No abstract

Aerial spraying is cost-effective.

Its insecticidal properties have been known for more than 150 years; although the earliest mention of the Chrysanthemum flowers from which it originates comes from early Chinese history, where it is believed that the flower passed into Europe along the silk roads. 1 The term "pyrethrum" refers to the dried and powdered flower heads of a white-flowered, daisy-like plant. belonging to the Chrysanthemum genus. Pyrethrum's insecticidal properties were recognized in the middle of the 19th century, when an American named Jumticoff discovered that many Caucuses tribes used it for the control of body lice.' The earliest cultivation of pyrethrum, also called "Persian pyrethrum" or "Persian pow ders", was in the region of the Caucuses extending into Northern Persia. 2 The first Persian powders that were processed and commercialized in Europe in the 1820s were most likely prepared from a mixture of C. roseum and C. corneum. During and after 1876, these preparations were introduced into the USA, Japan, Africa and South America. 3 ,4 The superior insecticidal properties of C. cinerariaefolium were first discovered around 1845 and these species sub sequently supplanted previously cultivated species. Chrysanthemum cinerpr iaefolium is currently cultivated in the

West Nile virus (WNV) has been a major public health concern in North America since 1999, when the first outbreak in the Western Hemisphere occurred in New York City. As a result of this ongoing disease outbreak, management of mosquitoes that vector WNV throughout the United States and Canada has necessitated using insecticides in areas where they traditionally have not been used or have been used less frequently. This has resulted in concerns by the public about the risks from insecticide use. The objective of this study was to use reasonable worst-case risk assessment methodologies to evaluate human-health risks for WNV and the insecticides most commonly used to control adult mosquitoes. We evaluated documented health effects from WNV infection and determined potential population risks based on reported frequencies. We determined potential acute (1-day) and subchronic (90-day) multiroute residential exposures from each insecticide for several human subgroups during a WNV disease outbreak scenario. We then compared potential insecticide exposures to toxicologic and regulatory effect levels. Risk quotients (RQs, the ratio of exposure to toxicologic effect) were < 1.0 for all subgroups. Acute RQs ranged from 0.0004 to 0.4726, and subchronic RQs ranged from 0.00014 to 0.2074. Results from our risk assessment and the current weight of scientific evidence indicate that human-health risks from residential exposure to mosquito insecticides are low and are not likely to exceed levels of concern. Further, our results indicate that, based on human-health criteria, the risks from WNV exceed the risks from exposure to mosquito insecticides.