Low blood lead concentration associated with various biomarkers in household pets

A former secondary lead smelter was in operation in Granite City, Ill, until the early 1980s. As a result, the surrounding area is heavily contaminated with lead. Soil concentrations as high as 5,000 ppm have been measured in prior studies. Because of growing concerns about health defects associated with low levels of lead exposure in human beings, a major study has been conducted on people living in the area. The study reported here was a corollary to the human exposure study. Lead concentration was determined in 84 dogs and 26 cats in the town and ranged between < 5 and 28 micrograms/dl. None of the dogs had clinical signs of lead poisoning. The CBC and serum biochemical values did not indicate many significant differences between dogs with a high (> or = 10 micrograms/dl) or low blood lead concentration (BLC). Hemoglobin concentrations were lower, and WBC counts were higher in dogs and cats with higher BLC, but they were still within reference ranges. Free erythrocyte protoporphyrin concentration was determined. Normal values appeared to be similar for dogs and cats. Only animals with BLC > or = 20 micrograms/dl were found to have somewhat increased concentration of free erythrocyte protoporphyrin. delta-Aminolevulinic acid dehydratase activity was measured and found to be negatively correlated with BLC. The relation was strong, even at low BLC (5 to 10 micrograms/dl) in both species. Age or sex difference was not observed. Therefore, biological changes associated with low BLC were limited to BLC in the 10- to 30-micrograms/dl range.