Rochester researchers have discovered a simplified way to measure how fast mercury from fish meals is expelled in humans—by looking at concentrations in hair strands. Preliminary findings show elimination rates vary widely among people, according to a study published online by Toxicological Sciences.
The work is exciting because it could open up a non-invasive, more personalized way to understand mercury exposures; and it may help to explain why some people ae predisposed to mercury toxicity due to differences in genetics, metabolism, and gut bacteria, said Matthew Rand, Ph.D., assistant professor of Environmental Medicine, who led the proof-of-concept study.
Methylmercury, a naturally occurring yet more neurotoxic form of mercury found in fish, has been in the news for years due to public health concerns. Studies of pregnant women and young children have shown mixed results about the safety of eating fish frequently.
Since methylmercury is slowly eliminated from the body, Rand’s lab focused on determining the best way to measure the rate of elimination to improve the understanding of who might be susceptible to toxicity. Typically, blood samples are collected but prior research suggests that mercury is evident in hair samples as well.
The Rand lab recruited eight people to eat three meals of wild-caught yellow fin tuna steaks at one-week intervals, in two separate trials. The volunteers ate six to eight ounces each time, with all tuna portions coming from the same fish. (The lab also collected mercury concentrations in the fish, finding that they were within the range of tuna values reported previously by the Food and Drug Administration.)
Researchers then collected stool samples from the volunteers to assess metabolism of methylmercury to a form that is more readily excreted after fish consumption. At the end of 60 days, the lab also collected hair samples from the scalp of each participant and resolved changes in mercury concentrations along the length of the hair using a mass spectrometer.
The high degree of variation in mercury elimination rates among the trial participants suggests that many biological factors influence mercury in the body. Rand was awarded a National Institutes of Health grant to investigate this issue further.
To read the full study, click here.