Panel discussion: exposure, remediation, and related research needs.

The panel opened with a request to J. LaVelle (U.S. EPA) to enlarge upon his presentation of a bimodlal disposition for the plasma reduction of hexavalent chromium (and subsequent urine concentration) in an occupational group exposed to chromium. He replie(d that he did not know the size of the population that was exposed, but that the group consisted of workers at a dichromate plant, and the sample size was not very large (1). He added that this distribution (loes appear to give credence to the theory that there is one reducing agent in plasma that controls the rate of the Cr'l redtetion. This is in opposition to the thought that many compounds can participate in this reduction, as opposed to one specific rate-determining reduction reaction. R. Wedeen added that it has been stated that the reduction capacity (for chromium) of plasma is 2 ppm and that the remainder of the hexavalent chromium, above that concentration, enters the erythrocyte, to be reduced there. R. Hazen (New Jersey Department of Environmental Protection) was then asked what evidlence there is of contact d(ermatitis in the population of Jersey City. To his knowledge this has not been investigated. Evidence of contact dcermatitis from chromium comes from occupationally exposed people and the occupationally exposed have not been investigated in Jersey City, nor to his knowledge, has anyone been tested there. LaVelle added that risk assessment is intended to project into the future, to predict riesults based on certain exposure scenarios, as opposed to being a (lescription of happenings at a specific site. The question was then asked of Hazen whether risk assessments for chromium have been or are being made for the Jersey City location. He answered that a risk assessment has been prepared by a contractor for the Department of Environmental Pro-