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Permethrin Data Sheet
Source of Exposure
Permethrin is a pyrethroid which is a class of compounds that are synthetic pyrethrim. It is used as an insecticide, termiticide and/or a wood preservative (Cellutec). Permethrin is used on various types of fruits and vegetables, and Pramex is commonly used for plant pests in greenhouses, bath houses, indoor landscaping and home gardens. Permethrin is also found in lice shampoo, termite sprays (Dragnet FT and Torpedo and Flee for general pest control.
Disposition
The low toxicity of pyrethroids in mammals is due largely to their rapid biotransformation by ester hydrolysis and/or hydroxylation. Many of the available formulations have permethrin contain poperonyl butoxide which inhibits cytochrome P-450 increasing the insecticidal efficacy by slowing the biotransformation in insects.
Toxic Levels
The primary adverse effects of pyrethroids are their allergenic properties. The pyrethroids are markedly less likely to cause allergic response than pyrethrum. Many cases of contact dermatitis and respiratory allergy have been reported. Persons sensitive to ragweed pollen are particularly prone to such reactions.
The LD50 ratio for mammals to insects is 1400. Acute toxicity in rats has been seen to cause aggressive sparring, sensitivity to external stimuli, and fine tremor progressing to gross whole-body tremor and prostration.
References
Aldridge, W.N.: Toxicology of pyrethroids. In Miyamoto, J. and Kearney, P.C. (eds.): Pesticide Chemistry: Human Welfare and the Environment, Vol. 3 Mode of Action, Metabolism and Toxicology, Pergamon Press, Oxford, 1983, PP. 485-90.
Narahashi, T.: Interaction of pyrethroids and DDT-like compounds with the sodium channels in the nerve membrane. In Miyamoto, J. and Kearney, P.C. (eds.): Pesticide Chemistry: Human Welfare and the Environment, Vol. 3 Mode of Action, Metabolism and Toxicology, Pergamon Press, Oxford, 1983, PP. 109-14.
Cassaret and Doull's Toxicology, The Basic Science of Poisons, 3rd ed.: Klassen, Curtis D., Amdur, Mary O., Doull, John (eds.): Macmillan Publishing Co., New York, 1986, p.553.
