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Home , Pesticide residue

Number 66 Issue Paper October 2019 Interpreting Residues in Food

While many consumers are concerned with pesticide residues on produce, the significant health benefits from eating a diet rich in produce and whole grains dramatically outweigh the miniscule risks from pesticide residues. (Photo from Monkey Business Images/Shutterstock.)

metabolites as an indicator of pesticide estimating food exposure. Abstract exposure, have suggested correlations The judicious use of in Consumers in the United States between pesticide exposure and specific food production also provides numerous are frequently exposed to residues of types of disease, but such studies are benefits to society. Such benefits include pesticides in their food. The existence of limited in their ability to measure both greater productivity, availability, and pesticide residues in food raises ques- disease and pesticide exposure and have affordability of food; a reduction in tions regarding what consumer health been inconsistent in their findings. As damage, food loss, and waste; and public risks, if any, are posed by such chemical an example, results of six epidemiologi- health benefits such as control of poten- contaminants. cal studies examining the relationship tially dangerous mycotoxins or fungi in This report concludes that there is between exposure to the our food. no direct scientific or medical evidence chlorpyrifos and childhood intelligence Consumers are frequently advised to indicating that typical exposure of con- are discussed. Two of the six studies avoid purchasing specific conventionally sumers to pesticide residues poses any indicated a positive correlation between produced fruits and vegetables because health risk. Pesticide residue data and chlorpyrifos exposure and reduced child- of contamination concerns. Research- exposure estimates typically demon- hood intelligence but both focused on ers have demonstrated that such advice strate that food consumers are exposed exposure from non-food sources (indoor lacks scientific justification and may to levels of pesticide residues that are pesticide use and agricultural pesticide result in some consumers reducing their several orders of magnitude below those use). Another study looking at indoor consumption of fruits and vegetables, a of potential health concern. Human chlorpyrifos use did not identify any practice strongly associated with adverse epidemiological studies, often employ- correlation to childhood intelligence nor health effects. The best thing consum- ing biomonitoring studies of pesticide did three other epidemiological studies ers can do is to eat a diet rich in fruits, CAST Issue Paper 66 Task Force Members

Authors Reviewers CAST Liaison

Dr. Carl Winter (Chair), Department Kaci Buhl, MS, Environmental and Dr. Donald C. Beitz, Department of of Food Science and Technology, Uni- Molecular Toxicology, Oregon State Biochemistry, Biophysics and Mo- versity of California at Davis, Davis, University, Corvalis, Oregon lecular Biology, Iowa State University, California Dr. Honglei Chen, Department of Epide- Ames, Iowa Dr. Carol Burns, Burns Epidemi- miology and Biostatistics, Michigan State ology Consulting, LLC, Sanford, University, East Lansing, Michigan Michigan Dr. Franklin Mink, MAI, Corinth, Dr. Steve Savage, Independent Kentucky Consultant, Vista, California

vegetables, and whole grains, whether the requiring a balanced and varied diet rich infants and children. foods are organic or conventional. in fruits, vegetables, and whole grains. While such links between exposure The pesticide regulatory system in the and disease have received considerable United States is simultaneously cited as media coverage and need to be taken seri- Introduction an important safeguard of the U.S. food ously, it is also important to understand There is a keen awareness among supply by some and as a cause for con- the strengths and limitations of epidemio- many consumers that pesticide chemicals cern by others. As an example, the results logical investigations for such results to frequently reach consumers in the form of federal pesticide residue testing from be evaluated appropriately. The quality of of food residues. This awareness can foods often demonstrate that a major- data used and obtained in such studies is be troubling to many consumers since ity of foods contain no detectable levels critical and findings from individual stud- pesticides are typically used because of of pesticide residues and violation rates ies should be compared with those from their ability to harm biological organ- are low, yet the same studies indicate other related studies to see if there are isms such as insects, plant diseases, that residues are frequently detected and overlapping similarities. It is also critical and weeds. Their presence in foods demonstrate that consumers are routinely to understand that such links between ex- introduces the question as to what risks, being exposed to pesticides in their food. posure and disease represent correlations if any, are consumers facing as they The relationship between allowable lev- or associations and not causes; additional consume ubiquitous pesticide residues els of pesticides on foods (tolerances) and plausible explanations for the links need in their diet. Because of safety concerns, safety is poorly understood and frequent- to be considered as well. consumers frequently receive advice ly implies that pesticide residue findings The uses and benefits of pesticides in from advocates concerning whether one that violate U.S. laws may pose health food production should also be recog- should eat conventional or organic foods, risks to consumers. This is particularly nized. Pesticides provide one tool to pro- which conventional fruits and vegetables true in the case of food imported into duce a safe, effective, and economically one should consider avoiding, which the United States from other countries, viable food supply, particularly when geographical sources of foods should be which frequently demonstrates much they are used in concert with a variety avoided, and what one could be doing to higher violation rates than food produced of other biological, genetic, cultural, and reduce exposures to pesticides by wash- domestically. mechanical approaches to control pests. ing, peeling, cooking, or scrubbing foods In addition to pesticide residue regula- Pesticides can improve land- and water- before they eat them. tory programs, biomonitoring studies use efficiencies that can minimize energy The scientific basis for such advice is have frequently detected metabolites of requirements and reduce greenhouse gas frequently lacking. The simple presence pesticides in urine samples from consum- emissions. In addition, pesticides provide of a pesticide residue on a food item is ers. Biomonitoring results may serve as a powerful tool in reducing food waste as not sufficient evidence of harm since an indicator of consumer exposure to pes- well as in increasing . pesticides, like all chemicals, obey the ticides and such results are often paired This CAST Issue Paper focuses on principles of toxicology. It is the dose, or with epidemiological studies to study the pesticide residues in the food supply and exposure to the chemical, that determines potential links between pesticide expo- describes several complex yet poorly the potential risks. Consumers may be sures and diseases. A handful of recent understood aspects that are key to evalu- choosing to follow questionable advice to epidemiological studies have suggested ating scientific papers, media food safety avoid specific foods because of poten- links between pesticide exposure and stories, and consumer advice regarding tial pesticide residues, contradicting the adverse male reproductive effects and which foods consumers should (or should sound advice from health care providers, developmental and behavioral effects in not) consume.

