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A Shopper's Guide to Pesticides in Produce 

Richard Wiles, Kert Davies, Susan Elderkin /  Environmental Working Group/The Tides Foundation
Nov95

An exhaustive review of Federal government data shows that you can reduce your health risks from pesticides in fruits and vegetables by half, and still eat a diet rich in all the nutrients and benefits they supply. How? Buy organic produce whenever possible. But if you can't, another option is to minimize consumption of the twelve fruits and vegetables that consistently carry the most pesticides, and the most toxic pesticides.

source: http://www.ewg.org/pub/home/Reports/Shoppers/Shoppers.html 

Foreword

You know what to eat if you want to lower your cholesterol. And you know what foods to cut back on if you're counting calories or trimming fat.

But what do you eat, and what do you avoid, if you want to eat less pesticides?

You can buy organic, of course. We recommend it. But organic produce is hard to find for many people, and it can be more expensive. Some supermarkets offer produce certified as having "no detected residue." Ironically, and for very different reasons, both conventional and organic producers find the middle ground of "NDR" highly objectionable. But if the standards are strict and really reduce pesticide levels, we think NDR is a viable option for some consumers when organic items aren't available.

Now you have another option: consult A Shopper's Guide to Pesticides in Produce. Pick from among the many fruits and vegetables that have relatively lower levels of pesticides, yet give you all the vitamins, nutrients and other goodies you need. And cut back on the dozen or so produce items that, according to Federal lab tests, tend to be tainted with the most, and most toxic, bug and fungus killers used by growers.

Richard Wiles, Kert Davies and Susan Elderkin of EWG have devised the first rating system for pesticides in produce, based on seven different measures of pesticide contamination and toxicity. Then, with help from nutritionists, the authors have listed tasty and nutritional alternatives to the twelve fruits and vegetables that had the poorest rating.

As we've said before, with current, weak pesticide laws and a growing but still small organic food industry, if you eat in America, you eat pesticides. Shop with the EWG guide if you want to eat less.

Kenneth A. Cook
President

Executive Summary

Fruits and vegetables are essential to a nutritious and healthy diet. At the same time, the health benefits of many of these fruits and vegetables are compromised by consistent contamination with combinations of pesticides classified by the Environmental Protection Agency (EPA) as probable human carcinogens, toxicity category one (most toxic) nervous system poisons, and endocrine (hormone) system disrupters.

What is a parent to do?

One answer is to buy certified organic produce, but this is simply not a viable option for the vast majority of families because only two percent of the nation's food is organically grown (USDA 1995). Another approach is to selectively purchase conventional produce that has consistently lower levels of fewer pesticides, and that has lower levels of highly toxic pesticides.

To help consumers minimize their exposure to pesticides in produce, and maximize the nutritional benefits of the fruits and vegetables they eat, we analyzed the results of 15,000 samples of food tested for pesticides by Food and Drug Administration during 1992 and 1993. We then ranked 42 fruits and vegetables according to seven different measures of pesticide contamination, such as the percent of the crop with detectable residues, and the potency of the average amount of cancer causing pesticides found each year on that crop.

We found:

The Shopper's Guide to Pesticides in Produce does not tell people what to eat. Instead the Guide provides easy to understand ranking of fruits and vegetables from those with the highest and most toxic contamination, to those with the fewest and least toxic levels of contamination. We then provide a simple selection of nutritious alternative fruits and vegetables with consistently lower pesticide risks.

For example, the Guide does not recommend that people never eat strawberries. The Guide will tell consumers, however, that strawberries had the highest combined score for pesticide contamination and toxicity of all fruits and vegetables examined, and that there are many equally or more nutritious alternatives to strawberries, with far fewer pesticides on them.

Similarly the Guide does not tell people to eat avocados. It does quite clearly reveal, however, that avocados have the lowest levels of the fewest number of pesticides of all 42 crops examined.

The Shopper's Guide is the fifth in a series of Environmental Working Group reports that analyzes pesticides in food and the risks they present to infants and children. In the past we have examined the particular susceptibilities of infants and children to pesticides, the presence of pesticides after washing and peeling produce, the underreporting of illegal pesticides by the FDA, and the presence of pesticides in baby food.

In previous reports the Environmental Working Group has recommended the phase-out of highly hazardous pesticides, including those classified by the EPA as probable human carcinogens; a strict health standard to protect infants and children from exposure to multiple pesticides in food, water, and the environment; and real incentives for the overall reduction of pesticide use in agriculture. We restate our support for these recommendations here.

In the current political climate, however, it seems just as likely that the Congress will weaken current pesticide standards as strengthen them. Our recommendation in this context is for consumers to vote with their wallets, and purchase produce with consistently lower and consistently less toxic pesticides on them.

This action will send two important signals:

Consumers will send a financial reward to growers of crops with fewer and less toxic pesticides at point of sale. In general (but not always), fewer residues result from less and smarter pesticide use. This will create a serious incentive for pesticide use reduction on the twelve most contaminated crops.

Chapter One -- The Results

To provide the most complete and meaningful rankings of pesticides in produce we created seven different measures of contamination and toxicity. Four categories focus on the amount or number of different pesticides typically found on the crop -- the percent of apples with detectable residues of a pesticide, the number of pesticides found, and so forth. The other three focus on the relative toxicity of the average load of pesticides found on the crop by considering such measures as the potency of the carcinogens or neurotoxins identified.

We looked at 38 popular fresh produce items (four of them in terms of imports vs. domestic sources, for a total of 42 distinct crops rated), and examined only those fruits and vegetables that the FDA sampled in significant quantities. The average sample size per crop over the two year period is 277, ranging from a low of 38 samples of Brussels sprouts to a high of 1,062 samples of lettuce. Because the FDA does not test for every pesticide on each sample, we limited our analysis to a pesticide/crop sample size of at least 20.

FDA Data

A Shopper's Guide to Pesticides in Produce is based in part on more than 15,000 records of FDA random pesticide surveillance data for Fiscal Years 1992 and 1993 for 38 fresh fruits and vegetables. For four of the 38 foods -- cherries, sweet peppers, grapes, and cantaloupe -- there were considerable differences between the pesticide residues from different major producing countries. These crops are presented by country of origin, with one ranking for the U.S. grown crop, and one for the imported crop.

The information we used from FDA includes:

 

EPA Data

All of the data used to rank the toxicity of the pesticide residues found are from the U.S. Environmental Protection Agency (EPA), except for the classification of pesticides as endocrine modifiers, which is from a review of EPA and other data published in the Journal of the National Institute of Environmental Health Sciences of the National Institutes of Health (Colborn et al. 1993).

In many cases additional studies conducted by or for such organizations as the International Agency for Research on Cancer or the National Toxicology Program are available for these pesticides. More often than not, these studies support findings of greater public health risks than the data generated by the pesticide manufacturers in compliance with EPA requirements. Even so, these studies are rarely used by the EPA. Cancer and neurotoxicity data not used by the EPA are not used in these rankings.

