2 - 61 ppm typically found in urban soil (58). The one sampling location with elevated concentrations was an area where petroleum products, food, or other materials were burned (3). PAHs are produced when such materials are burned (58). This area contaminated with PAHs would be a problem only if someone regularly worked at that spot. This appears unlikely (3,5).
Health effects due to the contaminants in Dunn Field sediment are very unlikely, even if exposure was daily. Daily exposure to contaminated sediment appears unlikely. As indicated on Table E2, the average levels of beryllium and PAHs at all 12 locations are similar to the means identified in the background sampling of the DDMT area. In addition, the PAH concentrations are within the levels of 0.2 - 61 ppm typically found in urban soil (58).
The 6 chemicals in Dunn Field sediment above comparison values were beryllium, benzo(a)anthracene, benzo(b)fluoranthene, benzo(a)pyrene, dibenz(a,h)anthracene, and indeno(1,2,3-c,d)pyrene. Of these 6, only beryllium had a health guideline for non-carcinogenic health effects. The highest concentration of beryllium was 250 lower than its health guideline (100). Health guidelines exist to identify cancer risk for benzo(a)pyrene and beryllium (58,100).
EPA's guidance for the quantitative risk assessment of PAHs was used to identify maximum cancer risk for the 5 PAHs (99). This was done because the other 4 PAHs do not have health guidelines. The additional maximum excess cancer risk for beryllium and each of the 5 PAHs is very low (about 5 in 100,000 to 6 in 1,000,000) if someone were exposed 5 days a week for 30 years.
Possible Health Consequences of Chemicals found on DDMT Main Facility
When a sample concentration exceeded a CV, the maximum level of that chemical was used to calculate an exposure dose, which was then compared was an appropriate health guideline.
Of the top 10 chemicals in soil with concentrations above CVs, four (arsenic, beryllium, dieldrin, and DDT) had health guidelines for non-carcinogenic health effects. Health guidelines exist to identify cancer risk for arsenic, benzo(a)pyrene, beryllium, dieldrin, and DDT (58,77,100,101). Table E2 on page 68 contains the results for these 5 chemicals for adult exposure doses. Exposure doses for small children were also calculated because they could have been exposed if they lived in the base housing which is located near the southeast corner of the Main Facility. Access of small children living around the DDMT Main Facility to on-site contaminants appears very unlikely because the main facility is and, reportedly, has always been fenced. A qualitative evaluation of the possibility of health consequences was done for the 5 chemicals [benzo(a)anthracene, benzo(b)fluoranthene, dibenz(a,h)anthracene, indeno(1,2,3-c,d)pyrene, and lead] for which no health guidelines exists.
Health effects due to arsenic in on-site soil samples are not likely to occur. The adult exposure doses for the maximum (84 ppm) and mean (15.7 ppm) arsenic concentrations are below the health guideline for non-carcinogenic health effects. The child exposure dose for the maximum arsenic level was above the arsenic health guideline, and for the mean level was below. In Figure G1, the 30 locations are identified where arsenic concentrations are above 20 ppm. Concentrations above 20 ppm result in a child exposure dose that exceeds the health guideline if exposure were all day every day. However, none of these locations appear close enough to base housing for small children to be regularly exposed. The cancer risk for the maximum arsenic level is low and not elevated for the mean level.
Health effects due to beryllium in on-site soil samples are not likely to occur. The adult and child exposure doses for the maximum and mean beryllium concentrations are below the health guideline for non-carcinogenic health effects. The cancer risk for the maximum and mean levels of beryllium was not elevated.
Health effects due to dieldrin in on-site soil samples are not likely to occur. The adult exposure doses for the maximum and mean dieldrin concentrations are below the health guideline for non-carcinogenic health effects. The child exposure dose for the maximum dieldrin level was above its health guideline, and for the mean level, it was below. In Figure G2, the 9 locations are identified where the dieldrin concentration is above 3 ppm. Above 3 ppm results in exceeding the child comparison value if exposure is all day every day. Only one location appears close enough to base housing for daily exposure to be likely. However, the dieldrin level at that spot (5.5 ppm) does not represent a public health hazard. The exposure dose for this level (0.0001 mg/kg/day) is 45 times lower than the no observed adverse health effects level [NOAEL] and 450 times lower than the lowest observed adverse health effects level [LOAEL] seen in the lowest valid animal study (98). No valid human investigation has been done. The cancer risk for the maximum and mean levels is not elevated.