2 COUNCIL FOR AGRICULTURAL SCIENCE AND TECHNOLOGY to consider “cumulative” exposure to the case of would a food Pesticide Residues in entire families of toxicologically related residue exceed the tolerance level. Foods: Regulation and pesticides possessing similar mechanisms of biological action. Regulatory Monitoring of Risk Assessment If, after investigating all of these is- The agricultural use of pesticides has sues, EPA scientists conclude consumer Pesticide Residues in the enabled food producers to increase their exposure to a pesticide represents a United States yields significantly in the United “reasonable certainty of no harm,” the The U.S. Food and Drug Administra- States and throughout the world. Pes- EPA will allow the pesticide to be legally tion (FDA) is the primary federal agency ticides provide a useful tool to control used on specified food and will set responsible for enforcing pesticide insects (), weeds (), the maximum allowable residue level, or tolerances. In 2016, the FDA laboratories plant diseases (), as well as tolerance, for the specific pesticide on the analyzed 2,670 domestic food samples other agricultural pests. specific food crop. On the other hand, if and 4,276 imported food samples for pes- One consequence of using pesticides consumer exposure to a specific pesticide ticide residues in its “Regulatory Moni- in agriculture is that pesticide residues exceeds a level of “reasonable certainty toring of Foods Program” using multi- are often detected on our foods. The use of no harm,” the pesticide will not be residue techniques capable of detecting of pesticides does not necessarily imply registered for specific food uses (Winter residues of more than 200 individual that residues will be encountered; many 2005). pesticides (USFDA 2018). Findings from pesticide applications are made prior The processes used to establish pesti- the 2016 FDA program are shown in to the emergence of edible portions of cide residue tolerances are complicated Figure 1. plants while in other cases, sufficient time and counterintuitive (Winter 1992a). The FDA found that a majority of between and crop Tolerances are not indicators of safety but samples from both domestic and import- harvest allows the pesticides to degrade serve instead as barometers to indicate ed foods contained no detectable pesti- below detectable levels. Nevertheless, if pesticide applications are performed cide residues while most of the detectable residues of pesticides on food crops com- according to good agricultural practices. residues were within tolerance levels. monly occur and their existence is often Tolerances are typically set to be slightly A large difference in violation rates was cause for consumer concern. higher than the maximum residue levels seen with domestic samples showing a observed when the pesticide application 0.9% violation rate while import sample is made according to legal directions (i.e., violations were much higher (9.8%). Regulation of Pesticide proper pesticide application rate, proper Pesticide residue violations can occur Residues in the United States number of applications per growing in two ways: (1) when residue levels ex- In the United States, pesticides are season, application made to the proper ceed the tolerance established for the spe- primarily regulated by the United States crop, adherence to an established interval cific pesticide/food combination, and (2) Environmental Protection Agency (EPA). between final application and harvest). As when residue levels—at any level—are In cases where specific pesticides may such, anticipated pesticide residue levels detected on foods for which a tolerance is pose the potential to expose consumers following legal application of pesticides not established (even if the pesticide is le- to pesticide residues from food, the EPA should fall below the tolerance level gally allowed on other foods). Violations will not permit specific uses of pesticides (usually far below the level) and only in in this category frequently occur through unless it is determined that consumer exposure to the pesticide from all sources represents a “reasonable certainty of no harm” according to the 1996 Food Qual- ity Protection Act (FQPA) (Winter 2005). The calculation of a “reasonable certainty of no harm” involves assessing realis- tic levels of human exposure through consideration of pesticide residue levels and food consumption patterns as well as comparisons of exposure estimates with toxicological criteria such as the refer- ence or benchmark dose. In addition, the FQPA requires the EPA scientists to consider the special potential susceptibili- Figure 1. The percentage of food samples tested by the FDA in 2016 with pesticide ties of infants and children to pesticide residues. Pesticide residue violations can occur when residue levels exposure, to consider “aggregate” expo- exceed the tolerance established for the specific pesticide/food combi- sure to the pesticide from food, drinking nation, and when residue levels are detected on foods for which a water, and residential environments, and tolerance is not established. Source: FDA 2018

COUNCIL FOR AGRICULTURAL SCIENCE AND TECHNOLOGY 3 drift of a pesticide applied legally to one legal requirements and as an economic laboratory animal studies that examine a crop that may reach a different crop for disincentive to discourage food produc- multitude of health and metobolic param- which the pesticide is not registered, ers from using pesticides inappropriately eters in an attempt to determine the most uptake from contaminated soil, or com- since foods shown to contain violative sensitive effect (one that occurs at the ingling of different agricultural products residues are not permitted for sale in the lowest dose of the pesticide) in the most during transportation, packing, or distri- United States. sensitive animal species. Once that effect bution. The FDA identified 25 domestic Violative residues, however, should has been established, the highest dose food violations for pesticide residues in not be equated with “unsafe” residues. given to the most sensitive animal species 2016; only four (16%) of the violations Tolerance levels could be raised signifi- that does not cause the most sensitive involved over-tolerance residues. Of the cantly without anticipating adverse health toxicological effect is identified as the no 418 imported food violations identified effects. As an example, the current U.S. observable adverse effect level (NOAEL) in 2016, 64 (15%) represented over-toler- tolerance for captan on strawberries is (Winter and Francis 1997) or the com- ance residues. Food identified as violative 20 parts per million, which is 12.5 times parable benchmark dose. Recognizing by the FDA is not allowed to enter the lower than the safety level. Winter and that humans could potentially be more channels of commerce. Jara (2015) estimated that residues of the sensitive to pesticides than the most sen- captan on strawberries would sitive animal species, prudent measures need to reach a level of at least 250 parts are taken into account when developing Interpreting Pesticide Residue per million prior to eliciting any prelimi- a RfD on the basis of the NOAEL. In Monitoring Results nary health concern. practice, a 10-fold uncertainty factor is The 2016 FDA residue findings applied that assumes humans are 10 times suggest, particularly for domestically pro- Assessing Consumer Risks more sensitive to the pesticide than the duced foods, that pesticide applications most sensitive animal species tested; this generally demonstrate compliance with from Exposure to Pesticides in is multiplied by another 10-fold uncer- legal and established agricultural prac- Food tainty factor that assumes some humans tices. For both domestic and imported The presence or absence of pesticide may be 10 times more sensitive than the foods, the majority of samples contained residues is not a valid indicator of health average human. Using this approach, the no detectable pesticide residues while risk to the consumer. Pesticides, like all NOAEL is divided by a factor of 100 (10 detected residues were typically present chemicals, obey the first principle of for animal/human extrapolation x 10 for at levels far below the tolerance levels. toxicology: “The dose makes the poison.” human/sensitive human extrapolation) Such findings are reassuring given that Thus, it is the amount of exposure and to yield the RfD (Winter and Francis tolerance levels are set to represent the not the presence or absence of a chemical 1995). In some cases, such as when it is maximum residues anticipated following that determines the potential for harm. determined that toxicology information legal application of pesticides. The calculation of consumer exposure is limited or when infants and children Much public focus concerns the viola- to pesticides includes two components: may be more susceptible to pesticides tion rates (0.9% for domestic foods, 9.8% (1) the level of pesticide residue on food, than adults, an additional 3- to 10-fold for imported foods) and the potential and (2) the amount of the food that is uncertainty factor may be included prior impact of violations on consumer safety. consumed. If a pesticide is found on mul- to calculation of the RfD. As discussed previously, most violations tiple foods, the contributions of exposure Dietary pesticide exposure assessment do not occur in cases where tolerance from each food are combined to provide often uses pesticide residue data collected levels have been exceeded but rather in an estimation of the total dietary expo- from programs such as the FDA’s “Regu- cases where the pesticide was detected on sure to the food (Winter 1992b). latory Monitoring of Foods” program and a commodity for which a tolerance was To determine the potential health risk the U.S. Department of Agriculture’s Pes- not established. Even in the infrequent from the estimated exposure, the expo- ticide Data Program (PDP). The FDA’s cases where tolerances were exceeded, sure level is compared to a toxicological regulatory monitoring program does not though, these instances very rarely con- indicator of preliminary health concern. sample foods randomly so data collected stitute cases of food safety concern since This indicator is commonly referred to as from this program are not considered to tolerances are set on the basis of good the reference dose (RfD) and represents be representative of the food supply. The agricultural practices and are not safety the lowest level of exposure of health PDP samples only a few food commodi- indicators (Winter 1992a). Tolerances are concern; exposures below the RfD are ties each year and thus its utility is also only established in cases where the EPA considered to be negligible in terms of limited. has already determined that the pesticide, health risks. RfDs may be calculated The FDA has conducted the Total through all its registered uses, poses a differently for acute (short term, aRfD) Diet Study (TDS) annually since 1961. “reasonable certainty of no harm” to con- exposures or chronic (longer term, cRfD) The TDS is a market basket study in sumers. Monitoring of foods for pesticide exposure. which the FDA inspectors purchase food residues therefore provides a valuable Since human toxicology data for pes- items from retail outlets in four separate check to identify if pesticide applications ticides are limited, most of the toxicology locations each year and prepare 280 food are being made according to established data used to calculate RfDs come from items for consumption. At the time the

