Uncertainty factor Environmental Protection

The Environmental Protection Agency derived a reference dose (RfD) of 0.08 mg/kg/day based on the same NOAEL from the Hart (1980) study. The RfD, however, utilized an additional uncertainty factor of 10 to extrapolate to chronic exposure. 

BPT = Best Practicable (Control) Technology EPA - Environmental Protection Agency FDA = Food and Drug Administration FSIS = Food Safety Inspection Service IARC = International Agency for Research on Cancer NSPS = New Source Performance Standards OWRS = Office of Water Regulations and Standards PSES = Pretreatment Standards for Existing Sources PSNS = Pretreatment Standards for New Sources RfD Dose u.f. = Uncertainty Factor... 

KEMI. 2003. Human health risk assessment. Proposals for the use of assessment (uncertainty) factors. Application to risk assessment for plant protection products, industrial chemicals and biocidal products within the European Union. Report No. 1/03. Solna, Sweden Body for Competence and Methodology Development, the Swedish National Chemicals Inspectorate and Institute of Environmental Medicine Karolinska Institutet, Solna, Sweden. 

It is noteworthy that the styrene reference concentration (RfC) in the Integrated Risk Information System is based on the biomarker-response relationship found in workers (Mutti et al. 1984 EPA 1998). The Environmental Protection Agency (EPA) used the relationship of urinary biomarker to ambient-air concentration of workers to develop an RfC that was adjusted for the difference in exposure time between the workplace and the general population. That is a valid approach because it derives a workplace concentration-toxicity relationship in workers, which can then be adjusted for the general population to account for differences in exposure time and can take uncertainty factors into account. It is different from direct adjustment of the styrene BEI to evaluate human population biomonitoring data on styrene metabolites in urine, which would have the uncertainties described above and in Chapter 5. 

The Environmental Protection Agency has established guidelines for toxicological dose and endpoints for acetamiprid. Using the no-observed-adverse-effect level (NOAEL) and uncertainty factor (UF), the reference dose (RfD) can be calculated. For acute dietary ingestion for infants and children, NOAEL = 10 mg kg RfD = 0.10 mg kg day Chronic dietary expo-... 

The Office of Environmental Health Hazard Assessment, California Environmental Protection Agency, has developed an inhalation reference exposure level of 50ppb (300 pgm ) based on a whole-body inhalation study in rats, 7hday, 5 days week for 6 months. The critical effects are pathological changes in the liver and kidney, with an (average experimental exposure) LOAEL of 5.3 ppm, and a total uncertainty factor of 300. 

A 90 day rat oral gavage study resulted in depressed body and organ weights and depressed food consumption in high dose males (3600 mg kg day ). No effects were noted at 900 mg kg day Erom these results, the US Environmental Protection Agency derived an oral reference dose of 0.9 mg kg day for ethyl acetate (uncertainty factor = 1000). 

Hexane is currently under review for its carcinogenicity however, it is not classified as a carcinogen at the present time. A US Environmental Protection Agency (EPA) reference concentration of 0.2mgm was calculated based on an epidemiological inhalation study with an uncertainty factor of 300. Critical effects were reported to be neurotoxicity and electrophysiological alterations. 

Uncertainty factors (UFs) Guidelines from Health Canada, the International Programme on Chemical Safety (IPCS), the Netherlands National Institute for Public Health and the Environment (RIVM), the US Agency for Toxic Substances and Disease Registry (ATSDR), and the US Environmental Protection Agency (EPA) Health Canada IPCS RIVM ATSDR EPA... 

See also Benchmark Dose Chemical-Specific Adjustment Factor (CSAF) Environmental Protection Agency, US International Programme on Chemical Safety Risk Assessment, Human Health Uncertainty Analysis. 

Abbreviations EPA, Environmental Protection Agency ATSDR, Agency for Toxic Substances and Disease Registry FDA Food and Drug Administration NOAEL no-observed-adverse-effect level LOAEL, lowest-observed-adverse-effect level UF, uncertainty factor SF, safety factor RfD, reference dose (an amount of a substance that is anticipated to be without adverse health effects in humans, including sensitive populations, when ingested daily over a lifetime MRL, minimal risk level (an estimate of daily human exposure to a hazardous substance that is likely to be without an appreciable risk of adverse noncancer health effects over a specified route and duration of exposure) pTDI, provisional tolerable daily intake (maximum daily exposure level to a contaminant provisional meaning that it is considered temporary until more data are available, especially the completed Seychelles study) JECFA, Joint FAO/WHO Expert Conunittee on Food Additives pTWl, provisional tolerable weekly intake. 

The recommended daily intake values as estimated by the United States Environmental Protection Agency (EPA) (4) and the Centers for Disease Control (CDC) (5,6) have been used for the present calculations. For the EPA the "Acceptable Daily Intake" (ADI) for 2,3,7,8-TCDD is 1 x 10" g/kg/day. This value is based on the lowest-observed-adverse-effect-level (LOAEL) of 1 X 10 g/kg/day for a reproductive effect in rats (7,8), a 10-fold uncertainty factor because a LOAEL is used as the basis of the calculation rather than a no-observed adverse effect level (NOAEL), and an additional uncertainty factor of 100 based on the existence of lifetime animal studies and lack of knowledge of the effects in man. (4). For a 10" (1/1,000,000) cancer risk, the EPA has estimated a 95% lower-limit criteria for a lifetime intake of... 

Risk assessments for anionic surfactants are obtained by comparing environmental exposure concentrations to effect levels (the quotient method). A protection factor that reflects the environmental safety of the material is calculated by dividing the exposure level by the effect concentration. If the protection factor is greater than 1, the material is deemed safe. Although this approach to assessing risk yields a numerical value that could be interpreted as the relative safety of a compound, comparisons of protection factors for different compounds should be avoided. The risk assessment for each material must be considered separately because of differences in chemical properties and differences in the database used to obtain the protection factor. In addition, the degree of uncertainty in the exposure and effect... 

The Predicted No Effect Concentration may be derived from laboratory, field or theoretical data. Studies conducted on single species such as acute toxicity to fish (IX so) over a relatively short time scale (normally 40 or % h) and with death as the only recorded endpoint is, by itself, only of limited value in deciding whether or not a predicted environmental level of a dye is, or, is not, acceptable. Extrapolation from acute effects to chronic and ecosystems effects involves numerous uncertainties. In order to protect the ecosystem, conservative assessment factors have been introduced based on the statistical analysis of a set of data [17] for chronic exposure. The US-EPA [18] has proposed to apply a factor of KXX) for a single acute L(E)Cso value or 100 to the lowest value if all 3 tests are available (fish, daphniae, algae). These models have in common that they assume steady state concentrations in the aquatic environment. 

Some variants of the LOPA methodology determine the harm more precisely in terms of harm caused to people and harm to the environment. This approach, which is required by the tolerability of risk framework for human safety. Reducing risks, protecting people, requires consideration of additional factors such as the probability of ignition, the performance of containment systems, and the probability of fatality. For a similar perspective of environmental issues assessors should consult the relevant Environment Agency sector BAT guidance. All of these factors may be subject to considerable uncertainty, and the way the LOPA is carried out needs to reflect this uncertainty. Uncertainties are present in all calculations but sensitivity analysis can be used to help understand the uncertainty. 

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