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EXTOXNET PIP - LAMBI,..,CYHALOTHRIN Page 2 of 4 eye irritation in rabbits (12). The formulated product, Karate, however, causes severe primary skin irritation in rabbits and mild skin sensitization in guinea pigs (107). Primary eye irritation also was observed with the technical product (107). In addition to the corrosive effects to skin and eyes, other acute effects due to exposure to lambda cyhalothrin, like those of other pyrethroids, will be mainly neuropathy (effects on the nervous system) (107, 108). Cyhalothrin may act on ion channels within the nerve cells (neurons) to disrupt proper function of the cells of both the peripheral and central nervous systems (108). At lower doses, this may take the form of stable, repetitive firing of the neuron, but high doses may result in depolarization of the nerve cell and blockage of conduction (108). These effects may result in observable effects such as: tingling, burning or numbness sensations (particularly at the point of skin contact); tremors, incoordination of movement , paralysis or other disrupted motor function; and confusion or loss of consciousness (108). Since most pyrethroids are generally absorbed only poorly through the skin (108, 109), the latter two systemic effects are unlikely unless the compound has been ingested. Effects are generally reversible due to rapid breakdown of the compound in the body (108, 109). Like many compounds of the pyrethroid family, the observed toxicity of lambda cyhalothrin may vary according to not only the concentration of the active ingredient, but also according to the solvent vehicle (62). • Chronic Toxicity: The principal toxic effects noted in chronic studies were decreased body weight gain and decreased food consumption. These effects occurred in rats at oral doses of 1.5 mg/kg/day (the highest dose tested) in a three-generational study conducted in 1984 (107, 110). In a two-year study in rats, no effects were observed at oral doses of 2.5 mg/kg/day and doses of up to 8.5 mg/kg/day produced no observable changes in the function or structure of the liver or nervous system (107, 110). In this study, decreased body weight gain and decreased food consumption occurred at doses of 12.5 mg/kg/day as did elevation of plasma triglycerides (107, 110). In a 26 week feeding study on dogs, doses of 2.5 mg/kg/day disrupted water absorption from the small intestine resulting in liquid feces (107, 110), and at doses of 3.5 mg/kg/day and higher, neurological effects were noted (109). In two teratology studies, no maternal toxicity was observed at doses of 10 mg/kg/day in both rats and rabbits (107, 110 ). It is unlikely that lambda cyhalothrin would cause chronic effects in humans under normal conditions. • Reproductive Effects: In two studies, lambda cyhalothrin caused reduced body weight gain at doses of 15 mg/kg/day in pregnant rats (highest dose tested) and at doses of 30 mg/kg/day in pregnant rabbits (also the highest dose tested) (107, 110), but these doses produced no observable reproductive effects. There were reduced numbers of viable offspring at doses of 50 mg/kg/day in the second and third generations in the three-generational rat study noted above (107, 110). It is unlikely that lambda cyhalothrin would cause reproductive effects in humans under normal conditions. • Teratogenic Effects: No teratogenic or fetotoxic effects were observed in teratology studies of lambda cyhalothrin in rats and rabbits at the highest doses tested in both species (15 mg/kg/day and 30 mg/kg/day, respectively;(107, 110). Based on these data, it is unlikely that lambda cyhalothrin causes teratogenic effects. • Mutagenic Effects: Lambda cyhalothrin produced negative results in all Ames mutagenicity assays using five different test strains, both with and without metabolic activation (12, 109). Results of other in-vitro cytogenetic assays and chromosomal structural aberration tests indicated no mutagenic or genotoxic effects were caused by lambda cyhalothrin (107, 109). The available evidence suggests that lambda cyhalothrin is non-mutagenic and non-genotoxic. • Carcinogenic Effects: No carcinogenic effects have been noted in studies of lambda cyhalothrin on various test animals (rats, rabbits, dogs) (107). The evidence regarding the carcinogenicity of lambda cyhalothrin is inconclusive, but suggests that it is probably not carcinogenic. • Organ Toxicity: No specific target organs or organ systems have been identified in the available studies of chronic toxicity. The nervous system may be affected after acute exposure. • Fate in Humans & Animals: In rat studies, lambda cyhalothrin is rapidly metabolized and http://extoxnet.orst.edu/pips/lambdacy.htm 9/21/2004