4 COUNCIL FOR AGRICULTURAL SCIENCE AND TECHNOLOGY food is ready to be eaten, it is analyzed highest daily exposure for all popula- Dozen” commodities and developed for residues of hundreds of different tion subgroups over 1,000 days) to the chronic dietary exposure estimates for pesticides as well as nutrients, metals, pesticide from all foods, drinking water, 120 commodity/pesticide combinations. and other contaminants. Pesticide residue and residential use is below the aRfD Winter and Katz indicated that estimated results are made available to the public level, exposure is considered to provide a exposures were far below chronic RfD and the FDA also provides consumption “reasonable certainty of no harm” and the levels in all cases. Only one of the 120 estimates for the 280 individual food pesticide and all of its associated uses are commodity/pesticide combinations items. considered safe for consumers. showed an exposure above one percent An analysis of consumer chronic of the chronic RfD while only seven exposure to pesticide residues, based exposures were greater than 0.1% of the upon 2004–2005 TDS results, was Interpeting Consumer Advice chronic RfD. Three-quarters of the expo- published by Winter (2015). Residues of Regarding Pesticides in Food sure estimates were below 0.01% of the 77 individual pesticides were detected Consumer concern has been influ- chronic RfD. The authors concluded that and exposure estimates for each of these enced by nontraditional and much less (1) consumer exposure to the most fre- pesticides were compared to chronic RfD rigorous approaches regarding pesticide quently detected pesticides on the “Dirty (cRfD) values. Exposures to only three residues in the food supply. Among Dozen” commodities was negligible, (2) pesticides exceeded 1% of the cRfD and these is “Shopper’s Guide to Pesticides,” substituting organic forms of the “Dirty included two pesticides no longer used released annually by a Washington, D.C.- Dozen” commodities would not appre- in agriculture but persistent enough in based environmental advocacy group and ciably reduce risks, and (3) the methodol- the environment that residues are still includes a list of the “Dirty Dozen” foods ogy used to develop the “Dirty Dozen” common. Exposures between 0.1 to 1.0% representing the 12 commodities most list lacked scientific rigor or subsequent of the cRfD were estimated for fourteen likely to contain pesticide residues. The credibility. pesticides, while 19 pesticides had expo- authors of this guide urge consumers to The health benefits of eating a diet sures between 0.01 to 0.1% of the chronic avoid purchasing conventional (non- rich in fruits, vegetables, and whole reference dose. Exposures to the remain- organic) forms of these foods to avoid grains have been well established and ing 41 pesticides that were detected in potential health effects from pesticide there is concern that attention given to the 2004–2005 TDS were below 0.01% exposure (Environmental Working Group inappropriate warnings of dire conse- of the cRfD. Since an exposure of 0.01% 2018). quences resulting from pesticide residue of the cRfD represents an exposure one The rankings of the “Dirty Dozen” and exposure could encourage consumers to million times lower than the NOAEL (the other fruits and vegetables are derived reduce their consumption of fruits and highest dose that does not cause effects in from PDP data collected by the U.S. vegetables. A recent study was conducted the most susceptible animal species), it is Department of Agriculture. Specific fruits of low-income shoppers who were pro- reasonable to conclude based on the data and vegetables are ranked on the basis vided a variety of statements regarding that chronic exposure to pesticides from of six criteria: (1) percentage of samples organic and conventional fruits and veg- food in the United States is typically at with detectable residues, (2) percentage etables (Huang, Edirisinghe, and Burton- levels far below those of health concern. of samples with two or more pesticides Freeman 2016). When responding to the Risk assessment for acute (single day) detected, (3) average number of pes- statement: “An environmentalist group exposures to pesticides is conducted ticides found on a single sample, (4) called the Environmental Working Group differently. Since both pesticide resi- average amount of all pesticides found, has developed a list of the 12 fresh fruits due levels and daily food consumption (5) maximum number of pesticides found and vegetables they say have the highest patterns vary significantly, probabilistic on a single sample, and (6) total number pesticide levels on average: apples, bell models have been developed to examine of pesticides found on the commodity peppers, carrots, celery, cherries, grapes, the distributions of both residues and (EWG 2018). kale, lettuce, nectarines, peaches, pears, food consumption. In the unlikely event A close look at the criteria used to and strawberries. They suggest that it is of a very high pesticide residue occurring rank pesticide “contamination” reveals best to buy these fruits and vegetables at the same time that a significant amount that none of the metrics are useful in organically grown,” a much greater num- of the food containing the pesticide terms of traditional dietary pesticide risk ber of low-income consumers indicated was consumed, it is possible that the assessment. Notably missing from the that they were less likely to purchase daily exposure could approach the acute methodology are the three key pillars of fruits and vegetables compared with their RfD (aRfD) level for the pesticide. The risk assessment: levels of residues, food responses to the other statements. EPA, in determining what constitutes a consumption estimates, and established Similar unfounded concerns regard “reasonable certainty of no harm” for toxicity indicators for individual pesti- the consumption of imported fruits and acute exposures, calculates individual cides. vegetables, which represent the pri- day estimates for a variety of population Using a more traditional approach, mary source of fruits and vegetables for subgroups—including infants, children, Winter and Katz (2011) analyzed PDP many U.S. consumers during the winter and women of childbearing age. If expo- data for 10 most frequently detected months. While pesticide residue viola- sure at the upper 99.9th percentile (the pesticides on each of the 2010 “Dirty tion rates tend to be greater for imported

