Children in Iqaluit, Nunavut, CA on a field trip.
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Children exposed to higher levels of mercury or lead are three to five times more likely to be identified by teachers as having problems associated with Attention Deficit Hyperactivity Disorder, according to a scientific study published today.
The study – of Inuit children in Arctic Quebec – is the first to find a high rate of attention-deficit symptoms in children highly exposed to mercury in the womb. In addition, the Inuit children more often had hyperactivity symptoms if they were exposed to the same low levels of lead commonly found in young U.S. children.
In the United States, one of every 10 children has been diagnosed with ADHD, according to the U.S. Centers for Disease Control and Prevention. It is one of the most common brain disorders of childhood.
Researchers from Laval University in Quebec surveyed teachers of 279 children in Nunavik between the ages of 8 and 14, using standardized questionnaires developed by psychiatrists for diagnosing ADHD.
Developmental psychologist Gina Muckle, the study’s senior author, said the findings are important because they show for the first time that mercury’s effects on children are not just subtle, but are actually noticeable to teachers.
The effects from exposure in the womb “may be clinically significant and may interfere with learning and performance in the classroom,” says the study, published online in the journal Environmental Health Perspectives.
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For lead, the Inuit children with the highest levels were four to five times more likely to have teacher-reported hyperactivity than their classmates with low lead levels. “We are seeing those effects at very low blood lead levels,” Muckle said.
Although the findings came from a study of Arctic children, the results likely are universal, Muckle said. “At similar levels of exposure without regard of the source of exposure, the effect should be similar,” she said.
Dr. Bruce Lanphear, a professor at Simon Fraser University in Vancouver, said evidence is mounting that a variety of toxic compounds are “shifting children’s behavior.”
“There seem to be a whole host of different toxicants that are associated with ADHD,” said Lanphear, who studies childhood effects of lead, mercury and other contaminants but didn’t participate in the Inuit study. That actually “makes sense” biologically, he said, because ADHD is a syndrome of 23 different behaviors. Each toxic chemical could be altering different parts of the brain during different times of its development.
“To me, what this [new study] confirms is that the pre-frontal cortex appears to be particularly vulnerable to environmental toxicants,” he said. That part of the brain controls not just hyperactivity and attention but also learning disorders and anti-social and criminal behaviors.
Whale and fish consumed by their mothers were the sources of the Inuit children’s exposure to mercury. The lead came from foods the children ate that contained lead shot from hunting.
One of the most intriguing findings was that mercury was linked to attention deficits while lead was associated with hyperactivity. The difference may be the timing of the exposures: in the womb for mercury and during childhood for lead.
Harvard School of Public Health epidemiologist Joe Braun said the findings “suggest the brain may be sensitive to different environmental chemicals at different times in development.”
“Future research will need to confirm this finding and examine the effect of joint exposure to both prenatal mercury and childhood lead,” said Braun, who was not involved in the study.
Mercury and lead exposures had a stronger effect on ADHD symptoms than mothers who smoked during pregnancy, a link reported by other scientists, Muckle said.
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7 Comments
Add CommentMy personal bet is on the use of ultrasounds on pregnant mothers, which has become a standard practice over the last 25 years or so.
Reply | Report Abuse | Link to thisMy English is not that good, so I may make some mistakes when trying to understand its contents. If it is true, the statistics at the beginning comes from questionnaire. Do scientists acquire other kind of data such as medical results and the like?
Reply | Report Abuse | Link to thisI agree with the statement that toxic chemicals such as lead or mercury can be found in fishes and these chemicals really do harm to human health, especially to children. And I wonder whether children who eat fish which contains mercury or lead, regardless of the amount, are sure to suffer from attention deficit?
"In the United States, one of every 10 children has been diagnosed with ADHD, according to the U.S. Centers for Disease Control and Prevention."
Reply | Report Abuse | Link to thisSeriously, how many of those children have parents that do not have patience? How many of those children are "status children," children that were born simply because the mother or father wanted to be the center of attention? I am tired of reading and hearing about people that have kids and then do not want to be bothered to teach the child right from wrong. Or the parent did not know that the kid would be more work than just a show they thought they could take out of a corner to show off to people!
Our medical profession should be more involved in reporting lazy parents who would rather put their child on drugs than to educate themselves on how to be a better parent. I agree that some children may have behavioral issues, but again seriously every tenth child seems to be an extreme over-exaggerated diagnoses!
