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5. Application of the Model to Chemical Hazards
Pages 100-139

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From page 100...
... Specifically, the committee recommended that risk assessment play a major role in the establishment of limits for chemical residues in meat and poultry products destined for human consumption, in the prevention and characterization of hazards, in the setting of priorities for controlling residues, and in the design of sampling methods. This chapter contains a discussion of risk assessment as a guide to the management of chemical hazards in poultry products, criteria for j udging the safety of poultry products con ~ tanning residues, some approaches to ensuring that safety criteria are met, and the types of data and analysis needed to assess the public health impact of chemical residues in poultry products.
From page 101...
... It is a premise of this report that predictive methods developed for and widely used in many areas of public health protection are appropriate for assessing the risks of exposure to chemical residues, establishing appropriate health protection standards for such residues, and guiding the development of programs to manage the risks presented by the residues. Parts or all of the s premise have been adopted by the Food and Drug Administration, the Environmental Protection Agency, and other government agencies charged with protecting consumers from such residues, especially for risk assessment and the establishment of standards.
From page 102...
... 102 0 o So o ° E ~ ~ o _ It he 5 In In U)
From page 103...
... Clinical investigations of exposed persons have provided information on the toxicity of consumer and industrial products (MacMahon and Pugh, 1970; OSTP, 1985~. There are, however, the following limitations in the use of both Epidemiological and clinical data for identifying the toxic properties of chemical substances: · The deliberate, controlled exposure of human beings to identify toxic effects is, with few exceptions , unethical.
From page 104...
... Animal experiments are the principal source of toxicity data for assessing the human risks and safety of pesticides, food and color additives, and food and drinking water contaminants, and there is no reason not to rely on such data for similar assessments of chemical residues in poultry products. Manifestations of Toxicity and Tests to Identify Them.
From page 105...
... , except when it is unusually potent. Determination of carcinogenicity usually requires that test animals be exposed for most of their lifetimes.
From page 106...
... This phase of risk assessment includes a critical review of clinical 9 epidemiological, and experimental toxicity data and identification of the inherent hazardous properties of a substance, the degree to which these hazards are known, and the uncertainties in the data. A critical feature of this process are j udgments about the strength of inferences for human risk from data derived from animal studies .
From page 107...
... . The experimentally determined relationship between dose and risk at high doses must therefore be used to assess risk for dose levels corresponding to human exposures.
From page 108...
... Exposure Assessment Exposure assessment is a highly complex subject, and is reviewed here only to the extent necessary to prepare for the later discussion of chemical residues in poultry products. In this phase of risk assessment, knowledge of the magnitude and duration of human exposure to environmental agents and, most importantly, the dose that results from this exposure, is essential As used herein, the term exposure describes a person's contact with a medium (e.g., poultry)
From page 109...
... 109 TABLE 5-1 Unit Cancer Risks and Strength-of-Evidence Categories for 47 Chemicals, as Evaluated by the EPA Carcinogen Assessment Groupa Level of Evidenceb Unit Cancer Risk .
From page 110...
... 110 TABLE 5-1 (continued) Level of Evidenceb Unit Cancer Risk Compound Humans Animals per mg/kg bw/dayC Dieldrin ~ S 30.4 Ep~chlorohydrin I S 9.9 x 10-3 Bis(2°chloroethyl~ether I S 1.14 Bis~chloromethyl~ether S S 9,300(In)
From page 111...
... , W (human occupational exposure) , and H (human drinking water exposure)
From page 112...
... Daily doses of chemical residues received by humans through poultry consumption are estimated by determining the chemical concentrations In various poultry products and the average daily intake of each product. FSIS's National Residue Monitoring Program has collected information on 20 chemicals found as residues in young chicken carcass samples examined from 1979 to 1984 (Table 5-2~.
From page 113...
