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6 PESTICIDE RESIDUES
Pages 203-266

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From page 203...
... Thus, sampling and residue testing methods to estimate levels of pesticide residues in the food supply are extremely important components of the risk assessment process. The committee examined pesticide usage, residue sampling and testing methods, and the data on pesticide residues to understand the relative quality of data sets available to EPA as a foundation for recommending practical improvements in data collection and testing; identify the foods in the diets of infants and children with residues of pesticides that cause the greatest public-health concern; assess the need for residue sampling methods and residue testing procedures that can provide the data needed to ensure the protection of infants and children; recommend residue monitoring methods that could be incorporated into an exposure assessment methodology that would ensure the protection of infants and children; identify steps to improve risk assessment and establish priorities for those steps; and determine which, if any, data are of sufficient quality to support risk assessment models designed to protect infants and children.
From page 204...
... Resources for the Future maintains a county-based file of annual pesticide usage estimates by county and by crop for the 184 widely used pesticides that appear on EPA's list for the National Ground Water Survey and the California Priority Pollutant List (Gianessi,1986~. The usage information was derived from the limited ERS surveys and from the annual California survey (State of California, 1981)
From page 205...
... 205 be cn _ _ Go ._ in o ._ ~5 En ._ On o ._ o cl)
From page 206...
... THE OCCURRENCE AND FATE OF PESTICIDE RESIDUES Pesticide residues originate when a crop or food animal (commodity) is treated with a chemical or exposed unintentionally by drift, in irrigation water, in feed, or by other routes.
From page 207...
... For these reasons, it is difficult to estimate actual dietary exposure to pesticides and any associated risk with a high degree of certainty. PESTICIDE REGISTRATION AND THE DEVELOPMENT OF ANALYTICAL METHODS Early in the development of a pesticide, the manufacturer must identify the analytical methods used to ascertain the concentrations of chemicals in formulations (formulation methods)
From page 208...
... To obtain a formal tolerance level, pesticide manufacturers must submit their analytical methods to EPA, which then verifies that the pesticide can be detected at a certain tolerance level for each proposed food use. It is not unusual for a food tolerance level to include the parent chemical and several breakdown products.
From page 209...
... may be too limited to provide the economic incentive needed for chemical companies to develop the analytical methods and residue data required for registration. In such cases, this work is performed by Interregional Project Number 4 (IR-4)
From page 210...
... This is usually done when field plots are sampled to determine residues for registration requirements, but less frequently for monitoring and enforcement of tolerance levels for registered chemicals. Sampling and sample handling for field trials are described by the National Agricultural Chemicals Association (NACA, 1988~.
From page 211...
... This results in an important gap in the residue data, since water represents such a large part of the diets of infants and children. There are two general types of analytical methods for determining residues in foods: single residue methods and multiresidue methods.
From page 212...
... In quantitation, MRMs are used to detect and measure multiple pesticide residues and their metabolites that might be present in a given sample. These MRMs are usually based on gas or liquid chromatography or both.
From page 213...
... must be analyzed separately so that these chemicals can be included in the analytical report. Detection Limits All analytical methods have a limit below which the chemical could not be detected even if present.
From page 214...
... To be of regulatory use, detection limits must be below established tolerance levels. The California Department of Food and Agriculture sets LODs at approximately one-tenth the tolerance level; FDA generally sets them at 0.1 to 0.01 ppm, depending on the chemical; and Florida's Department of Agriculture and Consumer Services sets them at or just below tolerance in order to screen large numbers of samples for clear violations.
From page 215...
... MONITORING The following discussion of monitoring activities for pesticide residues is based primarily on information that existed for 1988 and earlier. The committee realizes that changes in the design and scope of monitoring programs have occurred after 1988 but, unfortunately, information on more recent developments was not generally available for inclusion in the committee's discussion.
From page 216...
... enforces residue tolerance concentrations in meat and poultry; monitors residues in meat and poultry; develops analytical methods for monitoring; and gathers information on the incidence and concentrations of pesticide residues in the food supply. The Agricultural Marketing Service (USDA)
From page 217...
