Urinary 2-thiothiazolidine-4-carboxylic acid (TTCA) as the major urinary marker of carbon disulfide vapor exposure in rats

Male Sprague-Dawley rats (200-250 g; 60 per exposure group) were exposed to carbon disulfide (CS2) air concentrations of 0, 50, 150, and 500 ppm(v/v)for 6 hr/day, 5 days/week over six months. Following the exposures, nine rats from each exposure group had four sets of cumulated urines collected (between 0-8, 8-16, 16-24, and 24-48 hr). The urinary parameters measured were: 2-thiothiazolidine-4-carboxylic acid (TTCA), total thioethers (TE), and the compounds responsive to the iodine-azide (IA) test. Urinary TTCA elimination obeyed pseudo-first-order, one-compartment model kinetics of half-time (t(0.5)) 5.2 +/- 0.3 hr up to 16 hr of collection. The elimination of TE within 16 hr had a t(0.5) of 8.5 +/- 0.6 hr. TTCA, IA, and TE were correlated highly in the first 16 hr. After 16 hr, the t(0.5) for TE lengthened to 13.1 hr. At CS2 concentrations of 50, 150, and 500 ppm, the respective t(0.5) for IA-responsive compounds were 12.6, 6.1, and 4.4 hr. TTCA had the highest correlation coefficient and p-value relative to CS2 exposure concentration, and also was the most sensitive, precise, and selective urinary marker.