Male Hartley guinea pigs were orally administered a single dose of methylmercury (10 mg Hg/kg body weight). Nine days after the administration, samples of the brain, liver, kidney and blood were examined for lipid peroxides, antioxidants, lipid components and fatty acid composition. In the experimental group, lipid peroxidation was observed in the liver, kidney and plasma, which was confirmed by significant increases of thiobarbituric acid (TBA) reactants associated with decreases of vitamin E contents in these tissues. Significant increases of TBA reactants and conjugated dienes of polar lipid in the brain were also observed. Furthermore, it was also noted that the contents of polar lipid and cholesterol in the brain were reduced by the methylmercury-treatment. From the results obtained in the analysis of fatty acid composition, the decreasing ratios of some polyunsaturated fatty acids to total fatty acids were noted in polar lipids of the brain, liver and kidney. The suggestion is made that methylmercury induces the decrease of polyunsaturated fatty acids through the lipid peroxidative process to impair the constitution of membrane lipids and thereby causes the functional damages of biomembrane in the target tissues.
Exposure to organic solvent vapors was investigated in 40 unit work-places (with 189 workers) in 16 small-scale industries in north-east Japan (Tohoku District) in which synthetic urushi lacquer was applied to produce non-metal tableware (e.g. soup bowls, rice bowls), flower vases, home altars, etc. Two furniture factories were also studied. The equipment used was carbon felt dosimeters and a portable PID-GC (Model 10A10, Photovac, Ontario, Canada; with minor alterations). Under the conditions employed, the GC could analyze benzene-toluenexylenes within 150 seconds. Independent of the sizes of the factories studied, efficient local exhaust systems were very popular in spray painting rooms. Toluene was the major pollutant in the workplace air, with small quantities of xylenes, ethylbenzene, and much less frequently, n-hexane. Exposure did not exceed the current occupational exposure limit in all the cases except for the two workers, who were excessively exposed due to the generation of dense vapors in automated spraying process. In contrast, the maintenance of drying process was rather poor. In the cases of the production of high quality goods, no artificial ventilation system was allowed in afraid of pollution of finished surface with fine dust, and the vapor levels in the workroom tended to be higher towards the end of the shift.
Daily oral administration of Di-(2-ethylhexyl) phthalate (2000 mg/kg) to male rats for a period of 7 days triggered significant histoenzymic and histological alterations in the testes. Histopathological examination revealed marked degeneration of seminiferous tubules. Patchy loss in the activity of succinic dehydrogenase, NADH-diaphorase and acid phosphatase and increase in adenosine triphosphatase, glucose-6-phosphatedehydrogenase, andalkaline phosphatase was observed in treated rats. These alterations suggest that the disruption of cellular energetics in the testes may be responsible for the reported infertility in male rats.
Effect of cadmium treatment on brain lipids, lipid peroxidation and distribution of Zn, Cu and Fe in rat brain regions was investigated. Adult male rats were exposed to Cd (100 ppm Cd as cadmium acetate) in drinking water for 30 days. The Cd exposure resulted in a significant decrease in the phospholipid content and an increase in the lipid peroxidation in the cerebral cortex and cere-bellum. The total lipid content was not affected in any of the regions but a sign-ificant decrease in cholesterol and cerebroside contents were observed only in the cerebral cortex. A positive correlation between the increase in lipid peroxidation and decrease in the phospholipid content in the cerebral cortex and cerebellum was observed. A maximum accumulation of Cd occurred in the cerebral cortex. The Cu and Fe contents were significantly increased but the Zn levels decreased in the Cd-treated rats in all but the midbrain region. Results suggest that the increased peroxidation decomposition of structural lipids and the altered distribution of the essential trace metals in brain may play a significant role in Cd-induced neurotoxicity.
Simultaneous determination of water-soluble trivalent (Cr(III)) and hexavalent chromium (Cr (VI)) was examined using anion exchange HPLC with a UV monitor and atomic absorption spectrophotometer (AAS). The eluting solu-tion used was 0.03 M Na2CO3 (pH 11), and the flow rate was 2 mι/min. Cr (III) was changed into EDTA chelate before being submitted to chromatography. Sharp elution peaks of the Cr (III) chelate and Cr (VI) anions were obtained by both UV and AAS analyses. Retention time of the Cr (III) species was 2.2 min and that of the Cr (VI) was 5.5 min. The UV and AAS calibration curves for both chromium species showed good linearities. Detection limits of Cr (III) were 2 and 5 ng by UV and AAS analyses, respectively, and those of Cr (VI) were 0.2 and 5 ng. The recoveries of chromium ranged from 95% to 105%. Application of this method was able to determine the Cr (III) and Cr (VI) contents in the water extracts from chromium fume particles generated experi-mentally by a plasma flame method.
A simple and rapid X-ray diffraction method, employing a metal plate as a substrate standard for X-ray absorption correction, was developed for the determination of the quantity of free silica in airborne dust of the working en-vironment. A membrane filter or a Nuclepore filter, on which airborne dust in-cluding quartz was collected, is directly mounted on a zinc plate as a substrate standard. The X-ray absorption of the sample is corrected by the attenuation of the X-ray diffraction beam from the metal substrate standard. The lower and higher limit of the sample weight qualified by this method and the accuracy are both similar to those of the NIOSH method, which uses a silver membrane filter as a substrate standard. The advantages of the present method are reduction in the cost of analysis, because only a membrance filter is used together with a zinc plate, and avoiding the troublesome processes of sample preparation, such as ashing of the collection filter, ultrasonic treatment, and redeposition of the dust sample on a silver membrane filter, consequently excluding artificial effects. It is concluded that the present method is suitable for the quantitative analysis of microgram free silica in airborne dust in the working environment.