Lack of Relationship between Occupational Exposure to Carbon Disulfide and Endocrine Dysfunction: A Six‐year Cohort Study of the Japanese Rayon Workers

Abstract

Lack of Relationship between Occupational Exposure to Carbon Disulfide and Endocrine Dysfunction: A Six-year Cohort Study of the Japanese Rayon Workers: Toru TAKEBAYASHI, et al. Department of Preventive Medicine and PublicHealth, School of Medicine, Keio UniversityObjectives-A six-year prospective cohort study was conducted to clarify whether the current carbon disulfide (CS 2 ) exposure level is low enough to prevent subclinical health impairment and/or to ameliorate health effects due to previous high exposure. This paper describes the follow-up results, exposure assessment, and effects on the endocrine system. Methods-The study subjects were 432 male workers exposed to CS 2 at one of the 11 rayon factories in Japan and 402 referent workers from the same factories, all of whom were examined in 1992-93. 251 CS 2 -exposed, 140 former-exposed and 359 referent workers participated in the follow-up survey (follow-up rate 89.9%) in 1998-99. Urinary 2-thiothiazolidine-4-carboxylic acid (TTCA) at the end of a shift as internal exposure index and the time-weighted average CS 2 concentration as external exposure index were measured twice a year from 1992-1993. By using various blood indices, we evaluated effects on thyroid, hypophysis, and gonad function, as well as effects on glucose metabolism. Information on potential confounding factors, such as age, smoking and alcohol drinking, were collected and adjusted for. ResultsWhen the individual exposure level was represented by arithmetic mean for TTCA and CS 2 concentration, Received July 31, 2002; Accepted Jan 24, 2003 Correspondence to: T. Takebayashi, Department of Preventive Medicine and Public Health, School of Medicine, Keio University, 35 Shinanomachi, Japan geometric means (SD) of CS 2 workers were 1.61 (1.91) mg/g.crea and 5.02 (1.84) ppm, respectively. There were no exposure-related differences in glucose metabolism or any of the endocrinological indices. Conclusions-No biologically significant effects of CS 2 were found on endocrine function in Japanese rayon manufacturing workers when the average internal and external exposure levels were maintained below the current occupational exposure limit. (J Occup Health 2003; 45: 111-118)

Six year observational cohort study of the effect of carbon disulphide on brain MRI in rayon manufacturing workers

“…The intervening effects of research have improved the environment since 1992. 25 Thus, mean TTCA concentrations over six years could reflect the most recent exposure but could not reflect higher exposure concentrations in the past. Therefore, using urinary TTCA concentrations in 1992 alone, which might better reflect exposure prior to the observation period, the subjects were again classified into quartiles for evaluation.…”

“…[23][24][25] Briefly, the study subjects consisted of 432 male workers exposed to CS 2 and 402 male referent workers in 11 Japanese viscose rayon factories. None of the subjects had any medical history of cerebrovascular and cardiovascular diseases, including medically treated hypertension at baseline, determined by checking companies' medical records and through a self administered questionnaire.…”

“…After summarising the subjects' job records, some of the ex-exposed and referent workers were reclassified as exposed workers since they were still being exposed to CS 2 when they worked near rayon production areas, and some referent workers were excluded from the study subjects because they had histories of CS 2 exposure for 1-8 years before the observation period. 25 Therefore, 744 (89.2%) subjects were subject to analysis for the whole cohort study, which consisted of 259 exposed, 133 ex-exposed, and 352 referent subjects. From 744 subjects, 666 subjects who received a brain MRI at both the baseline and follow up surveys were subjected to MRI evaluation and analysis for this study, which includes 217 exposed, 125 exexposed, and 324 referent subjects.…”

“…25 Briefly, CS 2 concentrations in the workers' breathing zone were measured twice a year since the spring of 1993 during the study period with a Parkin-Elmer diffusive sampler tube. The level of 2-thiothiazolidine-4-carboxylic acid (TTCA), a metabolite of CS 2 , in urine was also determined twice a year beginning in the autumn of 1992 as a biological monitoring parameter.…”

Carbon disulfide. Just toxic or also bioregulatory and/or therapeutic?

“…Epidemiological studies of chronic CS 2 exposure are somewhat contradictory, particularly regarding reproductive [35][36][37] and cardiovascular issues. 38,39 From a brief overview of the literature, the described toxicity, pathology, and/or metabolism of CS 2 indicate a breadth of targeted biochemical effects.…”