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Study Indicates Secondhand Smoke Exposure Harms Children's Intellectual Development

Statement of Daniel E. McGoldrick, Director of Research, Campaign for Tobacco-Free Kids
January 04, 2005

Washington, DC — An important new study published in the January 2005 issue of the peer-reviewed journal Environmental Health Perspectives demonstrates a strong negative relationship between children’s exposure to secondhand smoke and their performance on tests measuring reading, math and reasoning skills. The negative impact of secondhand smoke on children’s cognitive ability was evident even at extremely low levels of exposure and held up when other possible explanations (e.g., poverty, parent education, etc.) were controlled. These disturbing findings add to the already long list of health harms caused by secondhand smoke to non-smokers of all ages. The study’s clear message to parents is that children must be protected from secondhand smoke both at home and in public places. Its clear message to state and local policy makers is that they should enact comprehensive smoke-free policies that cover all workplaces and public places in order to protect everyone’s right to breath clean air and help prevent the myriad health problems associated with secondhand smoke.

The new study, conducted primarily by researchers at Cincinnati Children’s Hospital Medical Center, involved nearly 4,399 U.S. children 6-16 years of age and measured exposure to secondhand smoke based on blood levels of a nicotine byproduct called cotinine. The study found that 84 percent of the children studied had detectable levels of cotinine and estimated that more than 33 million American kids are at risk for secondhand smoke-related reading deficits. This broad exposure, despite the fact that just 43 percent of the households reported a smoker in the home, suggests not only that parents should make their homes completely smoke-free, but that children are also exposed to dangerous levels of secondhand smoke outside the home. It is critical that parents be aware of the environments in which their kids are spending time and that elected officials implement polices to make all public places smoke-free.

The study found a strong negative correlation between levels of exposure to secondhand smoke and scores on standardized tests of reading, math and reasoning. Perhaps more important, even extremely low levels of secondhand smoke exposure were related to some decrease in performance. As the authors state, “we are unable to recommend a safe level of exposure to ETS (secondhand smoke) because there is no discernable threshold for the impact of ETS on cognitive functioning in children.”

In addition to these new findings, secondhand smoke is scientifically proven to cause lung cancer, heart disease, and other serious illnesses and is responsible nationally for thousands of deaths each year. Secondhand smoke contains more than 4,000 chemicals and 69 known carcinogens including formaldehyde, lead, arsenic, benzene and polonium 210. Studies show that kids are especially vulnerable to other people’s smoke, suffering more respiratory problems, ear infections and asthma.