Although it is well known that hypothyroidism is the most common thyroid disorder in North America and women more likely than men to develop the disease, there are very few studies about thyroid status of Newfoundlanders and Labradorians. An intriguing question has been does the environment influence thyroid status, especially those of Newfoundlanders and Labradorians?

Recent research suggests that presence of persistent organic pollutants (POPs) in the environment may affect thyroid function. One cause of exposure is through food contaminated with POPs. The pollutants are released into the environment through various human activities including industrial processes, agricultural activities and urban waste. Studies have also shown that there are high levels of POPs in certain marine animals, which when consumed might trigger hypothyroidism.

Recently, Drs. Atanu Sarkar, John Knight and Shree Mulay, as well as PhD student Nicole Babichuk, from the Division of Community Health and Humanities published a paper in the journal Environmental International titled Skewed Distribution of Hypothyroidism in the Coastal Communities of Newfoundland and Labrador. The paper provides evidence that incidence of hypothyroidism is higher in coastal communities which have waters flowing in from the St. Lawrence river basin, known for high levels of POPs. The paper was also presented at the 27th Conference of the International Society for Environmental Epidemiology Aug. 30-Sept. 3 in Sao Paulo, Brazil.

"We used secondary data sets from the Newfoundland and Labrador Centre for Health information on hospitalizations with hypothyroidism form 1998-2012 in 41 coastal communities of Newfoundland," said Dr. Sarkar. "We found that hypothyroidism rates on the west coast and southern coast of the island were significantly higher that the east coast communities."

Dr. Sarkar says there are many different factors still to examine, including how frequently people in the high-rate communities eat local fish and shellfish, which species are consumed and the levels of POPs in the fish samples.

This research has national importance because local food supplies in other parts of the country may have similar connections to health problems and pollutants. Environment Canada has already identified areas of the St. Lawrence River to be among the top POP-polluted water sources in the country due to industrialization and urbanization in the Great Lakes watershed and along the river.

Dr. Sarkar says their pilot study forms the basis of future studies because it is too early to make a causal link between hypothyroidism rates and POP levels in populations’ diets. The research team hopes to determine if there is an identifiable cause to the disease’s trend in the province.