Why were mercury-containing fungicides and pesticides prohibited in the United States?

In the United States, the use of mercury-containing fungicides and pesticides was prohibited in the early 1970s due to their significant contribution to environmental contamination and the associated health risks to humans and wildlife.1

Mercury is a highly toxic element, and its compounds—particularly organic mercurials—pose severe dangers when they enter the ecosystem. Once released into the environment, these compounds can be converted by bacteria into methylmercury, a highly toxic form that bioaccumulates in aquatic food chains. This process leads to high concentrations of mercury in fish and shellfish, which, when consumed by humans, can cause devastating neurological damage, such as that seen in [Minamata disease].213

Beyond aquatic contamination, the use of these substances in agriculture and consumer goods posed direct risks through ingestion, inhalation, and skin absorption. Because of the clear evidence that these products were causing widespread environmental pollution and posing a serious threat to public health, the government took the ethical step of banning their use to prevent further toxic exposure.21