Accumulation of urinary 2-thiothiazolidine-4-carboxylic acid (TTCA) among workers occupationally exposed to carbon disulfide for 1 week

Objectives: To investigate if carbon disulfide (CS2) accumulates after a 1-week exposure period, and how the work-shift duration and exposure magnitude affects this accumulation for the workers in viscose rayon industry. Methods: Six 8-h and seven 12-h workers in the spinning department historically known to be exposed to high air CS2 were recruited as the exposed groups. Seven workers from other non-CS2-exposed departments were recruited as non-exposure controls. Exposure monitoring covered a full work shift with personal breathing zone monitoring. Urine was collected pre- and post-shift every day throughout the 5 consecutive days. 2-Thiothiazolidine-4-carboxylic acid levels in the urine (U-TTCA) were determined. Results: No detectable values were found for airborne (<0.6 ppm) and urinary (<35 ng/ml) monitoring for the control groups. The exposure levels for a 12-h shift (11.3±1.47) (AM±S.D.) were significantly greater than for an 8-h shift (6.3±0.64). The linear accumulation trend for daily U-TTCA across the workdays was only significant for the 12-h shift at pre-shift. Statistical significance was found in the regression of the ratios for pre-shift U-TTCA to airborne CS2 levels on the preceding day to the day of the exposure at pre-shift for a 12-h shift (r=0.98, P=0.02). Conclusions: The U-TTCA accumulation for occupational exposure to CS2 was exposure-magnitude-dependent. The linear equations derived in this study indicated that the U-TTCA increment at pre-shift for each additional daily 12-h exposure, after an adjustment for the CS2 exposure level, was 0.02 mg/g creatinine/ppm of CS2. The long-term exposure response under such repeated and intermittent conditions should be noteworthy.