The largest study of chemical exposure ever conducted on human beings, was released on July 21, 2005 by the U.S. Center for Disease Control and Prevention (CDC). The national exposure report examined how chemicals are being absorbed into the human body. Dr. Julie Gerberding, the CDC Director indicated that most American children and adults were carrying in their bodies' dozens of toxic compounds and pesticides used in consumer products, many of them linked to possible health threats.
The CDC study documented bigger doses in children than in adults of many chemicals, including some pyrethroids. These substances are found in virtually every household pesticide. Also found were phthalates, which are in nail polish, other beauty products and soft plastics.
The 475-page CDC study looked at 148 toxic compounds in the urine and blood of about 2,400 people age six and older in 2000 and 2001. Gerberding said this is the largest and most comprehensive report of its kind ever released anywhere by anyone." The findings were broken down by age group and race.
CDC officials also relayed good news. Steep declines were found in children's exposure to lead and secondhand cigarette smoke. About 1.6% of young children tested from 1999 to 2002 had elevated levels of lead, which could lower their intelligence and cause brain damage. This figure is compared with 88.2% in the late 1970s and 4.4% in the early 1990s. Gerberding called this an "astonishing public health achievement." The reduction was attributed to the removal of lead from paint and gasoline.
Deeply troubling environmental health experts, however, was finding more than 100 other chemical substances in the human body, and particularly in children.
Dr. Jerome A. Paulson, an associate professor of pediatrics at the George Washington University School of Medicine and Health Sciences who specializes in children's environmental health said "The report in general shows that people C kids and adults C are exposed to things that aren't intended to be in their body," The doctor added, "In and of itself, that is a concern. Whether it's harmful or not we can't tell from this particular study."
"We have fouled our own nest," Dr. Paulson said. Adding, "We contaminated the environment sufficiently that there are measurable amounts of potentially toxic substances in people C kids and adults."
The CDC study did not try to gauge the health threat the chemicals might pose. A detectable amount of a compound in a person's body does not mean it causes disease or other damage, the Center noted.
For many compounds in the study, experts have little data on what amounts may be harmful or what they may do in combination. According to Dr. Thomas Burke, associate professor at the Johns Hopkins Bloomberg School of Public Health, "We are really at the beginning of a very complicated journey to understand the thousands of substances we are exposed to."
The discovery of pyrethroids in most people is especially significant. Previously no one had examined the human body for their presence. Pyrethroids are synthetic versions of natural compounds found in flowers. They have been considered safer than older pesticides, such as DDT and chlordane, that build up in the environment, and have been banned in the United States.
According to the experts pyrethroids in high doses, are toxic to the nervous system. Pyrethroids are the second most common class of pesticides that result in poisoning. At low doses, it is believed that these synthetic chemicals might alter hormones. The pyrethroids are used in large volumes in household pesticides, on farms and are often used to kill mosquitoes.
Pyrethroids were seen as an improvement over DDT and other banned pesticides. But according to Burke now we're beginning to understand that while they don't persist in the environment, many of us are exposed. We don't quite know what those levels mean.
In animal tests, and in one recent study of human babies, some of the compounds have been shown to alter male reproductive organs or to feminize hormones. Eleven of 12 phthalates tested were found in higher concentrations in children than adults. Phthalates are used in fragrances.
Representatives of the chemical and pesticide industry praised the report. They stated that human biomonitoring is the best available tool to measure exposure. Chemical industry officials echoed the CDC in saying that finding chemicals in the human body did not necessarily mean they posed a threat.
American Chemistry Council spokesman Chris VandenHeuvel said the CDC study demonstrates "that exposure to these man‑made and natural substances is extremely low." Director Gerberding said that "for the vast majority" of the 148 chemicals examined in the report, "we have no evidence of health effects."
Many toxicologists and environmental scientists, however, disagree. Some of these compounds are some bad actors," Dr. Burke said. Studies of the effect of these compounds on animals, and people, suggest that most of these substances can affect the brain, hormones, reproductive system or the immune system, or that they are linked to cancer.
Many of the compounds have not been studied sufficiently to know what happens with chronic exposure to low doses. "No evidence of health effects does not imply that they are not harmful," Paulson said. "It just means we don't know one way or another."
Accessing the impact of chemicals after humans have been exposed to them should not be the preferred approach. Chemicals, and in particular toxic substances, should be proven safe before exposing human populations to their effects.
In the US environmental groups have called for comprehensive tests to be done by chemical companies on the effects of industrial compounds. There is a similar proposal before the European Parliament.
The evidence suggests that many contaminants accumulate more in children than in adults. This means that children are exposed to larger amounts C perhaps from crawling, breathing more rapidly or from putting items in their mouths. Alternatively that their smaller bodies are less able metabolize or cope with the chemical substances.
Children undergo extraordinary cell growth, in the womb and in the first two years after birth, from brain neurons to immune cells. There are more opportunities for toxic compounds to disrupt the growing cells, Paulson said. Tests done on animals show that fetuses and newborns are more susceptible to harm from chemicals.
According to the CDC study, one of every 18 women of childbearing age, or 5.7%, had mercury levels that exceeded what the U.S. Environmental Protection Agency deemed safe to a developing fetus. Medical studies on school children show exposure to mercury in the womb can lower IQs, with memory and vocabulary also being impaired.
The CDC plans to expand the national study to test for more than 300 compounds in 2007 and expand to about 500 by 2009. An estimated 80,000 chemicals are in commercial use today.
With more chemicals in the environment humans, especially fetuses and children, are vulnerable. Many of the chemicals are known to have adverse effects. However, the presence of these chemicals is not natural and the long term effect of these substances individually and in combination is not known.
Many medical experts suggest that there is a link to increased exposure to chemical compounds, to rising cancer rates, allergies, breathing problems and lower human fertility.
London City Council considered passing a bylaw banning the cosmetic use of pesticides on July 25, 2005. In an 10-8 vote City Council adopted an Integrated Pest Management Bylaw which was supported by the Lawn Care Industry which allows the continued use of pesticides. Critics have called this watered down bylaw Abusiness as usual for the use of pesticides. Passing a bylaw banning the cosmetic use of pesticides would be a big step in improving our local environment and reducing exposure to toxic substances.
This submission is largely based on an article, Dozen's of Chemicals Found in Most American's Bodies, By Marla Cone, The Los Angeles Times, July 22, 2005.