Science News & Science Current Events
 
Email a Friend Send to a friend
Printer Friendly Print A silent pandemic: Industrial chemicals are impairing the brain development of children worldwide

A silent pandemic: Industrial chemicals are impairing the brain development of children worldwide

November 08, 2006

Boston, MA - Fetal and early childhood exposures to industrial chemicals in the environment can damage the developing brain and can lead to neurodevelopmental disorders (NDDs)-autism, attention deficit disorder (ADHD), and mental retardation. Still, there has been insufficient research done to identify the individual chemicals that can cause injury to the developing brains of children.

In a new review study, published online in The Lancet on November 8, 2006, and in an upcoming print issue of The Lancet, researchers from the Harvard School of Public Health and the Mount Sinai School of Medicine systematically examined publicly available data on chemical toxicity in order to identify the industrial chemicals that are the most likely to damage the developing brain.




The researchers found that 202 industrial chemicals have the capacity to damage the human brain, and they conclude that chemical pollution may have harmed the brains of millions of children worldwide. The authors conclude further that the toxic effects of industrial chemicals on children have generally been overlooked.

To protect children against industrial chemicals that can injure the developing brain, the researchers urge a precautionary approach for chemical testing and control. Such an approach is beginning to be applied in the European Union. It puts in place strong regulations, which could later be relaxed, if the hazard were less than anticipated, instead of current regulations that require a high level of proof. At present in the U.S., requirements for toxicity testing of chemicals are minimal.

"The human brain is a precious and vulnerable organ. And because optimal brain function depends on the integrity of the organ, even limited damage may have serious consequences," says Philippe Grandjean, adjunct professor at Harvard School of Public Health and the study's lead author.

One out of every six children has a developmental disability, usually involving the nervous system. Treating NDDs is difficult and costly to both families and society. In recent decades, a gathering amount of evidence has linked industrial chemicals to NDDs. Lead, for example, was the first chemical identified as having toxic effects to early brain development, though its neurotoxicity to adults had been known for centuries.

A developing brain is much more susceptible to the toxic effects of chemicals than an adult brain. During development, the brain undergoes a highly complex series of processes at different stages. An interference-for example, from toxic substances-that disrupts those processes, can have permanent consequences. That vulnerability lasts from fetal development through infancy and childhood to adolescence. Research has shown that environmental toxicants, such as lead or mercury, at low levels of exposure can have subclinical effects-not clinically visible, but still important adverse effects, such as decreases in intelligence or changes in behavior.

Grandjean and co-author Philip J. Landrigan, Professor at Mount Sinai School of Medicine, compiled a list of 202 environmental chemicals known to be toxic to the human brain using the Hazardous Substances Data Bank of the National Library of Medicine and other data sources. (The authors note that the list should not be regarded as comprehensive; for example, the number of chemicals that can cause neurotoxicity in laboratory animal tests exceeds 1,000.)

The authors then examined the published literature on the only five substances on the list-lead, methylmercury, arsenic, PCBs and toluene-that had sufficient documentation of toxicity to the developing human brain in order to analyze how that toxicity had been first recognized and how it led to control of exposure. They found a similar pattern in how the risks of each substance were documented: first, a recognition of adult toxicity and episodes of poisoning among children, followed by a growing body of epidemiological evidence that exposure to lower levels of the substances caused neurobehavioral deficits in children.

"Even if substantial documentation on their toxicity is available, most chemicals are not regulated to protect the developing brain," says Grandjean. "Only a few substances, such as lead and mercury, are controlled with the purpose of protecting children. The 200 other chemicals that are known to be toxic to the human brain are not regulated to prevent adverse effects on the fetus or a small child."

Grandjean and Landrigan conclude that industrial chemicals are responsible for what they call a silent pandemic that has caused impaired brain development in millions of children worldwide. It is silent because the subclinical effects of individual toxic chemicals are not apparent in available health statistics. To point out the subclinical risk to large populations, the authors note that virtually all children born in industrialized countries between 1960 and 1980 were exposed to lead from petrol, which may have reduced IQ scores above 130 (considered superior intelligence) by more than half and increased the number of scores less than 70. Today, it's estimated that the economic costs of lead poisoning in U.S. children are $43 billion annually; for methylmercury toxicity, $8.7 billion each year.

"Other harmful consequences from lead exposure include shortened attention spans, slowed motor coordination and heightened aggressiveness, which can lead to problems in school and diminished economic productivity as an adult. And the consequences of childhood neurotoxicant exposure later in life may include increased risk of Parkinson's disease and other neurogenerative diseases," says Landrigan.

The researchers believe that the total impact of the pandemic is much greater than currently recognized. In supplementary documentation (see below for a link), about half of the 202 chemicals known to be toxic to the brain are among the chemicals most commonly used.

Testing chemicals for toxicity is a highly efficient public health measure. However, less than half of the thousands of chemicals currently used in commerce have been tested to assess acute toxicity and, although new chemicals undergo more thorough testing, access to the data may be restricted because companies fear exposing proprietary information. Also, current toxicity testing rarely includes neurobehavioral functions.

"The brains of our children are our most precious economic resource, and we haven't recognized how vulnerable they are," says Grandjean. "We must make protection of the young brain a paramount goal of public health protection. You have only one chance to develop a brain."

Harvard School of Public Health



Related Brain Development Current Events and Brain Development News Articles Brain Development Current Events and Brain Development News RSS Brain Development Current Events and Brain Development News RSS
UCR researchers propose minocycline as a promising drug for patients with Fragile X syndrome
A UC Riverside-led team of biomedical scientists has found that a readily available drug called minocycline, used widely to treat acne and skin infections, can be used to treat Fragile X syndrome, the most common inherited cause of mental impairment and the most common cause of autism.

