RACHEL'S ENVIRONMENT & HEALTH NEWS #821
http://www.rachel.org
July 7, 2005


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.



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