In a previous study, lead absorption in cows grazing in the vicinity of a lead smeltery and in a control area was presented for two periods. The first period was in 1976, two years before the installation of an effective gas cleaning system in the lead smeltery, and the second period was in 1982, four years after the sanitation. The results obtained in the lead smeltery area revealed a highly significant improvement of all biochemical indicators of lead absorption intensity in cows during 1982 in comparison with the same findings during 1976. However, in spite of the lower lead absorption in 1982, blood lead concentration and {sigma}-aminolevulinic acid dehydratase activity in 1982 were still highly significantly different from the same findings in cows from the control area. Consequently the study was continued in 1984 and 1988 under identical conditions. The main object of the paper is a critical evaluation of the results obtained in relation to environmental monitoring in the same lead smeltery area.
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