Risk management strategy for products containing mercury: chapter 4

Exposure Sources

In the general population mercury exposure can occur through various pathways. Mercury is readily converted to methylmercury in waterways which is then absorbed by wildlife. Human exposure to methylmercury then occurs through the consumption of certain species of fish, aquatic mammals and waterfowl. Populations for which these species are significant food sources tend to have higher methylmercury exposures. Scientific research suggests that it is the developing fetus and the breast-fed children of women who consume greater amounts of the larger species of fish during pregnancy and lactation who are the most susceptible to health problems.

Exposure can also occur when mercury-containing products are broken and mercury is released or spilled at home or in the workplace. Another potential source of exposure is the use of mercury in various cultural practices and hobbies, including some types of jewellery, such as glass pendant necklaces and some artist's paints.¹⁰

Dental amalgam fillings can also represent an exposure source. According to Health Canada, while current evidence does not indicate that dental amalgam is causing illness in the general population, it is generally advisable to reduce exposure to mercury if this can be achieved at a reasonable cost and without other adverse effects.

Environmental levels can be affected by releases resulting from human activity. Mercury in the environment has undergone a two to four fold increase relative to pre-industrial times.¹¹ Although mercury is an element that occurs naturally, it is estimated that about half the mercury in the atmosphere today comes from human activities, such as the burning of coal, the smelting of metal, and the disposal and incineration of mercury-containing products.¹²

¹⁰ Health Canada - Mercury Questions and Answers

¹¹ Mason, et. al, 1994

¹² UNEP - Global Mercury Assessment, 2003