Pesticide residues are widespread on conventional crops, the Environmental Working Group found in analyzing reports by federal agencies.
The most recent round of tests show that as late as 2010, 68 percent of food samples had detectable pesticide residues, the EWG, a consumer advocacy group, said in a statement.
The EWG has released the eighth edition of its Shopper's Guide to Pesticides in Produce with updated information on 45 popular fruits and vegetables and their pesticide loads. The EWG highlights the worst offenders with its new Dirty Dozen Plus list and the cleanest conventional produce with its list of the Clean Fifteen.
“Our shopper’s guide to pesticides in produce gives consumers easy, affordable ways to eat a diet rich in fruits and vegetables while avoiding most of the bug killers, fungicides and other chemicals in produce and other foods,” said EWG president Ken Cook.
EWG researchers analyzed annual pesticide residue tests conducted by the U.S. Department of Agriculture and Food and Drug Administration between 2000 and 2010.
The samples were washed or peeled before being tested so the rankings reflect the amounts of the crop chemicals likely present on the food when it’s eaten.
The EWG found significant differences between the number of pesticides and amount of pesticides detected on the Dirty Dozen Plus and Clean Fifteen foods.
Among the findings
- About 98 percent of conventional apples have detectable levels of pesticides.
- Domestic blueberries tested positive for 42 different pesticide residues.
- Seventy-eight different pesticides were found on lettuce samples.
- Every nectarine USDA tested had measurable pesticide residues.
- As a category, grapes have more types of pesticides than any other fruit, with 64 different chemicals.
- Thirteen different pesticides were measured on a single sample of celery and strawberries.
New to the Shopper’s Guide: The Dirty Dozen Plus
This year, the EWG has expanded its Dirty Dozen with a Plus category to highlight two crops – green beans and leafy greens, such as kale and collard greens – that didn’t meet traditional Dirty Dozen criteria but were commonly contaminated with highly toxic organophosphate insecticides.
These insecticides are toxic to the nervous system and have been largely removed from agriculture over the past decade, the EWG said. But they aren’t banned and still show up on some food crops.
The EWG lists these on the new Dirty Dozen Plus as foods to avoid or to buy organic.
"Organophosphate pesticides are of special concern since they are associated with neurodevelopmental effects in children,” said EWG toxicologist Johanna Congleton. “Infants in particular should avoid exposure to these pesticides since they are more susceptible to the effects of chemical insult than adults."
Pesticides in baby food
For the first time since the USDA began its pesticide-testing program in 1991, the agency looked at pesticide residues on baby food.
Green beans prepared as baby food tested positive for five pesticides, among them, the organophosphate methamidiphos, which was found on 9.4 percent of samples, and the organophosphate acephate, on 7.8 percent of samples.
The pesticide iprodione, which the U.S. Environmental Protection Agency has categorized as a probable human carcinogen, was detected on three baby food pear samples.
Sweet potatoes sold as baby food had virtually no detectable pesticide residues.
Pesticides in drinking water
In 2010, USDA analyzed samples from 12 community drinking water systems that use surface water such as reservoirs, lakes, and rivers as their water sources.
Tests of 284 samples taken after treatment detected 65 pesticides or their metabolites. The toxic herbicide atrazine or its metabolites were found in every sample. The herbicides 2,4-D and metolachlor were detected in more than 70 percent of the samples. Six other pesticides were found in at least half the samples.
The pesticide residues for items on the EWG’s Clean Fifteen were much less.
The produce least likely to test positive for pesticides were asparagus, avocado, cabbage, grapefruit, watermelon, eggplants, pineapples, mushrooms, onions, frozen peas, and sweet potatoes.
More than 90 percent of cabbage, asparagus, sweet peas, eggplant, and sweet potato samples had one or fewer pesticides detected.
Of the Clean Fifteen vegetables, no sample had more than five different chemicals, and no fruit sample from the Clean Fifteen had more than five types of pesticides detected.
The EWG’s recommends consumers buy organic fruits and vegetables, when possible, and shop from the Clean Fifteen list when purchasing conventionally grown produce.