PUBLIC HEALTH ASSESSMENT
POWNAL TANNERY
POWNAL, BENNINGTON COUNTY, VERMONT
APPENDIX A - Maps and Diagrams
APPENDIX B - Tables of Contaminants
Appendix B, Table 1 - Contaminants Detected in On-site Surface Soil, Above Environmental Screening Values at the Pownal Tannery National Priorities List Site - Pownal, Bennington County, Vermont
| Contaminant | Concentration Range (ppm) |
Location of Maximum |
Screening Value (ppm) | Cancer Class |
||
| Minimum | Maximum | Value | Source | |||
| Arsenic | 7.8 | 12.5 | Central Tannery Building | 0.5 | CREG | A |
| Barium | 345 | 4,580 | Central Tannery Building | 4,000 | RMEG | |
| Cadmium | 22.8 | 33.4 | Northern Building | 10 | EMEG | B1 |
| Chromium | 10.7 | 64,000 | Northern Building | 80,000 | RMEG | |
| Iron | 20,800 | 424,000 | Northern Building | |||
| Lead | 381 | 1,380 | Central Tannery Building | 400 | SSL | B2 |
| Manganese | 301 | 15,000 | Clarifier Building | 7,000 | RMEG | |
| Vanadium | 124 | 1,640 | Northern Building | 550 | SSL | |
| 2-Methylnaphthalene | 0.34 | 9.1 | Central Tannery Building | |||
| 4-Nitroaniline | 0.58 | 0.58 | Central Tannery Building | |||
| 4,4'-DDT | 5.8 | 5.8 | Northern Building | 2 | CREG | B2 |
| Benzo(a)pyreneEquivalents | 3.29 | 80.36 | Central Tannery Building | 0.1 | CREG | B2 |
| Bis(2-Ethylhexyl)phthalate | 3.9 | 4,000 | Block Building | 50 | CREG | B2 |
| Dibenzofuran | 0.73 | 18 | Central Tannery Building | |||
| Endrin Ketone | 0.017 | 0.018 | Clarifier Building | |||
| Pentachlorophenol | 1.3 | 33 | Northern Building | 3 | SSL | |
| 2,3,7,8-TCDDTEQ | 0.00003 | 0.000459 | Central Tannery Building | 0.00005 | EMEG | |
Legends for Appendix B Data Tables
|
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|
CANCER CLASS
|
|
| A | Human carcinogen |
| B | Probable human carcinogen (Group B is subdivided into two groups) |
|
B1
|
Limited evidence of carcinogenicity from epidemiologic studies |
|
B2
|
Sufficient evidence of carcinogenicity in animals, but inadequate evidence or no data from epidemiologic studies |
| C | Possible Human carcinogen |
| D | Not classifiable as to human carcinogenicity |
| E | Evidence of noncarcinogenicity in humans |
Appendix B, Table 2 - Contaminants Detected
in On-site Sludge, Above Environmental Screening Values at the Pownal Tannery
National Priorities List Site - Pownal, Bennington County, Vermont
| Contaminant | Concentration Range (ppm) |
Location of Maximum |
Screening Value (ppm) | Cancer Class |
||
| Minimum | Maximum | Value | Source | |||
| Antimony | 11.1 | 232 | Central Tannery Building | 20 | RMEG | |
| Arsenic | 10.5 | 63.5 | Central Tannery Building | 0.5 | CREG | A |
| Barium | 329 | 8270 | Central Tannery Building | 4,000 | RMEG | |
| Cadmium | 14.5 | 16.2 | Northern Building | 10 | EMEG | B1 |
| Chromium | 5,710 | 126,000 | Central Tannery Building | 80,000 | RMEG | |
| Iron | 74,800 | 115,000 | Central Tannery Building | |||
| Lead | 36.7 | 619 | Central Tannery Building | 400 | SSL | B2 |
| 2-Methylnaphthalene | 57 | 57 | Northern Building | |||
| Benzo(a)pyreneEquivalents | 0.17 | 0.76 | Northern Building | 0.1 | CREG | B2 |
| 2,3,7,8-TCDDTEQ | 0.0000324 | 0.000191 | Northern Building | 0.00005 | EMEG | |
Appendix B, Table 3 - Contaminants Detected
in On-site Wood, Paint, and Concrete, Above Environmental Screening Values at
the Pownal Tannery National Priorities List Site - Pownal, Bennington County,
