University of Hawaiʻi at Mānoa Assistant Professor Catherine Pirkle is the primary author of “Managing mercury exposure in northern Canadian communities,” which was published in the Canadian Medical Association Journal. The journal is ranked in the top 10 medical journals in the world.
The review provides guidance for healthcare providers on the effects of mercury exposure and how to manage it in patients who consume diets high in fish and marine animals. Mercury exposure is common in communities in Canada’s north, especially in indigenous peoples who consume fish and other wild food with high mercury content, yet current clinical guidelines are not adequate for this population.
“Communities that frequently consume predatory fish and/or marine mammals have elevated mercury exposure,” said Pirkle. “It is important for clinicians to be clear on the potential risks, the complexity of the underlying epidemiological data and how to approach, in a culturally sensitive manner, communities where mercury exposure may be a concern.”
Dangers of mercury exposure
Mercury exposure in pregnant women can have multiple effects in children, affecting brain development. In adults, mercury poisoning can cause vision changes, numbness in extremities, muscle weakness, cognitive changes and even death. Symptoms of mercury poisoning are often difficult to detect and vary between people, requiring diagnosis by a toxicologist or neurologist.
The Nunavik Child Development Study, conducted by Université Laval Professor Gina Muckle, which for nearly 20 years has been following a cohort of children recruited before birth, found blood mercury concentrations above the Canadian guidance value in 16.9 percent of school-aged children. In another study of Inuit women aged 18–39 in northern Quebec, 53.3 percent had blood levels above the guidance value; the average in Canadians is 2.2 percent (Canadian Health Measures Survey).
Mercury levels influenced by location
Mercury levels vary widely in wild foods and are influenced by location, according to Melanie Lemire, professor with the Department of Social and Preventive Medicine at Laval. To help healthcare providers recommend appropriate consumption levels, the authors have included tables with consumption guidelines and blood mercury levels and information on how to test.
“The principles and suggestions in this paper apply directly to practitioners working in northern Canadian communities, where wild foods are important dietary components,” said Pirkle. “They are more broadly applicable to practitioners working with patients or in communities with high fish consumption.”
The authors caution that there should be a balance between appropriate consumption and overconsumption of wild foods with mercury; if physicians recommend complete avoidance, people may not have enough nutritious food to eat.
“Mercury exposure is one of many health concerns facing northern Canadian communities,” write the authors. “Counseling to reduce exposure must recognize and address wider food security issues and nutritional challenges, or it will unlikely be effective.”