Methyl mercury -- the type of mercury found in fish and some herbal remedies -- is a known neurotoxin, according to pediatrician Dr. Cara Natterson. It can affect the way nerves work inside the body. Symptoms of mercury poisoning include depression, slurred speech, loss of memory, irritability, and loss of coordination.
Ethyl mercury is the "mercury preservative" (also known as thimerosal) that was used in vaccines in the past. Ethyl mercury is not the same as methyl mercury and it does not accumulate in fish, according to Dr. Natterson.
What Moms Can Do about Mercury Poisoning
Fish and shellfish are low in saturated fat, are a good source of protein and other essential nutrients, and contain omega-3 fatty acids, according to the Environmental Protection Agency. A balanced diet that includes a variety of fish can promote heart health and proper children's development.
However, almost all fish and shellfish contain traces of mercury. Risks from mercury in fish depend on the amount of fish consumed and the levels of mercury in the fish eaten.
The EPA advises against the following fish due to high mercury levels: shark, swordfish, king mackerel, or tilefish. Eat up to 12 ounces weekly of a variety of fish and seafood that is lower in mercury.
Albacore tuna is higher in mercury than canned light tuna. The EPA recommends eating only 6 ounces of albacore tuna each week.
In 2004, the FDA joined with the EPA to warn women who might become pregnant and children to limit their consumption of certain varieties of canned tuna because the mercury it contains might damage the developing nervous system. Fresh tuna was not included in the advisory.
Dr. Natterson says, "What I tell my patients is not to eat tuna if possible. But if you absolutely have to, less is better." She recommends that kids eat canned tuna no more than once or twice a month, but says that it's better to skip it altogether. "For my own kids, I don't even keep tuna in the house," she says.
The EPA advises checking local advisories to find out how safe fish is before fishing in local lakes and other bodies of water.
When kids are exposed to high levels of mercury, it can impair their brain development.
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