Regulating Pesticides (1980) / Chapter Skim
Currently Skimming:
4. Risk Assessment
4. Risk Assessment
Pages 65-98
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 65... ...
Indeed, within the area of human health, oPP's attention is generally focused on possible oncological and mutagenic effects of suspect pesticides, since these are the most apparent adverse ejects of the chemical pesticides now in widespread use and currently being introduced. The discussion in this chapter will therefore concentrate on the assessment of dangers to human health and particularly on the danger of inducing cancers.
|
From page 66... ...
The second major section of the chapter deals, more briefly, with the analysis of risks other than those to human health. HAZARDS TO HUMAN HEALTH EXPOSURE ANALYSIS Current Approach The purpose of oPP's exposure analysis is to determine in as quantitative a manner as possible the number of people exposed to a pesticide by various routes and the doses they receive.
|
From page 67... ...
Data for Exposure Analyses Ideally, a detailed exposure analysis for a pesticide would include estimates of exposure by all routes, both for the entire U.~. population and for particular subgroups that may have different levels of exposure, especially applicators and pickers.
|
From page 68... ...
Relevant information for exposure through ingestion includes data on food tolerances, residues, food consumption patterns, food processing and distribution practices, and drinking water surveys (Severe 1977a)
|
From page 69... ...
Inhalation Exposure Estimates of respiratory exposure (i.e., via inhalation) are presented in terms of ambient air concentrations of the pesticide in the breathing zone of exposed persons (Severe 1978a)
|
From page 70... ...
Dermal Exposure Estimates of dermal exposure are presented in terms of milligrams of pesticide per hour that come into contact with the skin of exposed persons. The clothing worn by agricultural workers plays a critical role in the determination of dermal exposures (Severe 1978a)
|
From page 71... ...
Assumptions made in preparing exposure analyses for the three pesticides displayed in Table 4.1 are summarized in Table 4.2. oPP's approach to estimating exposure of spray applicators to chlorobenzilate, for example, was based largely on the assumption that inhalation and dermal exposures vary the same way under different application conditions.
|
From page 72... ...
of application Lindane Residues in treated commodities approach established tolerance levels Inhalation and dermal exposures vary the same way under different application conditions Lindane will continue to be used indefinitely at about the current rate(s) of application a Nitroso dipropylamine.
|
From page 73... ...
In considering enforcement, oPP assumes that label restrictions will limit occupational exposure to some extent, and in this context, develops various regulatory options that may result in reduced levels of exposure. For example, the recommended regulatory option for chlorobenzilate includes requirements for specific types of clothing and respirators to be worn during application (U.S.
|
From page 74... ...
Agricultural experiment stations are particularly important sites for these visits and have the added advantage of often directing attention to useful publications of the stations or other sources that the usual literature indexes do not include. Economic Life of a Pesticide For many pesticides, particularly those likely to induce cancers, the likelihood that an effect will eventualize is cumulative, so that estimates of lifetime exposures, rather than of rates of dosage during short periods, are relevant to risk assessments.
|
From page 75... ...
When regulatory options are considered on a use-by-use basis, as they are in this report and in the oPP evaluations, the 10-year average figure, with its accompanying range, appears appropriate for estimating anticipated economic lifetimes until more reliable estimates become available. This figure, however, is rough and purely provisional and should be quickly superceded.
|
From page 76... ...
The Committee's analysis of the exposure estimates for chlorobenzilate, given in Chapter 7, shows that in that instance the worst-case levels of exposure are highly improbable. The use of tolerance levels for estimating the concentrations of pesticide residues in foods is an extreme instance of the same bias.
|
From page 77... ...
. lion: For these reasons, the Committee makes the following recommenda · oPP should continue to use its current procedures (with the modifications discussed aboveJ for estimating exposures associated with various regulatory options.
|
From page 78... ...
Current Practice . The general procedures for assessing the risks to human health posed by suspected carcinogens are described in the Agency's Health Risk and Economic Impact Assessments of Suspected Carcinogens: Interim Procedures and Guidelines (U.S.
|
From page 79... ...
With regard to the second issue determining the extent of the cancer risks the guidelines commit the Agency to quantitative risk extrapolations (U.S. EPA 1976: Appendix I, 21404~.
|
From page 80... ...
At the same time, the guidelines recognize that there are considerable uncertainties surrounding these risk analyses (see below) , and accordingly emphasize that the extrapolation results should be interpreted only as a "warning signal" rather than as an actual indicator of excess cancer incidence.
|
From page 81... ...
