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Abstract: Objectives: We conducted a 6-year cohort study to evaluate the relationship between carbon disulfide (CS2) exposure and reductions in the motor and sensory nerve conduction velocity (MCV and SCV) of the median nerve. Methods: Study subjects at baseline included 432 exposed workers and 402 unexposed workers. Among the exposed workers, 145 workers terminated CS2 exposure during the follow-up period (ex-exposed workers). MCV and SCV were measured at baseline and followed up. CS2 personal exposure concentration was measured two times a year during a 6-year follow-up period and mean (range) CS2 exposure concentrations (ppm) were 5.96 (0.8-16.0) and 3.93 (0.6-9.9) in the exposed and ex-exposed workers, respectively. Results: Reductions in MCV during the follow-up period did not differ among the exposed, ex-exposed, and unexposed workers. Reduction in SCV (m/s) of the exposed workers (-4.47±3.94) was significantly larger than that of the unexposed (-3.38±3.97) and ex-exposed workers (-3.26±3.79). For SCV reduction, a partial multiple regression coefficient of (exexposed workers)/(unexposed workers) was significantly positive (+0.915, p < 0.01) after adjustment for confounding variables. Conclusions: This cohort study showed that 6-year CS2 exposure around a mean level of 6 ppm did not affect MCV reduction but induced significant SCV reduction beyond the influence of aging. The effect of CS2 on SCV around a mean exposure level of 4 ppm may be reversible, since it disappeared in the ex-exposed workers after CS2 exposure cessation for a mean period of 4.1 years.
(J Occup Health 2017; 59: 187-193)
doi: 10.1539/joh.16-0255-OA
Key words: Carbon disulfide, Nerve conduction velocity, Rayon
Introduction
Considerable studies have reported the adverse effects of occupational exposure to carbon disulfide (CS2; CAS No 75-15-0) on multiple organs.
We conducted a 6-year cohort study to comprehensively evaluate CS2 exposure concentration and health effects, including cerebrovascular, cardiovascular, ophthalmological, neurological, neurobehavioral, and endocrinological aspects, at baseline (1992-93) and follow-up (1998-99)1-6). The neurological system is considered to be the critical target of CS2-induced toxicity. Toxicity is most often manifested as slower nerve conduction velocity (NCV) in the peripheral nerves1,7) and impaired performance in psychomotor testing8). Peripheral nervous system effects have been reported in many cross-sectional studies on workers exposed to CS 2 in the viscose rayon industry1,7,9-13,14). The most common observations are characterized by slower motor (MCV) and sensory nerve conduction...