Health effects due to DDT in on-site soil samples are not likely to occur. The adult exposure doses for the maximum and mean DDT concentrations are below the health guideline for non-carcinogenic health effects. The child exposure dose for the maximum DDT level of 59 ppm was above its health guideline, but not any other concentration. However, this DDT level does not represent a public health hazard. The exposure dose for this level (0.001 mg/kg/day) is 50 times lower than the NOAEL and 250 times lower than the LOAEL seen in the lowest valid animal study (101). No valid human investigation has been done. The cancer risk for the maximum and mean levels is not elevated.
A review of the ATSDR Toxicological Profile for Lead indicates that daily exposure to lead at the locations identified on Figure G3 where lead levels were above 400 ppm, could be a health hazard for children less than 6 years old (79). However, small children probably could not have had enough exposure to result in health effects because none of the locations with lead levels greater than 400 ppm are near the base housing units. Base housing appears to be the only location where small children could regularly contact soil on DDMT. All but 2 of the locations with lead concentrations above 400 ppm are located on the west or north side of DDMT. The 2 locations on the same side of the facility (east) as base housing are about 600 feet away. A child under 6 could not likely travel to these two locations frequently enough to result in harm.
Five of the top 10 substances found above comparison values are members of the chemical group, polycyclic aromatic hydrocarbons [PAHs] (58). These 5 are benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, dibenz(a,h)anthracene, and indeno(1,2,3-c,d)pyrene. EPA's guidance for the quantitative risk assessment of PAHs was used to identify maximum cancer risk for the 5 PAHs (99). This was done because the other 4 PAHs do not have health guidelines. The additional maximum excess cancer risk for each of the 5 PAHs was low (1 in 10,000) to elevated (5 in 1,000) for the maximum levels but was not elevated for the mean levels if someone were exposed 7 days a week for 70 years. The cumulative additional excess risk for exposure to the maximum concentrations of all 5 PAHs is elevated (7 in 1,000).
However, this elevated cancer risk is focused around the west side of Building 629, the south side of Building 249 and between Buildings 689 and 690. Any individual who had or has regular contact with soil from these three locations for many years would have an elevated risk of cancer from exposure to PAHs. Whether anyone would have experienced this exposure situation is unclear. Risk of cancer does not appear to be elevated for the rest of the DDMT Main Facility because PAH concentrations are considerably lower.
These conclusions are based on the fact that the highest concentrations for each of the 5 PAHs came from the three sampling locations identified in the previous paragraph. The PAH levels found at most of the rest of the Main Facility sampling locations are within the PAH levels of 0.2 - 61 ppm typically found in urban soil (58).
The 15 chemicals in on-site sediment samples with concentrations above a CV (Table E4), do not currently present a public health hazard. These 15 are arsenic, antimony, benzo(a)pyrene, benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, beryllium, cadmium, chromium, dibenz(a,h)anthracene, DDT, gamma-chlordane, iron, lead, and total polynuclear aromatic hydrocarbons (PAHs). All the samples with concentrations above CVs, except for gamma-chlordane, were taken from Lake Danielson or the golf course pond. Figures G5 and G6 (pages 86 and 87) display the contaminant levels for arsenic and dieldrin. The sampling locations for the other 13 contaminants are the same as for these 2 chemicals.
It is not plausible that anyone could have been exposed on a regular basis to the sediments in the lake or pond as they would have to ingest the sediment. Indirect exposure to sediment contaminants through ingestion of fish from Lake Danielson or the golf course pond may have occurred before 1986 when fishing was banned because elevated levels of DDT, dieldrin, chlordane, and chlorpyrifos were found in sediment and fish tissue samples (3). The single sample of gamma-chlordane above the CV was found in the drainage for the western side of the main facility. For anyone to have regular exposure to sediment from any of these locations does not appear to be plausible because there appears to have been no facility operations at these locations (47).