 

Quantity Analysis

The measures that characterize the amount and number of pesticides found on a sample or an individual crop include:

 

Simple descriptive measures of pesticide contamination indicate the uncertainty of the risks posed by pesticides on these foods. The more pesticides found on a crop, the more uncertain the health risks to consumers. The higher the likelihood of multiple residues on a crop, the greater the uncertainty of the toxic effects.

EPA standards for pesticides on food assume that everyone is exposed to pesticides one pesticide at a time, and that additive effects from exposure to pesticides do not occur. This policy stands in stark contrast to reality, where many different pesticides are commonly found on single servings of fresh fruits and vegetables. It also contradicts the unanimous recommendations from every major scientific institution that has examined the question of additive effects of toxic substances, all of which have recommended adding together health risks from compounds with a common toxicity (WHO 1981, ACGIH 1983, OSHA 1983, NRC 1988, NRC 1989, NRC 1993). The data for these rankings clearly show that exposure to multiple pesticides in food is the norm.

 

Percent of the crop on which residues were detected by the FDA.

Celery topped the list with 81 percent of all samples positive for pesticides, followed by grapes from Chile (79 percent), cantaloupe from Mexico (76 percent), nectarines (74 percent), cherries grown in the U.S. as well as peaches (71 percent) and strawberries (70 percent) (Table 2).

Table 2. The percent of samples testing positive for pesticides. 
Source: Environmental Working Group, compiled from FDA and EPA data.

10 Worst Commodities 5 Best Commodities

The foods with the fewest samples testing positive for pesticides were sweet corn and avocados with one percent positive, followed closely by bulb onions (five percent), cauliflower (six percent), and asparagus (14 percent).

 

Percent of Samples with Two or More Pesticides

In 1993, the National Academy of Sciences released a five-year study, Pesticides in the Diets of Infants and Children, confirming the well-accepted principle that infants and children are generally more susceptible to pesticides than adults, and concluding that current regulations do not protect children adequately from pesticides. Integral to this finding was the committee's concern that children are exposed to many different pesticides each day, and that the additive toxicity of these exposures presents health risks that are currently not accounted for by food tolerances (NRC 1993).

The committee was especially concerned about the additive toxicity of an important class of neurotoxic pesticides known as organophosphates, that are commonly found in food. The committee noted that "...although the data are weak, the committee estimated that for some children [additive] exposure could be sufficiently high to produce symptoms of acute organophosphate poisoning," (NRC 1993 pg. 7).

Pesticides that disrupt the human endocrine system can also have an additive effect. In recent experiments at Tufts University Medical Center, ten pesticides mixed together at doses ten times lower than needed to elicit an estrogenic response alone, exhibited a potent estrogenic effect in combination (Soto et al. 1994).

One way to measure exposure to many different pesticides is to calculate the simultaneous occurrence of multiple residues on single samples of fruit. Topping the list of crops with multiple residues was cantaloupe from Mexico; forty eight percent of samples had two or more pesticides (Table 3), and 22 percent of samples had three or more pesticides. Two or more pesticides were found on 46 percent of the samples of domestically grown cherries and grapes from Chile, 38 percent of sweet peppers from Mexico and apricots, and 36 percent of strawberries.

Table 3. The percent of samples testing with two or more pesticides.
Source: Environmental Working Group, compiled from FDA and EPA data.

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No avocado or corn samples contained residues of more than one pesticide, and only one percent of asparagus, cauliflower and bulb onions samples contained multiple residues.

 

The Number of Pesticides on a Single Sample

Another way to measure exposure to pesticide mixtures is the number of pesticides found on single samples of a crop. Up to seven pesticides were found by the FDA on single samples of U.S. apples and peaches (Table 4). Six pesticides were found on single samples of grapes from Chile, lettuce, strawberries, tomatoes, and sweet peppers from the U.S. and Mexico.

Table 4. Five or more pesticides were found on single samples of 11 different crops.
Source: Environmental Working Group, compiled from FDA and EPA data.

Commodities with the most Commodities with the least

Just one pesticide was found on one sample of all avocados analyzed. Two pesticides were found in combination on single samples of cauliflower, imported cherries, sweet corn, bulb onions, and sweet potato samples.

Results from the Pesticide Data Program of the U.S. Department of Agriculture show that the situation is even worse than FDA data reveal. In the past two years, PDP technicians found 9 pesticides on a single apple sample and 8 on single samples of green beans and peaches (USDA 1995, USDA 1994).

 

Total Number of Pesticides on a Crop

This category reflects the intensity of pesticide use on a crop and indicates which crops carry the highest likelihood of exposure to the widest variety of pesticides. Heavy consumption of some foods may expose an individual over time to 30 or more pesticides. Heavy consumption of other crops may expose an individual to only ten.

Thirty-six different pesticides were detected on apples, followed by 30 on strawberries and tomatoes, 27 on squash, 26 on cherries grown in the United States and peaches, and 25 on cantaloupe from Mexico (Table 5).

Table 5. Twenty-five or more pesticides were found on all samples of 8 fruits and vegetables.
Source: Environmental Working Group, compiled from FDA and EPA data.

Commodities with the most Commodities with the least

Only one pesticide was found on all avocados tested, followed by sweet potatoes with, bulb onions and sweet corn with six, and bananas and Brussels sprouts with 7.

Toxicity Analysis

To understand the health impacts of exposure to numerous toxic pesticides, we supplemented FDA data on residue levels with information about the health effects of each pesticide detected. These health effects include:

 

 

Potency of the average total residue of carcinogenic pesticides.

Scientists generally agree that exposure to two carcinogens that present equal risk is twice as dangerous as exposure to only one. The World Health Organization, the American Council of Governmental and Industrial Hygienists, the Occupational Safety and Health Administration, and three committees of the National Academy of Sciences (the Safe Drinking Water Committee, the Committee on Methods for the In Vivo Testing of Complex Mixtures, and the Committee on Pesticides in the Diets of Infants and Children) have endorsed and formally recommended the notion of adding low dose cancer risks, as has the EPA's own risk assessment guidelines promulgated under the Reagan Administration (WHO 1981, ACGIH 1983, OSHA 1983, EPA 1985, NRC 1988, NRC 1989, NRC 1993). Ten years after adopting these guidelines, the EPA for the first time began using this methodology in the special regulatory review of the triazine herbicides.

The cancer potency rankings presented here are the sum of the average residue value of all the carcinogenic pesticides found on a given crop, times the potency (Q1*) of the respective carcinogens. For our calculations, we used the most recent cancer potency estimates from the EPA (See Note 1.) and the average residues of carcinogens reported by the FDA. All samples with non-detects were treated as zero, and all of these zeros were included in the averages.

Note 1.
Cancer risk figures are only computed for carcinogens classified as B2 and Cq by the Environmental Protection Agency. A B2 carcinogen is one that is identified as a probable human carcinogen; a Cq carcinogen is considered a possible human carcinogen where the risk (or cancer potency) can be quantified.

The purpose of the Guide is to help people choose which fruits and vegetables they want to eat, based on the quantity and toxicity of the pesticides typically found on these crops. The rankings do not incorporate the average food consumption figures typically used in EPA cancer risk assessments because we wanted to make an objective measure of the potency of the average load of carcinogens actually found on each fruit and vegetable, irrespective how much cantaloupe the average person in the United States eats (according to the USDA).

