Setting the research agenda for chromium risk assessment.

The process of assessing the public health risk of exposure to particular environmental contaminants is complicated and full of assumptions and uncertainties (1,2). However, the problems of assessing risks for chromium exposure are unusually complex (3,4). The problems posed by current investigations of chromiumcontaminated soil in northern New Jersey (5), in part, provided the impetus for a conference on a research agenda for chromium contamination and risk assessment. During the first half of the present century, northern New Jersey was the chromite-chromate industrial capital of the world, and we face today the legacy of chromium-containing slag left by this industry and distributed gratis to many locations and communities in Hudson County. The magnitude of this waste problem measured in millions of tons at dozens of sites is staggering (5), but this conference (to the disappointment of some) is not about New Jersey per se but about the generic environmental health problems posed by chromium in the environment and the resultant human exposure and health risks. Chromium, because of its unique properties, was rapidly exploited for many purposes, first as a mordant and oxidizer in the dyeing industry, later in tanning, and then in metallurgy for its alloying properties with iron, and even more recently for its metal-plating properties (6). Chromium has been in commercial use for less than 300 years. It is a rather rare mineral in the earth's crust, with only a few deposits around the world proving economically exploitable. Although it does not have a long history comparable to lead, iron, or mercury, for example, it appears to be making up for this lack of history by providing major challenges for exposure and risk assessment and public health policy. The greatest challenge of chromium for the risk assessor, and certainly for the risk communicator, lies in the differential toxicity and carcinogenicity of trivalent