Effective and Controversial Mosquito Pesticides


May, 2010

There is certainly lots of controversy surrounding the use of DDT - a synthetic pesticide first synthesized in 1874, "discovered" in 1939, and successfully used during World War II to treat malaria and typhus by means of killing the cause of said disease vectors - the mosquito. Widely used as an agricultural pesticide thereafter, DDT soon became highly suspected of causing cancer, genotoxicity, endocrine disruptions and threatening wildlife - most notably birds. In 1972, DDT was banned for agricultural use in the U.S., and later banned worldwide for agricultural use under the Stockholm Convention.

The one type of application/use that DDT has not been banned for hearkens it's original success as a mosquito disease vector control, albeit under strict, limited usage. This alone, has kept the controversy surrounding DDT alive, and thus, the search for a more eco-friendly, healthy replacement of DDT continues.

Recently, researchers have discovered great promise in the pesticide / insecticide, Chlorpyrifos-methyl, aka CS, and have published the findings of a study in February's edition of the Malaria Journal. Beating out DDT in early trials as a mosquito pesticide, a new modified version of Chlorpyrifos-methyl - which, normally has too short of a lifespan for controlling malaria - has displayed more effectiveness and longevity by undergoing a process known as microencapsulation.

Sounds great, does it not? Well, here's the rub. Chlorpyrifos-methyl is an organophosphate (OP), which are the most toxic class of pesticides, let alone mosquito pesticides, still in use today. Acting as neurotoxins in the human body and a highly toxic environmental pollutants, organophosphates are so dangerous that the EPA considers them its highest priority for review under the Food Quality Protection Act (Chlorpyrifos is still allowed for agricultural use). The EPA even operates an OP Pilot Public Participation Process to help make risk assessment decisions for individual organophosphate pesticides. Needless to say, Chlorpyrifos poisoning is a concern.

First registered for use on stored grain in 1985, the registrants of Chlorpyrifos-methyl's patent actually voluntarily cancelled its production of liquid and dust formulations. As part of the OP Pilot Public Participation Process, the registrants voluntarily phased out all but two uses of Chlorpyrifos-methyl rather than committing to develop additional data on the risks of CS use and potential Chlorpyrifos poisoning - in particular, acute, subchronic, developmental neurotoxicity studies, and toxicology data base.

Now that Chlorpyrifos is being purported to be an excellent alternative to DDT, it begs the question if this amounts to settling for the lesser of two evils. More testing is certain to be undertaken in the near future to reveal the necessary "data" needed to fully gauge the potential health and environmental risks of Chlorpyrifos-methyl as a mosquito pesticide and disease vector.


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