The following equation is used to calculate the cancer potency per unit of food:

 

Potency of the average total carcinogenic residue = The sum of the Mean Residue x Cancer Potency for each carcinogen detected on the crop with 20 or more samples. (See sample calculations below).

Calculating Neurotoxic and Cancer Potency Estimates

Neurotoxic potency of the average residue is expressed as a product of the average residues of neurotoxins multiplied by their respective chlorpyrifos equivalency factors. For cucumbers, the calculation was as follows. For each of the seven neurotoxic pesticides detected, the average residue was multiplied by the chlorpyrifos equivalency factor. The respective potencies for each chemical were totaled to derive the potency of the average residue of neurotoxins on the crop. Chlorpyrifos equivalency factors were calculated using the methodology described in the National Academy of Sciences report Pesticides in the Diets of Infants and Children where chlorpyrifos is assigned a value of 1 and all other neurotoxins are rated relative to that baseline based on the lowest dose that caused a cholinesterase inhibiting effect in animal studies, according to the EPA.

 

Pesticide

Average Residue (ppm)

Chlorpyrifos Equivalency Factor

Potency of Average Residue in Chlorpyrifos Equivalency Factor

Acephate

0.00060

0.8333

0.0000000335

Carbaryl

0.00250

0.0297

0.0000000054

Chlorpyrifos

0.00040

1.0000

0.0000000279

Diazinon

0.00040

4.0000

0.0000001060

Dimethoate

0.00005

0.4000

0.0000000013

Methamidaphos

0.00820

2.0000

0.0000011800

Parathion

0.00002

10.0000

0.0000000166

 

 

Total

0.0000013700

Cancer potency of the average residue is expressed as a product of the average residues of carcinogens multiplied by their respective potency factors. For strawberries, the calculation was as follows. For each of the five cancer causing pesticides detected, the average residue was multiplied by the EPA potency factor Q1*. The respective potencies for each chemical were totaled to derive the potency of the average residue of carcinogens on the crop.

 

Pesticide

Average Residue (ppm)

Q1* Potency

Potency of Average Residue

Benomyl

0.07

0.0042

0.00026

Captan

0.68

0.0036

0.0025

Carbaryl

0.12

0.0227

0.0027

Iprodione

0.31

0.0620

0.015

Propargite

0.02

0.0303

0.00053

 

 

Total

0.0212

Cancer potencies varied by more than two orders of magnitude (100-fold) among fruits and vegetables (Table 6). The two vegetables with the most potent average carcinogenic residues were spinach and cucumbers, followed by squash, domestically grown cherries and blackberries, and peaches. No carcinogens were detected on avocados and sweet corn, while very few were found on Brussels sprouts, sweet potatoes, and bananas.

Table 6. The potency of the average residue of the 10 most contaminated foods was 100 times greater than the cleanest crops.
Source: Environmental Working Group, compiled from FDA and EPA data.

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Potency of the average total residue of neurotoxins

The neurotoxic potency of the average residues presented here is based on residues of organophosphate insecticides plus the carbamate compound, carbaryl. For most crops carbaryl contributed a very small portion of overall neurotoxic potency. Organophosphate and carbamate insecticides block the normal functioning of the enzyme acetylcholinesterase at the nerve endings. Organophosphate insecticides are derived from the same nerve gas chemistry developed by Nazi scientists for prison camps in World War II. Severe organophosphate poisoning can lead to nausea, vomiting, muscle spasms, blurred vision, coma, and even death. Carbamate poisoning, which causes similar symptoms, is generally reversible within a 24 hour period. Organophosphates are toxic for a longer period of time.

Exposure to residues of neurotoxic organophosphate insecticides in the diet may pose serious health risks to children. According to the National Academy of Sciences about 1.3 percent of the nation's two-year-olds (or about 50,000 young children) receive a dose of five organophosphate insecticides on just eight foods, in excess of the EPA's acceptable limits (NRC 1993). The actual number of children at risk is most likely much higher because their are at least 15 organophosphates in widespread use on at least 40 fruits and vegetables.

Current federal regulations require that the additive toxicity of organophosphate pesticides be explicitly considered in tolerance setting (40 CFR 180.3). These rules have never been enforced.

Some of the most widely used organophosphate insecticides are chlorpyrifos, dimethoate, malathion, methamidaphos, and methyl parathion. Carbaryl is the most heavily used carbamate. The National Academy of Sciences (NAS) devised a methodology for adding the risks of organophosphate pesticides by expressing exposure in terms of chlorpyrifos equivalents (NRC 1993). We used the same conversion method as the NAS, expressing the potency of each organophosphate insecticide in terms of its chlorpyrifos equivalent, based on the lowest dose at which the insecticide produced a cholinesterase effect in animal studies.

The neurotoxic potency is computed in the following way:

 

Total average neurotoxic potency = The sum of the Mean Residue x Chlorpyrifos Equivalency Factor for each cholinesterase inhibiting pesticide with a sample size greater than 20. (See Sidebar for sample calculations).

The potency of the average neurotoxic residue was 500 times greater for the most contaminated crops than for the least contaminated (Table 7). The greatest amount of neurotoxins by far were on sweet (bell) peppers from the U.S. and Mexico (which account for 98 percent of all pepper consumption), followed by cantaloupe from Mexico, celery, pears, and green beans. Fruits and vegetables with very few organophosphate insecticides included bulb onions, corn, cauliflower, blueberries, and sweet potatoes.

Table 7. The potency of the average neurotoxic residue on the most contaminated crops was 500 times greater than the cleanest crops.
Source: Environmental Working Group, compiled from FDA and EPA data.

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Total Residue of Endocrine Disrupters and Reproductive Toxins

A growing body of science confirms that numerous pesticides and other industrial pollutants can disrupt the animal and human endocrine (hormone) system at very low doses, potentially contributing to a host of adverse health effects, including cancers of reproductive organs-- the breast, testicles, and prostate--which are all on the rise (Lancet 1995, Toppari et al. 1995). More subtle or bizarre effects have also been linked to these endocrine disrupters, including a 50 percent decline in human sperm count and quality in the industrialized world over the past 50 years, increased rates of cryptorchidism (non-descended testicles), hypospadias (a malformation of the penis), and skyrocketing rates of endometriosis (Carlson et al. 1992, Colborn et al. 1993, Gray 1992, Hileman 1994, Reir et al. 1993, Sharpe and Skakkebaek 1993, Soto et al. 1994, The Lancet 1995, Toppari et al. 1995).

Some of the most widely used pesticides are known to disrupt the endocrine system and leave residues on food, especially endosulfan (which can mimic the female hormone estrogen and was found on 30 out of 42 crops), carbaryl (detected on 27 crops), the EBDC fungicides (pesticides that are present on fruits and vegetables but are rarely tested for by the FDA), vinclozolin (found on 19 crops), and dicofol (the hydroxylated version of DDT, detected on 15 crops).

