FUTURE RISK FROM A HYPOTHESIZED RCRA SITE DISPOSING OF CARCINOGENIC METALS SHOULD A LOSS OF SOCIETAL MEMORY OCCUR

The future risk of a hypothesized Resource Conservation and Recovery A ct (RCRA) site disposing of carcinogenic metals, arsenic, chromium, ni ckel, cadmium, and beryllium in the U.S. is assessed. Societal memory is assumed to be lost regarding the site. A human intrusion scenario o n the site and a residential scenario one kilometer down-gradient of t he groundwater flow direction from the site are assumed, starting at 1 000 years after the site's closure. For the human intrusion scenario, the exposure pathways considered are fruit and vegetable intake, soil ingestion, and dermal contact with soil. The quantitative results obta ined for the three pathways are as follows: lifetime excess cancer ris k due to fruit and vegetable intake is 0.18; risk due to dermal contac t with the soil is 0.12; and risk due to soil ingestion is 2.6 x 10(-3 ). For the residential scenario, only qualitative discussion of exposu re via groundwater is presented due to the large uncertainties. The U. S. EPA (Environmental Protection Agency) attention to and requirements concerning long-term risk from RCRA sites containing metal carcinogen s, which never change due to radioactive decay, stand in sharp contras t to the stringent requirements over 10,000 years posed by EPA for geo logic disposal of high level radioactive wastes, and the long-term req uirements posed by the U.S. Nuclear Regulatory Commission for low leve l radioactive waste disposal sites.