August 18, 2011

Sweating the small stuff: engineered nano-materials in pesticides

Tyler Smith

Tyler Smith

Program Officer, Food Production and Public Health

Johns Hopkins Center for a Livable Future

Many public health hazards are too small to see.  This is especially true of engineered nano-materials, or ENMs.  As their name implies, these materials are small—no more than a few hundred nanometers in diameter.  (For perspective, one nanometer is one billionth of a meter, or one human hair split lengthwise 80,000 times!)

Sounds cool, right?  But consider this: ENMs’ small size could increase the health risk they pose for humans exposed to them.  There are a number of possible reasons for this.  Significantly smaller than most toxicants, some ENMs may be able to pass more easily through cell membranes, thereby reaching tissues other toxicants cannot.  (For an overview, see this lengthy 2009 review from the National Institute for Occupational Safety and Health.)

ENMs are probably in thousands of products.  I say “probably” because no one, including government regulators, knows for sure how many—let alone which—products contain them.  One estimate, from the Project on Emerging Nanotechnologies, put the minimum number at 1,300 and predicted an increase to 3,400 by 2020.

Environmental Health News

For an example, consider sunscreens.  The ingredients in some sunscreens have been engineered to be smaller than a wavelength of visible light, making the products translucent instead of white.  But while applying clear sunscreen looks better than slathering oneself in what looks like mayonnaise, there may be a cost to such aesthetics: scientists continue to debate whether the tiny ENMs in sunscreen can be absorbed through the skin…and whether they increase the risk of cancer.

This brings us to pesticides, already of grave concern to the public health and sustainable agriculture communities, but potentially riskier when they include ENMs.  The Environmental Protection Agency, the federal agency responsible for regulating pesticides under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), does not know which pesticides contain ENMs.  As a result, EPA cannot require tests on those pesticides to determine whether the ENMs increase the risk to human health that pesticides already pose.  (For a general overview of the regulation of ENMs, or lack thereof, see a report by the Institute for Agriculture and Trade Policy.)

Over the past several months, EPA has taken a number of steps to increase its knowledge of ENMs in pesticides and their health effects.  EPA is currently deciding how to use its existing authority under FIFRA to obtain information from manufacturers about the ENMs that their products contain.  The agency published a description of its options back in June and asked for public input.  On Wednesday, the CLF submitted a comment to EPA that encouraged officials to use more than one option in order to maximize the amount of information that the agency collects.  We also urged the agency to make that information available to the public for scrutiny.

As things stand now, it looks like EPA agrees with CLF.  Still, much work remains to be done.  EPA needs to know which pesticides contain ENMs, and to ensure that companies that manufacture these pesticides have conducted exhaustive testing to demonstrate the safety of their products’ ingredients, including engineered nano-materials.  Until that happens, it’s okay to sweat the small stuff.

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