Commonly found in thermometers and fluorescent lights, the mesmerizing liquid metal mercury can cause such dangerous ailments as headaches, loss of concentration and coordination, and impaired hearing, vision and speech. Recent studies have tied mercury in expectant mothers to attention issues in children, prompting a call for additional research.
Mercury enters our food chain as organic mercury or methylmercury. The EPA names fish consumption as the number one cause of mercury poisoning in the U.S., and children are the most at risk. Approximately 200,000 people in the U.S. suffer from symptoms of mercury poisoning and Earth Share, a national environmental group, reports, “Methylmercury affects 630,000 newborns each year, interfering with brain and nervous system development.” Once in the body, methylmercury can take up to a year to leave the body naturally.
The uses and negative effects of mercury have a long history. Alchemists believed it could transform common metals into gold. In ancient China, people drank mercury to ensure eternal life, only to hasten their deaths. In the 19th century, hat makers who used mercuric nitrate to prepare felt for hats developed symptoms that inspired the phrases “mad as a hatter” and “the Danbury shakes.” (Danbury was once the hat capital of the world, manufacturing 5 million hats per year.)
Today, airborne mercury originates from coal-fired power plants, chemical manufacturing plants, waste incinerators, pesticides and natural sources. It can travel long distances, returning to Earth via snow and rain. Starting with microorganisms in fresh and salt water, mercury builds up through stages in our food chain, eventually reaching humans. The largest and oldest fish, having consumed the greatest amount of smaller fish, likely contain the highest levels of methylmercury and thus pose the greatest health risk.
The Connecticut Department of Public Health recommends strict consumption restrictions for women who are pregnant, planning to become pregnant or nursing, and for children under 6 years old. Aside from trout, fish from Connecticut lakes and rivers should be limited to one meal per month. Bluefish longer than 25 inches and striped bass from Long Island Sound should never be eaten. Store-bought swordfish and shark also should not be eaten, and canned tuna and tuna sushi should be limited to one meal per week. The general population should also limit certain fish, referring to available guidelines.
In October 2012, The Archives of Pediatrics and Adolescent Medicine published research linking low-level exposure of mercury in pregnant women to increased risk of attention deficit-related disorders in their children. In other words, fish consumption previously considered safe for expecting mothers (two six-once servings per week) might no longer be advisable, depending on the specific mercury levels of the fish.
The benefits of eating fish – for omega-3 fatty acids for cardiovascular disease prevention – must be balanced with the risk of overexposure to mercury. Environmental and health specialists continue to study and recommend standards for ensuring public health. Using published guidelines is a good place to start.