The Stanford team used a novel and simplistic “risk difference” measurement to compare pesticide residue levels in organic vs nonorganic foods, and concluded that organic foods have a risk difference of 30%, compared to nonorganic foods. This metric is seriously flawed and easily misinterpreted. Let me explain.
The Stanford team found that nonorganic foods are likely to contain pesticide residues 37% of the time and organic foods 7% of the time. Given those percentages, then the risk of exposure to pesticides increases by 81%, when someone chooses to consume nonorganic vs organic foods (37-7/37=81%). The risk of exposure to pesticide residues increases by 81%, not 30%.
Further, the Stanford team did not account for synergistic effects of multiple pesticide residues commonly found in nonorganic foods, even though USDA pesticide detection data confirms that nonorganic foods consistently are contaminated with multiple pesticides, whereas organic food are often free of pesticide residues. When residues occur in organic foods, they are typically for one compound, rather than multiple compounds.
In examining human health impacts, the Stanford team made no mention of the effects of organic vs nonorganic production on the most essential nutrient – water! Research from the University of Minnesota and Washington State has shown that organic practices protect groundwater from nitrate contamination. Persistent, carcinogenic pesticides are not allowed in organic production, meaning that organic methods protect drinking water from these contaminants.
The Stanford paper contained no discussion of the health impacts of pesticides on farmers, farmworkers, and rural residents. It has been well established that exposure to agricultural pesticides is associated with an increased risk of prostate cancer. Research has shown that twice as many children of Iowa farmers developed childhood lymphoma as the control population.
Argentinean physicians have reported significant increases in birth defects, miscarriages and child cancer in towns surrounded by GMO soy fields sprayed with glyphosate. In Chaco Province, the rate of birth defects has gone from 19.1 per 10,000 in 1997 to 85.3 per 10,000 in 2008. Cases of child cancer rose from 29 to 40 per year from 1985 to 2001.
The Stanford study contained no discussion of emerging human health research findings related to genetic engineering, the use of which is prohibited in organic production. Researchers in Canada have established that Cry1Ab, a specific type of Bt toxin from genetically modified (GM) crops, has been detected in human and fetal blood samples and crosses the placental barrier.
French researchers have found side effects linked with GM corn consumption, including kidney and liver damage. Other effects were also noticed in the heart, adrenal glands, spleen and haematopoietic system. Researchers in Indiana have concluded that genetically engineered Bt toxins are found in streams and rivers at least six months after the harvest of Bt corn.
The Stanford paper had no discussion of the human health impacts of livestock growth hormones, which are commonly used in nonorganic animal production but are prohibited in organic. It did not address artificial flavors, colors and preservatives, common in nonorganic foods but prohibited in organic. Other factors not addressed, all of which have human health implications, include soil health; biologic and genetic diversity; carbon sequestration and climate change; energy use; economic vitality; and food security.
Likely the most favorable outcome of the Stanford study is that it has opened up a conversation about the verified multiple benefits of organic production and the need for expanded research on organic agriculture and human and environmental health.
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 Environmental Health Perspectives, 112:631-635.
 Maternal and fetal exposure to pesticides associated to genetically modified foods in Eastern Townships of Quebec, Canada Reproductive Toxicology, Volume 31, Issue 4, May 2011, Pages 528-533
 de Vendômois JS, Roullier F, Cellier D, Séralini GE. A Comparison of the Effects of Three GM Corn Varieties on Mammalian Health. Int J Biol Sci 2009; 5(7):706-726.
 “Occurrence of maize detritus and a transgenic insecticidal protein (Cry1Ab) within the stream network of an agricultural landscape” http://www.pnas.org/content/early/2010/09/22/1006925107.full.pdf