... This informationgathering activity is one component of a larger effort to design a national human exposure survey that, among other things, will measure the route, magnitude, duration, and frequency of human exposure to environmental chemicals. In May 1988, FDA's MRMs included 316 pesticides for which tolerance levels had been set, 74 pesticides with temporary and pending tolerances, 56 pesticides with no EPA tolerance levels (those previously canceled or those used only in foreign countries)
From page 218...
... Since the early 1960s, FDA has gathered its information on pesticide residues through its Total Diet Study (TDS) , also called the Market Basket Study, in which the dietary intakes of pesticide residues (as well as some
From page 219...
... Because of the limitation of the food intake data and residue monitoring methods, coverage is not complete. Human exposure to all pesticides cannot be estimated because some pesticides cannot be detected by the analytical methods used.
From page 220...
... To coordinate pesticide residue data from states and the FDA, the Mississippi State Chemical Laboratory, with FDA funding, has developed two U.S. data collection and dissemination programs: FeedCon provides information on contaminants in animal feeds;
From page 221...
... Tolerance levels must be established for any residue that concentrates during food processing (e.g., milling, cooking, and dehydrating)
From page 222...
... Of these, 8,056 were negative for Alar. From 1988 to the present, NFPA has been building a new pesticide residue data base that currently contains almost 74,000 samples, 97.5% of which had residues below the limit of quantification (LOQ)
From page 223...
... At present, however, NFPA is requiring that each contributor of data complete a residue report form for each reported pesticide-food combination. Among the information required are the analytical method used, detection limits, quantitation limits, and recovery information.
From page 224...
... This is in addition to the inherent variability of residues due to uneven field applications of pesticides to the commodity of interest. Thus, a residue analysis that yields a 1-ppm level should be assigned a range of 0.3 to 3 ppm in the absence of any accompanying data relating to the actual error limits (Keith, 1983; Hance, 1989~.
From page 225...
... Residues that exceed established EPA tolerance levels are subject to confirmation and are included in the residue reports. Residues below the tolerance levels are usually reported but are not always confirmed.
From page 226...
... Surveillance or compliance samples are directed to problem areas suspected of violating tolerance levels and therefore involve intense appraisal of products to which the compounds have been applied. The biases that exist in terms of the number (frequency)
From page 227...
... Moreover, no single survey of pesticides in food commodities has included both surface and groundwater sources of drinking water. As a consequence, it is not yet possible to estimate with any degree of certainty all the variations that must be considered in assessing dietary exposure to pesticide residues in water used in the processing and preparation of foods.
From page 228...
... draws its drinking water from groundwater sources (USGS, 1988) , which supply 40.1% of the water in public systems (USGS, 1990~.
From page 229...
... . The investigators found that 12.95% of the wells contained detectable residue levels of herbicides, the five highest being atrazine in 11.68%, alachlor in 0.78%, metolachlor in 1.02%, cyanazine in 0.28%, and simazine in 1.6%.
From page 230...
... Surface Water Surface water contributes 59.9% of the water in public water systems (USGS, 1990) and supplies drinking water to approximately 47% of the U.S.
From page 231...
... o 10 8 6 ~AC (ug/L) 4 o ~_ F M A M J J A S O N D Month Sandusky River , atrazine metolach lor alach lor ~ ~' ~' J F M A M J JA S O N D Month Honey Creek Atrazine o Metolachlor 0 Alachlor J F ~ A ~ J J A S O N D Month FIGURE 6-3 Monthly time-weighted mean concentrations of atrazine, alachlor, and metolachlor in 1983-1988 reported at the Maumee River, Sandusky River, and Honey Creek stations in Ohio.
From page 232...
... The Importance of Water Data to Infants and Children As demonstrated in Chapter 5, water is an important component of the diets of infants and children. Water consumed by itself, water added to infant formula, and water used in the preparation of foods may represent a significant source of pesticide exposure by ingestion.
From page 233...
... Water treated in this manner is therefore considered by the manufacturers to be free of pesticide residues. Infant formulas are broadly classified into two categories: those based on cow's milk and those based on soy protein.
From page 234...
