Blood lead level in children living close to a smelter area: 10 years later.

A survey conducted at the end of the summer of 1989 in Rouyn-Noranda showed that children living near the smelter had blood lead levels between 2.3 and 26.9 mg/dl. A comparison with a similar survey done in the same area in 1979 shows that there are fewer children today with a blood lead level higher than 20 mg/dl, that is 7 versus 18, ten years ago. The soil lead level of the area where these children live was elevated but comparable to that of 10 years ago, even if the smelter atmospheric lead emissions show an important decrease, as is the case for atmospheric lead contamination by leaded gas. Shall we reconsider our criteria for remedial action on the soil?

Blood lead and maximal urinary excretion of delta-aminolevulinic acid.

Reliability and ease of use are certainly the two major qualities of a screening test or medical surveillance in the workplace. The advantages of using a reliable urinary test thus are evident: the sampling is easy, rapid, noninvasive and, therefore, well accepted. Screening tests or medical surveillance can measure the toxic chemical itself, its metabolites or its consequences on metabolism. In this study the relation between blood lead levels--the most commonly used test for screening and surveillance of saturnism--and urinary excretion of delta-aminolevulinic acid (ALA-U) was measured. The original part of this study is that it takes into account the chronobiology of ALA-U excretion. The samples are collected in the afternoon when ALA urinary excretion is at its highest level. Using a 5 mg/g of creatinine level as a threshold to detect blood lead levels equal to or higher than 60 micrograms/dL the test has an 88% sensitivity, a 91% specificity and a 37% positive predictive value. No worker whose blood lead level is equal to or higher than 65 micrograms/dL has been missed. It is suggested that using 5 mg of ALA-U/g of creatinine as a threshold to prescreen workers who should have their blood lead level measured could be useful in workplaces where lead exposure is moderate or low.