Babies' exposure to high levels of air pollution in the womb may lead to a type of DNA damage, typically associated with ageing, called telomere shortening, warned a study.

Telomeres are the caps at the end of each strand of DNA that protect our chromosomes. Telomere shortening is the main cause of age-related breakdown of our cells and has been linked with cancer and heart disease, cognitive decline, ageing, as well as premature death.

Babies exposed to air pollution in utero, showed higher levels of PAH-DNA cord adducts -- a biomarker for exposure to polycyclic aromatic hydrocarbons, a toxic component of air pollution from coal plants. Elevated levels of these adducts in cord blood were associated with shorter telomeres as well as with lower levels of brain-derived neurotrophic factor (BDNF) -- a protein involved in neuronal growth. "An individual's telomere length at birth is known to influence their risk for disease decades later during adulthood," said Deliang Tang, Professor at the Columbia University in the US.

For the study, which appeared in the journal Environment International, the team analysed telomere length in the umbilical cord blood of 255 newborns, born both before and after the closure of a coal-burning power plant in Tongliang, China in 2004. In May 2004, high levels of air pollution in Tongliang prompted the government to shut down the local coal-burning power plant to improve community health. "Further follow-up is needed to assess the role telomere length plays in health outcomes in the context of early life exposure to air pollution," Tang said.