Rankings were based on a simple sum of the mean residues of endocrine disrupters for all pesticides with a sample size of 20 or more for an individual crop. Non-detects were all treated as zeros, and all zeros were included in the calculations of averages.

The produce with the highest average residues of endocrine disrupters had more than 1000 times the residues of the cleanest fruits and vegetables. The most contaminated crops include strawberries (0.72 ppm), spinach (0.59 ppm), cabbage (0.54 ppm), pineapples (0.52 ppm) and domestic cherries (.43 ppm) (Table 8).

Table 8. The average residue of endocrine disrupting pesticides on the most contaminated crops was up to 1,000 times more than the cleanest crops.
Source: Environmental Working Group, compiled from FDA and EPA data.

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The produce with the lowest endocrine disrupter concentrations are sweet corn with none, and avocados, sweet potatoes, limes, potatoes, bulb onions, and plums (all with less than 0.003 ppm).

Consumers Need to Know What is in Their Food

There is little doubt that synthetic chemicals added to food, air and water contribute to some level of cancer and other health effects in our society. Cancer incidence is up 48 percent in the past forty years, even when the figures are adjusted for an aging population, and when lung and stomach cancers, which have known causes, are eliminated from the calculation. (Lung cancers are up dramatically during the past forty years, primarily due to smoking; stomach cancers are down during the same period, primarily due to refrigeration and the reduced consumption of nitrates in cured meat products.)

Federal environmental laws allow an unlimited amount of toxic chemicals into air, water and food, with the only stipulation being that each chemical, on its own, irrespective of any other pesticide or chemical in the environment, meet the cost/benefit standard of the respective law under which it is regulated. In spite of a deluge of compelling evidence in animals that hundreds of these chemicals cause cancer, nervous system damage and many other forms of adverse health effects, and the fact that the rates of cancer and other diseases are increasing in an otherwise very healthy population (Miller et al. 1994), there is no systematic effort in place to reduce the overall load of pesticides and toxics that people eat, breath, and drink everyday. In essence, a grand experiment in chemical toxicity is being conducted on the human population.

Because shoppers have no information on which foods have fewer and safer pesticides on them, they have no ability to reduce their risk from pesticides in food.

The shortcomings in knowledge and the current pesticide regulatory approach are well identified and include a laundry list of issues. A sampling of these issue includes the following:

Chapter Two -- Pesticide Contamination Rankings

The twelve most contaminated fruits and vegetables consistently contain the most residues of the most toxic pesticides, and include such popular foods as peaches, strawberries, celery, green beans and apples. Obviously, none of these foods is so contaminated with pesticides that it should never be eaten. On the other hand, people can substantially reduce exposure to pesticides in food without losing any of the nutritional or health benefits of a diet rich in fruits and vegetables by minimizing consumption of the twelve most contaminated crops (Table 9). Chapter Four presents a list of nutritious alternative fruits and vegetables that provide equal, or in many cases, superior nutritional and health benefits.

Table 9. The twelve most contaminated fruits and vegetables.

Rank

Crop

Score (200 = most toxic)

1

Strawberries

189

2

Bell Peppers (tie)

155

2

Spinach (tie)

155

4

Cherries (USA)

154

5

Peaches

150

6

Cantaloupe (Mexico)

142

7

Celery

129

8

Apples

124

9

Apricots

123

10

Green Beans

122

11

Grapes (Chile)

118

12

Cucumbers

117

Source: Environmental Working Group, compiled from FDA and EPA data.

#1 Strawberries

Strawberry growers everywhere use large amounts of pesticides, particularly fungicides. The end result is a popular fruit that contains a myriad of toxic chemicals. Of the 42 fruits and vegetables we examined, strawberries ranked first in combined contamination, with 189 out of 200 possible points.

Seventy percent of the strawberry samples tested positive for one or more pesticides, and 36 percent contained two or more chemicals, including 19 samples with four pesticides, four samples with five, and one with six different pesticides. The FDA detected 30 different pesticides on strawberries, second only to apples with 36. More significantly, however, is the toxicity of the pesticides detected and the percentage of the crop and levels at which they are found. Based on the results of 361 samples of strawberries by the FDA over a two year period:

Strawberries had the highest average levels by far of pesticides that disrupt the endocrine system. The mean amount of endocrine disrupters was more than 20 percent higher than the next vegetable, spinach. The carcinogenic potency of the average residue on strawberries ranked seventh overall. The neurotoxic potency of the pesticides on strawberries was 15th out of the 42 produce items evaluated.

#2 Bell Peppers (U.S. and Mexico)

Sweet peppers (or bell peppers) from the U.S. and Mexico constitute approximately 98 percent of U.S. sweet pepper consumption, and have a considerably worse pesticide profile than peppers from any other country.

Sixty-four percent of the sweet pepper crop from the U.S. and Mexico contained residues of at least one pesticide, and 36 percent contain two or more pesticides. Of the 393 samples taken between 1992 and 1993, 11 contained residues of five different pesticides and 3 samples had residues of six pesticides. In total, 26 pesticides were detected on U.S. and Mexican sweet peppers.

The neurotoxic potency of pesticide residues on U.S. and Mexican sweet peppers was the highest of any crop tested-- 65 percent higher than the potency for the next highest food. Methamidophos was found on 42 percent of the samples, acephate was found on 25 percent, carbaryl on 18 percent, and chlorpyrifos and dimethoate on 10 percent. Endocrine disrupters ranked 12th out of 42 crops tested, while the cancer potency of the average residue was relatively low at 32nd out of 42.

#3 Spinach

Spinach has residues of fewer pesticides than other crops in the list of the twelve most contaminated, but the concentrations for certain cancer-causing and endocrine disrupting chemicals are considerably higher than those for other produce. Just over 50 percent of the spinach samples tested positive for one of 17 different pesticides. Seventeen percent contained two to four pesticides.

The most commonly detected pesticide on spinach was permethrin, a possible human carcinogen and endocrine disrupter. Permethrin was found in relatively large amounts, which helped make spinach second only to strawberries in the total mean residue of endocrine disrupters and reproductive toxins. The neurotoxic potency of the average residue, in contrast, was 28th out of the 42 crops tested.

The cancer potency of the average total residue on spinach was the highest of any of the produce analyzed. And actual levels of carcinogens on spinach are likely to be higher than we estimated. One reason is that chlorothalonil, a probable human carcinogen, was found at relatively high levels on several spinach samples. The FDA, however, tested only 17 out of 189 samples for chlorothalonil. Because of our sample size requirement of 20 per pesticide/crop combination, these results were not included in the overall ranking.

Spinach also had relatively high levels of DDT which was found in 10 percent of 186 samples.

DDT and DDE

DDT and its breakdown product DDE are not going away any time soon. They find their way into a large percentage of the food we eat because they persist in the soil for decades after use and because continued use in the developing world sends DDT and other persistent chlorinated pesticides into the atmosphere, around the globe, and into the food we eat. Scientists have now documented a global distillation effect, whereby DDT and other pesticides that are still applied in the tropics, volatilize into the atmosphere and are deposited in the temperate regions where they have been banned (Simonich and Hites 1995).

