Exposure to tobacco smoke during pregnancy, including passive smoking, may lower selenium levels in children, according to research conducted at the Wrocław Medical University.
Selenium is a trace element essential for immunity, metabolism and protection against oxidative stress.
“Although selenium is a trace element, its importance for health cannot be overstated. It participates in regulating the immune system and supports neurological development. Selenium deficiency may increase the risk of infections, cardiovascular disease, cancer, and neurological disorders,” the university said in a press release.
Nearly 70 percent of the children included in the study had low blood selenium levels. Researchers identified prenatal exposure to tobacco smoke as one of the most significant risk factors.
A team led by Professor Paweł Gać and Professor Krystyna Pawlas examined 299 early school-age children from industrialised areas. The study measured blood selenium concentrations and analysed maternal exposure to tobacco smoke during pregnancy, including both active and passive exposure.
Children whose mothers were exposed to tobacco smoke during pregnancy had significantly lower selenium levels. The differences were statistically significant regardless of whether the mother smoked or was only exposed to second-hand smoke. By contrast, current exposure to tobacco smoke in childhood, for example at home, did not affect selenium concentration. The prenatal period was identified as decisive.
“The study protocol did not include a trimester division, so we are unable to determine which period of pregnancy may be most sensitive to the effects of tobacco smoke in terms of selenium levels in the child. This is an important research problem and a potential direction for further analysis,” said Professor Gać, Head of the Department of Environmental Health, Occupational Medicine, and Epidemiology at the Faculty of Health Sciences at Wrocław Medical University.
Cigarette smoke contains free radicals and toxic substances that can cause oxidative stress. Selenium acts as a major antioxidant, and exposure to smoke may accelerate its depletion. Researchers also noted that pregnancy can impair micronutrient transport across the placenta.
The authors concluded that prenatal exposure to tobacco smoke should be regarded as an independent risk factor for selenium deficiency in children. Given selenium’s role in immune and nervous system development, the potential consequences may be long-term.
Only 33.8 percent of the children studied had normal blood selenium concentrations, defined as at least 80 micrograms per litre. Prenatal tobacco smoke exposure was associated with an average reduction of 4–6 micrograms per litre. Other independent risk factors for selenium deficiency included older child age, being underweight and maternal exposure to cigarette smoke during pregnancy.
Researchers called for routine assessment of tobacco smoke exposure as part of standard prenatal care. They also suggested that selenium supplementation for at-risk groups could be considered, although further research is needed.
“We are considering applying for a grant to reassess the studied group of children (...). It would undoubtedly be interesting to assess whether the reduced blood selenium concentration persists in subsequent years and translates into specific health problems,” Professor Gać said. (PAP)
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