Study Links Mercury in Dolphins to Exposure in Humans

For the first time, scientists have taken findings from research on marine mammals and applied it to explore potential risks facing humans with regard to mercury exposure.

Three of the dolphins that inhabit the Indian River Lagoon.

By carin smith | 11/30/2015

What do mercury levels in dolphins say about mercury levels in humans? Quite a bit, according to a new study by scientists at FAU Harbor Branch, which sheds light on the potential dangers of consuming locally caught seafood.

 This is the first time that researchers have closed the loop between marine mammal and human health, by taking findings from their research and applying them to explore the potential risks facing humans living in the same region.  

The study centers around dolphins living in the Indian River Lagoon (IRL), Florida and humans who live along the estuary and consume much of the same seafood as the dolphins. Initial studies of IRL dolphins showed high levels of mercury, which led scientists to conduct a follow-up study of humans who live in the same geographic area. The most toxic form of mercury known as methylmercury builds up in fish, shellfish, and animals that eat fish, and are the main sources of mercury exposure in humans.

The findings from this study, published in the current issue of the journal Veterinary Sciences, showed that the cross-section of people tested also had high levels of mercury and that much of that mercury was due to consumption of locally obtained fish and shellfish. More than  half of the participants in the study had a concentration of mercury in their hair, which was greater than the guideline for exposure defined by the U.S. Environmental Protection Agency.

“This research exemplifies the role of dolphins as an animal sentinel in identifying a public health hazard,” said Adam Schaefer MPH, FAU Harbor Branch epidemiologist. “It is a unique and critical example of closing the loop between animal and human health.”

Mercury is an important global health problem, most of which is due to consumption of fish and shellfish that become contaminated through the food web. The major human health risk results from high exposure during pregnancy, since the developing nervous system of a fetus is highly vulnerable to environmental insults such as maternal exposure to mercury. Long-term effects have been shown in poorer performance on standardized tests of learning, memory, visual-motor skills and cognitive development in multiple studies around the world. 

"Fish consumption is recommended for a healthy diet and has many benefits including a reduction in the risk of developing cardiovascular disease,” said John Reif, D.V.M., Colorado State University research professor and collaborator on the study. “Pregnant women can balance the risks and benefits of seafood consumption by continuing to eat fish, but avoiding fish caught in the Indian River Lagoon where the levels of mercury are higher.”

Gregory Bossart, D.V.M., of the Georgia Aquarium, also was a collaborator on this study.

For more information, contact Carin Smith 772-242-2230 or at

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About Harbor Branch Oceanographic Institute:
Founded in 1971, Harbor Branch Oceanographic Institute at Florida Atlantic University is a research community of marine scientists, engineers, educators and other professionals focused on Ocean Science for a Better World. The institute drives innovation in ocean engineering, at-sea operations, drug discovery and biotechnology from the oceans, coastal ecology and conservation, marine mammal research and conservation, aquaculture, ocean observing systems and marine education. For more information, visit   
About Florida Atlantic University:
Florida Atlantic University, established in 1961, officially opened its doors in 1964 as the fifth public university in Florida. Today, the University, with an annual economic impact of $6.3 billion, serves more than 30,000 undergraduate and graduate students at sites throughout its six-county service region in southeast Florida. FAU’s world-class teaching and research faculty serves students through 10 colleges: the Dorothy F. Schmidt College of Arts and Letters, the College of Business, the College for Design and Social Inquiry, the College of Education, the College of Engineering and Computer Science, the Graduate College, the Harriet L. Wilkes Honors College, the Charles E. Schmidt College of Medicine, the Christine E. Lynn College of Nursing and the Charles E. Schmidt College of Science. FAU is ranked as a High Research Activity institution by the Carnegie Foundation for the Advancement of Teaching. The University is placing special focus on the rapid development of critical areas that form the basis of its strategic plan: Healthy aging, biotech, coastal and marine issues, neuroscience, regenerative medicine, informatics, lifespan and the environment. These areas provide opportunities for faculty and students to build upon FAU’s existing strengths in research and scholarship. For more information, visit