Early-Life Environmental Exposures Linked to Multiple Health Outcomes Into Adolescence

A team led by the Barcelona Institute for Global Health, known as ISGlobal, has published a study in Science Advances that maps how the environment a child is exposed to before and after birth lines up with health outcomes years later. The institute is supported by the "la Caixa" Foundation, and the work was done with the French National Institute for Health and Medical Research, Inserm. It draws on the Human Early Life Exposome project, called HELIX.

The central idea is the exposome: the totality of environmental exposures a person meets over a lifetime, from diet and tobacco smoke to air pollution. Rather than testing one exposure against one outcome, the researchers used what they call an outcome-wide approach, looking at many exposures against many outcomes at once. Augusto Anguita-Ruiz, a researcher at ISGlobal and the University of Barcelona and the study's first author, said this allowed them to analyze the associations jointly instead of separately.

The scale was considerable. The team used data on 69 prenatal exposures and 129 childhood exposures, and set them against 11 health outcomes measured in two windows: childhood, from ages 6 to 11, and adolescence, from 12 to 18. The outcomes fell into four domains. Cardiometabolic health covered body mass index and blood pressure. Mental health covered ADHD, internalising symptoms such as anxiety and depression, and externalising symptoms such as aggression and impulsivity. The respiratory domain covered asthma and wheezing, and the allergic domain covered dermatitis and rhinitis.

Six prenatal exposures and 42 childhood exposures were associated with multiple outcomes and more than one health family at the same time. No single exposure touched all four domains. Even so, Valérie Siroux, an Inserm researcher and senior co-author, noted that around one in three of the selected exposures was linked to more than one domain, which she said suggests some exposures may have broad, multisystem effects.

The factors examined were wide-ranging: diet, physical activity, sleep and other individual behaviours, tobacco smoke, indoor and outdoor air pollution, chemical pollutants, metals, and characteristics of the built environment. Two findings stood out. Maternal smoking during pregnancy was associated with higher BMI and more externalising behaviours in children, both in early childhood and in adolescence, and with more ADHD symptoms in adolescence. Higher maternal meat intake during pregnancy was associated with several mental health outcomes and with asthma in children, as well as with wheezing and dermatitis during childhood.

Many associations first seen in early childhood were still visible years later in adolescence. The authors read this as a sign that early environmental conditions may leave relatively durable health signatures.

The study also produced a public tool: an open, interactive atlas of paediatric exposome–health associations. Users can explore the links across environmental factors, health outcomes and developmental stages, and the authors say it can help generate new hypotheses and guide future research. They point to tobacco smoke, indoor air pollution, dietary quality and features of the built environment as factors that may matter for prevention and policy.

The researchers are explicit about limits. Xavier Basagaña, an ISGlobal researcher and senior co-author, stressed that the study does not establish that these exposures cause the health outcomes observed. Larger and more diverse populations will need to be studied, he said, to understand the relationships better and to determine whether changing some of these exposures can alter health trajectories through childhood and adolescence.