Pesticides in produce: why seasonal, organic matters
Sound Consumer | July 2012
By Chuck Benbrook, Ph.D.
Those of us living in the Pacific Northwest are blessed this time of year with a steady flow of high-quality and affordable local, fresh fruit and vegetables. With nectarines, peaches, tomatoes and other summer favorites hitting the markets, it's a good time to remember why choosing in-season, organic produce is important.
American fruit and vegetable farmers have made impressive progress in reducing reliance on high-risk pesticides since passage of the Food Quality Protection Act (FQPA) in 1996. Average pesticide dietary risks in conventional apples grown in Washington have fallen 10-fold since 1996, based on the pesticide residue data collected by the U.S. Department of Agriculture's (USDA) Pesticide Data Program (PDP).
Much less impressive reductions have been achieved by fruit and vegetable farmers abroad. For some imported foods, risks actually have increased in recent years.
For instance, USDA last tested pesticides in both nectarines and peaches in 2008. Insects love these soft-skinned fruits as much as people do, and both crops are vulnerable to plant diseases. It's not uncommon for peaches and nectarines to be sprayed 20+ times.
But with today's lower risk, "soft" pesticides, U.S.-grown peaches and nectarines pose relatively low risks — 0.3 and 0.2 using our "Food Supply-Dietary Risk Index" (FS-DRI). This measure of pesticide risk is grounded in U.S. Environmental Protection Agency (EPA) risk assessment policies and USDA's residue data, widely regarded as the highest-quality residue data available anywhere in the world. FS-DRI values for a food exceeding 1.0 represent potential dietary risks above EPA's typical "level of concern."
Non-organic nectarines and peaches from Chile, tested the same year, posed clearly worrisome risks. The Chilean nectarine FS-DRI score was 4.2, and the peach score was 5.9. Moreover, pesticide risks are moving in the wrong direction in Chilean fruit. In 1996 the peach FS-DRI was 3.1, compared to 5.9 in 2008. Over the same time period, peach FS-DRI values for domestically grown fruit went down from 13 to 0.3.
The very-high-risk organophosphate (OP) insecticide methyl parathion accounted for a FS-DRI score of 11.8 in domestic peaches in 1996 — off the charts. Fortunately, EPA used the FQPA to stop all methyl parathion uses on human food crops about 10 years ago.
Since the mid-1990s, I've been tracking trends in pesticide residues and risk in domestic and imported foods, and non-organic versus organic foods, using PDP data. Overall, U.S. fruit and vegetable farmers have reduced risks dramatically. For most soft-skinned produce vulnerable to pest attacks, risk levels have fallen at least two-thirds, and many by tenfold or more. So, there is progress to celebrate.
The key to major risk reduction, however, is the same in nearly every crop — phasing out use of high-risk OP insecticides. Unfortunately, OP residues still are common, especially in imported foods, and they still account for the lion's share of pesticide dietary risk.
Organic is best
Organic crops occasionally contain detectable residues of pesticides, but these pose very small risks. An increasing share of residues detected in organic food is from applications of biopesticides that are allowed for use on organic farms. Another portion represents legacy residues of persistent organochlorine insecticides such as DDT applied in the 1950s through the 1970s, the decade when most of these insecticides were banned.
A small and falling portion of the residues in organic produce are synthetic pesticides that cannot be used on organic farms or food. Essentially all are present at very low levels because they got onto organic fields via drift, movement in fog or contaminated irrigation water.
Many residues on organic food are low-risk fungicides that tend to move around in storage facilities and packing houses. Eliminating these residues will require packing and distribution channels dedicated to just organic food. Steady growth in organic produce sales will attract the capital needed to build or transition such facilities, a process underway in Washington.
Remember, the health benefits of eating more fresh produce nearly always outweigh any risks. Still, it makes sense to minimize pesticide risks by choosing organic when possible.
With some planning this summer, we Northwesterners can enjoy ample quantities of nutritious, safe local fruits and vegetables all year.
Chuck Benbrook is a research professor at WSU's Center for Sustaining Agriculture and Natural Resources and former chief scientist at The Organic Center. The facts and figures in this piece draw on his presentation at a June organic tree-fruit conference in Leavenworth, sponsored by WSU and several tree-fruit organizations.