Comparison of blood and tissue lead concentrations from cattle with known lead exposure

Blood lead (Pb) is used to diagnose Pb poisoning and exposure in cattle, but there are limited data comparing circulating Pb with concentrations in beef from the same cattle. This study determines whether there is a correlation between blood Pb and tissue Pb concentrations in accidentally exposed cattle. Pb analyses were carried out on ante-mortem blood and post-mortem tissues (including, if available, brain, liver, skeletal muscle, bone, gastrointestinal contents and kidney, and also foetal tissues from one cow) collected from 13 cattle known to have accidental Pb exposure and from three control cows with no known exposure. Variables from cattle were analysed statistically using a Shapiro-Wilk normality test and non-parametric descriptive and association statistics. Blood Pb from exposed cattle rank-correlated with liver, bone and kidney Pb concentrations, but not with the Pb concentrations of brain, skeletal muscle or gastrointestinal contents. The lowest blood Pb concentration associated with a detectable skeletal muscle Pb concentration (> 0.1 mg kg^-1 dry matter) was 4.57 μg dl^-1. Based on these findings, we recommend that cattle with blood Pb > 2.5 μg dl^-1 be withheld from slaughter and that liver, bone and kidney from all cattle with known Pb exposure be withheld from the human food chain.