(HealthDay News) — Children exposed to secondhand smoke at 4 months of age may be at risk for tooth decay by age 3, according to research published online October 21 in The BMJ.

Researchers collected data on 76,920 children born between 2004–2010. The children were examined at birth, 4, 9, and 18 months of age, and at 3 years of age. In addition, their mothers completed questionnaires about smoking in the home, along with their child’s exposure to secondhand smoke, their dietary habits and dental care.

The researchers found that 55.3% of the parents smoked and 6.8% of the children were exposed to secondhand smoke. Those children were roughly twice as likely to have cavities as children whose parents didn’t smoke. In all, 12,729 cases of cavities were identified. A mother’s tobacco use during pregnancy was not a factor, the researchers added.

“Secondhand smoke is one of the major public health problems still unsolved,” lead researcher Koji Kawakami, MD, PhD, chairman of pharmacoepidemiology and clinical research management at Kyoto University in Japan, told HealthDay. Exposure to secondhand smoke is widespread, affecting four out of 10 children around the world, he said. “In our study, more than half of children had family members who smoked, and most smokers were their fathers.”

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