We’re all concerned about contaminants in our environment. We worry about drinking clean water, breathing clean air, and eating non-toxic food. A recent study published online Oct. 8 in Archives of Pediatrics & Adolescent Medicine reveals another possible concern: mercury hidden in fish. The study links mercury exposure in expectant mothers to ADHD symptoms in their children at the age of 8. Mercury is known to affect the human nervous system.
As with other studies of mercury and its possible link to ADHD, the current study “adds to concerns about mercury consumption and to evidence about the benefits of fish consumption,” said Dr. Susan Korrick. Korrick is the study’s co-author and an assistant professor of medicine at Harvard Medical School and Brigham and Women’s Hospital in Boston. Korrik’s team found that more mercury exposure leads to a higher incidence of ADHD symptoms. However, more fish consumption — the main source of mercury exposure — leads to a decreased risk.
“How much fish you eat is not equivalent to how much mercury you are exposed to,” said Dr. Korrick. “I think the public health conclusion that I would come to is that one can benefit from fish consumption, but it’s important to try to consume fish that are low in mercury.” Fish high in mercury include swordfish,shark, and fresh tuna. Fish with lower levels of mercury include salmon, haddock, shrimp, and cod.
Korrick and her reviewed data on children at age 8 from the New Bedford, Mass., area who were born between 1993 and 1998. New Bedford is on Massachusetts’ coast and is a fishing community where fish consumption is popular. Fish consumption is a primary source of mercury. Korrick’s team investigated whether greater mercury exposure before birth, prenatal exposure via mothers’ wombs, might lead to more behavioral problems in kids later in life.
The researchers tested the children and evaluated teacher reports. The researchers found that some children of mothers who had the highest levels of mercury before birth were 40 percent to 70 percent more likely to have the behavioral problems.
There are flaws to the research because of its design. It doesn’t prove that mercury is directly responsible for the behavioral problems or ADHD although prior studies have found links. Also, children in the study were not actually diagnosed with ADHD because the study only looked at ADHD symptoms. Better to be safe than sorry regarding mercury consumption.