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Leafy greens – kale and collards, hot peppers

EWG's 2014 Shopper's Guide to Pesticides in Produce™

Two American food crops - leafy greens and hot peppers - are of special concern for public health because residue tests conducted by the U.S. Department of Agriculture have found these foods laced with particularly toxic pesticides. Among the chemicals at issue are organophosphate and carbamate insecticides no longer detected widely on other produce, either because of binding legal restrictions or voluntary phase-outs.

Leafy greens did not qualify for EWG's Dirty DozenTM list this year under the traditional EWG Shopper's Guide rating system, which highlights produce with the highest number and concentrations of pesticides. Still, because of the extraordinary toxicity of the pesticides detected on them, we are highlighting them in this special Plus section.

USDA tests of 739 samples of hot peppers in 2010 and 2011 (USDA 2010, 2011) found residues of three highly toxic insecticides — acephate, chlorpyrifos, and oxamyl — on a portion of sampled peppers at concentrations high enough to cause concern. These insecticides are banned on some common crops but still allowed on hot peppers.

In tests conducted in 2007 and 2008, USDA scientists detected 51 pesticides on kale and 41 pesticides on collard greens (USDA 2007, 2008). Several of those pesticides — chlorpyrifos, famoxadone, oxydemeton, dieldrin, DDE and esfenvalerate — are highly toxic. Although many farmers may have changed their pesticide practices since 2008, some of these chemicals are still permitted on leafy greens. The pesticides DDE and dieldrin were banned some years ago but persist in agricultural soils and still make their way into leafy greens grown today.

EWG recommends that people who frequently eat leafy greens and hot peppers buy organic varieties. If you cannot find or afford organic types, cook them, because pesticides levels typically diminish when food is cooked.

The federal Food Quality Protection Act of 1996 mandated that the U.S. Environmental Protection Act improve its regulation of pesticides and reduce the risks of pesticide exposure for children. The act prompted EPA to restrict the use of many chemicals, including organophosphate pesticides, which are potent neurotoxins. Even in low doses, they can impair children's intelligence and brain development. Over the past two decades, organophosphates have been withdrawn from many agricultural uses and banned from household pesticides. Yet they can still be applied to certain crops.

Several long-term studies of American children initiated in the 1990s found that children's exposures to toxic organophosphate insecticides in not only agricultural communities but also cities were high enough to cause subtle but lasting damages to their brains and nervous systems (Bouchard 2011, Rauh 2011, Engel 2011).

The EPA and some in the agriculture industry argue that restrictions enacted after these children were born would ensure that contemporary children's exposures to these pesticides from food are safe.

However, a study led by Stephen Rauch of British Columbia's Children's Hospital and published in 2012 in the scientific journal Environmental Health Perspectives found decreases in infant birth weight and shorter pregnancies among 300 Ohio mothers exposed to organophosphates during pregnancy (Rauch 2012). These pregnancies occurred after major organophosphate restrictions took effect in the early 2000s. The Rauch study indicates that organophosphate exposures must be further curtailed to protect children's health.

The EPA should continue to restrict toxic pesticides, including organophosphate and carbamate insecticides that are still allowed on many crops. Until this happens EWG will continue to publish a Dirty Dozen PlusTM list that highlights crops tainted with unusually risky pesticides. The USDA should expand its produce-testing program to conduct more frequent analyses of pesticide residues on popular foods. To name a few, celery, kale, collard greens, nectarines, peaches, strawberries, cherries and tomatoes have not been tested since 2008 and are overdue for retesting.


Bouchard M, Chevrier J, Harley K, et al. 2011. Prenatal Exposure to Organophosphate Pesticides and IQ in 7-Year Old Children. Environ Health Perspect 119(8): 1189–1195.

Engel SM, Wetmur J, Chen J, et al. 2011. Prenatal Exposure to Organophosphates, Paraoxonase 1, and Cognitive Development in Childhood. Environ Health Perspect 119(8): 1182-1188.

Rauch SA, Braun JM, Barr DB, et al. 2012. Associations of Prenatal Exposure to Organophosphate Pesticide Metabolites with Gestational Age and Birth Weight. Environ Health Perspect. 120(7): 1055–1060.

Rauh V, Arunajadai S, Horton M, et al. 2011. 7-Year Neurodevelopmental Scores and Prenatal Exposure to Chlorpyrifos, a Common Agricultural Pesticide. Environ Health Perspect. 119(8): 1196-1201.

USDA. 2007. Pesticide Data Program: Annual Summary, Calendar Year 2007. U.S. Department of Agriculture. December 2008.

USDA. 2008. Pesticide Data Program: Annual Summary, Calendar Year 2008. U.S. Department of Agriculture. December 2009.

USDA. 2010. Pesticide Data Program: Annual Summary, Calendar Year 2010. U.S. Department of Agriculture. May 2012.

USDA. 2011. Pesticide Data Program: Annual Summary, Calendar Year 2011. U.S. Department of Agriculture. May 2013.


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