Now, however, findings published in April in The New England Journal of Medicine strongly suggest not only that any amount of lead is harmful to a child's brain but also that greater damage seems to occur at levels below 10 micrograms than above that. In other words, there is no threshold for lead's effects on the brain, and just small amounts seem to have relatively large effects. If a blood level of, say, 15 micrograms can shave 2 points off a child's IQ, then a level of 5 micrograms might reduce IQ by 5 points or more.
Dr. Richard L. Canfield of Cornell University led the analysis of data collected in a lead dust control research program. The conclusions published in April are significant because they are based on a study that looked, for the first time ever, at a population of children whose blood lead concentration never went above the government’s current benchmark of 10 µg/dL. Dr. Canfield and his co-investigators found that children with blood lead levels below 10 µg/dL had a decrease in IQ of 1.37 points for every increment of 1 µg/dL of blood lead burden. This is actually higher than the one-half-point decrease per 1 µg/dL that has been consistently found in populations with children above the official 10 µg/dL limit.
Note the latter report is written by socialists who blame the use of lead on the profit system. I'd be curious to see data about lead levels collected from people in the USSR back when the USSR still existed. My guess is that they used lead paint and lead in gasoline as much as was the case in the US. Also, the US banned lead in gasoline a couple of decades sooner than some of the less capitalistic European countries.
The half life of lead in bones is 20 to 30 years. So if someone has been exposed to lead for a long time the bones will be a continuing source of release of lead into the blood for years after exposure to lead has stopped. Good nutrition helps. There is a fair amount of research literature on the protective effects of thiamin for instance. Because of the lack of restrictions on lead release in India a number of scientists have looked for cheap ways to protect people from lead toxicity and thiamin has been found beneficial for humans and animals (PDF format). Also, adequate calcium in the diet may decrease lead absorption.
Given the long term economic costs of lower IQs (lower incomes, high crime rates, etc) this latest result argues for more vigorous efforts to remove lead from old houses and apartments.
|Share |||Randall Parker, 2003 August 05 11:00 AM Brain Enhancement|