The Effects of Mercury-Infected Fish

Industrial mercury is released into the air and settles into our oceans, rivers and lakes. Bacteria absorb the mercury and convert it into its organic form: methyl mercury. As it travels up the food chain, methyl mercury accumulates at greater levels. The National Resources Defense Council (NRDC) reports that large fish can contain mercury levels 10,000 times higher than that which is in their habitat.



In 2000, the National Research Council (NRC) published the then-known health effects of mercury in fish on humans. Humans are especially sensitive to methyl mercury, and it poses the most risk to children, pregnant women and women of childbearing age.

Cancer and Genetic Effects

• More studies are needed to determine mercury's genetic effects.

  NRC wrote that two studies have found a link between mercury exposure and acute leukemia, but not enough research has been done to be conclusive. Mercury has been classified as a "possible" human carcinogen.

  Studies of genetic damage in humans due to mercury exposure have been inconclusive. Some researchers have found abnormal chromosomes in people exposed to mercury, but the studies weren't carefully controlled for other possible causes.

Immune, Renal and Reproductive Effects

• Mercury may affect a woman's fertility.

  There hasn't been research on the effects of methyl mercury on the human immune system, but workers exposed to elemental mercury compounds have had allergic reactions, as mercury can be absorbed through the skin reports the National Institute of Health's Office of Research Facilities (ORF).

  Multiple animal studies, such as those performed by NRC, have found that mercury can affect developing immune systems, the cellular immune response and the ratio of immune cells.

  Humans exposed to mercury through work or dental fillings can develop autoimmune responses writes NRC, and animal studies have found that mercury can reduce tolerance to self-antigens: the animals' own immune systems attacked their kidneys.

  Inhalation of elemental mercury affects human kidneys in a variety of ways, according to NRC. Kidney damage with exposure to methyl mercury seems related to neurological damage.

  Elemental mercury increased miscarriages in a 1991 study titled "Paternal Exposure to Mercury and Spontaneous Abortions." Another study noted by NRC found evidence that occupational exposures to mercury can affect fertility in women.

Cardiovascular and Circulatory Effects

• Mercury can affect blood pressure and heart rate.

  Diets that include fish have a number of positive health benefits writes NRC, but fish high in methyl mercury can negatively affect the cardiovascular system. Both elemental and methyl mercury can affect blood pressure and heart rate. NRC notes that animal studies have found that mercury may increase the risk of anemia and blood clotting.

Nervous System Effects

• Mercury can be concentrated in the umbilical cord of a pregnant woman.

  Mercury is a neurotoxin, and methyl mercury is a very potent toxin to the brain and nervous system. In the developing nervous systems of fetuses and children, mercury can cause blindness and deafness. Mercury exposure can cause cerebral palsy and mental retardation in children. It can also affect attention, language, memory, speech and walking. Mercury also affects the nervous system of adults.