Early response to the exposure of cadmium includes the enhancement in lipid peroxidation with the concomitant impairment in antioxidative defence mechanism. This investigation deals with the delayed responce of cadmium induced stimulation of endogenous defence response against its oxidative damage. The administration of cadmium led to an increase in the hepatic enzymatic and nonenzymatic defence armory in a dose dependent manner 72 hrs post its administration. This includes respectively an increase in the activities of superoxide dismutase, glutathione peroxidase, glucose-6-phosphate dehydroge-nase and in the levels of glutathione, metallothionein and zinc. Cadmium administration also stimulated serum ceruloplasmin activity in a dose dependent manner. These changes are accompained by the concomitant decrease in the peroxidative damage to lipids. Our results suggest the development of a delayed adaptive/defence response as a result of exposure to cadmium.
The study was undertaken to assess the potential risk of exposure to methyl bromide (MB) gas of plant quarantine fumigators who wore full facepiece gas masks with respirator canisters. The mean ambient concentrations of MB determined by a personal sampling device exceeded the TLV-ACGIH level of 5 ppm in the degassing processes at three fumigation sites except at the silos. The mean urinary bromine concentration of 379 non-MB workers was 6.3±2.5 mg/l with 95% confidence limits of 10 mg/l. There were 44.6% of 251 MB workers whose urinary bromine levels exceeded the 10 mg/l. There was a significantly positive correlation between the urinary bromine concentrations of the MB workers and the ambient MB concentrations in the degassing process. The MB levels in the workers' exhalation were positive in the degassing process, while those were below the detection limit in the dispersion process. Three possible routes through which the workers are exposed to MB gas are considered to exist: leakage through the interstice between the facepiece of a gas mask and the wearer's face, breakthrough of MB gas in the respirator canister, and percutaneous absorption of MB gas. Biological monitoring of urinary bromine and exhalatory MB as well as environmental monitoring of the ambient MB provided useful information for evaluating exposure of workers to MB.