An analysis of US Governemnt Data

of Pesticide Residue in Foods, 1999

Consumers Union of United States, Inc. Public Service Projects Department Technical Division

Edward Groth III, PhD, Project Director Charles M. Benbrook, PhD, Consultant Karen Lutz, MS, Consultant


We analyzed data collected by the U.S. Department of Agriculture's Pesticide Data Program (PDP) to compare the relative amounts and toxicity of pesticide residues in different foods. We obtained pesticide residue data on over 27,000 food samples tested by the PDP in 1994-97. We weighted the amounts of residues present to account for differences in the toxicity of individual pesticide chemicals, and computed a Toxicity Index (TI) for each food.

Our TI integrates measures of the frequency of pesticide detection, the levels of residues present and the relative toxicity of the detected residues, yielding an index of the relative toxicity loading of each food.

Larger TI values represent greater toxicity;that is, foods with high TI scores have greater amounts of pesticide residues, residues that are more toxic, or both, compared to foods with low TI scores. TI values for the foods tested by the PDP in 1994-97 range from 0.01 to 5,376.

But the majority of foods have TI values between 10 and 300, and a few more have values between 300 and 600. That is, the relative toxicity loading of the widely consumed foods tested by the PDP spans a range of at least 60-fold.

In our judgment, values greater than 100 on the TI scale show comparatively high pesticide contamination, and values less than 10 indicate that those foods are comparatively quite "clean." (Values in the range from 10 to 100 represent increasing degrees from "low" to "moderate" levels of pesticide contamination.)

Our Toxicity Index does not measure risk, per se; the degree of risk associated with pesticide residues in foods also depends on food intake and on personal factors like age, illness, exposure to other sources of pesticides, and so forth. There is no sharp line between "safe" and "unsafe" scores on our Toxicity Index.

With some exceptions noted later, the residues detected by the PDP are within the established U.S. legal limits for those pesticides on those foods. However, legal limits do not define safety, and residues of some chemicals on some foods would frequently expose a young child to a dose greater than the U.S. government's official estimate of the "safe" daily intake of those pesticides.

Our TI values permit a variety comparisons among foods: Which Foods Have the Lowest TI Values? Six foods had very low TI's (10 or less) each time they were tested: Frozen/canned corn, milk, U.S. orange juice, U.S. broccoli, bananas, and canned peaches. Not quite as low, but still relatively "clean," were frozen/canned sweet peas, U.S. and imported apple juice, frozen winter squash from Mexico, tomatoes from Canada, Brazilian orange juice, and U.S. wheat.

Which Foods Have the Highest TI Values?

Seven foods consistently had high or very high TI's each time tested: Fresh peaches (both domestic and imported); frozen and fresh winter squash grown in the U.S.; domestic and imported apples, grapes, spinach and pears; and U.S.-grown green beans.

Among these, U.S. peaches and frozen winter squash had TI Values about 10-fold higher than even the other "high" scores. See page 14 and Table 4 for details.

How Many Residues?

Some foods have residues of many more pesticides than others. Up to 37 different pesticide chemicals were detected in apples by the PDP, for example, and more than 20 are found in peaches, pears and spinach, while only 10 were found in broccoli, and fewer than that in apple juice, orange juice, bananas and corn. Individual food samples often have multiple residues on them.

An apple grown in the U.S. typically contains four pesticides, and some have as many as 10 different residues. Peaches, winter squash, spinach, carrots and grapes are more likely than not to have two or more residues in a sample. One sample of spinach had residues of 14 different pesticides on it.

Are Imported Foods More Contaminated Than U.S. Crops?

No. Eleven of the 12 highest TI scores are for U.S.-grown foods. There are 39 cases with 10 or more samples of a food from a specific other country to compare with U.S. samples; in 26 cases (67 percent), U.S. samples had higher TI's.

Some differences exist between importing countries, as well as between the U.S. and other countries. Cases where imports are worse include Chilean grapes, Canadian and Mexican carrots, Mexican broccoli and tomatoes, Argentine and Hungarian apple juice, and Brazilian orange juice.

U.S. samples are worse than imports for fresh peaches, fresh and frozen winter squash, fresh green beans, apples, and pears. U.S. apple juice has a higher TI than apple juice from Germany or Mexico, and U.S. grapes have higher TI's than those from South Africa and Mexico.

The size of the differences varies from food to food. In two cases with the highest TI's of any foods, U.S. peaches have 10 times the TI of Chilean imports, and U.S. frozen winter squash has a TI 143 times as high as Mexican winter squash has. Only two imported foods, Mexican broccoli and Brazilian orange juice, have TI's more than 10-fold larger than those of U.S. samples, but in each case the higher score is still comparatively low.