... because of the hydrophobic nature of chlorpyrifos (R.C. Gelardi Infant Formula Council, personal commun., 1990~.
From page 235...
... This calculation is based on the preceding worst case assumptions and the percentages of lactose and condensed skim milk in a typical cow's milk-based infant formula, as noted in Figure 6-4. Thus, although condensed skim milk and lactose are major ingredients in infant formulas based on cow's milk, they are not expected to contribute greatly to potential pesticide residues.
From page 236...
... 130F Cream FIGURE 6-6 Steps in the production of condensed skim milk and nonfat dry milk from raw cow's milk. SOURCE: Infant Formula Council, Atlanta, Georgia, unpublished.
From page 237...
... Since soy protein isolate typically constitutes 2% of soy-based infant formulas, Me potential maximum possible level of Water 86.6% ...
From page 238...
... Thus, the reductions of pesticide residues achieved by processing raw agricultural commodities combined with the relatively low concentrations of these ingredients in infant formulas account for the extremely low residue levels that can theoretically be predicted for infant formula, assuming maximum pesticide residue at EPA tolerances are initially present on the raw agricultural commodity. As stated earlier, extensive analytical testing of infant formula has failed to result in the detection of any pesticide residues.
From page 239...
... Theoretical maximum residue contributions in infant formula and limits of quantification are shown in Table 6-4. PESTICIDES IN HUMAN MILK Tissue concentrations of chlorinated organic pesticides are found in most people in the United States, although generally in declining levels in recent years as chlorinated pesticide use in the United States and worldwide has declined.
From page 240...
... Surveys conducted before 1986 Jensen, 1983; Wolff, 1983; Jensen and Slorach, 1990) demonstrated that p,p'-DDT or its metabolite p,p'-DDE were present in quantifiable concentrations in essentially all human milk samples assayed.
From page 241...
... In previous surveys conducted in the United States, HCH isomers were found in quantifiable concentrations in 4 to 68% of the human milk samples analyzed Jensen, 1983; Wolff, 1983; Jensen and Slorach, 1990~. a-HCH and y-HCH, because of more rapid clearance, are generally found in fewer samples and in lower concentrations.
From page 242...
... are closely related cyclodiene pesticides (WHO, 1984; Murphy, 1986; Kurtz et al., 1989; Baker and Wilkinson, 1990~. Surveys conducted in the United States have demonstrated that between 25% and 100% of human milk samples analyzed had quantifiable concentrations of heptachlor or heptachlor epoxide ranging from 0.035 to 0.13 ppm Jensen, 1983; Jensen and Slorach, 1990~.
From page 243...
... The mean concentration of heptachlor epoxide in these samples with detectable levels was 0.128 + 0.209 ppm, also the highest mean level of all the regions surveyed in the United States. Similar studies of human milk in Pennsylvania (Kroger, 1972)
From page 244...
... The FDA Surveillance Data The FDA monitors pesticide residues in all food other than meat, milk, and eggs. The agency's monitoring program is not designed to determine dietary exposure to pesticides.
From page 245...
... 22 1568.2 Fer~itrothion5,171 300.6 Quinalphos40 30750 Methoxychlor5,643 360.6 Phorate40 3690.0 Phosphamidon3,499 631.8 Chlorfenvinphos9,299 660.7 Methomyl2,706 692.5 Aldicarb1,141 766.7 Phosalone11,857 820.7 Profenofos9,689 1051.1 Disulfoton15,121 1170.8 Daminozide514 12524.3 Primiphos-methyl4,449 1763.9 Monocrotophos18,617 1911.0 Dicofol12,430 2161.7 Parathion-methyl30,361 2400.8 Benomyl1,023 29228.5 Ethylenebisdithiocarbamate (EBDC) 2,539 29611.6 Phosmet15,604 3352.1 Methidathion15,948 4372.7 Azinphos-methyl15,320 4743.1 Parathion40,029 5911.5 Carbaryl11,212 6325.6 Diazinon35,896 6481.8 Ethion30,588 6992.3 Malathion39,226 1,1612.9 Mevinphos25,639 1,3205.1 Dimethoate40,496 1,4183.5 Captan30,108 1,4995.0 Chlorpyrifos45,418 2,1804.8 Acephate39,940 3,8459.6 SOURCE: Based on FDA Surveillance Data, 1988-1989, unpublished.