DDT and DDE caused the near extinction of the bald eagle and the peregrine falcon. DDE has recently been linked with an increase in breast cancer in women (Wolff and Wolff reply in Myers, Davis and Bradlow 1995), and DDE has been shown in several studies to decrease the length of time that breast feeding mothers can produce milk for their babies (Gladen and Rogan 1995). Breast cancer rates are up 52 percent in the past 40 years (when adjusted for age) (Miller et al. 1994), and numerous reports support the claim that a global shortening of the period of human lactation is occurring (Gladen and Rogan 1995).

DDE causes these effects by interfering with the normal functioning of the extraordinarily delicate human endocrine system (hormones). DDE is now known to have antiandrogenic properties, meaning that DDE blocks the normal functioning of the male hormone androgen (which is present in different amounts in both women and men).

Our analysis of 44 fruits and vegetables discovered DDT/DDE on 17 foods grown domestically or imported, including ten percent of spinach samples, seven percent of carrot samples, and six percent of green onion samples. Dieldrin was also found in significant amounts on several crops (Table 10).

DDT/DDE levels in human tissue in the United State declined after DDT was banned, but have now stabilized, and in some regions of the country body burdens are actually increasing. Until DDT is banned worldwide, further declines in human exposure in the United States are unlikely.

Table 10. DDT/DDE and Dieldrin, banned 20 years ago, are still found in some fruits and vegetables.

DDT/DDE

Samples

Detections

Spinach

186

18

Carrot

292

20

Sweet Potato

184

7

Lettuce, Loose Leaf

640

20

Celery

101

3

Potato

519

9

Grapefruit

81

1

Cantaloupe

437

5

Squash

642

7

Dieldrin

Samples

Detections

Cucumbers

410

28

Squash

642

23

Cantaloupe

437

8

Spinach

186

2

Potato

519

4

Watermelon

286

2

Source: Environmental Working Group, compiled from FDA and EPA data.

#4 Cherries (United States)

Cherries grown in the United States have a far different pesticide profile than those that are imported. While imported cherries are among the cleanest fruits and vegetables analyzed, U.S. cherries are the fourth worst. The detections on domestic cherries reveal a panoply of pesticides--26 different pesticides, more than three times the number found on imported cherries.

Seventy-one percent of U.S.-grown samples contained residues of one or more pesticides, compared with 35 percent of imported samples. More significantly, almost half of all U.S. cherries are likely to contain multiple pesticide residues, whereas, in comparison, only two percent of imported cherries contained more than one pesticide. Up to five pesticides were found on single domestic cherry samples.

Domestically grown cherries rank fourth in terms of cancer potency of the average residue, ninth in average amount of endocrine disrupters and reproductive toxins, and 14th in neurotoxic potency of the average residue.

#5 Peaches

The summer peach. So juicy, so tasty...so full of pesticides. Peaches ranked high in each of the seven categories we examined. Seventy-one percent of the peach crop sampled by the FDA tested positive for pesticides, fifth among the 42 fruits and vegetables analyzed. Thirty two percent of samples contained two or more pesticides, including six samples with five, two samples with six, and one peach sample with residues of seven pesticides, the highest multiple residue in a single sample found by the FDA over the two year testing period (along with two apple samples). In total, 26 different pesticides were found on peaches.

Many of the most commonly detected chemicals are probable human carcinogens, most notably iprodione and captan. Peaches ranked sixth in cancer potency of the average residue, and eleventh for the average residue of endocrine disrupters and twelfth in potency of the average neurotoxic residue.

#6 Cantaloupe (Mexico)

Nearly 15 percent of cantaloupes consumed each year in the United States come from Mexico. Compared to U.S. grown cantaloupe, Mexico melons are much more contaminated with pesticides.

Seventy-six percent of the samples tested positive for at least one pesticide, number three overall. And this may be an underestimate. One hundred percent of 70 samples tested positive for chlorothalonil, a probable human carcinogen. These 70 samples, however, are just 40 percent of the 173 samples of cantaloupes from Mexico tested by the FDA during 1992-1993.

Forty-eight percent of cantaloupes from Mexico tested positive for two or more pesticides, more than any other crop analyzed. Up to five different pesticides were found on single samples of cantaloupe from Mexico. In contrast, just 47 percent of cantaloupe grown in the U.S. contained any pesticide, and only 16 percent of domestic samples contained two or more pesticides.

Cantaloupes from Mexico ranked number two for the neurotoxic potency of the average residue. The average residue of endocrine disrupters was 13th out of the 42 crops analyzed, while the cancer potency of the average residue was 26th of 42 crops.

#7 Celery

Nearly every bite of celery we take is also a bite of pesticides. Eighty-one percent of the 188 celery samples tested positive for pesticide residues, more than any other crop analyzed. And, an analysis of detection rates for some pesticides reveals that this figure may be too low. For example, 91 out of 94 (96 percent) of domestic and imported celery samples were positive for the probable human carcinogen chlorothalonil. Overall, however, this amounted to about one half of the 182 samples of celery that were tested for pesticides by the FDA.

FDA's lack of testing for some heavily used pesticides makes crops appear to have fewer pesticides on them than they actually do. Even with this caveat, thirty five percent of celery samples contained residues of two or more pesticides, and up to five different pesticides were found on a single sample.

Celery ranked third in the neurotoxic potency of the average residue, 14th in the cancer potency of the average residue, and 20th out of 42 for the average residue of endocrine disrupters.

#8 Apples

Apples are the quintessential American fruit. Apple pie, apple sauce, the apple of my eye, an apple a day keeps the doctor away. Apples also have more different pesticides on them than any other fruit or vegetable -- 36 different pesticides according to FDA data -- and more pesticides -- seven -- found on a single sample than any other crop. Sixty one percent of apple samples tested positive for pesticides, and multiple pesticides on single samples are common. Thirty three percent of apple samples contained two or more pesticides, 18 samples had five, five had six, and two samples were contaminated with seven different pesticides.

Of the thirty six pesticides detected on apples, eight are classified by the EPA as possible or probable human carcinogens, and 15 are neurotoxic organophosphate insecticides. Apples also contain a high concentration of endocrine disrupters. Apples ranked tenth in average residue of endocrine disrupting pesticides, 16th in the neurotoxic potency of the average residue, and 23rd in the cancer potency of the average residue.

#9 Apricots

Apricots contain consistently high levels of multiple pesticides, including carcinogens like captan on 35 percent of all samples. Sixty-four percent of the FDA samples contained one or more pesticides, and 38 percent had two or three residues. Fourteen different pesticides were detected on apricots.

Apricots ranked eighth out of 42 fruits and vegetables in average residue of endocrine disrupting pesticides, 19th in the neurotoxic potency of the average residue, and tenth in the cancer potency of the average residue.

#10 Green Beans

Twenty-three different pesticides were detected on green bean samples in 1992 and 1993. Eighteen percent of these samples had residues of more than one pesticide--up to four on a single sample. More than 13 percent of samples contained residues of three pesticides, and twenty-eight percent of samples tested positive for chlorothalonil, a probable human carcinogen.

