Rats were exposed to trichloroethylene (TriCE) and tetrachloroethylene (TetraCE) at concentrations of 200, 400, and 800 ppm for one month. The effects of inhalation exposure on neurotransmitter candidates of the rat brain were studied. Changes in the acetylcholine (ACh) content of the striatum were investigated by pyrolysis gas chromatography. The dopamine (DA) in the striatum, norepinephrine (NE) in the hypothalamus, NE and serotonin (5TH) in brain regions containing cortex and hippocampus were analyzed by high-performance liquid chromatography. (1) The DA in the striatum was slightly increased by TriCE and decreased by TetraCE, but the change were not statistically significant. (2) The ACh in the striatum was markedly reduced dose-dependently by these two organic solvents. The decreases in ACh at 800 ppm of TriCE and TetraCE were significant (p<0.05). (3) The NE was slightly increased by these solvents, except that the NE in the cortex and hippocampus was reduced by TriCE. (4) The 5HT in the cortex and hippocampus was increased by TriCE and TetraCE, but the increase was not statistically signi-ficant. It is suggested that long-term exposure to organic solvents may cause some disturbance of the cholinergic neurons of the central nervous system.
In order to prevent workers from occupational exposure to toxic air-borne sub-stances, a method for deciding the acceptability of the work environment is pro-posed. The condition of the work environment is expressed as a function of both the geometric mean and geometric standard deviation of the general air concentra-tions of the hazardous substance in the work environment. This method permits a classification of the condition of the work environment into three control zones with the help of two control levels which are derived from the exposure limit values. In order to check the validity of this method, the exposure concentrations of 118 workers in 29 unit workplaces to various hazardous substances were examined. When the condition of the work environment fell below the first control level, the probability that the concentration to which the workers were exposed exceeded the exposure limit value was less than several percent. When the condition of the work environment exceeded the second control level, the probability was more than 50%.
The two described colorimetric methods are based on the development of colour on dilution of the reaction product of menthol with dimethylaminobenzaldehyde (DMAB) or vanillin in concentrated sulphuric acid medium. The analytical techniques for determination of menthol by the described methods have been optimised. Both the methods are sensitive to 2μg of menthol in 2.5 ml aliquote of sample in concentrated sulphuric acid. The coefficient of variation of the DMAB and vanillin method has been found to be 4.4 and 4.0% respectively. Concentrated sulphuric acid has been found to be a suitable air sampling medium for menthol vapours.
Estimations of human exposure levels to aromatic nitro-and amino-compounds (ANA) are often made by Bratton-Marshall's diazo reaction. In Japan, the environ-mental conditions of the ANA industries have recently improved remarkably. The workers in ANA plants excrete somewhat higher levels of diazotizable substances in the urine than healthy controls and the contributory ratio of the exposed ANA substances to the total diazotizable ones in the urine appears to be of the order of 10 to 20%, most of the time. Under such circumstances, it is necessary to measure the contributory ratio of physiological ANA substances such as hydroxyanthranilic acid to the total diazotiz-able substances. A simplified assay method for hydroxyanthranilic acid in the urine was devised employing cation exchanging resins for the separation of the hydroxyanthranilic acid from other contaminating substances in the urine, and using fluorometry in alkaline solution for intensifying the fluorescence of hydro-xyanthranilic acid. The reproducibility of the fluorimetric method was tested by an enzymatic assay method for hydroxyanthranilic acid determination in human urine, and the correla-tion coefficient was satisfactorily high (r=0.890, p<0.01). The normal excretory value of hydroxyanthranilic acid in the human urine ranges from 1.71 to 11.2 (μg/min), which is equivalent to 10 to 70 μmoles/day.
The chemical species of arsenic in the hair, blood and urine of workers exposed to the dust of arsenic trioxide were studied. The total arsenic concentration in the hair of the workers was very high, and analysis of the arsenic compounds for chemical species showed that inorganic arsenate accounted for the major portion. These arsenic compounds seemed to have been attached externally to the hair. The arsenic concentration in the blood was 3 to 4 times as high as the control value, and analysis of the arsenic compounds for chemical species indicated slight increases in inorganic arsenite and arsenate. The arsenic outputs in the urine of workers exposed to a high concentration dust of arsenic trioxide and those (As3+) in the urine of workers exposed to a low con-centration dust were comparatively studied. The arsenite (As+3) output in the urine of workers exposed to the high concentration dust was significantly greater than that in the urine of workers exposed to the low concentration dust, while no significant difference was noted in dimethylarsinic acid (DMAA) output between the 2 groups. This study demonstrated that the urinary output of inorganic arsenite (As3+) increase in the subjects exposed to arsenic trioxide.