The chemicals in the on-site surface water samples with concentrations above CVs (Table
E5), do not present public health hazards because the risk of cancer and other effects is not
significant. Two chemicals, arsenic and dieldrin, were above CVs (Figures G7 & G8). The
maximum levels of arsenic and dieldrin are well below the noncarcinogenic health effects
comparison values and the additional lifetime cancer risk from exposure to them is not significant (2 in 1,000,000 to 4 in 100,000).
APPENDIX G - CONTAMINANT MAPS
Note: The 8 maps in this appendix display the sampling locations and concentrations for the top contaminants at DDMT. These were arsenic, benzo(a)pyrene, dieldrin, and lead in soil; arsenic and benzo(a)pyrene in sediment; and arsenic and dieldrin in surface water. The concentration ranges displayed on these maps are based on the comparison values for each contaminant. The contaminant data displayed on these maps came from electronic files provided by DDMT through the Corps of Engineers and their contractor, CH2MHILL. The latitudes and longitudes for nearly all the sampling locations were also provided electronically to ATSDR by CH2MHILL. Some sampling locations for the 1990 RI were estimated by ATSDR using Figure 2-1 in the 1990 RI (3). The streets, creeks, and railroads displayed on the maps in this appendix come from the TIGER files generated by the U.S. Census Bureau. The locations of the open drainage ditches and the DDMT site boundaries were estimated by ATSDR using Figure 3-1 from 1990 RI and Drawings 1 & 2 from the 1995 Generic RI/FS Workplan (3,67).
APPENDIX H - ANALYSIS OF SURFACE WATER PATHWAY
Evaluation of Surface Water Drainage around DDMT24
(1) Water on the southeast side of the main facility flows through concrete-lined ditches to four discharge points near the southeast corner . The water then flows into 4 shallow unlined ditches off-site. These ditches eventually combine and discharge into Nonconnah Creek to the west of the airport. One of these 4 ditches flows through a neighborhood (Muller Road) between Ball and Ketchum Roads . ATSDR staff have observed children playing in this ditch .
(2) On the westside of the main facility, water flows through pipes and ditches to a discharge point midway between the north and south ends of the main facility . This water flows west through the neighborhood west of DDMT in the Tarrent Branch, which is now a lined ditch but earlier was a natural intermittent stream. This branch eventually runs into Nonconnah Creek near the junction of I-240 and I-55.
As displayed on Figure 5, drainage plans for DDMT from 1953 and 1960 identify a second open ditch coming off the west side of DDMT between Tarrent Branch and Dunn Avenue (63,62). This ditch was not displayed on a 1982 map, so it appears that sometime between 1960 and 1982, the on-site drainage was altered so that the water that once left the site in this ditch, was rerouted to Tarrent Branch (7).
(3) Drainage from all of Dunn Field, except the northeast corner, flows to the west side of Dunn Field and exits at three points . Water at the northern most of these points flows in a shallow unlined ditch through that portion of Rozelle Street to the west of Dunn Field. This ditch then discharges into a lined ditch that runs east and west at the south end of this isolated segment of Rozelle Street. This lined ditch also receives the water from several industrial discharge points before it runs by the end of Rozelle Street.
After leaving the Rozelle area, this ditch goes into a pipe, then goes under the Illinois Central railroad line, and then goes northwest . This pipe discharges into Cane Creek between Hamilton High and the Elvis Presley Blvd. Bridge, just downstream from the high school. Therefore, water from the Dunn Field/Rozelle area apparently does not currently flow under Hamilton High. However, long-term residents indicate that an open ditch used to carry water from Dunn Field to Cane Creek so people living in this area could have had contact with water from Dunn Field.
(4) Water from the northeast corner of Dunn Field drains into 2 lined ditches that cross Dunn Field . These ditches drain at least some of the neighborhood south of Person and Hayes. These 2 ditches join before leaving Dunn Field. Another discharge point drains the north end of Dunn Field (Figure 5). These 3 ditches run into Cane Creek north of the Ragan Street Bridge and upstream of Hamilton High School. Thus, water from the northeast corner of Dunn Field does flow under Hamilton High School.