COUNCIL FOR AGRICULTURAL SCIENCE AND TECHNOLOGY 5 foods than for domestic foods, it is also tions. The quality of the answers can the exposure occurred. Since most of the clear that violative residues are rarely vary with the seriousness of the disease; observations correspond to levels well indicative of health consequences. Katz diagnoses of cancer are harder to forget below the doses administered to labora- and Winter (2009) estimated dietary ex- (or mischaracterize on a questionnaire) tory animals in toxicological studies, posure to pesticides detected on domestic than vague symptoms such as fatigue, such findings would generally provide and imported produce during the FDA’s headache, or being out of breath. The reassurance rather than alarm. 2003 Regulatory Monitoring Program. more robust studies make Even though violation rates were much the effort to confirm the sensitivity and Source of Exposure higher for the imported produce, expo- specificity of the underlying data. For How do epidemiologists know that sure estimates indicated that exposure to example, to study heart disease the best one person has more exposure than an- specific pesticides was more frequently practice is to obtain medical records to other? How do they know that it is from lower from consuming imported produce confirm the diagnosis, date of onset, and food residue? than from consuming domestic produce. treatment. Biomonitoring, from urine or blood, is In the case of one pesticide that resulted Similarly, with exposure, the quality both solution and problem. The advan- in thirty six import violations and one of the information varies widely. Self-re- tage of one or more urine (or blood) domestic violation, overall exposure to ported exposure(s) based on daily habits, samples is that they can be analyzed for the specific pesticide was still lower from like smoking or drinking coffee or one’s traces of specific pesticides and other consumption of imported produce while job tend to be more accurate, even in the chemicals. The levels tell us “what” and well below levels of safety concern for distant past. However, sometimes it is “how much.” The problem is that most both domestic and imported produce. difficult to determine if people have been pesticides used today break down to other exposed to specific agents such as to a vi- components within days of application rus or a chemical. This is particularly true in the field as well as often within hours esticide pidemiology P E for pesticides. Whereas farmers and ap- after ingestion. This means that when and Biomonitoring plicators may know what they have used, pesticide metabolites are found in human Epidemiology studies look for pat- their internal exposure(s) is determined urine, it is impossible to tell whether terns and potential causes of disease. In by a host of determinants such as what the individual was exposed to the parent contrast to laboratory studies, because was applied, how it was applied, and the compound or the metabolite (Sudakin human subjects are observed, the concept type, if any, of protective clothing worn. and Stone 2011). Futher, the biomonitor- of causality is softened with terms like For those not involved in agriculture ing information is only relevant for the risk factors, linkages, and associations. and especially those living far from the previous day or two. Unless the exposure Regardless of the language, epidemiology source, we have little to no information is from a food item that is eaten regularly, investigations look for clues of health and about pesticide exposure. As noted previ- the investigator can’t determine exposure exposure status between groups. Through ously, exposures to pesticides may occur last month (or year), which may be the careful observation, epidemiology from trace residues on fruits and vegeta- important time period for disease onset. research has identified many risk fac- bles. Random sampling programs in the Some studies of pesticide applicators tors for diseases. Factors such as obesity, United States and Canada have collected and farmers can infer the source of expo- smoking, high cholesterol, hypertension, urine and blood from men, women, and sure, especially if collection occurs soon and physical inactivity have been deter- children across the country to identify after an application (Arbuckle et al. 2002; mined to to increases in heart disease levels of all sorts of chemicals includ- Mandel et al. 2005; Thomas et al. 2010). (Fryar, Chen, and Li 2012). Relatively ing metals, industrial contaminants, and A study conducted in New York City as- uncommon diseases such as birth defects pesticides (Health Canada 2010; CDC sumed that the participants were exposed were found to be associated with too 2015). Researchers have shown that some as the result of indoor pesticide treat- much of one thing (alcohol) and too little pesticides and/or their metabolic break- ments (Whyatt et al. 2005). Other studies of another (folic acid) (Streissguth 1978; down products are detectable and may be with no other information simply assume Viswanathan et al. 2017). The successes found in large percentages of the popula- the source is from food (Fortenberry et of the disease detectives who compared tion. The limit of detection, or the ability al. 2014; Imai et al. 2014; Ji et al. 2011). the noncases to the cases with toxic shock to identify a chemical through laboratory The lack of concrete data on the sources syndrome, for example, led scientists to analysis, has gotten smaller over time. of pesticide exposure is concerning when better define the disease and determine Scientists today can detect up to 100 associating diseases and pesticides levels how it was spread (Schuchat and Broome times lower levels of the 2,4-D from biomonitoring data. 1991). than just a few decades ago (LaKind et al. Income, for example, is a common Historically, the success of epidemiol- 2017). The U.S. Centers for Disease Con- factor when evaluating health among ogy as a science depends on two criti- trol and Prevention (CDC) clearly states populations that may also impact pes- cal pieces of information: disease and that detection alone is not an indication ticide exposure. Table 1 illustrates how exposure. To gain information for a study, of health concern (CDC 2015). Further, specific population groups may differ investigators will often simply ask study this “snapshot” does not provide any among each other with respect to pesti- participants about their medical condi- information about when, how, or where cide exposure by income levels. It can be

