Trichloroethylene health risk assessment: a new and improved process.

Trichloroethylene (TCE), an environmental contaminant of National concern, is the focus of a new health risk assessment process incorporating the Proposed Cancer Risk Assessment Guidelines. This paper describes not only how TCE became an environmental problem for the Air Force, but also details the new Risk Assessment process envisioned by the Environmental Protection Agency's (EPA) National Center for Environmental Assessment (NCEA). Insights on epidemiological evaluations, both past and future, and their impact on the cancer classification of TCE are discussed. Examples of how physiologically based pharmacokinetics and dose-response characterization described in the new Cancer Guidelines are applied to TCE are provided. In addition, a variety of modeling techniques are discussed for the development of reference doses (oral exposure) and reference concentrations (inhalation exposures) for TCE. Finally, the role of risk communication is included. This new process provides an example of how interagency (EPA, Department of Defense. Department of Energy) and extramural (industry, academia) partnerships can provide greater gains to the nation, as a whole, than any of the parts on their own.

Immunologic responsiveness and safety associated with the Coccidioides immitis spherule vaccine in volunteers of white, black, and Filipino ancestry.

A trial of the killed Coccidioides immitis spherule vaccine was undertaken with 151 healthy skin test negative adult volunteers and controls to evaluate the safety of selected regimens, the induction of humoral and cell-mediated immune responses, and to determine if there were immunogenetic differences in these responses. The vaccine was given as three intra-deltoid doses over 8 weeks. No severe systemic symptoms were noted, although 3% of 3.5 mg doses (but no 1.75 mg doses) were associated with severe local reactions. Half the vaccinees had skin test conversions, which generally persisted greater than or equal to 6 months, two-thirds showed boosting of lymphocyte transformation in vitro, and 16% given three 3.5 mg doses developed antibody. There was an association between degree of local adverse vaccine reaction and immunostimulation, and a trend to immune response in persons of O blood type and with some HLA phenotypes. There was no evidence of deficient response to vaccination in subpopulations known to respond to coccidioidal infection poorly. A regimen of three 1.75 mg doses appears to be safe and without reduced immunogenicity, and there is no evidence dosage modification for certain subpopulations would be necessary in efficacy studies.