Green beans ranked fifth out of 42 crops in the neurotoxic potency of the average residue, sixth in average residue of endocrine disrupting pesticides, and 19th in the cancer potency of the average residue.

#11 Grapes (Chile)

From January through April, ninety percent of the grapes eaten in the United States are from Chile, where growers use less sophisticated pest control techniques than grape growers in the United States. Consequently, a far higher percentage of Chilean crop tests positive for pesticides.

According to the FDA, seventy-nine percent of grapes grown in Chile contained pesticide residues in 1992 and 1993, the second highest of all 42 fruits and vegetables analyzed. Forty-six percent of the Chilean samples contained two or more pesticides, with up to six different pesticides found on a single sample of Chilean grapes. In contrast, only 17 percent of the U.S. grapes contained detectable residues, and only 6 percent contained multiple residues. In total, seventeen different pesticides were found on the Chilean crop.

The probable human carcinogens captan and iprodione were found on 64 and 28 percent of Chilean grape samples respectively, compared with four and five percent of all samples of domestically grown grapes, respectively. Twenty seven percent of Chilean grapes contained the endocrine disrupting fungicide vinclozolin, compared to just one sample (less than one percent) of grapes from the United States.

The cancer potency of the average residue on Chilean grapes was 11th out of 42 crops, and the average load of endocrine disrupting pesticides was 19th. The neurotoxic potency of the average residue was in the bottom third of all crops evaluated, at 30th.

#12 Cucumbers

Cucumbers complete the list of the twelve most contaminated due primarily to residues of a cancer causing insecticide, dieldrin, that was banned in the United States over 20 years ago. Even though dieldrin is not directly applied to the crop, it is persistent in the soil and is taken up by cucumbers. One out of every 14 cucumber samples from across the United States and Mexico contained residues of this highly toxic compound. As a result, cucumbers ranked number two in cancer risk of all 42 crops evaluated.

Most other results are in the middle of the pack. Cucumbers rank 23rd for residues of endocrine disrupting pesticides, and 22nd for neurotoxic potency of the average residue. Forty percent of cucumbers had detectable residues, according to the FDA, and 12 percent of samples had two or more residues detected. Twenty different pesticides were found on cucumbers over the two year period from 1992 through 1993.

The Concentration of Health Risks

To determine the distribution and possible concentration of health risks from pesticides on these 42 fruits and vegetables, we calculated the percent contribution to each of the toxicity measures (cancer, nervous system, and endocrine system toxicity) that was accounted for by the twelve most contaminated fruits and vegetables.

The result? The twelve most contaminated fruits and vegetables present the majority of the health risks from pesticides that cause cancer, neurotoxic, and endocrine effects.

For cancer-causing and neurotoxic pesticides, the twelve most contaminated fruits and vegetables accounted for 53 and 49 percent of the total potencies, respectively, of all the pesticides found on the 42 crops analyzed. For endocrine disrupters, the twelve most contaminated fruits and vegetables accounted for 57 percent of the total residues found on these foods.

Avoiding the twelve most contaminated fruits and vegetables can reduce an individual's health risks from pesticides on these foods by half. Fortunately, eating a diet rich in fruits and vegetables that steers clear of this produce presents no nutritional or other health risks.

Chapter Three -- Eating Healthy and Reducing Pesticide Risks

Thanks to the bounty of fruits and vegetables in most American supermarkets, people can radically minimize consumption of the twelve most contaminated fruits and vegetables with no nutritional risk. All of the vitamins, nutrients, and carotenoids provided by the crops on the list of the twelve most contaminated, are found in abundance in other fruits and vegetables available in just about any grocery store.

Carotenoids include the relatively well-known beta carotene and a host of other related chemicals. Carotenoids have been linked to reduced incidence of cancer, reduced rates of macular degeneration and resulting blindness, and reduced rates of heart disease (CSPI 1995).

In fact, few of the twelve most contaminated foods, with the notable exception of spinach, provide high levels of vitamins and carotenoids. A quick review of the list reveals plenty of equally nutritious, and safer, substitute foods (Table 10).

Table 10. There are many nutritious and healthful alternatives to the 12 most contaminated fruits and vegetables.

Rank

Twelve most contaminated foods

Principal nutrients

All of these alternatives are a good source* of most or all of the principal vitamins and nutrients in the contaminated food.

1

Strawberries

Vitamin C

Blueberries, raspberries, blackberries, oranges, grapefruit, cantaloupe, kiwis, or watermelon.

2 (tie)

Bell peppers:

 

 

 

Green peppers

Vitamin C

Green peas, broccoli, or Romaine lettuce.

 

Red Peppers

Vitamin A (Carotenoids), Vitamin C

Romaine lettuce, carrots, broccoli, Brussels sprouts, asparagus, or tomatoes.

2 (tie)

Spinach

Vitamin A (Carotenoids), Vitamin C, Folic Acid

Broccoli, Brussels sprouts, Romaine lettuce, or asparagus**.

4

Cherries (U.S.)

Vitamin C

Oranges, blueberries, raspberries, blackberries, grapefruit, cantaloupe, or kiwis.

5

Peaches

Vitamin A (Carotenoids), Vitamin C

Nectarines, U.S. cantaloupe, watermelon, tangerines, oranges, or red or pink grapefruit.

6

Cantaloupe (Mexican)

Vitamin A (Carotenoids), Vitamin C, and Potassium

Buy U.S. cantaloupe in season (May-December), or watermelon.

7

Celery

Carotenoids, not a good source of vitamins.

Carrots, Romaine lettuce, broccoli, or radishes.

8

Apples

Vitamin C

Pears, oranges, grapefruit, cantaloupe, kiwis, watermelon, nectarines, bananas, tangerines, or virtually any fruit not on the list of the most contaminated foods.

9

Apricots

Vitamin A (Carotenoids), Vitamin C, Potassium

Nectarines, U.S. cantaloupe, watermelon, tangerines, oranges, red or pink grapefruit, or watermelon.

10

Green beans

Not a good source of vitamins or carotenoids

Green peas, broccoli, cauliflower, Brussels sprouts, potatoes, or asparagus.

11

Grapes (Chilean)

Vitamin C

Buy U.S. grapes in season (May-December).

12

Cucumbers

Not a good source of vitamins or carotenoids

Carrots, Romaine lettuce, broccoli, radishes, or virtually any vegetable not on the list of the most contaminated foods.

*Includes 10% or more of the daily value of at least one of the vitamins in the contaminated food.

**Spinach and other leafy greens like kale and collards contain lutein (a carotenoid) that is not abundant in these substitutes. Lutein may reduce the risk of macular degeneration, the most common cause of blindness in the elderly.

Sources: Environmental Working Group, compiled from FDA and EPA data; Center for Science in the Public Interest. Nutrition Action Health Letter, January-February 1995, October 1994, May 1992, December 1991.

