ADHD in Children Linked to Lead, Mercury Exposure

Attention deficit hyperactivity disorder (ADHD) has been linked to lead and mercury exposure in young children, according to an emerging study.

The study, which followed about 300 Inuit children born in northern Quebec, Canada, found that young children exposed to heavy metals are at increased risks for attention and behavior issues later in life, said WebMD Health News. The study was published in the journal Environmental Health Perspectives.

Apparently, the beluga whale can be high in mercury and also makes up one of the main sources of protein in the Inuit diet. The children are exposed to lead whey they consume shot pellets in the geese and duck they eat, WebMD Health News noted.

As we’ve explained, ADHD is a neurobiological development disorder that is generally characterized with hyperactivity and some attentional problems with behaviors typically occurring together and presenting themselves before the age of seven. The National Institutes of Health (NIMH) describes ADHD as involving difficulty staying focused, paying attention, and controlling behavior, and with hyper- or over-activity.

WebMD points out that the potent toxins can wreak havoc on children’s developing brains with children suffering from mercury poisoning experiencing problems with language skills, attention, and coordination, to name a few. Lead, as WebMD notes, affects learning and memory.

For this study, the team tested a sample of Inuit children’s umbilical cord bloods at birth, looking for a number of environmental contaminants and nutrients. When the children were 8-14 years of age, the children’s teachers were asked to complete questionnaires concerning their behavior, said WebMD About 14% of the children involved in the study had the inattentive behaviors of ADHD; about the same percentage also had the hyperactive-impulsive behaviors of ADHD. Those children who tested with the greatest mercury levels in their umbilical cord blood experienced more attention problems than children with lower levels and were also some three times likelier to be identified by their teachers as having these ADHD symptoms, said WebMD.

The mercury levels seen in this study were inordinately high. In the U.S., young women have blood levels about 1/3 as high, said the U.S. Centers for Disease Control and Prevention (CDC). Some groups—Asian-Americans born in China, who consume diets rich in large fish (shark, tuna, and swordfish)—test with similarly high levels, researcher Gina Muckle, PhD, of Laval University in Quebec, Canada, told WebMD. Meanwhile, Inuit children with low-to-moderate lead blood levels—similar to levels seen in the U.S.—had a four-fold increased likelihood of developing hyperactivity levels when compared to children with lower levels.

We’ve long explained that reports of ASDs are on the rise, in part because of better diagnostic tools, but many have long believed the increase could be due to environmental exposures. The origins of autism have long been questioned and critics have blamed PCBs; mercury; vaccinations; some antidepressant medications; pesticides; pollution; lead; and high-fructose corn syrup (HFCS), which was found, in two studies, to contain mercury. A prior study on which we’ve written found a link to ADHD in children exposed in utero to tobacco smoke and, during childhood, to lead.

ASDs include not only autism, but also Asperger’s syndrome and pervasive developmental disorder, not otherwise specified, and involve issues with social interaction, verbal and nonverbal communication, and repetitive behaviors.

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