At least 50 000 people were affected to some extent and more than 2000 cases of Minamata disease were certified. Vapors may be present in such workplaces as dental offices, smelting operations, and locations where mercury has been spilled or released. Mercury poisoning can cause severe symptoms and put the body at unnecessary risk.A person can help prevent mercury poisoning by making changes to their diet and environment that limit exposure to the toxic metal.Mercury is a naturally occurring metal that is in many everyday products, albeit in tiny amounts. Chewing gum causes the release of mercury from amalgam fillings “greatly above normal.” To make a concerning situation even more concerning, our mouth’s flora converts some of this mercury to oxidized mercury and methylmercury, which have been shown to then be incorporated into the body’s tissues. Almost all people in the world have at least trace amounts of methylmercury in their bodies, reflecting its prevalence in the environment. Once in the environment, mercury can be transformed by bacteria into methylmercury.
The mercury poisoning of some 10,000 people who lived around Minamata Bay during 1956 to 1974 showed that children can be poisoned by daily ingestion of fish polluted at only 0.11 ppm. When it comes to mercury levels in our bodies, a normal whole blood mercury level is considered to be between zero and nine nanograms per milliliter (ng/mL). More than 95% of the mercury in fish takes the chemical form called methyl mercury, which is the most toxic form of the element. This is true, but the biological half-life of mercury in the brain is 230 days — and the brain is the main organ that mercury attacks.
Some people choose to replace their amalgam fillings to reduce their long-term exposure to mercury.Mercury poisoning may also be due to direct or environmental exposure. The highest concentrations of methylmercury are generally found in large fish that eat other fish. These effects may be more pronounced in children who are still developing.Mercury poisoning also poses a risk to the reproductive system. Note that the numbers in parentheses (1, 2, etc.)
For example, the Agency for Toxic Substances and Disease Registry has proposed that the US adopt the WHO's mercury standard of 0.47 g/kg/day. EPA believes that the critical population is women of child-bearing age (15 to 44), of which there are 58.6 million in the US. This is 4.7 times as strict as the World Health Organisation's standard of 0.47 µg/kg/day. People with numerous dental fillings who are also exposed to mercury from other sources, such as seafood or work environments, are most at risk.” – Xiaozhong “John” Yu, assistant professor of environmental health science and co-author of the studyElemental mercury is found in dental fillings as well as glass thermometers, fluorescent light bulbs and electrical switches. Thus one good-sized serving of fish per week is about all that is safe, if the fish are contaminated at average levels.
WHO publishes evidence about the health impacts of the different forms of mercury, guidance on identifying populations at risk from mercury exposure, tools to reduce mercury exposure, and guidance on the replacement of mercury-containing thermometers and blood pressure measuring devices in health care. Methylmercury exposure in the womb can result from a mother's consumption of fish and shellfish. The EPA's reference dose, as strict as it seems to some people, was developed based on certain questionable assumptions. Although whole-blood mercury concentrations are typically less than 6 μg/L, diets rich in fish can result in blood mercury concentrations higher than 200 μg/L; it is not that useful to measure these levels for suspected cases of elemental or inorganic poisoning because of mercury's short half-life in the blood.
(You might be wondering how mercury even gets into fish.
An example of acute exposure would be mercury exposure due to an industrial accident.