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ROLE OF ENVIRONMENTAL HEAT AND COLD STRESS ON THE PHYSIOLOGICAL RESPONSE TO ORGANOPHOSPHATES AND OTHER TOXICANTS.
Citation:
GORDON, C. J. ROLE OF ENVIRONMENTAL HEAT AND COLD STRESS ON THE PHYSIOLOGICAL RESPONSE TO ORGANOPHOSPHATES AND OTHER TOXICANTS. Presented at 23rd International Neurotoxicology Conference, Little Rock, AR, September 17 - 21, 2006.
Description:
Most toxicological and pharmacological studies are performed in laboratory rodents maintained under comfortable environmental conditions. However, exposure to toxicants as well as some drugs can occur under stressful conditions during rest or while exercising. Heat stress can exacerbate the biological efficacy and uptake of toxicants and drugs in several ways: The increase in pulmonary ventilation when exposed to a hot environment results in an increase in uptake of airborne toxicants. Transcutaneous absorption of organophosphates and some other pesticides on the skin as well as drugs delivered by skin patches can be markedly accelerated during heat stress. This increased uptake is a result of the combined elevation in skin blood flow coupled with a moist skin from sweating. The toxicity of most insecticides and most other classes of toxicants is proportional to tissue temperature. Small rodents are capable of eliciting a hypothermic response following acute toxicant exposure, a response shown to improve survival to the toxicants. However, a rapid hypothermic response is attenuated with an increase in body mass. Thus, adult humans exposed the organophosphates in the heat are at greater risk because of (i) increased uptake of the toxicant through the skin and lungs and (ii) greater toxicity due to higher tissue temperatures. Overall, environmental heat and cold stress can influence the thermoregulatory responses to environmental toxicants which impacts on their pathophysiological effects. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.