Pesticides and Produce

Pesticides and Produce

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Pesticides are chemicals designed to kill living organisms (insects, rodents, plants, etc), which makes them inherently toxic. The primary way children are exposed to pesticides is through the foods they eat.1 Although rinsing fruits and vegetables is a common household practice, rinsing produce reduces some but not all pesticide residues to varying degrees but has not been proven to decrease pesticide exposure.2 Additionally, some pesticides are systemic, which means they are absorbed into the produce while other pesticides are sprayed onto the food post harvest to extend shelf life, and these pesticides can transfer to other foods when they come in contact.3

The amount of residual pesticide on produce varies widely.

The US Department of Agriculture (USDA) monitors pesticide residues on some of the produce we eat through its annual Pesticide Data Program (PDP).4 The foods tested are washed and sometimes peeled, as is customary for the particular food item, prior to analysis so that the pesticide residue detected is similar to what we would consume. The results from the most recent analysis showed that residual pesticide levels in our produce varies widely. In 2014, 59% of all the produce samples tested had detectable pesticide residue, though 99% of the samples with pesticide residues had levels below the tolerances established by the Environmental Protection Agency (EPA).However, there were some fruits and vegetables that almost always had some level of pesticide residue on them, and often there were residues from multiple different pesticides on a single produce sample.

Is it safe to eat foods with residual pesticides?

The EPA determines the upper level, or tolerance, of a residual pesticide that is considered safe to consume on a daily basis with “reasonable certainty of no harm.”6 Each tolerance is set by examining toxicity data collected from animal studies on a single pesticide and levels detected on produce are typically much lower than the set tolerance. However, many of the pesticides allowed for use in the US are organophosphates, which are known neurotoxins, or classified by the US EPA as “likely” carcinogens.7 Also, since there are frequently multiple pesticide residues on a single fruit or vegetable and we eat (or at least should) multiple different types of produce a day, we are exposed to many pesticides in combination. Since 1996, the EPA has been required by the Food Quality Protection Act to assess combined risks from exposure to multiple pesticides that act through a common mode of action.8 However, the risk assessments are calculations conducted for various index (example) chemicals and are not exhaustive.

Although the current tolerance levels for pesticides in use are considered safe, there are no studies to date that have experimentally examined the causal relationship between exposure to pesticides from consumption of conventionally grown foods and health outcomes. There are, however, numerous studies that examine the health effects of pesticides on farm workers and families living near farms. Chronic exposure among farm workers to organophosphate pesticides has been associated with numerous adult health problems, including respiratory problems, memory disorders, dermatologic conditions, depression, neurologic deficits including Parkinson’s disease, miscarriages, birth defects and cancers.And a large prospective birth cohort study that measured organophosphate pesticide exposure in pregnant Californian farm workers and followed their children found lower mental development index scores at 24 months of age and attentional problems at 3.5 and 5 years of age.10,11

Given that pesticide consumption can not be good, and is probably bad, for our health below are some guidelines on produce and pesticides to follow to ensure that you are eating wisely.

Guidelines on produce and pesticides to follow to ensure that you are eating wisely.

1. Minimize consumption of produce with pesticide residues

There are enough unknowns about the long term health effects from chronic low dose exposure to pesticides that warrant making judicious produce choices when grocery shopping. In an effort to educate consumers, two separate organizations, Consumer Reports, and the Environmental Working Group (EWG) have compiled lists of fruits and vegetables that have the highest residual pesticides. The EWG analyzed data from the USDA PDP to compile its list of produce with the highest levels of pesticide residue, also known as the Dirty Dozen.12 Consumer Reports (CR) went a step further and created a Dietary Risk Index (DRI) which assesses the amount of residue pesticide, the toxicity of the pesticide, as well as the serving size of the food and the weight of the person consuming the food.3

2. Avoid produce with organophosphate pesticide residues

33 million pounds of organophosphate pesticides were used in the US in 2007, the most recent year data was available from the EPA, and organophosphates accounted for 35% of all insecticides used in the US.7 Organophosphates are a class of insecticides that affect the nervous system by disrupting an enzyme that regulates acetylcholine, a neurotransmitter also found in the nervous system of mammals.3 When studying the health effects of pesticide exposure, organophosphates are typically evaluated because of their toxicity and frequency of use. The NIH has stated that “research suggests that early childhood exposure to pesticides, which can go undetected because of the lack of overt symptoms, to certain organophosphates can lead to lasting effects on learning, attention, and behavior.”13

3. Avoid produce with “likely to be carcinogenic” pesticide residues

All active ingredients in pesticides are required by the EPA to be tested in animals or using in vitro tests for their likelihood of causing cancer. The Health Effects Division of the EPA’s Pesticide Program performs an independent review of all the available evidence to classify active ingredients according to their potential to cause cancer.14 The EPA uses the descriptor “likely to be carcinogenic” when the weight of the evidence for a specific pesticide is adequate to demonstrate carcinogenic potential to humans. Evidence to support this classification can vary, ranging from a plausible association between human exposure and cancer to a positive animal tumor study that raises additional biological concerns beyond that of a statistically significant result.15 

Below is a table containing the fruits and vegetables considered by the EWG and Consumer Reports to have high levels of pesticide residue, along with Consumer Reports’s purchasing recommendations. The chart also includes some important information from recent UDSA PDP reports: percentage of samples tested with detected pesticide residue, whether an organophosphate pesticide was detected, and whether a pesticide classified by the EPA as a “likely” or “possible” carcinogen was detected. Based on all of this information, Feed Them Wisely has assessed these foods and made one of two recommendations: avoid (wise-apple-0-01) or acceptable (wise-apple-50-01).  Avoid means simply that: whenever possible, avoid the conventionally grown produce by either purchasing the organically grown version or choosing a different option all together. Acceptable is a little more nuanced: the conventionally grown version of this food is probably okay if these are foods that you and your family eat infrequently. But if your family eats, for example, grapes or carrots almost daily, it is wisest to choose the organic version.

