From: Robina Suwol
Date: 05 Aug 2005
Time: 15:45:41
Remote Name: 70.243.216.61
Environmental Toxicants and Developmental Disabilities - By Tim Montague
"Sixth grade was a trying time for Karen Singer's autistic son, who spent
recess wandering the periphery of the playground by
himself and sometimes hid in the school bathroom when he needed a safe place to
cry. He knew he was doing something wrong as he reached the social crucible of
middle school, but he did not know how to fix it. At home he begged his mother
to explain:
"Why am I like this? What's wrong with me?" ...Parents, educators, researchers
and clinicians all say that the majority of such children become conspicuous in
the third grade and are bullied or ostracized by the time they reach middle
school."[1]
Developmental disabilities such as autism, attention deficit hyperactivity
disorder (ADHD), dyslexia and uncontrollable aggression currently affect an
estimated 12 million U.S. children under age 18 -- almost one child in five. A
group of public health scientists led by Dr. Susan Koger estimates that between
3 and 25% of all developmental disabilities result from exposure to neurotoxic
chemicals in the environment.[2] These disabilities ultimately impact all
aspects of human development -- our ability to learn, socialize and become
productive members of society.
Reading and writing difficulties affect nearly 4 million school-age children.
Disabilities in children pose lifelong difficulties for the affected
individuals. It is harder for them to keep jobs, learn new skills, work and
generally get along with others. Many developmental disabilities (like
aggression and impulsivity) are precursors to violent and criminal behavior. In
2004, the U.S. prison/jail population increased at the rate of 933 each week and
75% of these new inmates were black or Hispanic -- populations
disproportionately impacted by heavy metals and other toxicants.[3]
Costs to Society
Even if the developmental effects of environmental toxicants are subtle (which
is not always the case), the economic and social impacts can be profound.
Consider reduced intelligence: If the cumulative effects of environmental
toxicants reduced the average American's IQ by just one percent (about one IQ
point) the annual cost to society would come to $50 billion and the lifetime
costs to trillions"[4]. The impacts are felt at both ends of the intelligence
spectrum -- there is a greater burden on the social system, reduced productivity
en masse, and there are fewer shining stars to discover new and better ways of
living sustainably.
Mercury emissions from power plants alone impact approximately 500,000 children
each year in the U.S. Their resulting lowered
IQ translates into an annual economic loss of $1.3 billion (in 2000 dollars;
this estimate is $8.7 billion if you consider all sources of environmental
mercury).[5] And these statistics say nothing of the other costs to society
including medical/therapeutic treatment, special education, incarceration,
addiction counseling, etc.
Meanwhile, industry and government argue that its not economically viable to
take a precautionary approach. As a result, Americans spend between $81 and 167
billion dollars each year on neurodevelopmental deficits, hypothyroidism and
related disorders.
The Bush administration actively puts down European initiatives like REACH
(Registration, Evaluation and Authorization of Chemicals) that would force
industry to evaluate the safety of chemicals prior to their marketing to the
general public. This kind of precautionary stance might cost the U.S. $30
billion in lost sales of chemicals and products.[6] One study concluded that
today's generation of newborns has a $110 to $318 billion GREATER earning
capacity as a result of NOT being exposed to the levels of lead faced by infants
a generation ago. [7]
Toxicants' Effect on the Developing Child
Growing children are particularly at risk to chemicals in their environment
because they face greater exposure and are physiologically more susceptible.
They ingest more food/water per pound of body weight than adults. Children spend
more time near the ground and thus breathe up to ten times more dust and
residues than adults. Children also put contaminated items in their mouths. When
the National Academy of Sciences studied pesticides and children's health in
1993, the Academy concluded, "A fundamental maxim of pediatric medicine is that
children are not 'little adults'.... In the absence of data to the contrary,
there should be a presumption of greater toxicity to infants and children."[8]
Dr. Koger reviews some the literature on lead, mercury and pesticides: We now
know that environmental exposure to lead causes learning disabilities, reduced
IQ, attention deficit, impulsivity, hyperactivity and violent behavior.
