« Art vs. Food??? | Gene Expression Front Page | Where did the brown chix go? »
April 17, 2003

Lowered IQs

'Safe' Lead Levels Lower IQ in Children, Study Finds. Excerpt:


Blood levels of lead below current federal and international guidelines of 10 micrograms per deciliter produce a surprisingly large drop in IQ of up to 7.4 points, a U.S. team reports in today's New England Journal of Medicine. Researchers estimate that one in every 50 U.S. children has lead levels above that guideline and that one in every 10 has levels of 5 micrograms/deciliter or above well within the dangerous range.

Posted by razib at 04:34 AM




the problem with most of these lead studies is that they fail to hold constant the socioeconomic status of the families. Those exposed to lead generally are poorer, since they are more common in old and less maintained properties, and we know that poor children score lower on IQ tests for a variety of reasons unrelated to lead. This doesn't prove lead isn't at work, but I'm skeptical.

But you have to love the unquestioned use of IQ when it serves one agenda, while it is considered meaningless when it has other, less progressive, implications.

Posted by: eric at April 17, 2003 08:12 AM


As one who has taught many Intro Psych classes, I must say, "intelligence" is one of those sell words, which everyone wants to claim as his own. You mustn't imply that anyone is less intellligent than anyone else. That's politically incorrect. That's slighting someone else as less than perfectly equal.

So, psychology has offered different KINDS of intellegence, this way everyone can have equal share of the word. In one intro text, it pictured (juxtaposed) a black rap singer, a black athlete, and a white astronaut in the middle. True equality. Everyone owns that word, intelligent.

Posted by: David Yeagley at April 17, 2003 09:58 AM


david, so we brand differentiate with g.

Posted by: razib at April 17, 2003 11:16 AM


The press release for the study is here: http://www.niehs.nih.gov/oc/news/leadiq.htm It says: The researchers controlled for many other factors that contribute to a child's intellectual functioning, such as birth weight, mother's intelligence, income, education, and amount of stimulation in the home.

Posted by: tc at April 17, 2003 11:18 AM


Razib, I think it's all about word power. To control someone else's words is the way to controlling his thoughts. Mind control. I wonder what the genetic codes are for those prone to lie and decieve? This is the short cut to power. Are these folks more "aggressive?" They want to be considered "intelligent," without being intelligent, but only aggressively demanding to be called intelligent, for purposes of power. At least, those behind this sort of thinking are being thus aggressive.

Posted by: David Yeagley at April 17, 2003 02:49 PM


Keep in mind that there are groups with a vested interest in seeing the "safe" lead level lowered. The level was lowered from 25 to 10 in 1991, and many cities adopted aggressive lead paint removal programs at about the same time. There are now very few new cases of childhood lead poisoning at a level of 10 or higher - which means that the lawyers who were making a living suing landlords for failure to abate lead hazards have to find another line of work. If the medical and legal threshold for lead poisoning is reduced to a blood lead level of 5, then there will be a whole rash of new cases.

Conspiracy theory? Maybe. On the other hand, the lead poisoning prevention programs I mentioned above required legislation, and were the result of lead intoxication researchers working hand in hand with lawyers. Many of the top research physicians working on lead poisoning have worked closely with trial lawyers for a decade or more, and the influence has gone both ways. I wouldn't be surprised if there was at least some subtle impetus from the legal community to undertake this study.

Posted by: Jonathan Edelstein at April 19, 2003 05:00 PM


Has anyone tried finding out if lead levels are correlated with voting for Democrats?

Posted by: Joseph Hertzlinger at April 19, 2003 07:25 PM