Vermont
| Contaminant | Concentration Range (ppm) |
Location of Maximum |
Screening Value (ppm) | Cancer Class |
||
| Minimum | Maximum | Value | Source | |||
| Barium | 389 | 4,100 | Central Tannery Building | 4,000 | RMEG | |
| Cadmium | 2.6 | 98.3 | Central Tannery Building | 10 | EMEG | B1 |
| Lead | 23.2 | 9,500 | Northern Building | B2 | ||
| Aldrin | 2.3 | 4.1 | Northern Building | 0.04 | CREG | B2 |
| N-Nitroso-di-n-propylamine | 1.8 | 42 | Central Tannery Building | 0.1 | CREG | B2 |
| Pentachlorophenol | 0.49 | 68 | Northern Building | 6 | CREG | B2 |
| Benzo(a)pyrene Equivalents | 7.44 | 13.47 | Northern Building | 0.1 | CREG | B2 |
| Dieldrin | 4.5 | 4.5 | Central Tannery Building | 0.04 | CREG | B2 |
| 4-Chlorophenyl phenyl ether | 0.56 | 7.8 | Central Tannery Building | |||
| 4-Nitroaniline | 0.86 | 45 | Central Tannery Building | |||
| 4-Nitrophenol | 22 | 22 | Central Tannery Building | |||
| Dibenzofuran | 0.45 | 0.45 | Central Tannery Building | |||
| Bis(2-Chloroethoxy)Methane | 2.5 | 8.5 | Central Tannery Building | |||
| 2,3,7,8-TCDDTEQ | 6.41E-6 | 0.00017 | Northern Building | |||
Appendix B, Table 4 - Contaminants Detected
in On-site Lagoon Sludge, Above Environmental Screening Values at the Pownal
Tannery National Priorities List Site - Pownal, Bennington County, Vermont
| Contaminant | Concentration Range (ppm) |
Location of Maximum |
Screening Value (ppm) | Cancer Class |
||
| Minimum | Maximum | Value | Source | |||
| Antimony | 36 | 78.6 | Lagoon 1 | 20 | RMEG | |
| Arsenic | 1.7 | 9.6 | Lagoon 1 | 0.5 | CREG | A |
| Cadmium | 5.3 | 115 | Lagoon 1 | 10 | EMEG | B1 |
| Chromium | 10.6 | 445,000 | Lagoon 1 | 80,000 | RMEG | |
| Lead | 7.3 | 2,870 | Lagoon 1 | 400 | SSL | B2 |
| Mercury | 1.6 | 85.2 | Lagoon 1 | 23 | SSL | |
| Thallium | 4.3 | 15 | Lagoon 1 | |||
| 2-Methylnaphthalene | 11 | 11 | Lagoon 1 | |||
| 1,1,1-Trichloroethane | 0.012 | 0.012 | Lagoon 4 | |||
| 2-Hexanone | 0.012 | 0.012 | Lagoon 4 | |||
| 4-methyl-2-pentanone | 0.012 | 0.012 | Lagoon 4 | |||
| 2,3,7,8-TCDDTEQ | ND | 0.11564 | Lagoon 1 | 0.00005 | EMEG | |
Appendix B, Table 5 - Contaminants Detected
in On-site Standing Water, Above Environmental Screening Values at the Pownal
Tannery National Priorities List Site - Pownal, Bennington County, Vermont
| Contaminant | Concentration Range (ppm) |
Location of Maximum |
Screening Value (ppm) | Cancer Class |
||
| Minimum | Maximum | Value | Source | |||
| Aluminum | 625 | 46,000 | Northern Building | |||
| Copper | 12.7 | 5,480 | Central Tannery Building | 1,300 | MCLG | |
| Iron | 175 | 188,000 | Northern Building | |||
| Lead | 3.6 | 650 | Northern Building | 15 0 |
Action Level MCLG |
B2 |
| Magnesium | 4,260 | 41,300 | Northern Building | |||
| Manganese | 8.2 | 1,650 | Northern Building | 50 | RMEG | |
| Mercury | 1.2 | 4.8 | Central Tannery Building | 2 | LTHA | |
| Nickel | 3 | 112 | Northern Building | 100 | LTHA | |
| Sodium | 34,800 | 49,000 | Northern Building | 20,000 | MCL | |
| Vanadium | 1 | 119 | Northern Building | 30 | iEMEG | |
| Zinc | 208 | 7,530 | Central Tannery Building | 3,000 | EMEG | |
| 4-Methylphenol | 2 | 2 | Northern Building | C | ||
| Bis(2-ethylhexyl)phthalate | 8 | 8 | Central Tannery Building | 3 | CREG | B2 |
| Carbazole | 18 | 18 | Northern Building | |||
| Pentachlorophenol | 2 | 2 | Central Tannery Building | 0.3 | CREG | B2 |
