Nude mice each attached to a respirator to avoid pulmonary uptake were exposed in a glass exposure chamber to 200, 1000 or 3000 ppm of benzene, toluene or tetrachloroethylene (perclene) for 2, 4 or 6 h. The animals were killed at the end of the study and the amount of each solvent retained in the whole body was determined by gas chromatography. Skin absorption rates were calcu-lated from the amount retained in the whole body using the single compartment model (elimination rate constant) obtained in a previous experiment. There was a linear relationship between the amount of skin absorption and exposure time, and also a linear relationship between the skin absorption rate and concentration of exposed vapors. Skin absorption of solvent vapors occurs by passive diffusion as defined by Fick's law. The skin absorption coefficient (cm/h) of each solvent vapor was calculated by dividing the skin absorption rate by exposure concentra-tion; the values were 1.24 for toluene, 1.00 for perclene and 0.619 for benzene. The coefficient may be useful for evaluating the amount of skin absorption of solvent vapors in the work environment. The amount of skin absorption (ng) was calculated by multiplying the skin absorption coefficient (cm/h), concentration of solvent vapor (ng/cm3), exposure time (h) and exposed skin area (cm2).
Male rats were repeatedly given 1, 2-dibromo-3-chloropropane (DBCP) at 10, 30, or 100 mg/kg twice a week for 12 weeks and were examined pathologically at the 12th, 24th and 36th week. DBCP produced primary lesions in kidneys and testes dose-dependently. The renal lesions were the lining of the proximal tubules in the outer medulla by enlarged, occasionally giant, epithelial cells. Testicular lesions were the atrophy of the seminiferous tubules. These lesions were qualitatively and quantitatively similar throughout the experiment. The results indicated that repeated exposure of relatively low doses of DBCP produced irreversible lesions in the kidney and testis, and that the effects on these tissues may be cumulative.
Intraperitioneal administration of 0.4 mg/kg Cadmium (Cd) daily for 45 days was found to inhibit the activities of glutathione peroxidase and catalase in liver, kidney, testis and various brain regions at different time intervals. The magnitude of inhibition was increased with the period of exposure. Cd produced significant inhibition of glutathione peroxidase at 15 days in liver, kidney and cerebellum only; however, the enzyme activity was found to be decreased in all the tissues, except corpus striatum, at 30 and 45 days of exposure. Hippocampal glutathione peroxidase remained unaltered throughout the experiment. Catalase was found to be inhibited in all the tissues at different time intervals. The withdrawal of Cd treatment for 15 days after 45 days of exposure did not show significant recovery in the activity of both enzymes of different organs, except kidney and testis where partial and full recoveries respectively were observed. Since these two enzymes constitute an important part of cellular defence mechanism against oxidation, their widespread persistent inhibition may be of great signifi-cance in view of the recent reports showing the possible involvement of oxidative stress in the mechanism of Cd toxicity.
To investigate the relationship between job-stress and blood pressure increase, 373 male blue collar workers without hypertension were followed for one year. 5 kinds of perceived job-stress were assessed by means of mailed question-naires. Stepwise multiple regression analysis was conducted to examine significant determinants of blood pressure increases during follow-up. Job-stress due to complicated machine operation was found to be a significant predictor of diastolic blood pressure increase independent of other significant factors, i.e., systolic and diastolic blood pressure at the beginning of the follow-up, age, total serum cho-lesterol, alcohol consumption, type A behavior and family history of hypertension. Job-overload, physical discomfort, human relations and job-dissatisfaction, on the other hand, bore no significant relation to systolic and diastolic blood pressure increases. The results suggest that the use of production machines involving complicated operations and newly developed technology might be a risk factor for high diastolic blood pressure.