An analysis of the U.S. Department of Agriculture data found that “nearly 70% of samples of 48 types of conventionally grown produce were contaminated with pesticide residues.”[i] On the more than 35,000 produce samples tested by the USDA were found 178 different pesticides and residues, which remained on the fruits and vegetables even after washing, according to the Environmental Working Group (EWG).
The EWG released its annual “Dirty Dozen” list of produce that contain the most pesticides based on the USDA data. Topping the list for the second year in a row was strawberries, followed by spinach, nectarines, apples, peaches, pears, cherries, grapes, celery, tomatoes, sweet bell peppers and potatoes. New to this year’s list are pears and potatoes while cherry tomatoes and cucumbers fell down the list.
“More than 98% of samples of strawberries, spinach, peaches, nectarines, cherries and apples tested positive for residue of at least one pesticide.”
Strawberries were found to have at least 20 pesticides, “while spinach jumped into the second spot with twice as much pesticide residue by weight than any other crop.”[ii] Three-fourths of spinach samples had residues of a neurotoxic pesticide banned in Europe for use on food crops.
In addition to its “Dirty Dozen,” the EWG also released its list of “Clean Fifteen,” which highlights produce that have fewer pesticides and lower concentrations of residues. Topping the list were sweet corn, avocados, pineapples, cabbage and onions. According to the analysis, only one percent of samples of avocados and sweet corn showed any detectable pesticides while more than 80 percent of pineapples, papaya, asparagus, onions and cabbage showed no pesticide residue.
In response to the EWG report, the Alliance for Food and Farming, which represents organic and conventional farmers and farms of all sizes, released a statement suggesting, “A peer reviewed analysis of the “dirty dozen” list found EWG uses no established scientific procedures to develop the list. This analysis also found that EWG’s recommendation to substitute organic forms of produce for conventional forms does not result in a decrease in risk because residue levels are so minute, if present at all, on conventionally grown fruits and vegetables.
“Further an analysis by a toxicologist with the University of California’s Personal Chemical Exposure Program found that a child could literally eat hundreds to thousands of servings of a fruit or vegetable,” including 1,508 servings of strawberries in a day, “and still not have any effects from pesticide residues.”[iii]
In January 2016, the USDA released a report that “confirms that overall pesticide chemical residues found on the foods tested (as part of the Pesticide Data Program) are at levels below the tolerances established by the Environmental Protection Agency (EPA) and do not pose a safety concern.”
Pesticide residue laboratories are required to complete the analyses of an ever-increasing number of samples. The analyses typically involve use of multi-residue methods (both GC-MS and LC-MS) to test for over 500 pesticide residues. The QuEChERS extraction has become the method of choice for pesticides multi-residue analyses in a wide range of matrices because of its ease of use and proven robustness. Teledyne Tekmar Automate-Q40 automates the QuEChERS sample preparation workflow and helps to improve precision and accuracy of pesticide analysis.