LEAD BURDEN IN LONG BONES OF NORTH AMERICAN RIVER OTTERS

Acute lead poisoning resulting from lead paint in the home is well documented. Regulations, continued blood testing, and treatments have significantly lowered the adverse effects of lead poisoning due to ingestion of toxic levels of lead in contaminated paint. Childhood lead levels have been reduced to 8% in the United States since the 1980’s. Unfortunately, in the last 5 years, lead levels in children tested have not decreased significantly. In contrast, instances of lead toxicity to other mammals, particularly aquatic, and semi-aquatic animals has increased. It is hypothesized that in aquatic settings, where this metal has accumulated, low levels of lead have bypassed monitoring and entered the food web. This increase warrants research into other possible pathways of lead exposure that could affect humans. River otters have proven to be an ideal sentinel species for heavy metal exposure in freshwater food webs. Lead levels in North American river otter liver tissue from 2019 were found to have the same range of lead levels as river otters tested in 1987. Once exposed to lead, it may remain in the liver for as long as 28 days; however, the lead burden in large bones, such as femurs, can last as long as 10 years. When bones regenerate, lead may be re-introduced into the body and blood stream, creating a continuous low-level exposure over several years. For this project, river otter femurs were dissected and tested for lead levels via ICP-OES. Sections were also viewed under a microscope to document visual effects of lead storage. These levels will be compared to liver lead levels of the same mammals to evaluate acute versus chronic lead exposure via fresh water food webs.