A method has been developed for sampling and determination of vapors of benzotrichloride and related compounds in the work environment. Air sample is drawn by a personal sampling pump through a tube packed with Tenax GC, in which the benzotrichloride and related compounds are adsorbed. Those compounds are desorbed with carbon tetrachloride and an aliquot of the resulted solution is analyzed by gas chromatography. Results on break-through, desorption, storage and reproducibility are presented.
Practical indicators for the health care of 64 workers exposed to a low concen-tration of lead were looked for from an experience of the five-year health examina-tion carried out at six month intervals starting from the pre-employment in a modern industry producing ceramics. Blood lead levels in workers changed in relation to the amount of lead materials consumed for the production of ceramics. Furthermore, blood lead levels and delta-aminolevulinic dehydratase activity were different in each section of mixing, spray-drying, pressing, calcining, lapping, electroding and polarizing processes. Significant correlations between blood and urine lead concentrations were found when the blood lead level was higher than 20μg/100 ml of blood. Anemic markers of red blood cell count, hematocrit, hemo-globin levels and specific gravity of whole blood did not show a significant correla-tion to blood lead level, urinary lead level or ALAD activity. But, a positive or negative correlation was recognized between two items among blood lead level, urinary lead level, and ALAD activity. For these results, it is suggested that the most satisfactory examinations for diagnosis of the effect of low lead exposure are blood lead levels and ALAD activity in red blood cells. These parameters are useful for the preventing of lead poisoning.
Human urine samples, 81 from the non-exposed, 36 from those with intensive exposures to tolueue, and 23 from the less intensively exposed, were analyzed for hippuric acid by colorimetry, gas liquid chromatography (GLC), and high perform-ance liquid chromatography (HPLC). The colorimetric method always gave higher values than the GLC method. In the case of the non-exposed, the value by the former method was more than double the value by the latter. When the colori-metric values were plotted on the abscissa against the GLC values on the ordinate, the slope of the calculated regression line was 0.444 for the non-exposed while it was 0.882 for the exposed. The value was higher as the exposure was more intensive.A conversion formula between colorimetric and GLC values was calculated from the values observed and it was y=x(1-1.78e-0.43x)+0.50 where x and y are the colorimetric and GLC values (mg/ml), respectively, with a correlation coefficient of 0.82. The equation is however not applicable when x is smaller than 0.6. The HPLC values essentially agreed with the GLC values, the regression line being y=0.993z+ 0.009 where y and z are the GLC and HPLC values (mg/ml), respectively. The correla-tion coefficient, r, was 0.994.
To quantify the free silica in a working environment by phosphoric acid method, a few grams of the standard free silica powder is necessary. It is, however, not easy to prepare the amount of the powder in the laboratory because they are usually found in a small phenocryst in some volcanic rocks. A new method for separation of cristobalite and tridymite particles from mother rocks is developed by using hot phosphoric acid with heavy liquid and very effective. It is known that most part of free silica particles survives in a hot phosphoric acid, while silicate particles are dissolved in the acid1)2)3). It is, therefore, expected that the acid residue is formed of the particles of a few sorts of free silica min-erals, and that some of these particles can be separated from the acid residue with the help of heavy liquid4). Present paper shows a new trial on preparation of the cristobalite or tridymite particles from the mother rocks by combination of pho-sphoric acid method and heavy liquid method.