Not everyone ages gracefully. That’s true for people who don’t take care of themselves as adults, but it’s also true for someone whose health was jeopardized at a young age from contact with something harmful, like air pollution or poor diet. In particular, smoking exposure during early development has been linked with numerous adverse health conditions, and now a new study shows that it, as well as other harmful pollutants, can cause advanced biological aging.
Early life, beginning in the womb through childhood, is a crucial phase in human development where susceptibility to environmental exposures is higher. Changes brought about during this time period can have a lasting effect on a person’s metabolism and physiology, thus leading to either good health or diseases later on in life.
Knowing which and why certain exposures are beneficial or detrimental to early development provides evidence for avoidance or increased contact with them. Because aging is a continuous process that occurs at a cellular level throughout life, it can be measured to estimate health risks. One innovative way to measure biological age is through the use of what is known as an “epigenetic clock”, which measures DNA methylation in specific regions of the genome.
In an analysis led by the Barcelona Institute for Global Health (ISGlobal), researchers investigated the association of over 100 various environmental exposures and the epigenetic clock of 1,000 or more children. What they found was that tobacco smoke, above all, positively correlated with advanced aging.
“The epigenetic clock allows us to assess whether someone’s biological age is older or younger than his or her chronological age,” explains author and ISGlobal researcher, Mariona Bustamante.
Biological, or epigenetic, age acceleration has been linked to several age-related conditions like cancer, cellular senescence, mortality, and more. Although DNA methylation is used to calculate epigenetic age, it is just one mechanism by which epigenetics affects gene expression. Histone modifications, chromatin state, and non-coding RNAs can also impact how genes are expressed.
In the past, most epigenetic aging studies have been performed on adults to evaluate environmental exposure, and usually for just one type of exposure. This study was the first to assess a link between early-life exposome of some 83 prenatal and 103 in early childhood exposure with epigenetic age. The results can be found online in the Environment International journal.
While tobacco use stood out as a top factor impacting aging, it was determined that maternal smoking during pregnancy accelerated epigenetic aging during the first years of childhood, as did parental smoking and indoor levels of black carbon (air pollution from partial fuel combustion).
The study also indicated two exposures that proved to have a protective effect against aging. They included the organic pesticide dimethyl dithiophosphate (DMDTP) and a persistent organic pollutant called polychlorinated biphenyl (PCB)-138.
“Further research is needed to explain these results, but the former could be due to a higher intake of fruits and vegetables,” said first author Paula de Prado-Bert, “while the latter could be explained by its correlation with body mass index.”
The results regarding smoking are in-line with other studies done on adults. The researchers believe the epigenetic modifications involved here most likely affect similar pathways for immune response, cell cycle, and detoxification, and therefore ultimately impact health from early life onward.
Although the study did have its limitations, like covering all variables of the exposome, it is a start to hopefully more studies that will provide convincing evidence to the dangers of certain toxins on childhood, especially smoking. Aging is a public health issue that everyone should be concerned about. So future research is needed to help drive government policy toward reducing environmental exposures and promote a “healthy aging” from the very start of life.
Source: Paula de Prado-Bert, et al. (2021). The early-life exposome and epigenetic age acceleration in children. Environment International.
Reference: Exposure to Tobacco Smoke in Early Life is Associated with Accelerated Biological Ageing. Barcelona Institute for Global Health (ISGlobal). August 26, 2021.