Initially scientists believed that there was a threshold for lead toxicity but
recent studies have confirmed that there is no safe level of lead exposure. If
you ingest lead your IQ will be reduced. In the mid-1970s, 40% of American
children under age 5 had average (mean) lead levels of 20 ug/dl or more. 10 ug/dl
blood lead is the current safety threshold established by EPA. Among
African-American children in the mid-1970s, more than half had blood-lead levels
greater than 15 ug/dl.[9]
Methylmercury (an organic form of mercury that accumulates in fish and the
animals that eat fish) acts directly on the central nervous system by damaging
or destroying nerve cells. It impairs brain development and can lead to mental
retardation, cerebral palsy, lowered IQ, loss of memory, reduced attention span
and physical coordination. The FDA and EPA currently recommend that nursing
mothers and young children avoid fish known to have high mercury levels
(including albacore tuna, shark, swordfish, and king mackerel).[5] The major
sources of environmental mercury are coal burning power plants, waste
incinerators and volcanoes. Human sources account for 70% of the 5,500 metric
tons (12.1 million pounds) of mercury released into the environment each
year.[5] The EPA estimates that 1.16 million women of childbearing age "eat
sufficient amounts of mercury-contaminated fish to pose a risk of harm to their
future children."[10]
Pesticides are toxic by design and meant to kill weeds, insects, rodents and
other pest organisms; they do so by impairing the nervous and immune system
function. Many pesticides and their byproducts (which include PCBs) are highly
toxic, persistent and bioaccumulative in humans. Because our nervous system
shares basic physiology with other living things, pesticides also harm the human
nervous and immune systems [see Rachel's #660]. Of the 140 pesticides officially
known to be neurotoxicants, only 12 (8.5%) have been tested for potential
impacts on children's development.[10] A study of Mexican children exposed to
pesticides found impaired memory, creativity and motor skills compared to an
unexposed population. The pesticide exposed children had trouble drawing an
ordinary stick figure of a human, something the unexposed children could readily
do.[11]
Limits of Science
Koger identifies six reasons why it is inherently difficult to document a
cause-effect relationship between toxicants and impaired health:
1. Lack of a control group -- because environmental toxicants are so widespread,
it is difficult (though not impossible) to find unexposed groups for comparison
with exposed individuals;
2. Multiple chemical exposure -- the interaction between chemicals may cause
different effects than a chemical acting alone;
3. Behavioral and cognitive effects are typically subtle and difficult to
measure;
4. The majority of research on toxicants is done on lab animals which limits
their application to human health;
5. The effects of exposure may not be seen for months or years;
6. The brain and other systems of the human body are more susceptible to
chemicals during specific development phases -- exposure at one time may have no
effect while the same exposure at a different developmental stage could have
significant effects; and
7. Genetic variation and gene-environment interactions greatly complicate the
matter.
Conclusions and Regulatory Issues
Humans have long recognized the potential harm of environmental chemicals to
child development. Unfortunately, regulatory efforts focus on proving harm
before limiting the exposure of countless innocents, with the associated cascade
of health, social and economic losses. When the U.S. finally banned lead in
paint and gasoline, blood levels of lead improved dramatically. But left to its
own devices, industry will do what is best for industry -- pursue profits for
shareholders at any cost (see Rachel's #771, #419, #421, and #427). The
alternative is to take a proactive approach like that being pursued by Sweden
which calls for new products to be largely free from (a) persistent and
bioaccumulative substances; (b) polyvinyl chloride (PVC) plastics and endocrine
(hormone system) disruptors; (c) heavy metals like lead, cadmium and mercury.[2]
The U.S. is currently standing on the sidelines of this significant ethical and
technological advancement for society.
Dr. Koger calls on her colleagues in the scientific/mental health professions to
take a stand against the historical risk-assessment- reliant prove-harm approach
that costs society so much human suffering and misery. The grand human
experiment currently being conducted by industry is inconsistent with the
ethical standards applied to pharmaceutical testing where erring on the side of
precaution is customary.
Koger urges psychologists -- as the most qualified front-line professionals
dealing with the problems of developmental disabilities -- to play a more active
role in exploring alternatives like integrated pest management, speaking out in
their local community, and applying their technical expertise to the widespread
and growing problem of environmental toxicants. As scientist-citizens
psychologists can reduce the toxic burden shared by all. A healthy and
sustainable future for our children depends on it.
========
[1] Jane Gross, "As Autistic Children Grow, So Does Social
Gap," THE NEW YORK TIMES, February 26, 2005, p. A1.
[2] Susan M. Koger, Ted Schettler, and Bernard Weiss,
"Environmental Toxicants and Developmental Disabilities: A
Challenge for Psychologists," AMERICAN PSYCHOLOGIST (April
2005) Vol. 60, No. 3, pgs. 243-255.
[3] Incarceration Project
http://www.sentencingproject.org/pdfs/1044.pdf
[4] Bernard Weiss, "Vulnerability of children and the
developing brain to neurotoxic hazards," ENVIRONMENTAL HEALTH
PERSPECTIVES, (June 2000) Vol. 108 (Supplement 3), pgs.
375-381.
[5] Leonardo Trasande and others, "Public Health and Economic
Consequences of Methyl Mercury Toxicity to the Developing
Brain," ENVIRONMENTAL HEALTH PERSPECTIVES (May 2005) Vol. 113,
No. 5, pgs. 590-596.
[6] Elizabeth Becker, "White House Undermined Chemical Tests,
Report Says," THE NEW YORK TIMES, April 2, 2004 p. C2.
[7] S.D. Grosse, and others, "Economic gains resulting from the
reduction in children's exposure to lead in the United States,"
ENVIRONMENTAL HEALTH PERSPECTIVES, (June 2002) Vol. 110, No. 6,
pgs. 563-569.
[8] Philip J. Landrigan and others, PESTICIDES IN THE DIETS OF
INFANTS AND CHILDREN (Washington, D.C.: National Academy Press,
1993), pg. 9.
[9] James L. Pirkle and others, "The Decline in Blood Lead
Levels in the United States," JOURNAL OF THE AMERICAN MEDICAL
ASSOCIATION (July 27, 1994) Vol. 272, No. 4, pgs. 284-291.
[10] Ted Schettler and others, IN HARM'S WAY: TOXIC THREATS TO
CHILD DEVELOPMENT (Cambridge, Mass.: Greater Boston Physicians
for Social Responsibility [GBPSR], May 2000).
[11] Elizabeth A. Guillette and others, "An Anthropological
Approach to the Evaluation of Preschool Children Exposed to
Pesticides in Mexico," ENVIRONMENTAL HEALTH PERSPECTIVES (June
1998) Vol. 106, No. 6, pgs. 347- 353.