Children of boys who used snus more often have asthma and allergies
New research findings show that boys who use snus during puberty risk passing on an increased risk of asthma, chronic bronchitis and eczema to their future children. The researchers behind the study believe the results likely apply to nicotine pouches as well, and are calling for action now.
What a boy puts in his mouth at age 14 can affect the health of children he may not have until 15–20 years later.
That is the conclusion of a new study published in the journal International Journal of Epidemiology. The study followed more than 1,000 father-child pairs from Sweden and shows that men who began using snus before the age of 15 have children with 42 percent higher odds of allergic asthma and more than twice the odds of chronic bronchitis – compared with men who have never used snus.
The team behind the study has previously shown that boys who smoke during puberty increase the risk of asthma in their future children. But finding the same to be true of snus came as a surprise to the researchers.
"We had already seen this with smoking, but we were surprised to find the same signal from snus. It's an exposure you intuitively think of as more localised – it takes place in the mouth, after all. But our results suggest that is enough to produce a systemic effect," says Vivi Schlünssen, professor at the Department of Public Health, Aarhus University, and one of the researchers behind the study.
Timing is everything
The explanation lies in a biological detail most people never consider. Even as a boy, you already carry precursors to the sperm cells that could one day become your children. And they are vulnerable.
"The environment we live in helps determine which parts of our genetic material are activated. This means that what you are exposed to as a teenager can affect the precursors in sperm cells – and potentially be passed on to the next generation," explains Vivi Schlünssen.
This is the mechanism researchers call epigenetics, and it may explain why timing is so critical in this study. Fathers who only began using snus after puberty showed no increased risk in their children.
What about nicotine pouches?
The study concerns snus, so the question is whether the same findings apply to the nicotine pouches that are now ubiquitous among young people in Denmark. Vivi Schlünssen is cautious about drawing too many conclusions, but does not dismiss the possibility.
"Animal studies suggest that both tobacco and pure nicotine can have harmful cross-generational effects. But we still lack human studies that can distinguish between the two. This is something we need to investigate far more quickly than is currently happening."
Should prompt action
The researchers emphasise that this is an observational study – meaning they have identified an association, not proven direct causation. But they believe the cumulative body of evidence is strong enough that policymakers and public health authorities should respond.
"We already know that tobacco and nicotine are harmful. Now the research suggests the harm may not stop with the person using the product – it could extend to the next generation. I think that is reason enough to act," says Vivi Schlünssen.
In the meantime, the message to boys is simple, according to the researcher. The teenage years are probably the point in life when tobacco and nicotine do the most damage – not only to oneself, but potentially to one's future children as well.
About the research
Study type: Observational epidemiological cohort study
Collaborating partners: University of Bergen, University of Gothenburg, Uppsala University, Umeå University, Università di Verona, University of Melbourne.
External funding: None from Denmark. The study was funded by Norwegian, Swedish and European research foundations. The funding sources had no involvement in study design, data collection, analysis or manuscript preparation.
Potential conflicts of interest: None from Denmark. Two of the study's international authors have affiliations with the NHMRC and industry-funded research (AstraZeneca, GSK, Sanofi) in unrelated areas. The remaining authors declare no conflicts of interest.
Link to scientific article: https://academic.oup.com/ije/article/55/2/dyag035/8554136
Contact
Professor Vivi Schlünssen
Aarhus University, Department of Public Health
Email: vs@ph.au.dk
Phone: +45 28992499