(5) Water from the northern side of the main facility moves off-site in a lined ditch at Dunn and Custer Streets or in storm sewers [3,47]. The ditch at Dunn and Custer switches from a lined ditch to a pipe and back to a lined ditch before flowing into a large-lined ditch that runs southeast to northwest to the northeast of the main facility . This large ditch flows into Cane Creek to the north of the Ragan Street Bridge . The storm sewers appear to flow directly into Nonconnah Creek . Thus, some of the water from the northern side of the DDMT Main Facility does flow under Hamilton High School, but the rest goes directly to Nonconnah Creek.
(6) Water from the central east portion of the Main Facility, which is the area around the
DDMT Administration Building, leaves the site in storm sewers which appear to discharge
into Nonconnah Creek [3,5]. Thus, water from around the administration building does not flow under Hamilton High School.
2. Based on several discussions with DDMT staff.
3. Sampling of the area around DDMT was done in late 1995. Sampling locations were selected by staff from DDMT and its contractors, EPA, TDEC, and ATSDR; and a local environmental activist. This last individual was at the time a co-chair of the DDMT RAB.
4. From discussion with Denise Cooper, DDMT, on January 27, 1997.
5. A former worker indicated to John Crellin on September 9, 1999, that some workers performed cleanup and other tasks on Dunn Field periodically. They would work on Dunn Field 8 hours a day for several days in a row.
6. Conversation with DDMT-CCC member in November 1998.
7. Conversation with a member of DDMT-CCC during a site visit in June 1997.
8. These population estimates were made by John Crellin using geographic information systems (GIS) techniques. After creating 100- and 500-foot zones around the five drainage ditches, population numbers for these 2 zones were then identified using 1990 census data for Shelby County.
9. The Memphis Fire Department estimated immediately after the incident that 1,500 - 2,000 gallons were released (64). After the incident, the Depot estimated that only 327 gallons had been released and that this was diluted by 37,000 gallons of rainwater (65).
10. These data were provided to ATSDR in September 1998 as an electronic file. The actual sampling of these locations was done in late 1995. Sampling locations were selected by staff from DDMT and its contractors, EPA, the Tennessee Department of Environmental Conservation, and ATSDR; and a local environmental activist. This last individual was at the time a co-chair of the DDMT RAB.
11. Discussion with Michael Grayson, Health Physicist, Federal Facilities Branch/DHAC/ATSDR.
12. Discussion with Denise Cooper, DDMT environmental staff, on January 27, 1998.
13. Conversation among a DDMT-CCC member, John Crellin, Rueben Warren, Sandee Coulberson, and others on September 9, 1999.
14. This is based on an evaluation of the ground elevations found on the USGS topographic map for the DDMT area and my (John Crellin) observations of the area.
15. The concerns about breast cancer, prostate cancer, and hypertension were identified during a public availability session on May 29, 1998.
16. Phone call to John Crellin from a DDMT-CCC member on March 24, 1998.
17. John Crellin had several conversations concerning this issue: conversations with a DDMT-CCC member in March and April 1998, with Ben Moore (ATSDR) in March 1998, with Glen Kaden (DDMT) in March 1998, and with Shawn Phillips (DDMT) in August 1999.
18. This is based on a discussion with a DDMT-CCC member on January 21, 1999. This individual drove me (John Crellin) by Norris and Dunn Elementary. I agreed that these two schools are about the same distances from the western boundary of DDMT.
19. This concern was expressed to John Crellin on October 17, 1998 by a DDMT-CCC member.
20. This response was developed with the guidance of Allan Susten, Ph.D., DABT. He is the Assistant Director of Science in ATSDR's Division of Health Assessment and Consultation.
21. These toxicologic thresholds would be the no or lowest observed adverse effects levels (NOAELs and LOAELs) for the chemical of interest.
22. This has been expressed by former workers on several occasions including the January, March, and April 1999 Restoration Advisory Board (RAB) meetings.
23. This is a list of the substances tested for in any of the 4 recent environmental sampling programs at DDMT. The actual number of parameters tested in any one of the 4 programs varied from about 70 in the 1995 RI program to about 200 in the screening sites program.