Strawberries are a good source of vitamin C, but vitamin C is very common in fruits and vegetables. Strawberries also have consistently high levels of fungicides, including two, captan and iprodione, that are classified by the EPA as probable human carcinogens, and another, vinclozolin, that blocks the normal functioning of the male hormone, androgen. Strawberries are also routinely contaminated with endosulfan, a relative of DDT that interferes with normal hormone function by imitating the hormone estrogen. Nutritious substitutes with far lower pesticide residues are blueberries, raspberries, blackberries, kiwis, and a host of other fruits rich in vitamin C.

Green bell peppers are a good source of vitamin C, and red bell peppers add vitamin A and a moderate dose of carotenoids to a meal. Unfortunately, bell peppers are more heavily contaminated with neurotoxic insecticides than all other crops analyzed. Good alternatives include broccoli, romaine lettuce, or carrots among many others.

Spinach is rich in vitamins, iron, folate and carotenoids. It is also high in DDT, permethrin, chlorothalonil and other cancer causing pesticides. Other greens such as kale, Swiss chard, mustard greens, collard greens are good nutritional substitutes, but have a roughly equivalent pesticide contamination profile. For raw spinach, romaine lettuce is far less contaminated alternative that is relatively high in carotenoids. For cooked spinach, broccoli or brussels sprouts are reasonable substitutes that are high in carotenoids, vitamins A and C, and folate (folic acid).

Cherries are a marginal source of vitamin C, but have little other nutritional value. Cherries from the United States, in contrast to their imported counterparts, are heavily contaminated with pesticides. Nutritious substitutes with far lower pesticide residues are blueberries, raspberries, blackberries, kiwis, oranges, watermelon, and a host of other fruits rich in vitamin C.

Peaches provide low amounts of vitamins A and C, and negligible amounts of carotenoids. They also deliver a heavy dose of the cancer causing fungicides captan and iprodione, and the neurotoxic pesticide, methyl parathion. Many fruits with lower and less toxic pesticide loads provide the same or better nutritional benefits. Nectarines, tangerines, cantaloupe, and watermelon provide more vitamins A and C, and many other fruits -- like oranges, grapefruits, papayas, or kiwis --provide high levels of one of these two vitamins.

Cantaloupe is a highly nutritious fruit, packed with carotenoids, and over 90 percent of the U.S. Recommended Daily Allowance (USRDA) for vitamins A and C. To avoid cantaloupes with high pesticide residues, hold off on this fruit during January through April, when imports from Mexico are at their peak. The rest of the year, enjoy this marvelous melon.

Celery is a marginal source of carotenoids, but provides virtually no vitamins or minerals. It is a major source of exposure to neurotoxic pesticides and the probable human carcinogen, chlorothalonil. Celery also had the highest percentage of samples with detectable residues (81 percent) of all 42 fruits and vegetables analyzed. Romaine lettuce and carrots are just two of the many safer salad substitutes.

Apples provide low amounts of vitamin C, but provide very little else in the way of measurable nutrients or carotenoids. Their pesticide load, in contrast, is disturbingly high. There were more pesticides detected on apples (36), and more pesticides found on single samples of apples (7) than any other fruit or vegetable analyzed. Safer and more nutritious substitutes would include just about any fruit or vegetable not on the most contaminated list.

Apricots are a nutritious fruit providing relatively high levels carotenoids, vitamins A and C and potassium. Unfortunately, they typically contain high levels of pesticides, including the probable human carcinogen, captan, and the endocrine (hormone) disruptors endosulfan and carbaryl. An equally nutritious and safer substitute is cantaloupe from the United States. A host of other fruits and vegetables provide vitamins C, A and other nutrients.

Green beans provide modest amounts of vitamins C and A, and potassium, but little in the way of carotenoids. Green beans are also a major source of the cancer causing fungicides chlorothalonil and mancozeb, the neurotoxin methamidophos, and the endocrine disruptor, endosulfan. Safer and more nutritious alternatives include green peas, broccoli, zucchini, potatoes and many other vegetables.

Grapes are tasty, but provide few vitamins or carotenoids. Complimenting this slim nutritional profile, grapes from Chile add a load of cancer causing and endocrine disrupting fungicides. The solution for grape lovers is simple, eat U.S. grown grapes in season; avoid grapes from January through April, when grapes from Chile dominate the market.

Cucumbers have few vitamins or carotenoids. They do, however, have a tendency to absorb dieldrin, a banned, extremely potent carcinogenic pesticide, from the soil. When eaten, dieldrin persists in human body fat for decades. Substitutes for cucumbers include just about any vegetable not found on the most contaminated list.

Foods too good to be true.

Some foods are low in pesticides and pesticide risks and high in vitamins, minerals, and carotenoids. Sweet potatoes, broccoli, watermelon, and Brussels sprouts fit this bill, providing lots of vitamins, carotenoids, and minerals, along with relatively few pesticides.

To complement the twelve most contaminated crops, we present the twelve cleanest crops. While no one should eat only these twelve foods, it is noteworthy that the fruits and vegetables with the lowest contamination scores also provide a broad array of nutritional and health benefits (Table 11).

Table 11. The twelve least contaminated fruits and vegetables provide substantial nutritional benefits.

Food

The twelve crops with the least pesticide contamination are a good source* of the following nutrients.

Pesticide Contamination Score (200 = most toxic)

Avocados

Vitamin A, Vitamin C, Folic Acid

7

Corn

Carotenoids, Folic Acid

14

Onions

Not a good source of vitamins or carotenoids.

18

Sweet Potatoes

Potassium, Vitamin A (Carotenoids), Vitamin C

20

Cauliflower

Vitamin C

21

Brussels sprouts

Folic Acid, Vitamin A (Carotenoids), Vitamin C

36

Grapes (U.S.)

Vitamin C

40

Bananas

Potassium, Vitamin C

42

Plums

Vitamin C

46

Green onions

Vitamin A (Carotenoids), Vitamin C

46 (tie)

Watermelon

Potassium, Vitamin A (Carotenoids), Vitamin C

47

Broccoli

Potassium, Vitamin A (Carotenoids), Vitamin C

49

*Includes 10% or more of the daily value of at least one of the vitamins in the contaminated food.

Sources: Environmental Working Group, compiled from FDA and EPA data; Center for Science in the Public Interest, Nutrition Action Health Letter, January-February 1995, October 1994, May 1992, December 1991.

Chapter Four -- Methodology: Ranking Produce for Pesticide Risks

What We Know and What We Don't

The philosophy of the Guide is that consumers have a right to know about the pesticides in the food they buy. Further, they have a right to know what the nation's health authorities say about the toxicity of these pesticides. And they have a right to know how slim the knowledge base really is when it comes to predicting the true risks of pesticides and pesticide combinations on human health.

The fundamental fabric of risk assessment is the pervasive uncertainty in the underlying science. While scientists know much about certain aspects of the toxicity of some pesticides and chemicals released into the environment, much more is not known about the effects of most chemicals, in humans, and in combination with each other. The art of risk assessment and regulation is an ongoing attempt to cope with this dubious and volatile understanding of true risks.

