メタコリン作業に発生した急性鉛中毒

Abstract

One case of acute lead poisoning with severe pain in joints of extremities and in upper abdomen occured in a lead metalizing workshop in Nagasaki City in December, 1962. This lead metalizing is an operation involving the melting of wire by a flame with a special device which sprays the atomized lead onto a sueface to be coated. Only 40% of the leadis used in the coating and the rest of it is scattered as dust and fumes around the workers. The total lead concentration in the ambient air during metalizing was 197.1-223.5 mg/m3. Even the fine lead particles, which were filtered through two sheets of ganze, showed high level concentrations as 65.7-94.0 mg/m3. The lead absorption was caused by inhalation of the dangerous dust and fumes. In this case, Burtonian line, anemia, stippled cells (1.9 ‰), coproporphyrinuria (639.5 μg/dl) and protoporphyrinemia (216.6 μg/dl of pcv.) were found as shown in Table 2 and Fig. 1. These signs, except protoporphyrinemia, were rapidly improved by oral administration of a daily dose of 2.5-3.2g of Ca-EDTA for about three weeks without any kind of side effects. Two workers engaged in this operation, one for only 2 and the other for 4 weeks, showed high level of protoporphyrinemia without anemia. The increase in the free erythrocytic protoporphyrin was considered as one of the cardinal signs of lead poisoning. It is often found before the appearance of anemia and stippled cells, and it persists for several weeks even after the findings by other usual tests, such as urinary coproporphyrin and ALA, have returned to normal limits by the Ca-EDTA treatment. Therefore, the determination of free protoporphyrin in red cells is a significant test for chronic lead poisoning.