Environmental Risks

Takatorige, Toshio; Hirose, Yukio; Nagamatsu, Shingo

We now explain the four-step environmental risk evaluation in Uchiyama's paper (Uchiyama 1996) with benzene. Benzene is produced from synthetic resin and other materials at the rate of about four million tons a year. Epidemiological studies of leukemia with workers in factories that use benzene as glue and animal experiments have confirmed that benzene is a carcinogenic hazardous material. The unit risk of benzene in terms of developing leukemia is the measure of the level increase in the risk of leukemia with lifetime intake of 1 microgram per 1 cubic meters. The volume-reaction relation, according to an overseas epidemiological study, estimates the unit risk of benzene at 3-7 for every 1 million persons. Measuring the benzene concentration in the air gives an estimate of exposure to benzene. If we calculate the environmental risk of benzene in Japan from its unit risk, concentration in the air, population, and average life, we can estimate the leukemia outbreak risk at several tens of people a year.