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Age-related differences in acetylcholinesterase inhibition produced by organophosphorus and N-methyl carbamate pesticides
Citation:
MOSER, V. C. Age-related differences in acetylcholinesterase inhibition produced by organophosphorus and N-methyl carbamate pesticides. Chapter 22, Stoytcheva M. (ed.), Pesticides in the Modern World - Pests Control and Pesticides Exposure and Toxicity Assessment. InTech, Rijeka, Croatia, , 495-506, (2011).
Impact/Purpose:
Generalizing these data along with other literature reports leads to a conclusion that relatively large age-related differences are evident more often with OP pesticides, whereas carbamates showed more moderate differences. However, fully half of both classes of chemicals showed essentially no age differences. These outcomes are mostly chemical-specific, and therefore assumptions that the young are always more sensitive to ChE inhibition are incorrect. For children's health, logic would dictate the use of pesticides showing less juvenile sensitivity. This retrospective analysis informs estimation of the likelihood for age-related differences in sensitivity for acute cholinesterase inhibition.
Description:
Introduction The concern that infants and children may be more susceptible to the toxic effects of chemicals, including pesticides, has received much attention in the scientific literature and the public media. Greater toxicity may be evident as long-term adverse outcomes, e.g., neurological and IQ deficits from early exposure to lead, or else as increased toxicological effects of acute or short-term exposures. A National Academy of Science panel reported in 1993 on the scientific and regulatory issues regarding relative sensitivity of the young (National Research Council 1993). This report stressed how little is understood regarding the magnitude and mechanisms of these differences, and called for systematic research on pesticide toxicity in developing organisms. The concern that regulatory practices may not adequately protect these subpopulations further led to the passage of the Food Quality Protection Act in 1996 (FQPA, Public Law 104-170, August 1996), which required the US Environmental Protection Agency (EPA) to take extra steps to protect infants and children in the regulation of pesticides. Specifically, the FQPA instructed that"an additional tenfold margin of safety" be applied for non-cancer effects of pesticides "to take into account potential pre-and postnatal toxicity and completeness of data with respect to exposure and toxicity to infants and children". Currently, the EPA Office of Pesticide Programs addresses this additional margin of safety during the risk characterization process (Lowit, 2006; US EPA, 2002). With pesticides for which direct or acute effects drive the assessment, one approach for determining this factor has often been an evaluation of relative sensitivity of young compared to adult animals (US EPA, 2006).