Hopkins researchers piece together gene 'network' linked to schizophrenia
Reporting this week in the Archives of General Psychiatry, researchers at the Johns Hopkins University School of Medicine have uncovered for the first time molecular circuitry associated with schizophrenia that links three previously known, yet unrelated proteins.

Smoking during pregnancy a 'double-edged sword' in SIDS
Premature infants whose mothers smoked during pregnancy may be at even higher risk for sudden infant death syndrome (SIDS) than preemies whose mothers did not smoke, according to new research out of the University of Calgary.

Pregnancy situations have impact on brain development in pre-term infants
Brain development in infants who are born very prematurely is still incomplete. Factors that cause premature birth may have an impact on the development of the premature infant's brain both during pregnancy and later on after birth.

Alcohol consumption can cause too much cell death, fetal abnormalities
The initial signs of fetal alcohol syndrome are slight but classic: facial malformations such as a flat and high upper lip, small eye openings and a short nose.

MU Researchers Study Facial Structures, Brain Abnormalities to Reveal Formula for Earlier Detection of Autism
Recently, Harvard researchers reported that children with autism have a wide range of genetic defects, making it nearly impossible to develop a simple genetic test to identify the disorder. Now, University of Missouri researchers are studying 3-D imaging to reveal correlations in the facial features and brain structures of children with autism spectrum disorder (ASD), which will enable them to develop a formula for earlier detection of the disorder.

Sensitivity to antidepressants linked with TrkB-mediated neural proliferation
Scientists have unveiled a functional link between production of new neurons and the effectiveness of antidepressants (ADs) in an animal model. The study, published by Cell Press in the August 14 issue of the journal Neuron, provides exciting insight into a mechanism that might underlie a poor response to antidepressive medications for anxiety or depression.

New insight into most common forebrain malformation
St. Jude Children's Research Hospital scientists have identified one of the molecular mechanisms underlying the genetic brain malformation called holoprosencephaly (HPE). The findings not only yield insights into the most common developmental malformation of the anterior brain and face in newborns, but also help in understanding the intricate process by which the brain forms in the developing fetus.

UT Houston Researchers Study Diet In Autistic Children
Researchers at The University of Texas Health Science Center at Houston have embarked on one of the first double-blind, clinical studies to determine whether gluten and dairy products play a role in autistic behavior as parents have anecdotally claimed.

New research on pre-eclampsia in mice may have important implications for humans
In a new March of Dimes-funded study of pre-eclampsia, a serious and potentially deadly disorder that affects about 5 percent of pregnancies, researchers have found results in mice that may have important implications for diagnosis and treatment in humans.
More Brain Development Current Events and Brain Development News Articles


What's Going on in There? : How the Brain and Mind Develop in the First Five Years of Life
by Lise Eliot

As a research neuroscientist, Lise Eliot has made the study of the human brain her life's work. But it wasn't until she was pregnant with her first child that she became intrigued with the study of brain development. She wanted to know precisely how the baby's brain is formed, and when and how each sense, skill, and cognitive ability is developed. And just as important, she was interested in...



The Fundamentals of Brain Development: Integrating Nature and Nurture
by Joan Stiles

In a remarkable synthesis of the research of the last two decades, a leading developmental neuroscientist provides psychologists with a sophisticated introduction to the brain--the system that underpins the functions that they study. In clear terms, with ample illustrations, Joan Stiles explains the complexities of genetic variation and transcription, and the variable paths of neural...



Your Child's Growing Mind: A Guide to Learning and Brain Development from Birth to Adolescence
by Jane M. Healy

The completely updated and expanded version of the 1987 classic hailed by parents and educators...



Your Child's Growing Mind: Brain Development and Learning From Birth to Adolescence
by Jane Healy

The classic guide to understanding children’s mental development is now updated and better than ever!Hailed by parents and educators, Your Child’s Growing Mind is a window into the fascinating process of brain development and learning. It looks at the roots of emotion, intelligence, and creativity, translating the most current scientific research into practical suggestions for parents and...



Baby Minds: Brain-Building Games Your Baby Will Love
by Linda Phd Acredolo, Susan Phd Goodwyn

More than 65 delightful games and activities to jump-start your baby's amazing brainpowerCan simply singing a song or blowing a dandelion under a toddler's nose help her mind to blossom? Can your baby count, remember events, and solve problems even before he can talk? The exciting answer to both questions is yes! Breakthrough research is revealing the extraordinary inborn abilities of infants. It...



Cognitive Development: The Learning Brain
by Usha Goswami

This is a thoroughly revised and updated edition of the bestselling Cognition in Children. The textbook has been rewritten from the perspective of brain science to include completely new chapters on social cognition, language acquisition and school-based learning. All chapters now include sections showing how new discoveries in cognitive neuroscience force us to reconsider traditional theories of...

Brain Development: Relationship to Dietary Lipid and Lipid Metabolism
by Jacqueline Jumpsen, MT. Clandinin



Our Spiritual Brain: Integrating Brain Research and Faith Development
by Barbara Bruce



Head First Software Development (Brain-Friendly Guides)
by Dan Pilone, Russ Miles

Even the best developers have seen well-intentioned software projects fail -- often because the customer kept changing requirements, and end users didn't know how to use the software you developed. Instead of surrendering to these common problems, let Head First Software Development guide you through the best practices of software development. Before you know it, those failed projects will be a...



Human Behavior, Learning, and the Developing Brain: Typical Development

This state-of-the-science volume brings together leading authorities from multiple disciplines to examine the relationship between brain development and behavior in typically developing children. Presented are innovative cross-sectional and longitudinal studies that shed light on brain-behavior connections in infancy and toddlerhood through adolescence. Chapters explore the complex interplay of...

© 2008 BrightSurf.com