| Benzo(a)pyreneEquivalents | 168.3 | 168.3 | Northern Building | 0.005 | CREG | B2 |
Appendix B, Table 6 - Contaminants Detected
in On-site Lagoon Groundwater, Above Environmental Screening Values at the Pownal
Tannery National Priorities List Site - Pownal, Bennington County, Vermont
| Contaminant | Concentration Range (ppm) |
Screening Value (ppm) | Cancer Class |
||
| Minimum | Maximum | Value | Source | ||
| Aluminum | 150 | 10,700 | |||
| Arsenic | 13.5 | 19 | 0.02 | CREG | A |
| Manganese | 5.2 | 12,600 | 50 | RMEG | |
| Sodium | 19,700 | 293,000 | 20,000 | MCL | |
| Thallium | 2.2 | 2.2 | 0.4 | LTHA | |
| 4-Methylphenol | 6 | 6 | C | ||
| 4-Methyl-2-pentanone | 1 | 1 | |||
| Chrysene | 0.3 | 0.3 | 0 | CLHA | B2 |
| Tetrachloroethene | 6 | 6 | 0.7 | CREG | UR |
Appendix B, Table 7 - Contaminants Detected
in On-site Landfill Groundwater, Above Environmental Screening Values at the
Pownal Tannery National Priorities List Site - Pownal, Bennington County, Vermont
| Contaminant | Concentration Range (ppm) |
Screening Value (ppm) | Cancer Class |
||
| Minimum | Maximum | Value | Source | ||
| Aluminum | 6,640 | 71,100 | |||
| Arsenic | ND | 55.7 | 0.02 | CREG | A |
| Cobalt | 8 | 95.5 | |||
| Iron | 15,800 | 146,000 | |||
| Manganese | 990 | 7,480 | 50 | RMEG | |
| Nickel | 200 | 597 | 100 | LTHA | |
| Vanadium | 7.4 | 74.2 | 30 | EMEG | |
| 4-Methylphenol | 41 | 41 | C | ||
| Endrin Aldehyde | 0.021 | 0.021 | |||
Appendix B, Table 8 - Contaminants Detected
in On-site Landfill Sediment, Above Environmental Screening Values at the Pownal
Tannery National Priorities List Site - Pownal, Bennington County, Vermont
| Contaminant | Concentration Range (ppm) |
Location of Maximum |
Screening Value (ppm) | Cancer Class |
||
| Minimum | Maximum | Value | Source | |||
| Arsenic | 1.1 | 10.5 | Dewatered Sludge | 0.5 | CREG | A |
| Cadmium | 2.9 | 76.1 | Dewatered Sludge | 10 | EMEG | B2 |
| Lead | 11.5 | 975 | Dewatered Sludge | 400 | SSL | B2 |
| Mercury | 0.11 | 39.1 | Dewatered Sludge | 23 | SSL | |
| Thallium | 1.4 | 6.2 | Dewatered Sludge | |||
| 4-Methylphenol | 60 | 500 | Dewatered Sludge | |||
| Pentachlorophenol | 32 | 100 | Dewatered Sludge | 6 | CREG | B2 |
| 2,3,7,8-TCDDTEQ | 0.000755 | 0.007027 | Dewatered Sludge | 0.00005 | EMEG | |
Appendix B, Table 9 - Contaminants Detected
in On-site Landfill Run-off Area Surface Water, Above Environmental Screening
Values at the Pownal Tannery National Priorities List Site - Pownal, Bennington
County, Vermont
| Contaminant | Concentration Range (ppm) |
Screening Value (ppm) | Cancer Class |
||
| Minimum | Maximum | Value | Source | ||
| Aluminum | 1,200 | 25,400 | |||
| Arsenic | ND | 11.8 | 0.02 | CREG | A |
| Iron | 2,730 | 53,300 | |||
| Lead | 5.1 | 77.7 | 15 0 |
Action Level MCLG |
B2 |
| Manganese | 1,800 | 7,980 | 50 | RMEG | |
| Vanadium | 3.2 | 40.8 | 30 | iEMEG | |
Appendix B, Table 10 - Contaminants Detected
in Hoosic River Sediment, Above Environmental Screening Values at the Pownal
Tannery National Priorities List Site - Pownal, Bennington County, Vermont
| Contaminant | Concentration Range (ppm) |
Screening Value (ppm) | Cancer Class |
||
| Minimum | Maximum | Value | Source | ||
| Arsenic | 1.7 | 7.7 | 0.5 | CREG | A |
Appendix B, Table 11 - Contaminants Detected
in Hoosic River Surface Water, Above Environmental Screening Values at the Pownal
Tannery National Priorities List Site - Pownal, Bennington County, Vermont