Produce with High Levels of Pesticide Residue

Looking through the above table, there are many fruits and vegetables that I knew had high levels of residual pesticides from frequently being listed on the “Dirty Dozen.” Berries, tree fruits, green leafy vegetables are common offenders. However, for me, there were a few surprises:

Tangerines. I was really surprised to learn that tangerines, which my family loves, were found to almost always have pesticide residue on them (97% of samples contained pesticide residue) – and that was after they were washed and peeled! I thought that removing the peel would remove the residual pesticide, but it does not. Tangerines are commonly treated with fungicide post harvest to prolong their shelf life.3  FTW rates tangerines as “acceptable” because they do not have any organophosphates or likely / probable carcinogens pesticide residues. However, if these are a food that your family loves, like mine, consider buying organic when you can. And most definitely wash and peel the tangerines before putting them in a lunch box for your children to enjoy.

Green Beans. Though “only” 70% of the green beans tested contained pesticide residue, there were several organophosphate and probable carcinogenic pesticide residues detected. And these residues were still present in the green beans after processing into baby food, canned and frozen forms. FTW rated green beans as “avoid” because of the toxicity of these pesticides and because green beans are a first vegetable that we feed our children. If you can, only buy organic green beans.

Summary.

Though, to date, there are no clinical studies demonstrating the adverse health effects of chronic low-level pesticide exposure from food, I believe there are sufficient emerging data to warrant caution when choosing the fruits and vegetables we eat and feed our families. The above table includes a long list of foods that we need to consider avoiding, buying labeled “pesticide free”, or buying organic to reduce our pesticide exposure. Switching to organically grown produce can have an almost immediate and measurable impact. A small clinical study evaluated the urinary pesticide residue levels of 23 children who regularly consumed conventional produce. The researchers found that the pesticide residue levels were reduced to almost undetectable levels when the children with switched to an organic produce diet for five days.19 Also, it is important to note that there are still many fruits and vegetables with minimal to no pesticide residues. Examples of conventional produce that can be enjoyed with minimal concern for pesticide resides include: asparagus, broccoli, sweet corn, cauliflower, avocados, pineapple, cantaloupe and honeydew melon. For more information, see EWG’s “Clean 15“.20 By making judicious food choices, we can reduce our family’s exposure to pesticides.

Please note:

Glyphosate Residue Not Addressed. Though some herbicide residues are regularly monitored in the USDA PDP program, residue from glyphosate (trade name Roundup®) is not routinely measured.5,16,17 Glyphosate is used while growing some genetically engineered crops and is the most commonly used chemical in agriculture.  In 2007 (the most recent date data are available from), 180 million pounds of glyphosate were used in the US alone.7

Organically grown food does not mean pesticide free. Organic farms utilize a tiered approach for pest management: prevention, avoidance, monitoring and suppression. If necessary, organic farmers may use an approved pesticide, such as naturally occurring microorganisms, insecticides naturally derived from plants, or one of a few approved synthetic substances. However, organic farms may not use organophosphate pesticides.21

References:

  1. National Research Council. Pesticides in the Diets of Infants and Children.  Washington, DC: National Academies Press; 1993 (link)
  2. Reduction of pesticide residues on produce by rinsing. Krol WJ, Arsenault TL, Pylypiw HM, Jr; Incorvia Mattina MJ., J Agric Food Chem. 2000;18(10)1666-1670 (link)
  3. Consumer Reports From Crop to Table Special Report. (link)
  4. USDA Pesticide Data Program Website (link)
  5. USDA Pesticide Data Program, 2014 (link)
  6. EPA Website, Food and Pesticides (link)
  7. EPA Pesticides Industry Sales and Usage 2006 and 2007 Market Estimates, 2011. (link)
  8. International Framework Dealing with Human Risk Assessment of Combined Exposure to Multiple Chemicals. European Food Safety Authority, 2013. EFSA Journal 2013;11(7):3313. (link)
  9. Organic Foods: Health and Environmental Advantages and Disadvantages. Joel Forman, Janet Silverstein (link)
  10. Organophosphate pesticide exposure and neurodevelopment in young Mexican-American children. Marks AR, Harley K, Bradman A, et al. Environ Health Perspect. 2007;115(5)792-798. (link)
  11. Organophosphate pesticide exposure and attention in young Mexican-American children: the CHAMACOS study. Marks AR, Harley K, Bradman A, et al. Environ Health Perspect. 2010;118(12):1768-1774. (link)
  12. The Environmental Working Group’s 2016 Shoppers Guide to Pesticides in Produce, the Dirty Dozen, 2016. (link)
  13. National Institute of Environmental Health Sciences.  Organophosphates Superfund Research Program (link)
  14. Recognition and Management of Pesticide Poisonings , 6th ed, 2013, Ch 21: Chronic Effects (link)
  15. EPA Guidelines for Cancer Risk Assessment, 2005 (link)
  16. USDA Pesticide Data Program, 2009 (link)
  17. USDA Pesticide Data Program, 2011 (link)
  18. Recognition and Management of Pesticide Poisonings , 6th ed, 2013, Ch 5: Organophosphates (link)
  19. Organic diets significantly lower children’s dietary exposure to organophosphorus pesticides. Lu C, Toepel K, Irish R, Fenske RA, Barr DB, Bravo R. Environ Health Perspect. 2006;114(2):260-263. (link)
  20. The Environmental Working Group’s “Clean Fifteen” list, 2016 (link)
  21. USDA National Organic Program, Organic Practices Factsheet (link)

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