Kohei Toyokawa

A simple method for the quantitative analysis of urinary delta-aminol evulinic acid to evaluate lead absorption

Wada, O., Toyokawa, K., Urata, G., Yano, Y., and Nakao, K. (1969).Brit. J. industr. Med.,26, 240-243. A simple method for the quantitative analysis of urinary delta-aminolevulinic acid to evaluate lead absorption. A procedure is given for the rapid, quantitative determination of urinary delta-aminolevulinic acid (ALA). Interfering substances are removed by n-butanol extraction. After pyrrole formation with ethyl acetoacetate, Ehrlichs reagent is added to produce the chromophore, which is then extracted with chloroform and measured spectrophotometrically or by comparison of the depth of colour with standard colour solutions. The recoveries were about 91% and the results agreed well with those obtained using ion-exchange column chromatography (r=0·985). This assay is simple, dependable, and suitable for large-scale screening of industrial workers exposed to lead poisoning, because the critical level of urinary ALA (20 mg./l. urine), which indicates dangerous lead absorption, gives a convenient absorbance.

Response to a Low Concentration of Mercury Vapor: Relation to Human Porphyrin Metabolism

The δ-aminolevulinic acid (ALA) dehydratase activity in erythrocytes, the cholinesterase (ChE) activity in serum, the urinary output of ALA, coproporphyrin, protein, and mercury, and the level of reduced glutathione (GSH) in erythrocytes were determined in mercury workers. A significant correlation (P < 0.01) was found between the urinary level of mercury and the values for the decreased activities of ALA dehydratase and ChE, and for the urinary level of coproporphyrin, though their values were not so prominent as in lead poisoning. It was concluded that the response of the biological system in vivo to the metals differs greatly from that in vitro, and that the maximum permissible urinary concentration of mercury would be 200μ g/gm creatinine.