Kyoto University study: Secondhand smoke in infancy may harm kids’ teeth

29 Oct

There are numerous reasons why smoking is considered bad for an individual and there are numerous research studies which list the reasons. Studies are showing how bad second hand smoke is for children. A MNT article, Smoking During Pregnancy May Lower Your Child’s Reading Scores:

Babies born to mothers who smoke more than a pack of cigarettes a day while pregnant have lower reading scores and a harder time with reading tests, compared with children whose mothers do not smoke.
This is the conclusion of a recent study conducted by researchers at Yale School of Medicine and published in The Journal of Pediatrics in November 2012. The reading tests measured how well children read out loud and understood what they were reading.

This isn’t the first study to suggest that smoking in pregnancy may affect a child’s future health and development. A study released in August 2012 said that smoking during pregnancy increases a child’s risk of asthma. In addition, a 2009 study linked smoking during pregnancy to behavioral problems among 3 and 4 year olds boys….

An Inserm and Pierre and Marie Curie University study adds behavior problems to the list of woes children of smokers suffer.

Science Daily reported in Early exposure to tobacco can cause behavioral problems in children:

Researchers from Inserm and Pierre and Marie Curie University (UPMC), in collaboration with the university hospitals of 6 French cities, have analysed data on pre- and postnatal exposure to tobacco in the homes of 5,200 primary school children. They show that this exposure is associated with a risk of behavioural disorders in children, particularly emotional and conduct disorders. The association is stronger when exposure takes place both during pregnancy and after birth. These data show the risk associated with smoking in early life and its behavioural repercussions when the child is of school-going age.These results are published in the journal PLOS ONE.

The consequences of tobacco exposure are widely documented. It leads to many illnesses, including asthma. However, the potential role of environmental tobacco smoke (ETS) is much less well known in terms of its link to behavioural problems in children. In this context, the team led by Isabella Annesi-Maesano, Inserm Research Director at Unit 1136, “Pierre Louis Public Health Institute” (Inserm/UPMC) examined the association between pre- and postnatal ETS exposure and behavioural problems in children….

These observations seem to confirm those carried out in animals, i.e. that the nicotine contained in tobacco smoke may have a neurotoxic effect on the brain. During pregnancy, nicotine in tobacco smoke stimulates acetylcholine receptors, and causes structural changes in the brain. In the first months of life, exposure to tobacco smoke generates a protein imbalance that leads to altered neuronal growth…..

Steven Reinberg reported in the Health Day article, Secondhand Smoke in Infancy May Harm Kids’ Teeth:

Want your baby to grow into a tot with a cavity-free smile? Don’t smoke when he or she is around.
Children exposed to secondhand smoke at 4 months of age may be at risk for tooth decay by age 3, Japanese researchers report.

Those children were roughly twice as likely to have cavities as kids whose parents didn’t smoke. 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,” said lead researcher Dr. Koji Kawakami, chairman of pharmacoepidemiology and clinical research management at Kyoto University.

Exposure to secondhand smoke is widespread, affecting four out of 10 kids around the world, he said.
“In our study, more than half of children had family members who smoked, and most smokers were their fathers,” Kawakami said.

He emphasized that this study only shows an association between exposure to secondhand smoke and cavities, however, not that smoking exposure causes tooth decay.

Even so, the findings support increased efforts to reduce secondhand smoke, he said.
“For example, education on the harm of secondhand smoke would increase if dentists become aware of the cavities risk due to secondhand smoke as well as tobacco smoking of their patients,” Kawakami said.
The report was published Oct. 21 in BMJ.

Dr. Jonathan Shenkin, a clinical associate professor of health policy, health services research and pediatric dentistry at Boston University who is a spokesman for the American Dental Association, said evidence of a link between exposure to secondhand smoke and increased risk of tooth decay has mounted over the past decade.
“Like the population in this study, exposure to secondhand smoke continues to be a problem in the U.S., suggesting value in additional research,” he said.

