Toxicology letters
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The Environmental Protection Agency (EPA)'s proposed guidelines for studies which estimate worker exposure to pesticides during application and related work activities are discussed. These guidelines are intended to aid pesticide registrants in conducting occupational exposure monitoring studies for pesticide applicators at indoor and outdoor sites. The Agency's rationale for requiring exposure to be monitored with passive dosimetry techniques or by biological monitoring is described. The practical and theoretical advantages and disadvantages of both approaches are also discussed.
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Rats were exposed to toluene at a concentration of 1000 ppm, 6 h/day, 6 times weekly, for 4 weeks. Functional disturbance of the circadian rhythm of spontaneous activity was found after repeated exposure to toluene, although single exposure under the same conditions did not influence the rhythm. The disturbance was characterized by a significant increase in distribution of activity in the "Light' (L) period, and a significant relationship was observed between the total number of days of exposure and the activity level in the L period. The toluene concentration in the blood immediately after the exposure was 6.8-7.2 microgram/ml after one and 18 days of exposure, respectively.