| Contaminant | Concentration Range (ppm) |
Screening Value (ppm) | Cancer Class |
||
| Minimum | Maximum | Value | Source | ||
| Aluminum | 163 | 25,400 | |||
| Arsenic | 11.8 | 11.8 | 0.02 | CREG | |
| Iron | 2,730 | 53,300 | |||
| Lead | 2.1 | 77.7 | 15 0 |
Action Level MCLG |
B2 |
| Manganese | 67.9 | 7,980 | 50 | RMEG | |
| Vanadium | 3.2 | 40.8 | 30 | iEMEG | |
Appendix B, Table 12 - Contaminants Detected
in the On-site Leachate Collection System, Above Environmental Screening Values
at the Pownal Tannery National Priorities List Site - Pownal, Bennington County,
Vermont
| Contaminant | Concentration Range (ppm) |
Screening Value (ppm) | Cancer Class |
||
| Minimum | Maximum | Value | Source | ||
| Antimony | 22.1 | 22.1 | 4 | RMEG | |
| Arsenic | 6 | 7.8 | 0.02 | CREG | A |
| Manganese | 124 | 1,350 | 50 | RMEG | |
| Sodium | 104,000 | 333,000 | 20,000 | MCL | |
Appendix B, Table 13 - Contaminants Detected
in On-site Wipe Samples at the Pownal Tannery National Priorities List Site
- Pownal, Bennington County, Vermont
| Contaminant | Concentration Range (ppm) |
Location of Maximum |
|
| Minimum | Maximum | ||
| Aluminum | 18.7 (ug/ft2) | 4,220 (ug/ft2) | Northern Building (1st Floor) |
| Antimony | 21.2 (ug/ft2) | 21.2 (ug/ft2) | Northern Building (Basement) |
| Barium | 2.4 (ug/ft2) | 9,180 (ug/ft2) | Tannery (1st Floor) |
| Beryllium | 0.7 (ug/ft2) | 0.7 (ug/ft2) | Northern Building (Basement) |
| Cadmium | 1.6 (ug/ft2) | 175 (ug/ft2) | Block Building |
| Chromium | 4.3 (ug/ft2) | 3,940 (ug/ft2) | Tannery (Basement) |
| Cobalt | 1.6 (ug/ft2) | 33.4 (ug/ft2) | Tannery (Basement) |
| Copper | 1.6 (ug/ft2) | 254 (ug/ft2) | Northern Building (Basement) |
| Iron | 41.9 (ug/ft2) | 67,700 (ug/ft2) | Tannery (Basement) |
| Lead | 5.5 (ug/ft2) | 4,640 (ug/ft2) | Tannery (3rd Floor) |
| Magnesium | 109 (ug/ft2) | 4,200 (ug/ft2) | Tannery (Basement) |
| Manganese | 2.1 (ug/ft2) | 312 (ug/ft2) | Tannery (Basement) |
| Nickel | 3.2 (ug/ft2) | 82.1 (ug/ft2) | Tannery (Basement) |
| Silver | 1.8 (ug/ft2) | 5.3 (ug/ft2) | Tannery (3rd Floor) |
| Vanadium | 1.5 (ug/ft2) | 164 (ug/ft2) | Northern Building (Basement) |
| Zinc | 4 (ug/ft2) | 14,800 (ug/ft2) | Tannery (2nd Floor) |
| Bis(2-Ethylhexyl)phthalate | 1 (ug/cm2) | 9 (ug/cm2) | Tannery (3rd Floor) |
| Bis(2-Chloroethoxy)Methane | 1.7 (ug/cm2) | 2 (ug/cm2) | Northern Building (Basement) |
| Butylbenzylphthalate | 3 (ug/cm2) | 3 (ug/cm2) | Tannery (Basement) |
| 2,3,7,8-TCDDEquivalents | 1.95 (ng/kg) | 30.2 (ng/kg) | Northern Building (Basement) |
APPENDIX C - Exposure Pathways Tables
Appendix C, Table 1 - Completed On-Site Exposure Pathways at the Pownal Tannery National Priorities List Site, North Pownal, Bennington County, Vermont
| Pathway Name |
Source | Medium | Exposure Point |
Exposure Route |
Receptor Population |
Time of Exposure |
Exposure Activities |
Estimated Number Exposed |
Chemicals |
| Trespassers in Buildings | Former site operations | Surface Soil | On-site Buildings | Incidental Ingestion, Dermal absorption, inhalation, Physical Hazards | Trespassers | Past, Current, Future | Trespassing and playing in buildings on the site | Less than 100 | Metals, Dioxin, PAHs, SVOCs (Table 1) |
| Hoosic River Recreational users | Site runoff | Surface water and sediments | Surface water and sediments of the Hoosic River near site | Direct contact, incidental ingestion, inhalation | Recreational users |
