Countermeasures against unforeseeable chemically induced occupational illnesses as future environmental risks

Abstract

The history of chemical intoxication shows that the countermeasures started only after miserable events occurred. This review discusses the necessary frameworks to counteract an environmental risk as chemically induced occupational diseases due to unknown toxicity, focusing mainly on solvent intoxication. In the 1950s, frequent occurrences of chronic benzene intoxication led to the restriction of benzene use as a solvent. Accordingly, benzene was replaced by n-hexane, considered safer at that time, which, in turn, resulted in frequent occurrences of peripheral polyneuropathy that had not been reported before. In 1995, reproductive toxicity and hematotoxicity were discovered in a Korean electronics factory after a degreaser had been replaced with a new one as a measure to mitigate ozone layer depletion on earth. The main component of the solvent was 2-bromopropane the toxicity of which was unknown. Since the late 1990s, a wave of occurrences of trichloroethylene hypersensitivity syndrome, which was different from typical acute/chronic trichloroethylene intoxication, has been recognized in the southern part of China. Trichloroethylene was used extensively in the area as a degreaser with low ozone depletion potential, as 2-bromopropane was used in Korea. In 2012, a cluster of cholangiocarcinoma among proof-printing workers became a public concern. It was concluded that the disease was due to long-term and high-level exposure to 1,2-dichloropropane or dichloromethane. The extensive exposure of the affected workers was attributed to the lack of regulation regarding enforced environmental measurements and health checkups for workers exposed to 1,2-dichloropropane. Another issue is 2-ethyl-1-hexanol that is detected at high concentration in certain rooms, which likely causes sick building syndrome. 2-Ethyl-1-hexanol is emitted from the floor by the hydrolysis of the compounds including phthalate plasticizers when flooring materials made of plastic have a direct contact with cement concrete. Today, although chemical management enforced by laws has been developed, exposure management based on the assumption that the chemical in use has unknown toxicity is necessary, especially if the chemical was commercially available when the law enforcement started. Cooperation between specialists in the field of medical science and technology is necessary to solve the problem of exposure to unexpected chemicals. The authors propose the advancement of curriculums in schools of technology in Japan, from the perspective of health, that is, toxicity of chemicals. In addition, attention must be paid to occurrences of chemically induced occupational diseases in industrializing countries that need to substantially develop occupational safety and health measures.