As risk assessment and toxicology evolves, knowledge sometimes replaces uncertainty. This knowledge, however, does not always relieve us of concerns about health and environmental risks. For example, we know now that DDT is a much more insidious toxin than previously thought. Not only does DDT cause cancer, but its principle metabolite, DDE, interferes with the normal functioning of the endocrine system, causing such unexpected human health effects as dramatically shortening the length of time nursing mothers are able to produce milk for their babies (Gladen and Rogan 1995).

More often that not incremental scientific advances deliver more questions than answers. The explosion of evidence over the past ten years that hundreds of commonly used pesticides and industrial chemicals can interfere with the normal functioning of the human endocrine system is just one example (Lancet 1995, Toppari 1995). Concern about the toxic effects of pesticides to the developing brain and nervous system is another (NRC 1992, NRC 1993). The effects of pesticides and other pollutants on the immune system is yet another (NRC 1993).

Coming to grips with the combined effects of the hundreds of chemicals in our food and water presents perhaps the greatest challenge of all. The sheer complexity of the pesticide and chemical permutations to which the population is routinely exposed, precludes any systematic evaluation of the toxic effects of these chemical mixtures (NRC 1988). Here uncertainty is at its zenith. Caveat emptor.

The Guide does not try to resolve the underlying issues of uncertainty. Instead the Guide measures pesticide contamination in various ways that allow a ranking of uncertainty, based on the number of pesticides detected and the percent of the crop that is contaminated. Simply put, crops that consistently have more pesticides on them present more uncertain levels of risk to consumers. For example, the higher the likelihood of multiple residues on single sample of a crop, the greater the uncertainty of the toxic effects.

Conversely, some toxic effects are well described by the current data. Consumers need this knowledge as well. Cancer and acute nervous system toxicity are two such effects. Consumers have a right to know which crops, on average, have the heaviest and most toxic load of pesticides that cause these effects.

Normalizing the Data

The Shopper's Guide is based on seven different measures of pesticide contamination, divided into two separate categories of analysis:

Quantity or Uncertainty Analyses, which measure the number and amount of pesticides found on produce:

Toxicity Analyses, which measure the potential health risks of pesticides found on produce:

The calculations used to estimate cancer potency, neurotoxic potency, and the average residues of endocrine modifiers are presented with the results of the respective analyses. All of the methods used are based on standard EPA toxicity measures and risk assessment procedures.

For each of the seven measures studied, scores for each food were "normalized" on a scale of 1 to 100. Normalizing allows for useful comparisons among different measures of pesticide contamination. Scores for all of the measures within each category were then combined to obtain a single score for the category, one score for toxicity analyses and one for quantity analyses. To give equal weight to each category of analysis, the scores for the two categories were again "normalized," and were combined to give a single score representing EWG's overall rating for the food.

The method of normalization was as follows: the food with the highest rank in each category (i.e., the riskiest food) was assigned a score of 100; the other foods were scored according to the following equation:

 

Score = (value for food being ranked/value for riskiest food in category) x 100.

For example:

 

Score for percent positive in apples = 0.61/0.81 x 100, which equals 0.753 x 100, or 75

Normalizing the data had several effects. First, all normalized scores fell within the range of 0 to 100, creating a roughly consistent scale for comparing among different measures of pesticide contamination. Second, normalized scores for different foods were exactly proportional to the values found in the raw data for those foods: if one food (say, carrots) was found with 2 different pesticides, and another food (say, peas) was found with 4 different pesticides, then the normalized score for peas was precisely twice as high as the normalized score for carrots. By maintaining such proportional relationships among different foods, normalizing allows for a comparison of the relative risks posed by different foods, according to each measure of pesticide contamination.

Generally, the raw data for the toxicity analysis showed greater variability than for the quantity analysis. Toxicity measures varied by as much as three orders of magnitude from the highest ranking (riskiest) foods to the lowest ranking (least risky) foods; in some toxicity measures, a small handful of foods scored substantially higher than all other foods examined. In contrast, quantity measures rarely varied by more than an order of magnitude from the riskiest to least risky foods. Because of the differences in the variability of the raw data, EWG elected to give each food a separate score for toxicity and quantity measures. Then, to give equal weight to each category of analysis, the composite toxicity and quantity scores were themselves normalized, and combined to give a single score for each food.

Lettuce and Oranges

Lettuce and oranges scored in the twelve most contaminated fruits and vegetables but were not included in the final ranking based on our judgment that the FDA data was not representative of the relative risks face by consumers as a result of eating these two foods.

The FDA does not peel or prepare produce for normal consumption prior to testing. This practice biases the results of FDA residue tests for some crops, particularly those that are peeled or otherwise prepared prior to consumption. Two crops that initially appeared in the twelve most contaminated -- lettuce and oranges -- were ultimately removed from the list because the FDA testing procedures disproportionately elevated the rank of these crops relative to other crops that are not peeled, or, in the case of lettuce, compared to other crops where the outer leaves are not removed prior to consumption.

To verify the fact that the FDA data unrealistically elevated the rank of lettuce and oranges relative to other crops, we compared the results of the Guide to the results of the Pesticide Data Program (PDP) from the U.S. Department of Agriculture (USDA 1995). The PDP is a special testing program designed to measure pesticide levels on a limited number of produce items after the crops are prepared for normal consumption. In the PDP the oranges are peeled and the lettuce is washed and outer leaves are removed prior to testing. The PDP, however, only tests twelve crops per year. When these twelve crops are ranked using FDA and PDP data, the comparative ranks of all crops are roughly the same with the notable exception of lettuce and oranges. In these two cases, the FDA data consistently ranked lettuce and oranges higher relative to the other crops, than data from the PDP.

For example, of the twelve crops analyzed:

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Acknowledgments

Special thanks to Molly Evans who designed and produced the report in hard copy and for the World Wide Web, and to Chris Campbell for computer assistance. We are grateful to Ken Cook and Mark Childress for their editing and insight.

A Shopper's Guide to Pesticides in Produce was made possible by grants from The Pew Charitable Trusts, The Joyce Foundation, The John D. and Catherine T. MacArthur Foundation, the W. Alton Jones Foundation, the Charles Stewart Mott Foundation, Alida R. Messinger, and Working Assets Funding Service. A computer equipment grant from the Apple Computer Corporation made our analysis possible. The opinions expressed in this report are those of the authors and do not necessarily reflect the views of The Pew Charitable Trusts or other supporters listed above.

Copyright © November 1995 by the Environmental Working Group/The Tides Foundation.
All rights reserved.
Produced in the United States of America.

Environmental Working Group

The Environmental Working Group is a nonprofit environmental research organization based in Washington, D.C. The Environmental Working Group is a project of the Tides Foundation, a California Public Benefit Corporation based in San Francisco that provides administrative and program support services to nonprofit programs and projects.

Kenneth A. Cook, President
Mark B. Childress, Vice President for Policy
Richard Wiles, Vice President for Research

To order copies

For information on ordering a copy of A Shopper's Guide to Pesticides in Produce, please e-mail info@ewg.org.

source: http://www.ewg.org/pub/home/Reports/Shoppers/shoppers.html 8jul01

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