Skip to content

ADD & ADHD Health Center

Kids Exposed to Mercury, Lead at Risk for ADHD

Font Size
A
A
A
By
WebMD Health News
Reviewed by Louise Chang, MD

Sept. 21, 2012 -- Young children exposed to certain heavy metals are at higher risk for problems with attention and behavior later in life, a new study shows.

The study followed nearly 300 Inuit children who were born in northern Quebec, Canada. One of the main sources of protein in the Inuit diet is beluga whale meat, which can be high in mercury. Inuit children are exposed to lead when they eat shot pellets that are used to kill geese and ducks.

Lead and mercury are potent toxins, and the developing brains of young children are vulnerable to their effects. Studies of kids with mercury poisoning show they have trouble with language skills, attention, and coordination, as well as other problems. Lead affects learning and memory.

Researchers tested a sample of Inuit children's umbilical cord blood at birth for a range of environmental contaminants and nutrients. Years later, when the children were between the ages of 8 and 14, researchers asked their teachers to complete questionnaires about their behavior.

Roughly 14% of the children in the study had inattentive behaviors of attention deficit hyperactivity disorder (ADHD). A similar percentage of the children had hyperactive-impulsive behaviors of ADHD.

Mercury and Lead Linked to More Symptoms of ADHD

Children with the highest concentrations of mercury in their cord blood had more trouble paying attention than those with lower levels. They were also about three times more likely to be flagged by their teachers as having these symptoms of ADHD. That was true even after researchers accounted for things linked to ADHD, like low birth weight and whether or not the mother used tobacco during pregnancy.

Researchers say the mercury levels seen in the study were extremely high. Most women of childbearing age in the U.S. have blood levels of mercury that are about one-third as high, according to the CDC. Certain groups of people, like Asian-Americans born in China, who eat traditional diets rich in large fish like shark, tuna, and swordfish, have been found to have blood levels of mercury that are in the same extreme range as found in this study, says researcher Gina Muckle, PhD, of Laval University in Quebec, Canada.

Today on WebMD

Post it notes
Symptoms and treatments.
Close up of eye
What's zapping your focus?
 
man driving car
How to manage your impulses.
Woman shopping for vitamins at drugstore
Should you take them?
 
concentration killers
SLIDESHOW
Woman taking a vitamin or supplement
Article
 
ADHD and Substance Abuse
Article
Reduce Side Effects ADHD Medications
Article
 

boy eating egg
Video
smiling man
Article
 
ADHD in Marriage and Romantic Relationships
Article
Adult man lying awake in bed
Article
 

WebMD Special Sections