LAUSR

Permethrin (PERM) is a synthetic type I pyrethroidal pesticide with broad-spectrum insecticide activity. This compound has been widely used over the past 50 years in agriculture, indoor pest control products, lotions or shampoos for head lice treatment, mosquito control and has been incorporated into the f abric of soldiers’ uniforms to combat insects [1]. PERM has relatively low volatility and can be readily adsorbed onto surfaces such as furniture, walls and carpets. Therefore, there are significant concerns related to exposure to low levels of PERM, which can occur routinely. Following domestic or agricultural uses of PERM, a significant amount of PERM residue may enter into the ecosystem which poses a potential threat to both human health and to other nontargeted species [2]. Human exposure to PERM can occur through inhalation, oral or dermal routes and due to its lipophilic nature, can accumulate in the brain and persist long after exposure [3,4]. Although PERM has low mammalian toxicity, it has been shown to cause a variety of adverse events in animals and humans such as neurotoxicity, immunotoxicity, cardiotoxicity, genotoxicity, fetotoxicity and hepatotoxicity [5]. Therefore, the availability of sensitive and accurate bioanalytical methods for the quantitation of this commonly used pesticide is essential to evaluate its toxic effects on mammals. Since deficits in cognition due to prolonged subthreshold exposures are particularly of interest (as these have been observed in many pesticides that target the cholinesterase pathway), the ability to accurately measure PERM in the brain is important. It is also ideal to be able to correlate these brain exposures to plasma or urine concentrations, since these are easily accessible fluids f ollowing exposures in humans. Commercially available PERM exists as a mixture of the cis-isomers and trans-isomers. Different methods of production lead to different ratios of the cis and trans-isomers, such as 40:60, 80:20 or 25:75. The two isomers have different rates of metabolism, activity and stability. Therefore, it is important to be able to assess the individual contributions of each isomer when measuring PERM. Currently, only two methods have been reported for the simultaneous measurement of these two isomers in rat plasma and the brain [6,7]. The chromatographic and sample preparation details of these methods will be d iscussed in the following section.