6 COUNCIL FOR AGRICULTURAL SCIENCE AND TECHNOLOGY speculated that lower income participants diagnosis. This is called reverse causality Example 1. Pyrethroid insecticides eat fewer servings of fresh fruits and veg- and makes interpretation of epidemiology and sperm quality etables since fresh produce is relatively studies difficult. Pyrethroids are a class of insecticides expensive, particularly in urban areas. If The problem is that speculation is that are widely used in the home envi- this is the case, it is reasonable to assume poor science and is far removed from ronment and in agriculture. In the body, that the lower income group may dem- the scientific method of basing conclu- pyrethroids break down quickly and onstrate lower urinary levels of pesticide sions on strong data-driven evidence. As several metabolize to the common me- metabolites than higher income groups. an example, a high-profile French study tabolite 3-phenoxybenzoic acid (3-PBA) Conversely, another rationale is that recently concluded that participants eat- that is detectable in urine. Due to their pesticide exposures may occur more fre- ing a high diet experienced widespread use, contact with pyrethroids quently among lower income participants a significant reduction in the risk of can occur from residues on produce. It due to treatment of pests in their home or cancer compared with those who did not has been proposed that pyrethroids may following pesticide appli- eat a high organic food diet (Baudry et al. affect the human reproductive system cations from nearby fields in more rural 2018). The women who reported a high and several investigators have evalu- environments. The opposite could be frequency of organic food consumption ated levels of urinary 3-PBA in men and inferred of high-income participants who were also more likely to eat a healthy diet semen quality (Imai et al. 2014; Ji et al. either eat organic produce (low pesticide and exercise frequently. Another limita- 2011; Meeker, Barr, and Hauser 2008; exposure) or have high consumption of tion is that the authors of this study didn’t Perry et al. 2007; Radwan et al. 2014; traditionally grown food (high pesticide actually test, even on a small sample, if Toshima et al. 2012; Xia et al. 2008). exposure). their reported score for organic diet was Each relied upon the same design, called Table 2 similarly illustrates that people correct. a cross-sectional study. During a single may change their behavior, and thereby visit, investigators collected urine and se- exposure, based on disease. Imagine Food Residue and Health men from the study participants. None of a family with a child on the What does the epidemiology literature the participants were a pesticide applica- spectrum. Their food choices and even say about pesticides in general? Here are tor and the exposure was presumed to be residence may change because of the two examples. from ingestion on food. Levels of 3-PBA and sperm quality were analyzed. When sperm quality was statistically signifi- Table 1. Theorized pesticide exposure by income. cantly lower among the men with higher 3-PBA the association is considered to be Low Pesticide Levels High Pesticide Levels inverse. Low Income Cannot afford fruits and Lives in pest-infested homes A summary of the results for sperm vegetables requiring treatments concentration and sperm motility from these studies is shown in Table 3. The Lives near agricultural fields collective evidence clearly shows that while some studies reported an inverse High Income Washes fruits and vegetables Consumes many fruits and association for sperm concentration, vegetables others did not. If there were a positive, Buys organic causal effect of pyrethroid exposure and decreased sperm quality, we would expect to see it in most investigations. Further, a different study observed an Table 2. Theorized pesticide exposure by disease. inverse association for sperm motility but found no adverse association with sperm Low Pesticide Levels High Pesticide Levels concentration. Without going into the No Disease Doesn’t follow any special diet Doesn’t worry about eating strengths and weaknesses of each study, organic a limitation common to all the studies is Doesn’t eat many fruits and that the exposure (urinary 3-PBA) and vegetables Eats traditionally grown outcome (sperm quality) were collected produce at the same time, preventing an evalua- Disease Washes fruits and vegetables Consumes many fruits and tion of temporality. In other words, it is vegetables impossible to determine if the exposure Buys organic preceded the outcome or vice versa, Moves to rural which is a hallmark of epidemiologic Keeps house very clean area for less pollutants evaluation (Hill 1965). In summary, this example suggests that there is no effect of Moves to city to be near doctor(s) pyrethroid exposure (as measured using

COUNCIL FOR AGRICULTURAL SCIENCE AND TECHNOLOGY 7 Table 3. Associations of urinary 3-PBA for selected sperm characteristics. was the alleged source for the Califor- nia participants (Berkowitz et al. 2003; Author, Year Published Country Sperm Concentration Sperm Motility Castorina et al. 2010). The three studies Imai, 2014 Japan No effect No effect that are relevant for general exposure via Ji, 2011 China Inverse No effect ingestion of residues on food found no link with impaired intelligence (Cartier Radwan, 2014 Poland No effect No effect et al. 2016; Donauer et al. 2016; Jusko et Meeker, 2008 USA No effect No effect al. 2019). Perry, 2007 China Inverse* Not reported Toshima, 2012 Japan No effect Inverse What Does This Mean to Xia, 2008 China Inverse No effect Consumers? *This was a pilot of 18 men, not statistically tested There remains the concern among some consumers that detectable expo- sures to pesticides may lead to certain Table 4. Association of estimated in utero chlorpyrifos levels and childhood diseases. This is inferred to be from intelligence. residues on foods, as well as from other sources. The types of diseases that have Author, Year Published Location IQ Score Exposure Source been reported range from reproductive Rauh, 2011 New York (Columbia) Decreased Indoor treatment effects in adult men, namely lower sperm Engel, 2011 New York (Mt. Sinai) No effect Indoor treatment counts and motility (Burns and Pastoor 2018; Koureas et al. 2012), to various Bouchard, 2011 California Decreased Agriculture developmental and behavioral outcomes Donauer, 2016 Ohio No effect Food residue infants and children (Burns et al. 2013; Cartier, 2016 France No effect Food residue Muñoz-Quezada et al. 2013; Reiss et Jusko, 2019 Netherlands No effect Food residue al. 2015). The studies vary in their ap- proaches, tests, and conclusions. Even the reviewers vary in their approach to evalu- ating the studies. Some regard outcomes urinary 3-PBA levels) and sperm quality. among children exposed to food resi- in more general categories and make This is in line with results for laboratory dues containing chlorpyrifos? There are conclusions that the evidence for some animals which are conducted at a dose six epidemiology studies that evaluated is indication of effects for all (González- level many times higher than humans chlorpyrifos (or a group of insecticides) Alzaga et al. 2014). Other reviewers take would encounter (USEPA 2011) and intelligence via an IQ test (Bouchard a more focused approach looking at evi- et al. 2011; Cartier et al. 2016; Donauer dence for specific pesticides and specific Example 2. Organophosphate in- et al. 2016; Engel et al. 2011; Jusko et outcomes (Burns et al. 2013). secticide and neurodevelopment al. 2019; Rauh et al. 2011). Looking Consumers desire to make educated Like the pyrethroids, organophos- at the results across all the studies, the choices about their purchases. Scientists phates are a broad class of several dozen findings are mixed. Only two of the six strive to allow people to also be educated insecticides. Each metabolizes within 24 studies reported a statistically significant consumers based on scientific evidence. hours in the body and can be detected decrease in IQ with increased estimates In the event of the reporting of controver- as the generic dialkylphosphate. One of exposure (Table 4). The exposures in sial new findings regarding pesticides and organophosphate, chlorpyrifos, has been all the studies were estimated from urine health outcomes, consumers should deter- discussed prominently for a connection or blood collected when the child was mine if the study adequately describes with brain development in growing chil- born. Only two studies evaluated expo- both exposure and health outcomes. dren. Not unlike the example of pyre- sures to the growing child and found no §§If exposure was based on residence, throids, the evidence is mixed. Published link with development (Bouchard, et al. did the authors provide evidence to reviews have highlighted the inconsisten- 2011; Cartier et al., 2016). It is important support their assumptions? cies across studies and limitations in con- to understand that several studies are not §§When relying on urine samples, did firming in utero exposure such as relying about trace residues on purchased food. the authors collect more than one on a single sample and using exposure The source(s) of exposure to the New sample? estimates that are not specific to chlor- York study participants were presumed §§Was information collected to reduce pyrifos (Burns et al. 2013; Li et al. 2012; to be from indoor cockroach and ant the speculation about how the study Mink, Kimmel, and Li 2012; Needham treatments that are no longer legal in the participants were exposed? 2005; Prueitt et al. 2011). United States and many other countries §§Importantly, is the exposure setting So does chlorpyrifos reduce or (Whyatt et al. 2005) while agricultural based on what is known about agricul- impair brain development, particularly drift and/or track-in from farm workers tural practices?