Do Processed Foods Have Less Pesticides Than Fresh Foods?

Generally, yes. But there are exceptions. TI values for apple juice and orange juice are far lower than for the fresh fruits, and the TI for canned peaches is 1/1,000 that of fresh peaches. Canned spinach has a TI about half as high as that for fresh spinach. Canned/frozen corn and canned/frozen peas also have among the lowest TI values, but no data on the fresh crops are available. But frozen and canned green beans and frozen winter squash each had TI scores higher than those for the corresponding fresh crops.

Were Any of the Residues Illegal?

Yes. About 1 percent of the residues detected by the PDP in 1994, 4 percent in 1995 and 1996, and 5 percent in 1997 violated U.S. tolerances. Most violations are not excessive residues of legally registered pesticides, but rather, low levels of chemicals that are not registered for use on that food.

Some violations are attributed to persistent residues in soils or to wind dispersal of pesticides applied legally to nearby fields, but we believe the PDP data show widespread illegal use of several insecticides on both U.S. and Mexican spinach.

Our analysis of the data also enables us to explain why different foods have the Toxicity Indices they do. We can break the TI for a food down into the components contributed by each pesticide chemical detected in that food. Doing that shows that a comparatively small number of uses of a few highly toxic insecticides accounts for most of the toxicity loading in the crops with high TI values.

For example, 22 different pesticides were detected in U.S. peaches in 1996, but one chemical methyl parathion accounts for more than 90 percent of the total toxicity load. Methyl parathion accounts for a large part of the TI values for apples, pears, green beans and peas, as well as peaches.

The high TI's for winter squash (fresh and frozen) from the U.S. are almost entirely due to residues of dieldrin, a very toxic, carcinogenic insecticide that was banned 25 years ago, but persists in some agricultural soils. A handful of other widely used insecticides and a few fungicides consistently accounts for the greatest fraction of toxicity loading in most crops.

We call pesticide uses that dominate the TI's for specific crops "risk drivers."

The fact that a few very toxic pesticides account for most of the toxicity loading in PDP-tested crops has important policy implications. The risks associated with pesticides in foods can be sharply reduced by focusing risk-management efforts on a few high-risk pesticide uses. Safer alternatives exist to manage most pests against which these high-risk chemicals are used (see Worst First, Consumers Union, 1998).

In 1996 Congress passed a law, the Food Quality Protection Act, that requires pesticide tolerances to protect children. This law could require the U.S. EPA to ban or severely restrict many of the high-risk insecticide uses responsible for the greatest part of the toxicity loading revealed by the PDP data.

Unfortunately, the EPA is making only slow progress in implementing the new law, and is faced with fierce resistance from agricultural interests and pesticide manufacturers.

While consumers await stricter government limits, there are steps they can take to minimize pesticide risks in foods they eat or feed their children. We do not recommend eating less fruits and vegetables; the health benefits of these foods outweigh risks from the pesticides they contain. However, consumers can:

1) Wash or peel fresh fruits and vegetables. Peeling apples, peaches and pears, in particular, can drastically reduce pesticide exposure from these foods, which have some of the highest Toxicity Indices.

2) Try to buy organically grown peaches, apples, grapes, pears, green beans, winter squash and spinach, if they are available where you live.

3) Choose a variety of foods; don't overdo it with any one fresh fruit or vegetable.

4) Choose foods that have relatively low scores on CU's Toxicity Index. This includes considering the country of origin for foods where domestic and imported samples have very different scores (peaches, apples, grapes, tomatoes, winter squash), and choosing processed fruits and vegetables that have TI scores substantially lower than fresh equivalents, such as canned peaches.

Thanks to Laurie M. at the Women's Cancer Resource Center for this information.

There is a fuller report available from the Consumer's Union.

Bacteria Thrives in Pesticide Environment

Study 10/00

Environment & Contaminants in Food Systems

Chapter from Annu. Rev. Nutr. 2000

German Study:Pesticide Use Reduction

Pesticide Action Network

Gerber Has Peach Suppliers Use LESS Organophoshates

World Food Regulation Review, 11/98

Integrated Crop Management - LESS PESTICIDES
Ann Fonfa's Letter to EPA on Human Subjects/ Pesticide Testing

August, 2003 sent via email to EPA

Non-Hodgkin's Lymphoma in Asthmatics Exposed to Pesticides

Intl J Cancer, 4/04 online

Pesticide Residues Survey in Citrus Fruits

Food Additives & Contaminants 5/05

Genotoxicity of Extracts pesticide-treated vegetables & grapes

Food Additives & Contaminants, June 2007

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