From page 246...
... ; benomyl (systemic residue; used on fresh fruits, berries, vegetables, and in fungicide problem areas; high percentage of residue occurrence in FDA surveillance program) ; captan (used on foods such as apples, peaches, and pears, which are consumed in large amounts by infants and young children; potential reproductive effects; high percentage of residue occurrence in FDA surveillance program)
From page 247...
... A more focused and specific monitoring system is indicated for targeting foods in infant diets. FDA monitoring is focused on crops with a history of residues exceeding EPA tolerance levels, residues with no EPA-established tolerances, and crops harboring the greatest number of different pesticides.
From page 248...
... Infant foods analyzed under TDS and through the incidence/level monitoring showed that residue levels were well below EPA tolerances and that residue intakes are well below ADIs set by the
From page 249...
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From page 251...
... 251 Z Z Z Z ~m0 ~i E~ o E~ mo ~ ~ ~ ~ E~ E- E- E-~ E~ oo o o o o o Lr)
From page 253...
... Positive Detections The ability of a survey to detect pesticide residues depends on at least three factors: the percentage of crop acreage treated with the pesticide, the sampling design of the survey, and the analytical limit of detection for the pesticide in that food. Other factors include the stability of the chemical; the time between pesticide application, harvest, and sampling; and the degree of postharvest processing.
From page 254...
... For the pesticides in the infant diet examined by the committee, the data show that positive pesticide residue detections are clearly more common in fresh fruits and vegetables, specifically in apples, peaches, pears, bananas, peas, green beans, and carrots (see Table 6-7) , than in other commodities.
From page 255...
... In all these cases, however, the mean concentrations were considerably below the established EPA tolerance level and therefore represented a very small number of the samples. The only chemical for which mean residues approached tolerance was EBDC on succulent peas, for which the mean (2.6 ppm)
From page 256...
... SOURCE: Based on FDA Surveillance Data, 1988-1989, unpublished.
From page 257...
... The committee reviewed unpublished data provided by the NFPA on pesticide residues found in foods used in processed baby foods. These foods, along with infant formula, comprise a large proportion of the infant's diet.
From page 258...
... LOQ. The highest concentration found 140 ppb is considerably lower than the EPA tolerance of 3,000 ppb.
From page 259...
... Knowledge of the form in which these products are consumed is important to the understanding of residue data. Virtually all the foods consumed by infants are processed, and most are manufactured by a limited number of processors, who exercise stringent controls.
From page 260...
... CONCLUSIONS AND RECOMMENDATIONS Data on residues on foods are collected by FDA, state agencies, the food industry, private organizations, and in university programs such as JR-4. Other government, industry, and academic sources were identified by the committee for specific categories such as water, infant formula, and human milk, which are particularly important in the diets of infants and children.
From page 261...
... Infant formulas and processed baby foods are routinely monitored to ascertain pesticide residue levels. Although sampling and analytical t"~hni~l1~ lark the de.~irable decree of uniformity, residues were not .
From page 262...
... FDA, working with USDA, EPA, and state and other federal agencies, needs to create: -a clearly explained sampling strategy that could be used to ascertain the representativeness of the results of food residue analyses; -guidelines for those generating, processing, and using residue data to ensure that an explanation of LOQs and nondetectables are provided with all reports and are uniformly used in data analyses (e.g., in averaging) ; -a residue data management system that will improve the quality, accessibility, and comparability of food residue data, including those generated by the commercial sector; and -a repository of information on the fate of compounds during food processing and preparation.
From page 263...
... 1989. Anticipated Pesticide Residues in Food.
From page 264...
... 1993. Infant formulas: Evidence of the absence of pesticide residues.
From page 265...
... 1981. National study of chlorinated hydrocarbon insecticide residues in human milk.
From page 266...
... 1981. Organochlorine pesticide residues in human milk in Hawaii, 1979-80.


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