Californians Face Increasing Obstacles To Healthy Development
From: Robina Suwol
Date: 09 Jul 2004
Remote Name: 188.8.131.52
Toxics and Environmental Health Program
Growing Up Toxic: Chemical Exposures and Increases in Developmental Disease
Environment California Research & Policy Center
Californians face increasing obstacles to healthy development, from the moment
of conception until they themselves attempt to conceive. Problems like
premature birth; male genital defects; learning, attention, and emotional
disturbances; early puberty; obesity; and low sperm quality have been
increasing in California and the nation as a whole over the past several
decades, impacting every stage of growth from conception to adulthood.
While a range of factors, from lifestyle to heredity, may contribute to any
one of these trends, a growing body of research suggests that toxic chemicals
play a significant role. Studies are revealing chemical contamination in human
bodies, finding associations between chemical exposure and human disabilities
and disease, and demonstrating toxic effects at increasingly lower levels of
The findings of this report are by no means comprehensive. While well-known
toxicants like mercury, lead, dioxin, and PCBs have been clearly linked to
human health damage, thousands of other chemicals that people are exposed to
in the home have never been studied for health effects. Here we focus on the
most recent science surrounding several emerging chemical hazardsa growing
body of evidence showing that chemicals found in the home and in common
consumer products may hinder normal development.
Chemical exposure is widespread. Human bodies are the repository for countless
chemicals encountered in everyday experiences and found in common consumer
products. Exposure to these substances during fetal development is
Phthalates, used to ³plasticize² some food containers, plastic wrap, toys,
shampoos, perfumes, and beauty products, are among the most frequently found
contaminants in human bodies.
Flame retardants, added to foams, plastics, and electronics, have been found
at exponentially increasing levels in women in California; levels in U.S.
women have reached up to 75 times the levels found in Europe and Japan.
Bisphenol-A, the main ingredient in hard polycarbonate plastics for baby
bottles, drinking water bottles, and food containers, has been detected in
pregnant women in Germany and Japan. It is one of the top 50 production-volume
chemicals in the U.S., and exposure likely is widespread.
Pesticides and their breakdown products are commonly found in people. In a
recent study, the U.S. Center for Disease Control and Prevention found 13
different pesticides in the average American, out of 23 pesticides under
At each stage of life, toxic chemicals may hinder normal development.
Even before their first breath, insurmountable challenges, from premature
birth to birth defects, await an increasing number of children.
Premature birth, which raises the risk for reduced intelligence and learning
and attention problems throughout life, is 23 percent more frequent now than
in the 1980s in the United States. One potential factor may be phthalates:
Babies exposed to a common phthalate in utero are born a week earlier on
average than babies without exposure.
Birth defects are the leading cause of infant death in the U.S. While the
specific causes of most birth defects are unknown, they could be linked to a
variety of chemical exposures, including:
Phthalates. In male lab rats, phthalate exposure in utero leads to undescended
testicles and malformed urinary tracts. The frequency of these conditions in
baby boys doubled from 1970 to 1993 in the United States.
Bisphenol-A. In experiments with mice, bisphenol-A can induce the genetic
defect that causes Down¹s syndrome, at levels comparable to those found in
women tested to date.
Pesticides. One study found an association between miscarriages caused by
birth defects and commercial pesticide applications within a nine square mile
area around the home. Another study found that boys conceived during the
period of most intense application of the herbicide 2,4-D were five times more
likely to have a birth defect than boys with no unusual exposure.
Infancy and early childhood is a time marked by rapid growth and learning.
However, a growing number of California children are suffering from
developmental disorders that impair their ability to learn normally.
