Does Secondhand Smoke Cause ADD?

By Dirk Hanson 07/13/11

Small study finds an “association,” but can’t draw conclusions.

Chasing down secondhand smoke.
Photo via healthtree

Every day, we thank our sainted mothers for steering us away from the practical arts—like high energy physics and statistics. Especially statistics. Scientists at the Tobacco Free Research Institute in Dublin, Ireland, have uncovered what they say is an intriguing statistical association between children exposed to secondhand cigarette smoke and a host of neurobehavioral disorders, including attention deficit hyperactivity disorder (ADHD) and assorted learning disabilities. The researchers caution strongly against drawing premature conclusions, but based on data about 55,000 American children under 12, published in the journal Pediatrics, the researchers found that children living in smoke-free homes were half as likely to develop such disorders as children growing up among smokers. “The findings of the study, which are associational and not necessarily causal, underscore the health burden of childhood neurobehavioral disorders that may be attributable to secondhand smoke (SHS) exposure in homes in the United States.”

Note that word, “may.” Here are the numbers: In smoke-free homes, 8.6% of kids developed a neurobehaviorial disorder. That’s about one child out of 12. In contrast, 20.4% of kids in homes with smokers ended up with a diagnosis of ADHD, a learning disability, or a conduct disorder. That’s one out of five, which is mind-boggling enough to be suspicious. We can’t know for certain yet whether it is the smoking itself, or something else related to a smoking household, that accounts for this increase—if the increase itself holds true. Much more research will be needed on this one. We’ll tell you when it’s time to panic. But it may be time to furrow your brow. The researchers conclude: “A total of 4.8 million US children younger than 12 years are exposed to secondhand smoke in their homes, and 3% to 8% suffer from 1 or more neurobehavioral disorders.”

Please read our comment policy. - The Fix
dirk hanson.jpg

Dirk Hanson, MA, is a freelance science writer and the author of The Chemical Carousel: What Science Tells Us About Beating Addiction. He is also the author of The New Alchemists: Silicon Valley and the Microelectronics Revolution. He has worked as a business and science reporter for numerous magazines and trade publications including Wired, Scientific American, The Dana Foundation and more. He currently edits the Addiction Inbox blog. Email: [email protected]org