Bifenthrin

Bifenthrin or (2-methyl-1,1-biphenyl-3-y1)-methyl-3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethyl cyclopropanecarboxylate (CAS number 82657-04-3) is a pyrethroid insecticide that affects the nervous system of insects. Products containing bifenthrin include Talstar, Capture, Bifenthrine, Spinosad, and Ortho Home Defense Max.

The United States Environmental Protection Agency (EPA) had classified bifenthrin in the past as a class C carcinogen (possible human carcinogen). It is highly toxic to fish, since it, like most pyrethroids, is also an ATPase inhibitor. Aquatic vertebrates are much more sensitive to ATPase inhibitors than terrestrial vertebrates due to their high dependence on ATP synthesis in the gills to maintain osmotic balance.

The material safety data sheet MSDS for Maxxthor (Bifenthrin's trade name) shows carcinogenic qualities to be virtually zero. It is probable that the earlier class "C" designation was based on older data and lack of studies. When reviewing data, note well the dates of the documents.


 * USA MSDS: http://www.kellysolutions.com/erenewals/documentsubmit/KellyData%5COK%5Cpesticide%5CMSDS%5C81824%5C81824-5%5C81824-5_Maxxthor_5C_9_23_2005_3_23_00_PM.pdf
 * Australian MSDS: http://www.rentokil.co.nz/images/pdf/Insecticide/Maxxthor.pdf
 * EPA Studies on Bifenthrin: (2002) http://www.epa.gov/EPA-PEST/2002/September/Day-27/p24484.htm

The last link contains the following statements about "Spinosad", a trade name (one of many) for Bifenthrin:

"4. Aggregate cancer risk for U.S. population. Spinosad has been classified as ``not likely to be carcinogenic in humans'' based on the results of a carcinogenicity study in mice and the combined chronic toxicity and carcinogenicity study in rats. Therefore, spinosad is not expected to pose a cancer risk to humans.

5. Determination of safety. Based on these risk assessments, EPA concludes that there is a reasonable certainty that no harm will result to the general population, and to infants and children from aggregate exposure to spinosad residues."

Based on the above findings, the "class C Carcinogen" designation was likely pre-2002, the date of this document.

Bifenthrins do have possible health impacts, however, and these should be understood.