title: 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.
authors.affiliation: New York State Veterinary Diagnostic Center and Department of Population Medicine & Diagnostic Sciences, Cornell University, PO Box 5786, Ithaca NY 14853-5786, USA. KLB72@cornell.edu
authors.forename: Karyn
authors.initials: K
authors.lastname: Bischoff
authors.forename: Belinda
authors.initials: B
authors.lastname: Thompson
authors.forename: Hollis N
authors.initials: HN
authors.lastname: Erb
authors.forename: William P
authors.initials: WP
authors.lastname: Higgins
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Ebel
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Hillebrandt
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000097:blood / Q000139:chemically induced*; D004781:Environmental Exposure; D005260:Female; D006207:Half-Life; D007854:Lead / Q000097:blood*; D007855:Lead Poisoning / Q000097:blood / Q000662:veterinary*; D008297:Male
chemical_list: D007854:Lead