... 50 5 . 00 PESTICIDES: Benzene ~ hexachloride 1981 Fat 467 S 1982 Fat 432 2 1983 Fat 422 2 1984 Fat 448 6 Chlordane: 1981 Fat 469 3 1982 Fat 433 1 1983 Fat 420 3 Dieldr~ n: DDT: 1 1979 Fat 221 10 1 1980 Fat 582 14b 1981 Fat 458 14 1982 Fat 426 7 1983 Fat 412 12 1984 Fat 428 26 1979 Fat 211 19 1 1 1980 Fat 502 92b 2c 1981 Fat 409 60 2 1 1982 Fat 414 19 1 1983 Fat 375 45 2 2 1984 Fat 391 61 1 Endrin: _, ~ 1980 Fat 595 1 1981 Fat 470 2 1984 Fat 452 2 Heptachlor: 1979 Fat 231 1 1980 Fat 590 6b 1981 Fat 768 4 1983 Fat 422 1 1 1984 Fat 447 7 Lindane: 1979 Fat 231 1 1980 Fat 588 8b 1981 Fat 470 2 1 1983 Fat 421 2 1 1984 Fat 447 7 MethoxYchlor: 1979 Fat 231 1 1984 Fat 452 1 Polychlorinated biphenyls: 1983 Fat 423 1 1 1 aFrom FSIS, National Residue Monitoring Program, unpublished data, 1979-1984.
From page 114...
... 00 PESTICIDES (cont.) Hydroxychlorinated biphenyls: 1979 Fat 225 7 1980 Fat 588 8b 1981 Fat 469 3 1984 Fat 450 4 p-Chlorophenol: 1981 Liver 0 6 3 1983 Liver 247 9 1 1 1 ENVIRONMENTAL CONTAMINANTS: Arsenic: 1979 Liver 42 15 15 23 46 81 30 1980 Liver 41 51b 230~ 43d Be 4 1981 Liver 30 23 17 42 103 152 39 2 1982 Liver 30 14 10 22 71 82 16 1 1984 Liver 50 11 12 19 77 130 28 1979 Muscle 1 1 1 1980 Muscle 0 6b 1c 1981 Muscle 41 48 4 1 1982 Muscle 1 1 1984 Muscle 1 1 Mercury: 1979 Liver 1 Selenium: 1979 Liver 4 7 1 1979 Muscle 4 3 3 1 1 1979 Kidney 1 6 5 PHARMACEUTICALS AND ANTIBIOTICS: Chlortetracvcline: 1984 1982 1984 Decoquinate: 1983 OxYtetracycline: Liver 3 Kidney 393 1 Kidney 274 2 Liver 198 1983 Kidney 342 PYrante1 tartrate: 1983 1983 Sulfadimethoxine: 1981 1982 Sulfouimoxaline: Liver 38 24 11 Muscle 2 2 Kidney 313 Kidney 286 1 1981 Liver 4 1 1981 Kidney 312 1 1 1982 Kidney 286 1 17 72 169 63 1 .
From page 115...
... The human population is also exposed to a wider range of other environmental agents and lifestyle factors, e.g., it includes people who smoke, drink alcoholic beverages, and take medicines. Because of such additional exposures, the background of risk for human populations is different and often higher than that of test animals and may generally increase the susceptibility of the human population in comparison to test animals.
From page 116...
... Smaller safety factors are sometimes used for certain populations (e.g., relatively healthy, adult worker populations) believed to be less vulnerabl e than the general population and, rarely, when adequate data on NOELs are available from studies in human populations.
From page 117...
... for additives be set at the lowest level at which the desired technical effect will be produced. Animal Drug Residues on Food FDA establishes ADIs for animal drug residues using the procedures described above for food and color additives.
From page 118...
... Industry has not had to supply all the data necessary to establish acceptable limits on exposure, although some relevant data are submitted to EPA or required by the Toxic Substances Control Act. LIMITATIONS AND UNCERTAINTIES IN RISK ASSESSMENT Assessments of risks are based on data that vary in quality and quantity among different environmental chemicals.
From page 119...
... CHEMICAL RESIDUES IN POULTRY PRODUCTS AND THEIR PUBLIC HEALTH RISKS Sources and Types The 1985 NRC report on meat and poultry inspection included a survey of the various types of chemicals that are used in meat and poultry production or that may occur as inadvertent contaminants (NRC, 1985~. For present purposes it is not necessary to duplicate that survey, but only to organize the information in a form more convenient
From page 120...
... Class 2. Widespread environmental contaminants to which poultry may be exposed because of their presence in poultry feed or drinking water.
From page 121...
... The methods of risk assessment described above could then be applied to residue concentration data and information on human intake of poultry products to estimate the public health risk posed by chemical residues in poultry products. This approach is discussed further in the last section of this chapter.
From page 122...
... 5. Establishing quality control programs to ensure that poultry feeds, drinking water, or other sources do not contain the chemicals of concern at levels exceeding those identif fed in Activity 4.
