The Impact of Pesticides - Academy Publish

INTRODUCTIONPopulations may be occupationally or environmentally exposed to pesticides bydifferent routes and different sources; the best approach to assess such exposure hasbeen recognized to be through biological monitoring. It provides information oninternal doses, and reflects actual rather than estimated exposure (He, 1993;Woollen, 1993; de Cock et al., 1995; He, 1999; Jakubowski and Trzcinka-Ochocka,2005). Furthermore, biomonitoring of exposure provides early warning signs beforeirreversible alterations occur and allows documenting inter- and intra-individualvariability (Jakubowski and Trzcinka-Ochocka, 2005).For many pesticides with short biological half-lives and largely eliminated in urine,urinary biomarkers are usually used as indicators of exposure (Barr and Needham,2002). Nevertheless, for a proper interpretation of biomonitoring results, knowledgeof the kinetics of the pesticide of interest and its metabolites as well as samplecollection strategy is necessary (Aitio, 2006). Once the pesticide kinetics isdocumented in humans, biological guideline values aiming at preventing harmfuleffects may then be derived by linking safe exposure levels with correspondingurinary biomarker values (Hoet and Lison, 1996; Maroni et al., 2000c). For thegeneral population, such biological limit values have not yet been proposed bygovernmental organizations for pesticides (Valcke and Bouchard, 2009; Angerer etal., 2011); biomonitoring values are rather compared to those obtained in large-scalelongitudinal epidemiological studies and considered as a reference for baseline orcontrol values (Barr, 2007; Angerer et al., 2011; Göen et al., 2011). Foroccupationally exposed individuals, the most often used biological reference valuesare the BEIs ® , set by the American Conference of Governmental IndustrialHygienists (ACGIH), and BATs of the Deutsche Fortschungsgemeinschaft (DGF).The only differences between both values are that BATs are ceiling values ratherthan time-weighted averages and have been applied only to non-carcinogenchemicals (Drexler et al., 2008; Ikeda, 2008; Angerer et al., 2011). However, bothcorrespond to compound levels in accessible biological matrices corresponding toinhalation threshold exposure limit values and no such values for pesticides havebeen proposed so far by these Agencies.Recently, biological reference values (BRVs) have been proposed for specificurinary biomarkers of some organophosphorus insecticides (OPs), a carbamateinsecticide and two phthalimide fungicides (Bouchard et al., 2003, 2005, 2006,2008; Gosselin et al., 2004; Valcke and Bouchard, 2009; Heredia-Ortiz et al., 2011;Heredia-Ortiz and Bouchard, 2011). These BRVs were established usingtoxicokinetic models developed for each substance, and relating the dose of theparent compound absorbed in the body to the time course of urinary metabolitesunder different exposure scenarios and to pesticide exposure doses causing earlyhealth effects in humans. Therefore, they correspond to safe biomarker levels inhumans, regardless of the exposure scenario. The purpose of this chapter is thus topresent a review of the toxicokinetic modeling approach used to determine theseBRVs and to illustrate the convenience of this approach by presenting the exampleof malathion, chlorpyrifos, parathion, carbaryl, captan and folpet in the context of anoccupational exposure and that of non-specific OP exposure in children.AcademyPublish.org - The Impact of Pesticides106