Animal exposure studies

During animal exposure studies, technicians experienced irritation of the eyes, nose, and respiratory tract. ... 

Dermal Exposure Levels. Setting acceptable maximum dermal exposure levels to specific pesticides has been difficult. This is primarily due to a lack of specific data on dermal transport rates for specific pesticides as related to adverse effect levels and presumed no-effect levels. We are now requiring such data from the registrants, and our Department has a suggested protocol (1) that is offered to registrants that will provide such information from animal exposure studies. This dermal transport rate information is important in setting minimum field reentry intervals for field workers as well as in evaluating exposure levels of mixers, loaders, and applicators. 

White Phosphorus Smoke. No human or animal exposure studies examining cancer following inhalation or dermal exposure to white phosphorus smoke were located. 

White Phosphorus Smoke. No human intermediate-duration inhalation exposure studies were located. In rats exposed to white phosphoms smoke for 6-13 weeks, death and respiratory effects were observed (Brown et al. 1981). The very short daily exposure duration (15 minutes/day) precludes using these animal exposure studies as the basis of an intermediate-duration inhalation MRL. It is not known if a longer daily exposure to white phosphoms smoke would be more toxic intermediate-duration exposure studies examining... 

The importance of the toxic effects of tire effluents has been rapidly increasing over the last 5 years. This chapter describes the types and effects of toxic effluents that tires produce, and the different methods that exist to assess tire toxicity, using animal exposure studies, laboratory scale, and large-scale generation of tire effluents, followed by a discussion on how different materials and fire conditions influence the generation of toxic products. 

There are no adequate epidemiologic studies of chronic exposure to MTBE or to any of these other ether-like fuel oxygenates that are not confounded by other exposures. Extrapolating effects of chronic animal exposure study findings to humans is questionable for a number of reasons. First, the... 

For each of the following effects, a minimum safety factor is applied to the No Observable Effect Level (NOEL) in test animals. In acute animal exposure studies, the maximum dose level which produces no detectable clinical illnesses, no biochemical changes, no histopathological changes and no deaths is considered to be the NOEL. 

In remarkable contrast to the observed association between ambient level particle exposure and mortality, animal exposure studies have often shown minimal or no effects at exposure levels manyfold higher than ambient. Human exposure studies, although few, have also not shown evidence of adverse effects from particle exposure. For example, healthy human volunteers have been exposed to sulfuric acid aerosols at coneentrations of 1000 J,g/m or higher for several hours. 

The experimental database has yet to provide insights into the mechanisms by which exposure to very low levels of particles exacerbate both respiratory and cardiac disease. We and others have speculated on the mechanisms and relations that could be involved, and tools are being developed to test these hypotheses in field studies, animal exposure studies, and human clinical studies. 

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