From page 123...
... EPA has collected information on many potential inorganic and organic contaminants of drinking water and has established maximum contaminant levels for many but not all of them. EPA, FDA, and USDA have collected information on some of the known contaminants of feed ingredients, and FSIS has gathered some data on residues in poultry products.
From page 124...
... Information useful in identifying such chemicals include historical and current reports on accidental exposure of poultry and accidental contamination of poultry products, drinking water, and poultry feed ingredients. Also useful are data on industrial activities in the vicinity of poultry production facilities and feed production operations O This type of information, which is available from several sources (e.g., EPA, FDA, USDA, various state agencies, and the scientific literature)
From page 125...
... More specific statements about the adequacy of the data cannot be made without ~ thorough literature review, which should make it possible to separate substances for which adequate risk assessments can be performed from those requiring additional toxicological data. Because substances in Class 2 are widespread environmental contaminants, chronic human exposure is possible.
From page 126...
... that can be tolerated by poultry to ensure that residue levels do not exceed tolerances. With such information, it would be possible to monitor poultry feed and drinking water as an alternative to, or in addition to, monitoring poultry products .
From page 127...
... The data from these studies can then be used to establish tolerance levels for Class 1 substances in drinking water or feed. The adequacy of the toxicological data base for establishing feed or drinking water tolerances for Class 1 substances is discussed under Activity 2.
From page 128...
... Analytical methods have not been developed for some substances in feed or water. Class 3 substances may be easily overlooked in monitoring feed and water, or they may be encountered at other points in poultry production The intensity and frequency of product monitoring, and priorities assigned to such efforts, should be related to the effectiveness of the feed and water quality control.
From page 129...
... Activity 7. Enforcement Monitoring programs to manage risks are not effective unless they can ensure that excessively contaminated poultry feed or water is not used and that excessively contaminated poultry products do not reach consumers.
From page 130...
... Nevertheless, it is commonly accepted that for all carcinogens there is an exposure ra5ge that6presents only a small risk, e.g., lifetime risks less than 10- or 10- , which reflect highly unlikely events O It is not possible to demonstrate that an ADI carries absolutely no risk for the human population. At best, all that can be claimed for an ADI is that any potential risk is not likely to exceed some very small but quantified risk In the absence of evidence to the contrary, and to provide two different toxicity scales for carcinogens and noncarcinogens, it may be assumed that the range of risk associated with an ADI is the same as that as that considered to be very small carcinogens ~ i .
From page 131...
... Frequent exposures to large fractions of the ADI (through poultry products only or through several environmental media) present higher potential risks than occasional exposures to only a small fraction of the ADI.
From page 132...
... 132 l o _ l in o or C: Sit v o 7 o _ I\ to ; ~ lo lo 70 To lo lo lo, _ _ _, _ _ ~ _ o ASIA ° C,9 a oo , _ o En ~-!
From page 133...
... assuming a lifetime risk no greater 6. The frequency and magnitude of consumption of the mayor tissues in which residues occur.
From page 134...
... In Chapter 7, the committee recommends criteria for sampling chemical res idues pos ing different levels of potential public health risk. Finall y, all eight essential activities of a risk-management program for chemical residues are based on applying, with varying degrees of rigor, the elements of a risk- assessment scheme based on specific types of data.
From page 135...
... are not by themselves adequate for risk assessment, because the following information is lacking: · the quantitative relationship between the levels of residues found in specific tissues examined by FSIS and the levels present in all other edible tissues; the amounts of different poultry products consumed by different segments of the population; the capability of the analytical methods used to detect residues below a certain level of contamination; toxicity data, ADIs, and UCRs for each residue; the level of human exposure resulting from other environmental media in which residues of the same chemicals may be present; and time trends in contamination patterns. The information necessary to perform residue-specific risk assessments is available for many substances, especially those in Class 1.
From page 136...
... Although the committee examined the data and found no evidence of significant public health risks attributable to chemical residues in broilers, risk assessments and data are needed before definitive conclusions can be reached. REFERENCES Asher, I
From page 137...
... 1986. Title 21, Food and Drugs; Section 520.2240a, Sulfaethoxypyridazine drinking water.
From page 138...
... 3. Report of the Safe Drinking Water Committee, Board on Toxicology and Environmental Health Hazards.
From page 139...
... 6. Report of the Safe Drinking Water Committee, Board on Toxicology and Environmental Health Hazards.


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