Moreover, such evaluations are not presented with confidence intervals. Second, at least two extrapolations of inadequately tested reliability must generally be applied to bioassay data to derive estimates of human cancer incidence.
|
From page 82... ...
Although there is obvious value to developing and verifying methods for extrapolating from observed experimental tumor responses in animals to erects at low doses in humans, current methods present significant and controversial scientific problems (see I=G 1979~. ~timately, when there is greater insight into the mechanism of carcinogenesis and methods are available for integrating variations in individual human susceptibility and the erects of exposures to other carcinogens and co-carcinogens, extrapolations based on this insight may provide reliable estimates of human cancer incidences from the use of a compound.
|
From page 83... ...
Recommendations For the preceding reasons the Committee recommends that EPA not require CAG to estimate the numbers of people who would be expected to contract cancer or other diseases as a consequence of pesticide (or other chemical) use under various regulatory options.
|
From page 84... ...
The Carcinogenic Activity Indicator The remainder of this subsection is devoted to a procedure by which the Committee feels compounds can be placed on a scale of relative human carcinogenic activity based on animal bioassay data. Expressions of the relative carcinogenic potentials of compounds have been described previously by means of a number of "potency indexes" (for example, see Meselson and Russell 1977~.
|
From page 85... ...
The CAYS shown were all computed from published experimental data. They show estimates of the percent of animals exposed to the compound listed that developed tumors as a result of the exposure in relation to the lifetime dose (in millimoles per kilogram of body weight)
|
From page 87... ...
~D _ ~act Ox - ~- ~ (~\ _ t_ 1- Ce ~t- ~ ~- Ce ~1 _ ~ ~_ _ _ ~ ~_ ~ l ~ ~ cry ~ ~ ~ ~ cry ~ ( V ~- ~ ~ ~ _ ~ _ Z O Z Z Z O Z ;~ d.
|
From page 88... ...
The table therefore can serve as a scale against which the pathological activity of any compound under review can be measured if experimental conditions are comparable (see Appendix B)
|
From page 89... ...
Accordingly: · The Committee recommends that when laboratory data are used to estimate pathological activity, potency indexes, such as the cods defined above, be used to indicate the pathological virulence of the pesticide under consideration and that no numerical estimates of elects on human morbidity or mortality be extrapolated from laboratory data. The estimated potency indexes should be presented as most probable values accompanied by indications of ranges of uncertainty.
|
From page 90... ...
The overall assessment of risks must take all these possibilities into account. For this reason, and perhaps others, the risk assessments in available oPP position documents have not followed a standard format.
|
From page 91... ...
The risk analysis data were therefore summarized by displaying the increase in the maximum, or worst-case, lifetime probability of contracting cancer for members of each of seven population groups and for seven possible regulatory options (see Table 6.1~. In the analysis of the risk associated with endrin (U.S.
|
From page 92... ...
The results must be presented as a table or graph that shows the numbers of people exposed to different doses. Furthermore, the dose to which each population segment is exposed may be different under different regulatory options, the ejects of which can be indicated by a comparative exposure graph as illustrated in Figure 4.2.
|
From page 93... ...
it can be shown that if doses Do and Dy are not very dissimilar, the applicator population, for example, is consequently exposed to pesticide Y at a dose equivalent to Dye units of pesticide X where Dy = CA~y CAix Dy. That is, Dyeis the dose of pesticide X that produces the equivalent pathological eject of the dose of pesticide Y that applicators might be expected to receive under regulatory Option B
|
From page 94... ...
Consequences of different regulatory options can then be compared by the methods just described, using the appropriate activity indicators and, when available, human data. ANALYSIS OF ENVIRONMENTAL RISKS In addition to considering the risks to human health posed by an RPAR compound, the Agency is also obligated under 40 CFR 162.11 to identify and weigh any environmental risks associated with the chemical.
|
From page 95... ...
When quantitative environmental risk analyses are made, we further recommend that estimates be reported as ranges. As for human exposure analyses, the ranges should be presented as a pair of numbers, one showing the most-probable environmental risk and the other showing the maximum-plausible estimate.
|
From page 96... ...
Exposure Analyses for Lindane. Hazard Evaluation Division, Office of Pesticide Programs, U.S.
|
From page 97... ...
Induction of stomach cancer in rats and mice by halogenated aliphatic fumigants. Journal of the National Cancer Institute 51: 199~1995.
|
From page 98... ...
(1978a) Draft Procedures Manual for Preparation of Human Exposure Analyses.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.