8 COUNCIL FOR AGRICULTURAL SCIENCE AND TECHNOLOGY It is critical that such questions be tions (Tedford and Brown 1999). In the a female to allow mating. This approach considered when interpreting the study big picture, the goal is “sustainable pest can be quite effective, but only if the and making personal, economic, and life- management.” overall insect population is low. Chemi- style decisions based upon study findings. The sustainable, integrated programs cal treatments targeting “hot spots” of involve chemical and biological crop pro- the insect in question are needed for the Pesticide Benefits tection products, genetic resistance within pheromone strategy to succeed (Dorn et the crop itself, cultural practices that al 1999). While much of the contemporary exclude or limit pests, and the encour- There are biological control products concern regarding pesticides involves agement of biological pest suppression that can be applied to crops, but in gen- pesticide residues in foods and their po- through the use of beneficial organisms. eral the best results are seen when those tential risks to consumers, it is important Pesticide products are often a key part of agents are combined or alternated with to understand how and why pesticides are the integrated system and this is true for chemical control agents. used in the production of our crops and both conventional and organic produc- In summary, the goal of modern, many of the benefits they provide. tion. Even so, the goal is to use such sustainable pest management is not to products in a way that is safe, effective, simply rely on chemical controls for How Pesticides Fit in Sustain- and economically viable. pests. Still, pesticides play an important able Pest Management Often a pesticide is important in role. Fortunately, the trend over time has Plants provide the foundation of the maintaining or enabling another strategy been towards pesticides that are intrinsi- food supply for all other living things. In to work and to continue to work. As an cally much less toxic to humans or the many cases there are mutually beneficial example, if there is a genetic resistance environment than their predecessors relationships between plants and their trait in a crop for a major pest, exclusive (Savage 2014). consumers. However, even in undisturbed dependence on that tool will enhance the Historic trends in the quantity and oral natural ecosystems, there are organisms likelihood that the pest will evolve resis- toxicity of crop protection agents used that eat, damage, or infect plants in ways tance to the genetic trait so that benefit for strawberries and apples are shown in that effectively qualify them as “pests.” will be lost (Feng et al 2014). Figures 2 and 3. Plants defend themselves from “pests” Some insect pests can be defeated in various ways ranging from thorns to through a strategy of “pheromone confu- The Benefits of Crop Protection repellants to the production of pest-toxic sion” in which non-toxic pheromone chemicals (Osbourn 1996). chemicals are deployed so that the male for Agricultural Communities The crops that have been domesticated insect can’t find a distinct scent trail to The humans most directly impacted by by humans are also subject to damage from pests such as insects, mites, nema- todes, fungi, bacteria, and viruses. Crops also must compete for water, nutrients, and light with other plant species that could be viewed as weeds within the production system. While plants growing in natural settings can succeed despite a certain degree of pest damage, the threshold for acceptable pest damage in agriculture is lower because of the impact on financial risk for farmers, overall resource-use-efficiency, and also food safety and quality. It is not a viable option to simply tolerate pest damage, but pest management today involves much more than just “pesticides” (Savage 2013). Since the 1970s, the trend in agricul- ture has been towards a more sustainable, integrated systems approach to the chal- lenges of pest management. This is often described as integrated pest management (IPM) that combines diverse tactics in the context of in-depth knowledge of crop and pest biology with real-time data to implement the most economical, effec- Figure 2. The example of Strawberry pesticide use and relative toxicity in the key tive and minimally disruptive interven- production area of Monterey County, California.

COUNCIL FOR AGRICULTURAL SCIENCE AND TECHNOLOGY 9 While farming operations must survive bad seasons from time to time, without a reasonable degree of , farm- ing enterprises become non-viable, and those failures will also compromise the viability of other regional businesses. An additional level of challenge oc- curs when new, invasive pests enter a growing region; control of this new pest may disrupt a previously well-developed IPM system. These events have oc- curred throughout agricultural history but are more recently increasing primarily because of increased world travel and climate change. As an example, a new kind of fruit fly appeared in North American fruit growing regions around 2013 which can lay its eggs in fruits that are ripe, but not Figure 3. The example of Apple pesticide use and relative toxicity in the key damaged. This is something that fruit production area in Washington State. flies were unable to do in the past. This means that fruit infested with maggots is much more likely to reach consumers. This infestation became a serious threat to the economic viability of various fruit and berry producers (Walsh et al. 2011). In these cases it becomes a very high priority for the growers and supporting researchers to find new strategies to bring the new pests under control to prevent the financial viability of the region to be threatened. Farm owners are not the only ones in agricultural communities who are impacted by pests, and likewise who benefit from using pesticides. For crops that are harvested by hand, pest damage can greatly reduce the picking efficiency, meaning the pounds that can be collected per hour of effort. Since pickers are typi- cally paid by the pound, a pest-damaged crop is much less attractive from the worker’s perspective. A farmer could pay by the hour in pest injury cases, but at a certain level of damage it becomes Figure 4. Estimated economic loss ranges averaging data from 393 crop/state necessary to leave the crop unharvested combinations: Adapted from Crop Life Foundation. because the cost of picking labor can be one of the single largest expenses for growers of fruit and vegetable crops. crop pests are farmers and the non-farm- plant pests. Farming generally involves Figure 5 is based on the most recent Uni- ing members of the agricultural commu- the need to make a substantial financial versity of California, Davis cost-return nities whose livelihood is closely linked investment well ahead of any income studies. For almonds, mechanical harvest to the farm economy. Farming is an from the harvest crop (i.e., seed, fertil- represents 9.6% of the total cost to farm. intrinsically risky enterprise as it seeks to izer, fuel, labor, land rent). If the quantity But, for hand harvested crops like broc- manage a complex biological system that and/or quality of the crop is compromised coli, romaine lettuce, and strawberries can be profoundly affected by variations by serious pest damage, the farmer can- the percentage spent for harvest is 53.5%, in weather and by risks associated with not repay those expenditures (Figure 4). 53.9% and 66.2% respectively.

