Ever wonder where the old saying "mad as a hatter" came from? Or, what made the Mad Hatter in "Alice's Adventures in Wonderland" (Lewis Carroll's 1865 classic) "mad"? Why did these hat makers or "hatters" have a reputation for strange, unpredictable behavior? The answer is, they were suffering from mercury poisoning.
In the 1800's, mercury nitrate was used in the felting process. Exposure to the chemical affected the workers nervous systems, causing them to display symptoms of chronic mercury poisoning: excitability, mental instability, a tendency to weep, fine tremors of the hands and feet, and personality changes.
Mercury is no longer used in the felting process, but it is still a common ingredient in many household and workplace items. If these items are broken or managed improperly, they can release mercury vapors into our homes, workplace, and environment.
Mercury affects the brain, spinal cord, kidneys, and liver. It affects the ability to feel, see, taste, and move. Long-term exposure to mercury can result in symptoms that get progressively worse and lead to personality changes, stupor, and coma.
Mercury is the only metal that is a liquid. It is a nerve toxin that can impair the way we see, hear, walk and talk. Mercury released from broken devices can vaporize, contaminate the air in our homes, and sometimes go down the drain. Mercury vapor eventually reaches the atmosphere. From there, mercury can mix with rain and snow and fall into lakes and waterways were it can mix with bacteria and be converted into methyl mercury. Methyl mercury contaminates the food chain and builds up in the tissue of fish and of wildlife and humans who eat the fish. Because of high mercury concentrations in the fish, many states issue advisories cautioning people to limit how much fish they eat.
About two-thirds of the mercury in the atmosphere comes from human-made sources like fossil fuel-burning power plants. The remaining mercury comes from natural sources, such as volcanoes and forest fires.
The most common routes of exposure are inhalation and ingestion
Inhalation exposure can occur while cleaning up a broken mercury-containing item. Ingestion usually occurs from eating contaminated fish.
Large, long-lived fish meat can contain toxic methyl mercury
Once in a water body, bacteria can transform mercury into its most toxic form, methyl mercury. Mercury does not break down; it only accumulates as it moves up the food chain toward humans. Since it's in the tissue (not the fat) trimming and cooking don't affect it.
This does not mean you should stop eating fish. It's a good source of protein and low in saturated fat. Moderation according to the type of fish, its origin, and your health status is the key.
Pregnant women should exercise extra caution as the fetus is highly susceptible to methyl mercury poisoning. Affected children show lowered intelligence, impaired hearing, and poor coordination.
For more information about fish consumption advisories, please check the U.S. Environmental Protection Agency (EPA)'s Fish Consumption Advisory Database.
The FDA has recommended that pregnant women, women of childbearing age, and young children avoid shark, swordfish, king mackerel, and tilefish/ocean whitefish. FDA advises these women to select a variety of other kinds of fish - including shellfish, canned fish (including tuna), smaller ocean fish or farm-raised fish - and that these women can safely eat 12 ounces per week of cooked fish.
It is also dangerous around children because it looks interesting and fun to play with
Several children have developed mercury poisoning after playing with vials of mercury they found at home or school.