Californians Face Increasing Obstacles To Healthy Development

From: Robina Suwol
Date: 09 Jul 2004
Time: 22:08:03
Remote Name:


Toxics and Environmental Health Program 
Growing Up Toxic: Chemical Exposures and Increases in Developmental Disease 
June 2004
Environment California Research & Policy Center
Executive Summary
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 exposure.
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 hazards‹a 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 unavoidable.
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 consideration.
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
PCBs. Consider:
Flame-retardant chemicals given to newborn mice in small doses permanently impair their learning and behavior, and small doses of bisphenol-A produce hyperactivity.
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 reproductive difficulties.
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 trend.
Men with high levels of phthalates or pesticides in their urine (including diazinon, heavily used in California agriculture) tend to have low levels of sperm production.
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 health:
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 last decade.
Policy Reforms
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 exposure.
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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Last changed: March 14, 2006