If you walked down the street and watched every ninth person give "downers" to the tenth person, you mostly likely would be appalled and demand that our government crackdown on illegal drug deals; however no one questions a parent that does not want to be bothered with the responsibility of being the center of a child's world. No, instead we allow the irresponsible parents to blame the oceans, the ground, the air, or other objects and people that are not meant to be responsible parents.
We, as a society, turn our heads away and condone lazy parents turning our medical professionals into their own personal drug dealers! It's illegal for a neighbor to give drugs to a child, simply so the child will sleep longer and the neighbor would not be bothered with the child. However, it is o.k. for a child's parent to drug the child for the same exact reason! Example of a typical lazy parent: "Little Johnny (or Suzie) always wants my attention! I can't watch my t.v. shows, talk on the phone, or play on the computer; because the kid keeps bothering me! I know I'll whine to the doctor that my child is too active and the doctor will give me medicine to sedate my child, that way I do not have to be responsible 24-hour/7-days a week for anyone but myself!"
Reply | Report Abuse | Link to thisOur medical professionals should take their own vitamins to get stronger backbones and report lazy parents to Child Welfare for endangering the health of a child; instead of giving into these spoiled-rotten, lazy, irresponsible adults! Lazy parents ARE endangering their child by giving them these drugs knowing the drug has side-effects and the parent not caring simply because the parent did not really want to be a care-giver in the first place!
Too many adults need a wake-up call to stop acting like over-grown, spoiled, whinny, annoying kids themselves! If you do not want the responsibility that comes with being a parent, THEN USE A CONDOMS AND OTHER BIRTH-CONTROL ITEMS! DON'T PUT YOUR KID ON DRUGS SIMPLY BECAUSE YOU DID NOT WANT TO TAKE BIRTH-CONTROL DRUGS YOURSELF!
(I wonder how many irresponsible parents are going to write back and try to justify their need to put their kid on drugs!)
Perhaps children who learn early to think for themselves are more likely to be seen as disruptive, therefore ADD, and more likely to take greater chances in playing with dangerous materials, such as mercury. Can one actually test for previous mercury poisoning?
Reply | Report Abuse | Link to thisI tend to see especially mental conditions in spectrums rather than categories and feel we all have some level of most symtoms.
I can appreciate what you wrote Daniel35; however does it really matter what age a child starts to "think for themselves"? It is eventually going to happen no matter what age they do. It is the responsibility of the parent(s) to know that their child will mature and know how to deal with the situation responsibly. To dope up a child simply because "mommy" and "daddy" do not what to be adults themselves and correct their child for doing something the child should not do is wrong on many levels! We, as a society, need to start holding parents more responsible for NOT correcting, teaching, or spending quality time with their child. We should be more serious about NOT condoning a parent that would rather constantly work over-time to buy non-essential items; such as a boat, jet-skis, motorcycle, fancy clothes shopping, fancy nails, etc. than spend time with their kid. Working over-time to put food on the table do to a bad economy is one thing, but to push a child aside so the parent can live a second childhood is not respectable behavior and we, as a society, need to start correcting the parents for their own childish attitudes. When we, as a society, stop condoning the spoiled adults, we will start to see more respectable behavior from their children. Until then we will continue down the path of social chaos such as; immature neighbors killing neighbors, illegal drug use, sky-rocketing fuel costs, and other social economic destruction. In movies and other media we discuss NOT indulging spoiled children; however we make the mistakes in real life by doing just that - we allow our court systems to give into bad behavior! People need to stop voting stupid and start noticing which judges do not use common-sense and instead indulge criminal behavior and vote those judges out of office. When we stop employing spoiled judges, we will start to see a huge change in the right direction of a better society. We will start to see adults thinking twice before making immature life choices themselves. That will then snowball into adults teaching their children to think twice before also making choices in life!
Reply | Report Abuse | Link to thisJust wondering: Way back in "my day" we played with mercury from broken thermometers, applying it to dimes to make them more shiney. We often washed grease off our hands with leaded gasoline. Did it take this long for some brilliant observer to discover ADD and associate it with lead and mercury? Where does ADD appear in my generation or, do scientists have another name for it...alzheimers, maybe?
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