 The stated principles of organic agriculture are health, ecology, fairness, and care. But if you ask people why they buy organic, the strongest predictor was concern for their own health or their families. People may spend more for organic, more for selfish rather than altruistic motives. Although organic foods may not have more nutrients per dollar, consumption of organic foods may reduce exposure to pesticide residues and antibiotic-resistant bacteria. Food safety-wise, they found no difference in the risk of contamination with food poisoning bacteria in general. Both organic and conventional animal products were commonly contaminated with salmonella and campylobacter, for example. Most chicken samples were found to be contaminated either way, with campylobacter, about a third, with salmonella. But the risk of exposure to multi-drug-resistant bacteria, resistant to multiple classes of antibiotics, was lower with the organic meat. So that both may carry the same risk of making us sick, but food poisoning from organic meat may be easier for doctors to treat. What about the pesticides? There's a large body of evidence on the relation between exposure to pesticides and elevated rate of chronic diseases, such as different types of cancer, diabetes, neurodegenerative disorders like Parkinson's, Alzheimer's, and ALS, as well as birth defects and reproductive disorders, but they're talking about people who live or work around pesticides. Take Salinas Valley, California, for example, where they spread a half million pounds of the stuff. Daring to be pregnant in an agricultural community like that may impair childhood brain development, such that pregnant women with the highest levels running through their bodies, as measured in their urine, gave birth to children with an average deficit of about 7 IQ points. 26 out of 27 studies showed negative effects of pesticide on brain development in children. These included attention problems, developmental disorders, and short-term memory difficulties. If you compare kids born with higher levels of a common insecticide in their umbilical cord blood, those who are exposed to higher levels are born with brain anomalies. And these were city kids, so presumably this was from residential pesticide use. Residential exposure to pesticides, like using insecticides inside your house, may be a contributing factor for cancers like childhood leukemia, suggesting that awareness be increased among populations occupationally exposed to pesticides about their potential negative influence on the health of their children, though I don't imagine most farm workers have much of a choice. Pregnant farm workers may be doubling the odds of their child getting leukemia and increase their risk of getting a brain tumor. So conventional produce may be bad for the pregnant women who picks them, but what about our own family when we eat them? Well, first of all, just because we spray pesticides on foods in the fields doesn't mean it ends up in our bodies when we eat it, or at least we didn't know that, until this study was published in 2006. Researchers measure the levels of two pesticides running through children's bodies by measuring specific pesticide breakdown products in their urine. Here's the levels of pesticides flowing through the bodies of 3 to 11 year olds during a few days on a conventional diet, then they went on an organic diet for five days, and then back to the conventional diet. It's clear that eating organic provides a dramatic and immediate protective effect against exposure to pesticides commonly used in agricultural production. The study was subsequently extended. Can you guess when the kids were eating organic? You don't even need the labels on the graph to tell. What about adults though? We didn't know until now. Thirteen men and women consume a diet of at least 80% organic or conventional food for seven days, and then switched. And no surprise, during the mostly organic week, pesticide exposure was significantly reduced, and not just by a little, a nearly 90% drop in exposure. So it can be concluded that consumption of organic foods does provide protection against pesticides, but does that mean protection against disease? We don't know. The studies just have not been done. Nevertheless, in the meantime, the consumption of organic food provides a logical, precautionary approach.