Lood en uw gezondheid*
Dat lood ongezond is is de laatste twintig jaar al bekend en ondanks dat het al zo lang niet meer gebruikt wordt wordt het nog steeds aangetroffen in het milieu zoals in oude huizen en de bodem. Oude huizen als gevolg van oude verf die lood bevat en de bodem vaak als gevolg van de loodhoudende benzine. Sommig speelgoed blijkt ook nog steeds lood te bevatten. Nu blijkt uit een langjarige studie dat in tegenstelling tot andere mineralen lood zelfs in elke, lage concentratie schadelijk is voor het menselijk lichaam, in het bijzonder de hersenen. Lood geeft bijna 100% meer kans op een hartaanval en wel 2,5 keer meer kans op een beroerte. Verder blijkt dat baby’s en kinderen die aan lood zijn bloot gesteld een aanzienlijk grotere kans hebben op gewelddadig gedrag.
20-Year Study: Lead Linked to Violent Crime and Shrinks the Brain
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 "Low levels of lead are not a problem," have been common.
It has been assumed that blood levels of lead under 10 micrograms per deciliter (mcg/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 it's known not to have any meaning. The figure was selected arbitrarily. This study clearly documents the falacy of making such an assumption.
About 310,000 American children between ages one and five have lead exposures over 10 mcg/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.
Results of an Earlier Lead Study
The average level of lead in 14,000 Americans who were tested in a study between 1988 and 1994 was 2.58 mcg/dcL of blood. The children of this study had between 4 and 37 mcg/dcL of blood. For every 5 microgram per deciliter increase in children's bloodstream lead, 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:
* Low Lead Group: Less than 1.93 mcg/dL
* Medium Lead Group: Between 1.93 and 3.63 mcg/dL
* High Lead Group: Over 3.63 mcg/dL
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 recent Cincinnati studies. The implications are shocking.
The Studies
Both reports in the 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. Any woman who was addicted, had diabetes, or a neurological or psychiatric condition was not included. If a woman refused to take part in the prenatal portion of the trial, they were also not included. Any neonate born at less than 35 gestation weeks or under 1500 grams (approximately 3.3 pounds) was not included. Serious medical or genetic problems, or an Apgar score less than 6 eliminated a subject from the trial. 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 lead levels were taken of the mothers' blood and in the children either two or four times per year until they reached age 6-1/2. The participants were recruited from Cincinnati prenatal clinics. 376 started the study and 250 completed it.
Statistical methods were used to minimize or eliminate extraneous factors, such as maternal smoking and socioeconomic status.
Study on Crime Related to Lead Levels
The study that reported on crime obtained arrests 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 mcg/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.
Study on Brain Size Related to Lead Levels
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.
Implications
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 successful lives 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 mcg/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.
References:
PLoS,
"Decreased Brain Volume in Adults with Childhood Lead Exposure"
PLoS,
"Association of Prenatal and Childhood Blood Lead Concentrations with Criminal Arrests in Early
Childhood",
PLoS,
"Neurological and Behavioral Consequences of Childhood Lead Exposure"
Los Angeles Times, "Lead Exposure in Children Linked to Violent Crime", by Thomas H. Maugh II and Marla Cone,
MedicineNet.com, "Lead in Blood: 'Safe' Levels Too High?" (September
2008)