Past, Current, Future | Fishing, wading, and other recreational activities | Children observed fishing in waters near site buildings | Metals (Tables 10 and 11) |
Appendix C, Table 2 - Potential On-Site Exposure Pathways
at the Pownal Tannery National Priorities List Site, North Pownal, Bennington
County, Vermont
| Pathway Name |
Source | Medium | Exposure Point |
Exposure Route |
Receptor Population |
Time of Exposure |
Exposure Activities |
Estimated Number Exposed |
Chemicals |
| On-site Groundwater | Chemical discharges | Groundwater | None known at this time | Ingestion, direct contact, inhalation |
None known at this time | Future | Drinking, cooking, shower and other potable uses of contaminated water | none known at this time | Metal, VOCs dioxins (Tables 6 and 7) |
| Landfill Run-off Area Surface Water | Chemicals buried in the on-site landfill | Surface water | On-site Landfills | Direct contact, incidental ingestion, inhalation | Trespassers | Past, Current, Future | Trespassing upon the Landfill | Unknown | Metals (Table 9) |
| On-Site Buildings During Remedial Activities | Chemical in and on the on-site buildings | Surface soil, wood, standing water, paint, and concrete | On-site buildings | Direct Contact, inhalation, incidental ingestion | Remediation Workers | Past, Current, Future | Remedial activities including sampling, excavation, and removal | Unknown | Metal, PAHs, dioxins, SVOCs (Tables 1, 3, and 5) |
Appendix C, Table 3 - Considered and Eliminated On-site
Exposure Pathways at the Pownal Tannery National Priorities List Site, North
Pownal, Bennington County, Vermont
| Pathway Name |
Source | Medium | Exposure Point |
Exposure Route |
Receptor Population |
Time of Exposure |
Exposure Activities |
Estimated Number Exposed |
Chemicals |
| Building Sludge | Past site operations | Sludge | Basement tanks and floor drains | Direct contact, inhalation, incidental ingestion | Trespassers | Past, Current, Future | None known at this time | None Known | Metals, PAHs, and dioxins (Table 2) |
| On-site Building Components | Past site operations | Wood, paint, and concrete | Building structures | Direct contact | Trespassers | Past | None known at this time | None Known | (Table 3) |
| Lagoon Sludge | Chemicals in on-site lagoons | Sludge | None at this time | Direct contact | None known | Past, Current, Future | Digging down into the lagoons | None Known | Metals, VOCs, dioxins (Table 4) |
| Building Standing Water | Past site operations | Standing Water | Basement | Direct contact | None Known | Past | Trespassing in Buildings | None Known | (Table 5) |
| Landfill Sludge | Chemicals in the on-site landfill | Sludge | None at this time | Direct contact | None Known | Past, Current, Future | Digging down into the landfill | None Known | Metals, dioxins, pentachloro-phenol (Table 8) |
| Collection System | Past site operations and buried wastes | Leachate | Leachate collection system | Direct contact | None Known | Past, Current, Future | None known at this time | None Known | Metals (Table 12) |
APPENDIX D - Health Guidelines, Exposure Dose Estimation, and Risk
Health Guidelines
Health guidelines provide a basis for comparing estimated exposures with concentrations of contaminants in different environmental media (soil and water) to which people might be exposed.
Non-Cancer Health Effects
ATSDR has developed a minimal risk level (MRL) for contaminants commonly found at hazardous waste sites. The MRL is an estimate of daily exposure to a contaminant below which non-cancer, adverse health effects are unlikely to occur. MRLs are developed for different routes of exposure, like inhalation and ingestion, and for lengths of exposure, such as acute (less than 14 days), intermediate (15-164 days), and chronic (365 days or greater). Oral MRLs are expressed in units of milligrams of contaminant per kilogram of body weight per day (mg/kg/day). Because ATSDR has no methodology to determine amounts of chemicals absorbed through the skin, the Agency has not developed MRLs for dermal exposure. The method of deriving MRLs does not include information about cancer, therefore, a MRL does not imply anything about the presence, absence, or level of cancer risk. If an ATSDR MRL is not available as a health value, then EPA's reference dose (RfD) is used. 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 (9).
Cancer Health Effects
The EPA classifies chemicals as Class A, Class B, Class C, Class D, or Class E. This classification defines a specific chemical's ability to cause cancer in humans and animals. According to EPA, Class A chemicals are known human carcinogens, and Class B chemicals are probable human carcinogens. Class B is further subdivided into two groups: Group B1 consists of chemicals for which there is limited evidence of carcinogenicity from epidemiological studies in humans; and Group B2 consists of chemicals for which there is sufficient evidence of carcinogenicity in animals, but inadequate evidence or no data available from epidemiologic studies in humans. Group C chemicals are possible human carcinogens. Group D chemicals are not classifiable as to human carcinogenicity and Group E chemicals are those for which there is evidence that they are not carcinogenic to humans. For carcinogenic substances, EPA has established the cancer slope factor (CSF) as a guideline. The CSF is used to determine the number of excess cancers resulting from exposure to a contaminant. The National Toxicology Program in its Annual Report on Carcinogens classifies a chemical as a "known human carcinogen" based on sufficient human data. Its classification of a chemical as being "reasonably anticipated to be a carcinogen" (RAC) is based on limited human or sufficient animal data. ATSDR considers the above physical and biological characteristics when developing health guidelines.
Exposure Dose Estimation
To link the site's human exposure potential with health effects that may occur under site-specific conditions, ATSDR estimates human exposure to the site contaminant from ingestion and/or inhalation of different environmental medium (). The following relationship is used to determine the estimated exposure to the site contaminant:
ED = © x IR x EF)/ BW
ED = exposure dose (mg/kg/day)
C = contaminant concentration
IR = intake rate
EF = exposure factor
BW = body weight
Standard body weights for adults, young children, and toddlers are 70 kg, 16 kg, and 10 kg, respectively. The maximum contaminant concentration detected at a site for specific medium typically is used to determine the estimated exposure. Use of the maximum concentration will result in the most protective evaluation for human health. The standard ingestion rates for water are 2 liters/day for adults and 1 liter/day for school-aged children Incidental ingestion of contaminants from surface soil was assumed to be 21 mg/day for children and 12 mg/day for adults. Some exposures are intermittent or irregularly timed. For those exposures, an exposure factor (EF) is calculated which averages the dose over the exposed period. When unknown, the biological absorption from the environmental media (air, water) is assumed to be 100%.
How Risk Estimates are Made
Non-Cancer Risks
For non-cancer health risks, the contaminant intake was estimated using exposure assumptions for the site conditions. This dose was then compared to a risk reference dose (estimated daily intake of a chemical that is likely to be without an appreciable risk of health effects) developed by ATSDR or EPA.
Non-cancer effects, unlike cancer effects, are believed to have a threshold, that is, a dose below which adverse health effects will not occur. As a result, the current practice is to identify, usually from animal toxicology experiments, a no-observed-adverse-effect-level (NOAEL). This is the experimental exposure level in animals at which no adverse toxic effect is observed. The NOAEL is then divided by an uncertainty factor (UF) to yield a risk reference dose. The UF is a number which reflects the degree of uncertainty that exists when experimental animal data are extrapolated to the general human population. The magnitude of the UF takes into consideration various factors such as sensitive subpopulations (for example; children, pregnant women, and the elderly), extrapolation from animals to humans, and the incompleteness of available data. Thus, exposure doses at or below the risk reference dose are not expected to cause adverse health effects because it is selected to be much lower than dosages that do not cause adverse health effects in laboratory animals.
