Effects of selected chelating agents on organ distribution and excretion of manganese after inhalation exposure to 54MnCl2. I. Injection of chelating agents.

The effect of 1,2-cyclohexylene-aminotetraacetic acid (CDTA), diethylenetriaminepentaacetis acid (DTPA) and 2,3-dimercaptol-1-propanesulphonic acid, sodium salt (DMPS) on Mn distribution and excretion in rats was examined after 1 hr exposure to 54MnCl2 (approximately 0.1 microgram Mn/m3). All complexing agents were injected i.p., 0.32 mM/kg/day, for 7 days, starting either immediately after exposure (day 0, group I), or 1 week after exposure (day 7, group II). The controls were injected i.p. with 4 ml/kg of 0.9% saline. Activity of 54Mn was determined in lung, liver, kidney, and brain, 24 hrs after the last treatment and in urine and feces collected for 24 hrs on days 1-7 and 8-14 respectively. CDTA and DTPA administered immediately after Mn exposure appeared to be most effective, resulting in a two-fold decrease of 54Mn in brain and kidney, and a statistically significant decrease in lung (DTPA) and liver (CDTA). In group II a two-fold decrease of 54Mn in kidney and liver was observed with CDTA. There was also a decrease after DTPA administration. DMPS was not effective in these experiments. On the first day after exposure, 54Mn levels in urine were more than 15 and 25 times higher for CDTA and DTPA, respectively than for saline, in the early treatment group. Excretion of Mn in feces was not affected. Our data show that the effectiveness of removing inhaled Mn depends both on the complexing agent and the time of its administration.