Poor inner-city children are still suffering from heavy lead burdens. They pay for it with decreased intelligence and lives of crime. Worse is that high levels of lead, known to be highly toxic, have been falsely deemed safe.
by Heidi Stevenson
A landmark study of children from birth into adulthood shows definitively that lead exposure leads to violent crime, that there are no safe levels of lead, and that it shrinks the brain. The study was reported in the Public Library of Science (PLoS), a well-respected, peer-reviewed, online journal of medicine.
Lead has no function in the human body. Unlike several other minerals that are necessary at low concentrations but poisonous at high ones, lead is always poisonous. The PLoS study documents this fact quite clearly.
Despite many previous studies that showed strong connections between lead exposure and both crime and brain dysfunction, including ones on animals that were definitive, the naysayers pooh-poohed the data. Statements like, “Well, humans aren’t animals, so nothing has been proven,” or “High levels of lead are not a problem,” have been common.
It has been assumed that blood levels of lead under 10 micrograms per deciliter (μg/dL) were safe. The United State’s Centers for Disease Control and Prevention has set that figure as acceptable, in spite of the fact that the figure was selected arbitrarily. This study clearly documents the fallacy of making such an assumption.
About 310,000 American children between ages one and five have lead exposures over 10 μg/dL in spite of the banning of leaded fuel years ago. Most exposure is from the paint in houses built before 1978. Because old paint can contain 50% lead, even when painted over with safe coatings, it peels and can contaminate. This is probably the source of 80% of lead intoxication. However, soils in cities are still found to be polluted from old auto exhaust, and new toys are found to be contaminated.
The average level of lead in 14,000 Americans who were tested in a study between 1988 and 1994 was 2.58 μg/dl of blood. The children of this study had between 4 and 37 μg/dl of blood. For every 5 micrograms per deciliter increase of lead in children’s bloodstream, there is a corresponding 50% increase in violent crime when they become adults.
The study of 14,000 people was followed for 12 years. The participants were divided into three groups, based solely on the amount of lead in their blood:
This study documented that those in the High Lead Group had an 89% increase in risk of heart attack over those in the Low Lead Group. The risk of stroke was 2-1/2 times greater in the High Lead Group.
Keep this study in mind when reading about the results of the Cincinnati studies. The implications are shocking.
Both reports in PLoS resulted from a single study of people who were followed while in their mothers’ wombs until age 19-24. Women from poor, largely African-American, areas with known high concentrations of lead in the housing were enrolled during the early months of pregnancy. Women whose health might be comprised and children whose health was likely to be less than ideal were not included. Excluded from the study were:
Of 376 initial participants qualified and signed up at birth, 250 were followed through ages 19-24. All of these had blood tests through the first six years of life.
Measurements of the mothers’ blood lead levels were taken, and the children’s lead levels were tested either two or four times per year until they reached age 6-1/2. The participants were recruited from Cincinnati prenatal clinics.
Statistical methods were used to minimize or eliminate extraneous factors, such as maternal smoking and socioeconomic status.
The study that reported on crime obtained arrest records for all causes from official Hamilton County records. The results are difficult to ignore, since the study did not focus on comparing the participants with statistics of the general public. Instead, comparisons were made between study participants. General arrest rates and violent crime rates were correlated with childhood blood lead levels. A shocking 50% increase in violent crimes occurred for each 5 μg/dcL increase in blood lead concentration.
The study concluded:
In a prospective birth cohort, we found that prenatal and childhood blood lead concentrations were predictors of adult arrests.
This is a strong statement for any peer-reviewed scientific study to make. There are no qualifiers to indicate any doubt in the results. Their choice of words for the association of blood lead levels with violent crime was almost as strong.
The study demonstrating shrinkage of brain size documents the unlikelihood that confounding—confusion associated with other factors, such as environmental stresses or poor parenting—undermines a link between behavior and lead levels. It focused on effects in the brain with exposure to environmental lead. MRIs were used to obtain brain images.
The results showed that the brain’s gray matter—the part associated with intellect and reasoning ability—was shrunk an average of 1.2%. The part of the brain most significantly affected was the anterior cingulate cortex. This part of the brain is involved in a wide range of functions, both autonomic and mental/emotional. Blood pressure and heart rate are affected, as well as empathy, emotion, and reasoning-knowledge storing abilities.
Did you remember how much greater the risks for stroke and heart disease were for the High Lead Group in the general population study reported earlier? Now consider that every single person in this study from Cincinnati had a significantly higher level of lead than almost all of the high-level participants of the general population study.
Think of the implications on the lives of children raised in such environments. They are doomed to less success and significantly poorer health and earlier death. As these studies document, any antisocial behavior must be considered the result of factors entirely outside their control.
In all likelihood, there will still be claims that no causality link between lead and these results has been shown. That’s true. Nonetheless, the lengths to which the authors went to eliminate any other potential cause were great. At this point, it would be obscene not to take these results seriously and act on them. The burden of proof for no link of causality belongs on those who claim there is none.
This study shows also how dangerous it is to assume the best when definitive studies aren’t yet done. Blood levels of lead well under the accepted 10 μg/dL clearly cause severe damage to brains. The children of this study might have had an opportunity for a decent life if the Centers for Disease Control and Prevention had taken the responsible and ethical stand that proof of lead’s safety would be required before any lead exposure would be accepted. Basing regulations for acceptable levels of any known or suspected toxin on proof of toxicity does not support the welfare of citizens.
Finding exactly how lead shrinks brains, destroys a sense of empathy, and wrecks health is not the issue. The issue is how we are going to resolve the problem and what will be done for the people whose lives have been so devastated.
Tagged lead brain size, lead burden, lead crime, lead criminality, lead health, lead intelligence, lead studies, lead toxicity, politics, science, washington dc lead contamination, water lead contamination