10 COUNCIL FOR AGRICULTURAL SCIENCE AND TECHNOLOGY cies plantings grown between the main growing seasons of annual crops as a way to decrease soil erosion, enhance soil quality and nutritive value, and help improved air and water quality. They are sometimes grazed, but are not harvested for commercial sales. This practice can qualify for government conservation payments and is recognized as highly desirable from a sustainability perspec- tive. However, it is critical that these crops are “terminated” prior to the next growing season so that they do not act as weeds and/or lead to cool and/or wet conditions for the germination of the crop seeds. Herbicides are an effective way to achieve timely and effective termination since tillage is counter-productive for the Figure 5. Cost structure comparison for four important California crops demon- soil health benefits and “winter killing” strating how much annual investment is being protected by minimizing is only effective for some cover crops in pest-driven yield losses. some regions (Legleiter et al. 2012).

Broad Societal Benefits Modern pest control methods such as irresponsible to allow excessive pest Food security and a diverse, afford- herbicides can also benefit workers by damage to undermine the efficient use of able, healthy food supply are key societal eliminating or greatly reducing the need the supplies that are available. benefits enjoyed in the developed world for potentially injurious and difficult Similarly, limiting pest damage is also in the modern era. Throughout human work such as hand weeding or weeding critical in efforts to minimize other key history such abundance has not been with a short handled hoe (Gianessi 2008). “footprints” of agriculture such as energy something that can be taken for granted. and greenhouse gas emissions. Once There are still marginalized populations Environmental Benefits again, these footprints are expressed per in developed countries and too many A sustainable pest management system unit of output. Thus, pest impacts on people in developing countries who do is critical to the overall sustainability of yield effectively increases these foot- not have food security. Only by keep- any cropping system because if usable prints per bushel, ton, hundredweight or ing pest damage to a minimum will it be yields are significantly reduced by pest other measure of yield. possible to extend food security to all of damage, land-use efficiency and water- In recent years there has been increas- humankind (Oerke and Dehne 2004). use efficiency are greatly diminished. ing appreciation for the role of “soil The enjoyment and health aspects of a These key performance indicators of health” both for ongoing agricultural diverse food supply are enhanced by the sustainability are expressed per unit of productivity and for a variety of ecosys- farmer’s ability to grow many different output (i.e., bushels/acre farmed, tons/ tem services that a healthy soil provides crops in many different environments. gallon of water applied). Over the past (i.e., water capture and retention, carbon This would not be possible without ways several decades, food and fiber pro- sequestration, nutrient buffering, surface to deal with pest challenges that can duction have increased to meet rising water quality protection). The farming vary enormously based on crop type and demand, but most of the gains have been practices that are widely recognized as geography. through increases in yield rather than best for soil health are often best enabled When insects damage some crops, through the addition of more farmed land. by key pest management tools (e.g., the crops can then be subject to future Pest control has been an important part reduced tillage and cover-cropping). Her- damage by certain fungi that produce of that success story. Ideally the further bicides allow farmers to control weeds dangerous chemicals called mycotox- growth expected in food demand over while still minimizing the soil-degrading ins. This serious threat to the safety of the next half century will be met through effects of mechanical disturbance inher- food and feed can be mitigated using an increased yields and minimal land-use ent in tillage (USDA 2017). While these integrated system of cultural methods, change, but this is only possible if pest “no-till” soils tend to be cooler and genetic resistance, and chemical and damage is minimized (Tilman et al. wetter, seed treatment fungicides and biological pesticides. Few high-income 2011). insecticides enable farmers to still suc- country consumers even know that they As water is likely to be a major chal- cessfully establish crops drilled into those are being protected from mycotoxin lenge in an age of climate change (Wal- soils (Hopkins 2017). exposure, particularly when enjoying lace 2000), it will become increasingly Cover crops are single or mixed spe- crops like tree nuts, peanuts, and grains.

COUNCIL FOR AGRICULTURAL SCIENCE AND TECHNOLOGY 11 In the low- and middle-income countries (e.g., juicing, trimming, animal feed), but there are quality advantages of that status. where there is not full access to the pest more severely pest damaged produce is Depending on the region and crop, there management “tool box,” mycotoxins are unusable and therefore waste. can be significantly more challenging a significant cause of illness and death For crops like apples and potatoes that pest issues in some locales. Areas with (Appell, Kendra, and Trucksess 2010). go into long term storage, very high pest more rainfall tend to have more fungal Some of the tools for mycotoxin mini- control standards are needed in the field pest issues. Warmer climate tends to have mization are available to organic farmers to sustain storage life. This is true both on more insect challenges. Because of these such as biological control with strains of the individual item level and to prevent challenges, pesticides provide significant the same fungal species which lack the major instances of waste where whole benefits that allow certain local farming ability to make the mycotoxin. If large containers are destroyed by fungal infec- industries to succeed. quantities of the spores of those strains tions spreading from item to item—hence are introduced into the field or orchard the old expression: “One bad apple can they can out-compete the dangerous spoil the whole bunch” (Ministry of Agri- Summary strains for colonization of those insect- culture, Food and Rural Affairs 2016). While it is reasonable for consumers injury sites. Biotech crops such as corn Pest-protected produce not only allows to be concerned about the presence of that express genes for the highly specific year-round access to these fresh products, pesticide residues in their foods, there is protein toxins from the soil bacterum it reduces the capital investment needed an absence of direct scientific or medical Bacillus thuringiensis prevent the insect to have the capacity to fulfill processed evidence demonstrating that pesticide damage insects thus greatly reducing the markets like frozen fries. A potato residues in the U.S. food supply pose a potential for contamination with aflatoxin processing plant using stored potatoes health threat to consumers. This conclu- or fumonisin. can handle the crop with a much smaller sion is based upon findings from risk capacity facility working throughout the assessment studies identifying large dif- Food System Benefits year. ferences between the estimated pesticide In recent years there has been in- “Latent” but non-visible infections exposure levels of consumers with the creased public awareness of the issue of of fruit in the field can cause subsequent levels required to be of toxicological food waste. Pest management is a very decay and thus waste at any stage of concern. Epidemiological studies have important component of mitigating food the distribution chain from transport, to suggested the potential for adverse effects waste of several types. When pests dam- warehousing, to retail display, to the con- but results from such studies are limited age crops in the field, that contributes to sumer’s home. In some cases this kind in their ability to measure both disease food waste to the extent that it renders of waste can be avoided by the use of a and pesticide exposure and have been the produce unharvestable or so undesir- “post-harvest” fungicide treatment with inconsistent in their findings. able so as to be avoided during harvest a chemical and/or biological fungicide Before pesticides are allowed to be (Creamer and Johnson 2017). Another which is sufficiently low in toxicity so applied to crops that are produced do- example of in-field food waste of grain that it can be applied close to the time mestically or imported from abroad, they crops is when damage by insects or of consumption (Adaskaveg and Forster must be registered for use by the EPA fungi weakens the stalk so that the plant 2009). and all uses of pesticides are required “lodges” or falls over and its grain will be In the international banana industry, to meet the “reasonable certainty of no missed by harvesting equipment (Nielsen there is a dramatic example of how pest harm” standard based upon anticipated and Colville 2014). In a handpicked, control reduces food waste and enhances consumer exposure and relation of such “field packed” crop like strawberries or food availability for consumers. There is exposure to toxicologically significant grapes, rotting fruit is simply left on the a banana disease called black Sigatoka, levels. The “reasonable certainty of no plant or dropped to the ground by the which only infects the leaves and not the harm” standard considers aggregate (i.e., pickers. fruit. However, if there is too much leaf food, water, residential) and cumulative Many fruit and vegetable crops are infection, the bananas harvested from (i.e., combining effects of toxicologically delivered in large bins from the field to a that tree will not survive the time it takes similar pesticides) exposure and also con- “packing plant” where various steps like for the energy-efficient means of ocean siders the potential increased sensitivity washing, sorting, packing, and chill- shipping the fruit. Instead of a container of population subgroups such as infants ing occur. There are generally detailed of fresh, consumable bananas, the harvest and children and pregnant women. requirements in terms of size, shape, and from an infected tree will be a lake of de- If it is anticipated that the agricul- color of the produce to meet industry composed mush. It is primarily because tural use of a pesticide may result in the standards or other customer specifica- of an effective fungicide program during presence of a residue on a food crop, the tions. Even relatively minor damage from growth that bananas can be enjoyed as EPA establishes a tolerance, represent- insects and/or diseases can render the one of the most widely consumed fruits ing the maximum level of the specific item to “cull status” (Baugher, Hogmire (Castelan et al. 2013). pesticide permitted on the specific crop. Jr., and Lightner 1990). Depending on Many consumers prefer to buy fresh While confusing to many consumers, the the severity of the issue that piece may and local food when it is available, and tolerance level is not based upon safety, be able to go into a side-product stream there are definitely some crops for which but represents the maximum residue