For this study, researchers collected data on nearly 77,000 children born between 2004 and 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.
About 55 percent of the parents smoked and almost 7 percent of the children were exposed to secondhand smoke, the researchers found.
In all, nearly 13,000 cases of cavities were identified….

Here is the British Medical Journal press release:


22 October 2015

The BMJ Press Release

Exposure to secondhand smoke linked to increased risk of tooth decay in young

Findings support extending public health and clinical interventions to reduce secondhand smoke

Exposure to secondhand smoke at four months of age is associated with an increased risk of tooth decay at age 3 years, concludes a study from Japan in The BMJ today
Although these findings cannot establish causality, they support extending public health and clinical interventions to reduce secondhand smoke, say the researchers
The level of dental caries in deciduous (baby) teeth in developed countries remains high –
20.5% in children ages 2 to 5 years in the US and 25% in children aged 3 years in Japan
While established methods for caries prevention in young children is limited to sugar restriction, oral fluoride supplementation and fluoride varnish, some studies have suggested associations between secondhand smoke and caries
But it is still uncertain whether reducing secondhand smoke among children would contribute to caries prevention
So a team of researchers based in Japan set out to investigate smoking during pregnancy and exposure to household smoke in infants at four months of age as risk factors for caries in deciduous teeth
They analysed data for 76,920 children born between 2004 and 2010 attending routine health checkups at 0,4,9, and 18 months and at 3 years of age at health care centres in Kobe City, Japan
Questionnaires completed by mothers were used to assess secondhand smoke exposure from pregnancy to 3 years of age and other lifestyle factors, such as dietary habits and oral care
Incidence of caries in deciduous teeth was defined as at least one decayed, missing, or filled tooth assessed by qualified dentists
Prevalence of household smoking among children included in the study was 55.3%, and 6.8% had evidence of tobacco exposure. A total of 12,729 incidents of dental caries were identified, mostly decayed teeth
Compared with having no smoker in the family, exposure to tobacco smoke at 4 months of age was associated with an approximately twofold increased risk of caries
The risk of caries was also increased among those exposed to household smoking, by 1.5 – fold, whereas the effect of maternal smoking during pregnancy was not statistically significant
This is an observational study so no definitive conclusions can be drawn about cause and effect, stress the authors, and results may have been influenced by other unmeasured factors
However, they conclude: “Exposure to secondhand smoke at 4 months of age, which is experienced by half of all children of that age in Kobe City, Japan, is associated with an increased risk of caries in deciduous teeth. Although these findings cannot establish causality, they support extending public health and clinical interventions to reduce secondhand smoke.

Notes to Editors:

Research: Secondhand smoke and incidence of dental caries in deciduous teeth among
Children in Japan: population based retrospective cohort study

About BMJ

BMJ is a healthcare knowledge provider that aims to advance healthcare worldwide by sharing knowledge and expertise to improve experiences, outcomes and value. For a full list of BMJ products and services, please visit

See, Prenatal care fact sheet

Our goal as a society should be a healthy child in a healthy family who attends a healthy school in a healthy neighborhood. ©


1. A History of Tobacco

2. American Lung Association’s Smoking and Teens Fact Sheet Women and Tobacco Use
African Americans and Tobacco Use
American Indians/Alaska Natives and Tobacco Use
Hispanics and Tobacco Use
Asian Americans/Pacific Islanders and Tobacco Use
Military and Tobacco Use
Children/Teens and Tobacco Use
Older Adults and Tobacco Use

3. Center for Young Women’s Health A Guide for Teens

4. Kroger Resources Teens and Smoking

5. Teens Health’s Smoking

6. Quit Smoking

Where information leads to Hope. Dr.

Dr. Wilda says this about that ©

Blogs by Dr. Wilda:


Dr. Wilda Reviews ©

Dr. Wilda ©

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: