Hazardous Waste Site Management Water Quality Issues (1988) / Chapter Skim
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9. ESTIMATING HEALTH RISKS AT HAZARDOUS WASTE SITES: DECISIONS AND CHOICES DESPITE UNCERTAINTY
9. ESTIMATING HEALTH RISKS AT HAZARDOUS WASTE SITES: DECISIONS AND CHOICES DESPITE UNCERTAINTY
Pages 152-176
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From page 152... ...
We present some of the complex characteristics of waste sites, a synopsis of risk assessment methodology, and a summary of several examples of comprehensive quantitative risk estimations. Finally, we discuss some of the inherent uncertainties in risk assessments and somes means of dealing with them to reach conclusions usable in risk management.
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From page 153... ...
provide an orderly means for analyzing scientific information, identifying critical data, elucidating uncertainties, and comparing estimates of risk and safety (i.e., acceptable risk)
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From page 154... ...
. Historically, risk assessments have been applied largely to single substances, but the need for comprehensive evaluations of complex exposure from operations such as manufacturing facilities and waste sites has spurred the development of methods for assessing risks from mixtures.
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From page 155... ...
. Such schemes afford the opportunity to achieve a collective estimate of cancer risks without ignoring biologic reality about differences in potency.
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From page 156... ...
and UCR of a substance can be compared to select a single chronic toxicity score. EXPOSURE CONS~ERATIONS Hazardous substances can escape from waste sites as vapors or fumes, dissolved in water, or attached to dust particles and carried by wind and water.
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From page 157... ...
Water in the vicinity of waste sites is another grave concern. The United States has many ground water reservoirs that are ideally situated to receive liquid wastes deposited in unlined cavities.
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From page 158... ...
Substances that are present in high concentrations and that axe likely to migrate from the site were scored high on the basis of likelihood of exposure. The third factor reflected governmental concerns about hazardous substances and the need for risk assessors to devote some attention to those chemicals singled out for public concern.
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From page 159... ...
The intensity of remediation efforts will probably depend, in part, on whether exposure from the gasifies sites constitutes a large or small fraction of background exposures. The Hyde Park Landfill Love Canal is probably the most notorious waste site in the world.
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From page 160... ...
1 (mg/kg/day) 1 Chemical Inhalation Ingestion Noncarcinogenic PAHe Acenaphthene Acenaphthylene Anthracene Fluoranthene Fluorene Naphthalene Phenanthrene Pyrene Carcinogenic PAHs Benzota)
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From page 161... ...
ENVIRON analyzed possible exposures through ingestion of and skin contact with contaminated water and soil, as well as through inhalation of volatile organic chemicals. The estimated upper bound to risks for cancer following lifetime exposure in the
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From page 162... ...
Butyl benzyl phthalate NA NA NA 25. di-n-butyl phthalate NA 7.59E-O9 NA 26.
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From page 163... ...
Inhal ( ) ( Nonjarclnogen Carci ogen Noncarcinogen Carcinogen Nonjarclnogen MDD/ADI RISK*
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From page 164... ...
Heptachlor epoxide NA NA NA 93. Hexachlorobenzene S.28E-11 NA 6.51E-11 94.
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From page 165... ...
Dermal (Water) Noncarcinogen Carcinogen (mg/m {S )
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From page 166... ...
NOTE: ADI = acceptable daily intake, MDD = maximum daily dose, and NA = not applicable.
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From page 167... ...
Carcinogen Noncarcinogen Carcinogen Noncarc~nogen (mg/m3 )
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From page 168... ...
In the meantime, the use of all privately operated wells for human consumption wan halted, and replacement water was provided from another source known not to contain TCE. The risk assessment conclucled that if the plume were allowed to migrate unchanged, the unwanted substance would contaminate the water supply of the entire community of some 80,000 residents in 2 to 5 years.
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From page 169... ...
Most important, a hydrogeologic investigation reveaTed that the ground was porous (no clay lens was present to act as a barrier against migration) ; that the materials had been deposited in a sinkhole that acted as a funnel into the underground aquifer; that the rock formation underlying one part of the area was greatly fractured, providing direct pathways to the well field; and that the direction of the flow of ground water was from the waste site to the well field.
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From page 170... ...
1 ADI (mg/kg/day) 1.1 x 101 Acenaphthene Acenaphthylene Acetone Anthracene Areenic Bensene Benzidine Benzo~ajanthracene B enso (k ~ fluoranthene Benzo(0perylene Beryllium B romodichloromethane Bromophenyl phenyl ether, d Butyl benzyl phthalate Cadmium Carbon tetrachloride Chlordane Chlorobensene Chloroethane B is (2 -chloroethoxy)
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From page 171... ...
Lead Malathion Mercury Methyl chloride Methyl-4,5-Dinitrophenol, 2 Methyl-d,6-Dinitrophenol, 2 Methyl ethyl ketone Methyl isobutyl ketone Naphthalene Nickel Nitrobensene Nitrophenol, 2 Nitrophenol, 4 Nitrosodimethylamine, N- 2.ff x 10 Nitrosodi-n-propylamine, N Parathion Pentachlorophenol Phenanthrene Phenol Pyrene Selenium Sil`,er Tet rachloroethylene Tetrahydrofurane Toluene Trichlorobensene, 1,2,4 Trichloroethane, 1,1,1 Trichloroethane, 1,1,2 Trichloroethylene Trichlorofluoromethane Trichlorophenol, 2,4,ff Trimethylbensene (mixed isomer) Xylenes 1 7 -2 7.8 x 10 1.S 1.S 2 1.d x 10 1.2 5.1x10 2 5.7 x 10 2 2.0x10 2 1.S 1.0 1 1.3x10 1 i.0 x 10 2 2.0 x 10 S.0xl0 5 2.0x10 5 S.OxlO 3.5 x 10 2 2.0 x 10 2.0 x 10 2.0x10 2 2.0x10 1.0 S.0 x 10 2 l.O x lO_ 1.S x 10 1.S x 10 S.OxlO ~ S.0%10 2 S.OxlO 1.0 x 10 l.OxlO 1 1.0x10 1 S.0 x 10 2.0 x 10 S.0 x 10_2 2.0x10 2 2.9 x 10 2.0x10 1 S.OxlO 1 2.S NOTE: ADI = acceptable daily intake, UCR = unit cancer risk.
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From page 172... ...
DIS CUSSION Data Problems Quantitative conclusions about the health risks associated with a site often appear precise and accurate. That appearance is not always correct, however.
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From page 173... ...
In turn, that basis provides the foundation for solidly based environmental standards of exposures to the waste products. CONCLUSIONS AND CATIONS Quantitative risk assessment is the only method currently available to estimate risks from waste sites.
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From page 174... ...
Tardiff's paper very interesting in that it touched upon several important issues that all of us involved in quantitative risk assessment of hazardous waste sites are concerned with. However, like many papers written in this field, it leaves us with many unanswered questions concerning the future of quantitative risk assessment.
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From page 175... ...
One of the major questions that we at the Agency for Toxic Substances and Disease Registry (ATSDR) are continually faced with deals with the issue of inhalation exposures from volatile organic compounds in contaminated ground water.
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From page 176... ...
~ wonder about the use of the MTD in the chronic bioassay and what appears to be a growing trend of treating high-dose carcinogens as noncarcinogens, or compounds that have thresholds, when we are looking at them in low-level concentrations. The final question deals with one of the specific critiques, the Hyde Park landfill, for which you quantify both the carcinogenic and noncarcinogenic risks from dermal exposure to contaminated water.
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