Environmental exposures during early life affect our health

The environment in which we live can significantly affect our health, with scientists arguing that 70 to 90 percent of the risk of developing a disease is determined by our “exposome” – a multitude of environmental (non-genetic) factors to which we are exposed throughout life. 

Now, a team of researchers led by the Barcelona Institute for Global Health (ISGlobal) has systematically documented all associations between a wide range of early life environmental exposures and molecular profiles at various levels, including the epigenome (DNA methylation), the transcriptome (gene expression), and the metabolome (metabolites).

“Early life is a particularly important period, since exposures during these developmentally vulnerable periods may have pronounced effects at the molecular level, which may not be clinically detectable until adulthood,” said study senior author Martine Vrijheid, Head of the Childhood and Environment Program at ISGlobal.

The scientists associated multiple chemical, outdoor, social, and lifestyle exposures (92 during pregnancy and 116 in the case of children aged 6-11) with these children’s molecular profiles. The investigation included 1,301 mother-child pairs from the Human Early Life Exposome (HELIX) project, a long-term cohort study in six European countries (Spain, the United Kingdom, France, Lithuania, Norway and Greece). 

The analysis revealed 1,170 significant associations (249 in pregnancy and 921 in childhood) that provide insights into potential sources of exposure and biological responses. For instance, while pregnancy exposures – such as maternal smoking, or the presence of the heavy metal cadmium and the trace mineral molybdenum – were found to be associated with DNA methylation, childhood exposures (for example, through various diets) were linked to signatures on all molecular levels, particularly metabolites in serum.  

“We identified novel multi-omics associations with childhood exposure to essential trace elements, weather conditions, indoor air quality, and phthalates and parabens,” reported study lead author Léa Maitre, an assistant professor of Non-Communicable Diseases at ISGlobal. “By visualizing these associations as networks, we can better understand if a given molecular profile is connected to several exposures or vice versa, and thereby identify potential biological pathways.”

These findings suggest plausible mechanisms of diseases for six groups of exposures: copper, tobacco smoke, indoor air quality, organic pollutants, phthalates and parabens, and weather conditions. For instance, exposure to copper during childhood was linked to almost 90 molecular features, such as increased levels of C-reactive proteins (an important marker of inflammation), while weather conditions like temperature and humidity were associated with serum metabolites involved in sleep and depression, proteins involved in thermoregulation, and immune response genes.

“With the rich exposome and molecular information available in our catalogue, we provide a valuable resource to the scientific community for finding exposure biomarkers, identifying exposure sources, improving the understanding of disease mechanisms, and, ultimately, promoting public health policies,” Vrijheid concluded.

The study is published in the journal Nature Communications.

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By Andrei Ionescu, Earth.com Staff Writer

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