Progress 10/01/06 to 09/30/09
Outputs
OUTPUTS: 30 head of cattle from herds with known lead exposure were added to this study from 4 different farms. Approximately 75 blood samples were collected from these cattle. 34 urine samples were collected from 16 cows on one farm. Numerous environmental samples were analyzed to determine the source of lead contamination on the farms. Additionally, carcasses of 2 euthanized cattle were purchased and complete necropsy and tissue collection was done. A total of 224 cattle from 7 farms have been sampled for this 3-year study. Samples have included blood, urine, and milk. PARTICIPANTS: Karyn Bischoff was the principle investigator. She is director of the analytical toxicology laboratory, where samples were analyzed. She has collected the data in spreadsheets and will continue to process it. She also coordinated local veterinarians who were involved in lead poisoning cases with local herds for sample collection. She was also involved in collection of environmental samples and assisted in collecting biological samples. Belinda Thompson was involved in communication with local veterinarians concerning cases of lead poisoning. As a veterinarian, she collected blood samples and other biological samples from affected cattle herds. William Higgins acted as liason with a large dairy cow herd in Maryland with a history of lead poisoning. Cynthia Gaskill acted as liason with a large herd in Kentucky. She analyzed blood samples for lead in her laboratory to compare lead analysis techniques with our laboratory. TARGET AUDIENCES: The target audiences for this study are cattle producers, veterinarians, and state regulators. Information from herds studied in Maryland and New York has been submitted to state Agriculture Departments and used to promote regulation of meat and milk from animals exposed to lead on the farm. Results from this study have lead to policy changes within these states. Information from this study has also been presented as a poster in a national "One Health" conference to show the importance of animals as sentinels for lead poisoning (Milstein Science Symposium. American Museum of Natural History, New York, NY). PROJECT MODIFICATIONS: The only major change was the collection and submission of blood samples from several farm animals (horses, cat, dog, goat) from a farm with known exposure in cattle. Since the other animals on the farm had similar exposure, and the owner of the farm also had an elevated blood lead concentration, the owner had blood collected from other farm animals for analysis. Blood lead concentrations were elevated in the cat and dog. This information has been accepted for publication.
Impacts
Analysis continues on the data collected. The blood half-life for lead in the cattle in this study ranged from less than 1 to 293 days. The half-life in milk ranged from 44 to 106 days, though excretion through milk was not consistent and would increase in some cows, most likely due to freshening. Urinary lead was only documented in one of the 16 cows for which urine samples were available. Analysis of tissues from 2 cattle with previous lead exposure that would have been deemed appropriate for human consumption with blood lead concentrations that had decreased below 5 micrograms/dL, revealed trace lead concentrations in edible tissues. The highest lead concentration detected in edible tissues was 7ppm (dry matter) detected in gastrocnemius muscle that was directly adjacent to bone. Other edible tissues contained less than 2 ppm lead (dry matter). Findings on cattle in these farms have been reported to veterinarians in the state in which the farms are located. Based on these findings, milk concentrations greater than 10 ppb are not acceptable for human food in the state of Maryland (based on individual cows, not bulk-tank samples). Cows with blood lead concentrations greater than 5 micrograms/dL are not acceptable for slaughter for human consumption in the state of New York. Lead poisoning in food animals is now reportable to the Department of Agriculture and Markets in the state of New York. These changes are intended to protect the human food supply. We were also able to compare our technique for blood lead analysis, AA, with two other techniques, ICP analysis and LeadCare(R) analysis. Information generated from the ICP to AA comparison will be used internally within the analytical toxicology laboratory for test validation and verification purposes. A paper on the comparison of AA and LeadCare(R) analysis has been submitted for publication. There was one farm where lead poisoning was diagnosed in the cattle and later diagnosed in other animals on the farm and the farm owner. The source of lead was paint in the barn and the farm house. This is the first known case where cattle acted as sentinels for lead poisoning in a human.
Publications
- Animals as sentinels in lead poisoning: 2 case reports. Poster presentation, April 2 & 3, 2009, Milstein Science Symposium. American Museum of Natural History, New York, NY.
- Bischoff K., Priest H*, Mount-Long A., Animals as sentinels in lead poisoning: a case report. Accepted by J Med Toxicol 2009.
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Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: We have continued to follow up on milk lead concentrations in cattle from the large farm in Maryland. Milk samples have been collected from approximately 130 cow over a period of 3 years since lead poisoning was first documented in the herd. All milk samples tested in 2008 had lead concentrations below the FDA tolerance limit of 10 ppb. We continue to follow blood lead concentrations in cattle on small farms in New York and New Hampshire. We have collaborated with a researcher at the Livestock Disease Diagnostic Center in Lexington, Kentucky to compare routine blood lead testing methods used in our lab, atomic absorption and inductively-coupled plasma-axial emissions spectrophotometry, with a rapid blood lead analysis kit for use in cattle. We tested 57 cattle from a herd with documented lead poisoning. PARTICIPANTS: Karyn Bischoff has formed a collaboration with Dr Gaskill of the Livestock Disease Diagnostic Center in Lexington, KY to develop a rapid screen for lead poisoning in cattle. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
We have found that 2 years after exposure to lead shot in the diet, milk lead concentrations were below the FDA limit of 10 ppb, which will have implications for future cases of lead poisoning affecting dairy cattle. Our current data also suggests that lead excretion via the milk varies with the stage of lactation. A manuscript has been prepared documenting lead poisoning one one of the farms in this study. This paper describes the use of cattle as sentinels for human lead exposure on a farm. It will be submitted for publication this year. Methods comparison data has been accumulated with help of the Livestock Disease Diagnostic Center in Lexington Kentucky and is awaiting analysis and eventual publication.
Publications
- No publications reported this period
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Progress 10/01/06 to 09/30/07
Outputs
Milk samples were collected seven times during the period from October 2006 through September 2007 from a herd in Maryland. Lead poisoning was documented in this herd in September, 2005. Approximately 35 cows were sampled during this period and 78 total milk samples were analyze and 31 contained concentrations of lead greater than 10ppb. Milk lead concentrations varied from sample to sample, sometimes increasing. Two more farms were added to the study, including one in the state of New York involving 3 surviving dairy calves and another in New Hampshire involving 4 dairy heifers. Forty to 50 environmental and necropsy samples, including tissues, were collected from this herd and are pending analysis.
Impacts
Early collection from the NH herd has indicated a shorter blood half-life for lead in this herd versus previous herds sampled. This could be indicative of the form of lead leading to rapid absorption(ash versus paint and shot in the previous NY herd and MD herd) or a biphasic half-life. Serial milk collections from the MD herd show that a simple half-life cannot be calculated and lead concentrations in milk concentrations may increase and decrease over time. This is most likely due to stage of lactation, as increased bone resorption for to produce calcium is likely to increase the bioavailability of lead. All results have been made available to the referring veterinarian for use in assessment and treatment of animals.
Publications
- No publications reported this period
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