A workshop to examine the research needs for acidic deposition, trace contaminants and their indirect human health effects was held in the Adirondack Mountains of NY, June 19-22, 1984. The purpose of the workshop was to: review the current knowledge base; and propose a research agenda concerning the relationship between acidic deposition and altered biogeochemical cycling of trace contaminants, as related specifically to increased human exposure (post-deposition). Working groups in atmospheric processes, biogeochemistry, bioaccumulation and human health effects developed state-of-the-art summaries concerning acidic deposition effects, summarized known and unknown aspects of the acidic deposition phenomenon and identified research needs.