Toxic Tuesdays

CHEJ highlights several toxic chemicals and the communities fighting to keep their citizens safe from harm.


Mercury is a naturally occurring metal that can be found in combination with other elements. It can be mined from the earth and also released as a byproduct from industrial facilities that manufacture chemicals. If mercury waste is not disposed of properly, it can enter the air, soil, and water. When mercury enters the water, it can build up in the tissues of fish in a process called bioaccumulation. Then, if people eat these contaminated fish, they can be exposed to high levels of mercury. Throughout the world, eating contaminated fish is the most common way people become exposed to mercury.

Most of the health effects of mercury exposure are related to function of the brain. It can impair vision or hearing, cause mood changes such as irritability, and even induce memory loss. Some of these effects can be permanent, persisting even after the affected person is no longer exposed to mercury. Children are especially sensitive to mercury, and damage to their brains can be particularly devastating because they are still developing. Because mercury can pass from a pregnant person to their fetus, mercury exposure during pregnancy can cause fetal brain damage and mental retardation. The Environmental Protection Agency (EPA) warns that some forms of mercury may cause cancer.

In 1956, residents of Minamata, Japan were falling sick with a mysterious illness that caused convulsions, difficulty walking, difficulty speaking, and blindness. In extreme cases, it lead to paralysis, coma, and death. This illness became known as Minamata disease, and researchers determined that patients were eating local fish that was contaminated with a dangerous metal. They identified the metal as mercury and discovered that a nearby chemical factory was releasing mercury-containing wastewater. After this was determined, the company that owned the factory hid information from government officials and did not install effective wastewater treatment mechanisms.

By 2001, over 2,000 people were identified as having Minamata disease and by 2004, the company paid over $86 billion in compensation. Starting in 2010, the United Nations held a convention to address mercury exposure and its effects on human health, called the Minamata Convention. A treaty supporting controls to protect human health from mercury exposure was signed in 2013 by 128 countries including the United States. The Minamata Convention on Mercury now runs an annual conference for treaty signatories to propose new regulations and evaluate the efficacy of existing ones in protecting people from exposure to mercury. Global efforts to reduce mercury use and regulate its disposal will be crucial to ensuring no other communities will have to face toxic mercury exposure like Minamata did.

Furthermore, In 2014, the FDA and EPA issued a guideline recommending the appropriate types and amounts of fish to eat when pregnant. A 2016 study by the Environmental Working Group (EWG) invalidated this guideline, finding that these measures failed to limit mercury exposure amongst 60 percent of a group of 300 women who followed them. For the women who regularly ate fish, they were 11 times more likely to have been exposed to toxic levels of mercury compared to the women who do not eat fish. Although this finding seems to indicate all pregnant women should avoid eating fish, this is a misdirection since fish contains vitamins like omega-3 fats which promote healthy fetal development. Instead, federal guidelines should be more limited on fish choices and caution against larger fish like tuna, which seem to be the most popular source of mercury exposure.  

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