Tuesday, April 12, 2011


What is a poison? Socrates swallows the hemlock, clutches his belly, and dies, right?

We think of poisoning as immediate, but unfortunately for us and especially our children, that's almost never the case. Most poisons--and we live amidst thousands of them--exert their effects in small but cumulative increments, over years and decades. Examples are the many organic compounds that permeate our lives, like food additives, pesticides, and plastic breakdown products. Isolated doses might be rather harmless, but long-term aggregate exposure can be tangibly hazardous.

For example, in every school in my region, employees regularly apply herbicides to the landscaping, that practice being ostensibly cheaper than hand-weeding. They try to do this on weekends and holidays, allowing time for the chemicals to degrade before kids are present. When I inform parents about this practice, they usually respond that their children don't seem to have suffered ill effects. This is unjustifiably sanguine, ignorant of the fact that multiple exposures over years add up.  

Take the herbicide glyphosate, brand name Roundup, of which we use plenty. In 2007 alone, American farmers applied 185 million pounds of it, double the amount used only six years earlier. Roundup's been effective not only in wiping out crop weeds, but also in keeping gardens and golf courses pristine.

Its manufacturer, the Monsanto Corporation, has also genetically modified corn, soybeans and cotton to be "Roundup Ready," or immune to the herbicide's effect, so that farmers can grow crops amidst weed-killing concentrations of glyphosate. It's understandable, then, that some U.S. farm organizations say this chemical is too beneficial to give up. But critics say glyphosate may not be as safe as initially believed, and farmers should be cautious.

For one thing, Roundup is beginning to fail its own purposes. Just as pathogenic bacteria exposed to antibiotics mutate resistant strains, weeds are learning to ignore Roundup. More than 130 species have developed herbicide resistance in the United States, raising the question of whether this chemical is morphing from Dr Jekyll into Mr. Hyde.

Roundup might be harmful to human health as well. The EPA is now examining a study that claims to have detected concentrations of glyphosate in the urine of farmers and their children in two American states. Higher levels were found in farmers who did not wear protective clothing when they used glyphosate or who otherwise improperly handled it.

The agency also said it's looking at a study partly sponsored by the National Institutes of Health that found some users of glyphosate had a higher risk of multiple myeloma, a cancer affecting bone marrow, than people who never used the chemical. The Institute of Science in Society has called for a global ban on glyphosate, citing research showing the chemical has "extreme toxicity," including indications it can cause birth defects. The EPA plans to rule on whether to ban glyphosate possibly by 2015.

Canada is also re-evaluating glyphosate, but through a different lens. Where the United States offers chemicals the same protection it offers citizens--innocent until proven guilty--Canada follows what's called the "precautionary principle," which bans chemicals with suspected toxicity.

We need to rethink our concept of poison. Since the poisons we actually live with are subtler than we've believed, we've developed public health policies that award chemicals greater protection than children in a schoolyard. 

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