The measure used to describe the potential for non-cancer health effects to occur in an individual is expressed as a ratio of estimated contaminant intake to the risk reference dose. If exposure to the contaminant exceeds the risk reference dose, there is concern for potential non-cancer health effects. As a rule, the greater the ratio of the estimated contaminant intake to the risk reference dose, the greater the level of concern. A ratio equal to or less than one is generally considered an insignificant (minimal) increase in risk.
Cancer Risk
Increased cancer risk were estimated by using site-specific information about exposure levels for the contaminant of concern and interpreting them using cancer potency estimates derived for that contaminant by EPA. An increased excess lifetime cancer risk is not a specific estimate of expected cancers. Rather, it is an estimate of the increase in the probability that a person may develop cancer sometime in his or her lifetime following exposure to that contaminant.
There is insufficient knowledge of cancer mechanisms to decide if there exists a level of exposure to a cancer-causing agent below which there is no risk of getting cancer, namely, a threshold level. Therefore, every exposure, no matter how low, to a cancer-causing compound is assumed to be associated with some increased risk. As the dose of a carcinogen decreases, the chance of developing cancer decreases, but each exposure is accompanied by some increased risk.
There is no general consensus within the scientific or regulatory communities on what level of estimated excess cancer risk is acceptable. Some have recommended the use of the relatively conservative excess lifetime cancer risk level of one in one million because of uncertainties in our scientific knowledge about the mechanism of cancer. Others feel that risks that are lower or higher may be acceptable, depending on scientific, economic, and social factors. An increased lifetime cancer risk of one in one million or less is generally considered an insignificant increase in cancer risk.
Sources of Health Guideline Information
ATSDR has prepared toxicological profiles for many substances found at hazardous waste sites. Those documents present and interpret information on the substances. Health guidelines, such as ATSDR's MRL and EPA's RfD and CSF are included in the toxicological profiles. Those health guidelines are used by ATSDR health professionals in determining the potential for developing adverse non-cancer health effects and/or cancer from exposure to a hazardous substance. Preparers of this public health assessment have reviewed the profiles for the contaminants of concern at the Pownal Tannery National Priorities List site.
APPENDIX E - Comparison of Estimated Exposure Dose to Health Guidelines
Appendix E - Results of Comparison of Estimated Exposure Dose to Health Guidelines for Persons Exposed to On-Site Contaminants in Building Surface Soil at the Pownal Tannery National Priorities List Site, North Pownal, Bennington County, Vermont
| Contaminant | Health Guideline (mg/kg/day) | Cancer Class | ||
| Value | Source | Exceeded by Estimated Exposure Dose | ||
| Arsenic | 0.0003 0.0003 |
MRLc RfD |
No | A |
| Barium | 0.07 | RfD | No | |
| Cadmium | 0.0002 0.001 |
MRLc RfD |
No | B1 |
| Iron | Unknown | |||
| Lead | None | B2 | ||
| Manganese | 0.005 | RfD | Yes - child | |
| Vanadium | 0.003 | MRLi | No | |
| 2-Methylnaphthalene | Unknown | |||
| 2,3,7,8-TCDD | 1E-9 2E-8 2E-7 |
MRLc MRLi MRLa |
No | RAC |
| 4-Nitroaniline | Unknown | |||
| 4,4'-DDT | 0.0005 | MRLi MRLa RfD |
No | B2 |
| Bis(2-Ethylhexyl)phthalate | 0.4 1 0.02 |
MRLi MRLa RfD |
No | B2 |
| Dibenzofuran | Unknown | |||
| Endrin Ketone | Unknown | |||
| carcinogenic PAHs | None | B2 | ||
| Pentachlorophenol | 0.001 0.005 0.03 |
MRLi MRLa RfD |
No No No |
B2 |
APPENDIX F - ATSDR Plain Language Glossary of Environmental Terms
Revised -15Dec99
APPENDIX G - Public Comments and ATSDR's Responses
ATSDR released the Pownal Tannery Public Health Assessment on September 5th, 2000 for public comment. A letter was sent to local citizens announcing the availability of the document, the comment period, and repositories where the document could be reviewed in early October. The official comment period ended October 16th, 2000, but ATSDR allowed an additional 30 days for comment.
No public comments were received by ATSDR.