Stop WN Spraying Now: Risk

Risk Assessment

In late July of 2006 fourteen states moved to force the Bush administration to require manufacturers to disclose even "inert" ingredients that the state officials say pose an undisclosed health hazard in pesticides. "Inert ingredients make up as much as 99 percent of a pesticide, the state officials said. Inert ingredients are known or suspected causes of cancer, nervous system disorders, liver and kidney damage and birth defects as well as environmental damage." "To allow consumers to be misled in this way is unconscionable, said Massachusetts Attorney General Tom Reilly." Pyrethrum is considered an axonic poison by the EPA.

As of August of 2005 the U.S. EPA was halfway through the process to reevaluate the registration of Pyrethrins and PBO for use in pesticides. The preliminary risk assessment indicates new areas of concern. There is significant evidence that the preliminary risk assessment must be revised as it underestimates risk of harm. We attach here a summary of concerns in the preliminary ecological risk assessments, as well as a summary of human health data requirements, for ingredients of the mosquito adulticide spray for West Nile Virus. Keep in mind that these do not yet address the public concerns raised through the comment period (e.g., SF Bay Regional Water Quality Control Board and the California Stormwater Quality Association). More information can be found at http://docket.epa.gov/edkpub/index.jsp, see Docket No. OPP-2005-042 for PBO and Docket No. Opp-2005-0043 for pyrethrins.

The EPA has classified pyrethrins and PBOs as possible human carcinogens with moderate acute toxicity but has no data on long term effects. In a letter dated April 12, 2005, to the Metro Public Health Department, Nashville, Professor Wallace LeStourgeon of Vanderbilt University urges the Board to consider scientific data and facts before spraying Nashville for West Nile Virus. Based on studies from the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute and from peer reviewed published research on pyrethroids and the synergist, piperonyl butoxide, he states “I believe that if the general public knew this information, they would choose not to expose themselves or their children to a risk that likely exceeds that from mosquito-borne illness . . . piperonyl butoxide has been shown to induce DNA damage in several different assays for genotoxicity and also to function as an endocrine disruptor.” He also reports that “ . . . only 2% of all cancers result from the inheritance of defective parental genes. Rather, 95-98% of the present cancer burden is due to environmental factors that can directly or indirectly induce somatic mutations in oncogenes . . . The data is simply too compelling to trust the false and misleading information from the pesticide industry.” He refers to PBO and synthetic pyrethrins as genotoxic compounds and "disruptors of human biochemical pathways." Emphases ours.

"The dose makes the poison," so the argument goes, and then the implication often is that the chemical in question is being applied in such a small dose that there could be no possible harmful effect. This comes from the so-called "dose-response relationship," which has governed pesticide regulation for years. The theory is that any substance is harmless if applied at levels below a certain amount, a response then occurs as the amount is increased past that point, the response increases as the dose is increased, and the response eventually levels off after a point. However, this is out-of-date, and pesticide regulation has not kept pace but is slowly being revised. There are reports of situations in which no minimal level of dose has been found that does not generate a response, and there are situations with inverted dose-response relationships -- decreased responses at increased doses. See the ABCs of Toxicology for further details.

This article, Rachel's #824, gives details of some of the history over roughly the last decade of the controversy of the potential for man-made chemicals to disrupt the endocrine systems of animals, including humans. The author suggests that “Now, almost 10 years later, the debate over hormone disruption seems to be over." The Wall Street Journal conceded this summer that low levels of industrial chemicals are linked to rising rates of childhood cancer and brain disorders, among other maladies.

We have seen many claims that WNV poses special risks for children, although we have seen no evidence of this. On the other hand, "Recent research shows that pesticides are particularly hazardous for children," as is reported in this article from the "Journal of Pesticide Reform," Summer 1999, Vol. 19, No. 2.