Declines in blood lead concentrations in clinically affected and unaffected cattle accidentally exposed to lead

Abstract

Lead (Pb) poisoning remains a common cause of morbidity in dairy and beef cattle. Although Pb toxicosis is typically diagnosed in cattle with clinical signs of acute or subacute Pb poisoning, it has been hypothesized that subclinical chronic exposure of cattle to Pb, which often goes undiagnosed, poses more of a risk to the human consumer. There is not adequate information on Pb kinetics to determine when or if Pb-exposed cattle can safely enter the food chain. The objectives of the current study were to determine whether subclinical elevations in blood Pb (bPb) were present in cattle from herds where 1 or more individuals had clinical Pb poisoning and to determine the half-life (t(1/2)) of bPb in Pb-exposed cattle. Samples of blood were collected and analyzed for Pb from 126 cattle from 9 farms. Blood lead concentrations ranged from below the detection limit (2.50 µg/dl) to 423.0 µg/dl. Only 11 of the 94 cattle with detectable bPb had clinical signs such as diarrhea, blindness, bruxism, or seizures. When possible, cattle with detectable bPb had serial samples taken. The mean t(1/2) calculated from 44 serially sampled cattle was 135 days (standard deviation: 125 days, range: 3-577 days). A source of Pb on the farm was determined for all but one herd.

Post-epidemic lead exposure to animals following a decontamination exercise in gold mining village of Bagega, Zamfara State, Nigeria

“…The possibility of recontamination of the environment or, at least, increased background exposure compared to the non-mining areas could exists (Bartrem et al, 2014). This could result in chronic toxicosis due to the gradual accumulation of toxicants over time or subclinical toxicosis in animals that may seem healthy but have derangements that may not be observed by routine physical and clinical examinations (Goyer, 1990;Bischoff et al, 2014).…”