Neurodevelopmental and mental health disabilities are rapidly rising in
California. Autism cases in California have more than tripled since 1994, and
the number of students in public schools with learning disabilities increased
65% from 1985 to 1999. No one cause has been implicated, but scientific
evidence raises questions regarding numerous potential factors, including
exposure to toxic flame retardants, bisphenol-A, perchlorate, pesticides, and
the well-established culprits of lead, mercury, dioxin, and
Flame-retardant chemicals given to newborn mice in small doses permanently
impair their learning and behavior, and small doses of bisphenol-A produce
The rocket fuel component perchlorate, found in the drinking water sources of
16 million Californians, affects the thyroid hormone system at very low levels
of exposure. Children born to mothers with thyroid problems have higher rates
of learning disabilities.
Children exposed to agricultural pesticides show deficiencies in intellectual
development, stamina, balance, hand-eye coordination, and short-term memory.
As children develop into young adults, they struggle with the rapid changes in
their bodies that lead to sexual maturity. However, several unexplained trends
suggest that children face additional health challenges at this stage of life,
including early puberty and obesity.
In the last four decades, the number of obese adolescents in the U.S. has
quadrupled, and girls in the U.S. appear to be reaching puberty six months to
one year earlier than in the past, with a small number of girls developing
breast tissue when they are as young as three years of age. Both trends could
be tied to endocrine-disrupting chemical exposures in utero.
Rodents exposed to bisphenol-A give birth to female offspring that grow
faster, weigh more, and enter puberty earlier. If applicable to humans, these
effects could predispose exposed children toward obesity and early puberty.
Finally, upon reaching adulthood, many people choose to have children of their
own. However, chemical exposures may be contributing to infertility and other
Sperm density has declined 40% in the U.S. since World War II. Exposure to
phthalates, pesticides, and flame retardants may be contributing to this
Men with high levels of phthalates or pesticides in their urine (including
diazinon, heavily used in California agriculture) tend to have low levels of
Male rats exposed to even a single low dose of PBDE flame retardants while in
the womb have significantly decreased sperm counts.
Reducing exposure can prevent harm. Several instances where regulatory
agencies took action demonstrate the value of reducing exposure for human
The EPA banned household uses of the pesticides chlorpyrifos and diazinon in
2001. It appears that this health-protective action had a nearly immediate
effect. After 2001, mothers in New York City had lower levels of these
compounds in their bodies and, remarkably, gave birth to heavier and longer
babies than those born before the pesticide ban.
The phasing out of leaded gasoline and other efforts to reduce lead exposure
have reduced the number of children with toxic levels of lead by half over the
The newly discovered connections between chemicals and disease outlined here
just begin to scratch the surface of the potential impact of chemicals on
public health. Tens of thousands of industrial chemicals on the market have
not been tested for developmental health effects at low doses. No public
health information exists for close to half of the high production-volume
chemicals. Moreover, where significant evidence of harm to public health
already exists, inadequate resources and legal authority often prevent
regulatory agencies from taking protective action.
In order to protect children from toxic exposures, we must take firm steps to
remedy the ignorance about health effects of widely-used chemicals and empower
regulatory agencies to ensure that consumer products do not contain dangerous
chemicals. These steps include:
1) Phasing out chemicals that persist in the environment, accumulate in
organisms, or for which evidence of potential harm to human health exists from
2) Requiring chemical manufacturers to develop analytical techniques to detect
the chemicals they produce, and relevant breakdown products, in environmental
media and organisms, and to submit these techniques to the state. Currently,
taxpayers pay for scientists to guess at what emerging chemical threats may be
present in our environment and bodies and then develop the testing methods to
detect them. This causes significant delay in determining which chemicals pose
the greatest threat to public health.
3) Requiring chemical manufacturers to supply the state and federal government
with toxicity data for their products, including low-dose effects on
development and reproduction. The European Union recently developed a model
policy, known as Registration, Evaluation and Authorization of Chemicals
(REACH), that would vastly increase the amount of information available to
determine the safety of chemical products.
4) Encouraging the federal government to stop lobbying heavily against the new
European Union chemicals policy on behalf of U.S. industry, and to take a
stronger stand for public health.
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