From the WashPost on Monday:

Secondhand Smoke and Kids' IQ Exposure to secondhand smoke reduces children's scores on math, reading and spatial skills tests by the equivalent of two to five IQ points, depending on how much smoke a child takes in, a study by the National Institute of Environmental Health Sciences has found.

The study, the largest and most scientific of its kind, involved 4,399 children and, for the first time, used the level of cotinine in the blood as a biological marker for smoke exposure. Cotinine is a breakdown product of nicotine. The research not only found a general correlation between high cotinine levels and low test scores, but also that the group of children with the highest levels had the lowest test scores. This kind of "dose response" is seen by researchers as strong evidence of a cause-and-effect relationship.

"We estimated that over 21.9 million children are at risk for [secondhand smoke]-related reading deficits," the study concluded. Although calling for more research, the authors said that "this analysis along with other studies provides adequate evidence to support policy to further reduce childhood exposure."

The study, published in this month's issue of Environmental Health Perspectives, relied on data from the third National Health and Nutrition Examination Survey. The children studied were ages 6 to 16. The report does not explain how or why secondhand smoke reduces test scores, but previous research has linked high smoke exposure to ear infections, sudden infant death syndrome, and being held back in school.

What I’ve found sad is that the folks I notice who seem to be using tobacco products - cigarettes, and chewing tobacco, are the people who can least afford to buy the stuff. They’re mostly blue collar types or middle income folks for whom two bucks or two and a half buck is real money - yet they’re spending it on smokes. Also, based on what we read above, really hurting their kids. Nonetheless, I know just how hard it is to quit. It took me several tries over three or four years to finally kick the habit. That was 20 years ago. Gollee, how time flies!