12 COUNCIL FOR AGRICULTURAL SCIENCE AND TECHNOLOGY anticipated provided the pesticide ap- tion of fruits and vegetables, a practice tive links were from studies looking at plication was made following all legal strongly associated with adverse health exposure from indoor pesticide use. Con- requirements. Levels of pesticide residues effects. sidering the conflicting evidence from detected in excess of the tolerance levels Results from a handful of recent these epidemiological studies as well as indicate product misuse but rarely indi- epidemiological studies have suggested from classical toxicological risk assess- cate the potential for consumer health links between pesticide exposure and ments for the organophosphate pesticides concerns. Levels of pesticide residues of disease, such as male sperm abnormali- examined, the overall weight-of-evidence health concern are typically far above tol- ties and childhood neurodevelopment. would indicate that the link between food erance levels and not commonly detected It is critical to realize that such links residue exposure to organophosphates in the U.S. food supply chain. represent correlations and that the effects and child neurodevelopment deficits is far Pesticide monitoring studies routinely could be caused by other factors or most from established. demonstrate that most residues on foods likely due to chance. As an example, one Finally, it is important to recognize the are far below tolerance levels—if they study indicated that frequent consumers benefits that pesticides provide for the are detected at all—and very few samples of organic produce have lower risks of agricultural sector and consumers. From show residue levels in excess of toler- particular diseases than do those who do a public health perspective, pesticides ance levels. The majority of pesticide not frequently consume organic produce. provide a tool that can help control fungi residue violations occur when residues of However, it was also the case that those capable of producing mycotoxins of pesticides approved for use on other food frequently consuming organic foods also significant health concern. crops are detected—at any level—on have greater income, have greater educa- It is critical that farmers continue to foods for which tolerances have not been tion, and exercise more frequently; these be able to maintain a sustainable pest established. As is the case with over-tol- and other factors may be responsible for management regime that includes the erance residues, such violations are rarely the lower incidence of disease in this co- judicious use of pesticides. If growers of health consequence. hort, rather than lower pesticide residue did not prevent the damage the pests can Since pesticide tolerances are not exposure. cause, our food supply would be more safety standards, referencing results It is extremely difficult to study the expensive, less diverse, potentially dan- from pesticide monitoring programs that role of diet and health in an epidemio- gerous, and of lower quality. Food waste primarily focus upon enforcing tolerances logical study, let alone to study the role of is a complex issue and pest management is of little utility in evaluating consumer trace levels of pesticides associated with importantly contributes to its manage- risks from exposure to pesticide residues our food. Consider trying to remember ment. in foods. Other studies, such as the FDA’s what you ate last week and how much! Perhaps most importantly, without Total Diet Study, provide evidence of the Unfortunately the quality of the epidemi- effective pest control the small sector of levels of pesticide residues existing on ology data for diet and the resulting pesti- our society that still engages in the high- foods immediately prior to their con- cide residue exposure is often quite poor. risk business of growing our food would sumption, and, through consideration of Dietary exposure to pesticide residues be unable to continue. The farm workers the residue levels as well as food con- is often estimated based on biomonitor- and rural businesses would also be hurt, sumption rates, allow estimates of con- ing studies looking at the presence of pes- as would “local growers” in pest-chal- sumer exposure from pesticide residues ticide metabolites in the urine but these lenging regions. in foods to be calculated. Studies using cannot determine when, how, or where Crop protection chemicals and biolog- this approach frequently demonstrate that possible pesticide exposure occurred. ical agents are an important part of what such exposure is often more than one Other studies have focused upon agri- is required to limit pest damage. The EPA million times lower than levels that cause cultural workers and have inferred that and other agencies intensively scrutinize no effects in laboratory animals exposed links between occupational exposure to those products for human and environ- to pesticides daily throughout their pesticides and disease provide evidence mental safety. That regulatory oversight lifetimes. These levels are intentionally that similar links might be evident from covers the tools used in both organic and protective of public health and not pre- consumer exposure to food residues. conventional farming. As long as the dictive of human disease due to multiple If a strong correlation between regulation continues to be science-based, levels of uncertainty factors employed by pesticide residue exposure and disease farmers will continue to have the tools the regulatory agencies involved in food were to emerge, it is likely that results they need to provide the food and feed safety. from a variety of related epidemiologi- crops on which we all depend. Consumers are frequently advised to cal studies would share similar findings, seek out organic foods and/or to avoid but evidence does not indicate that this purchasing specific conventionally- is the case. For example, in studies of produced fruits and vegetables due to the relationship between organophos- contamination concerns. Research has phate pesticide exposure and childhood demonstrated that such advice lacks intelligence, studies looking at general scientific justification and may result in pesticide exposure from food residues some consumers reducing their consump- found no consistent link. The only posi-

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Citation: Council for Agricultural Science and Technology (CAST). 2019. Interpreting Pesticide Residues in Food. Issue Paper 66. CAST, Ames, Iowa

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