Prenatal pesticide exposure increases risk of adolescent obesity

Exposure during pregnancy to persistent organic pollutants (POPs) - organochlorine pesticides, industrial products, etc. - could increase the risk of metabolic disorders in adolescence, such as obesity and higher blood pressure. This is the main conclusion of a study by the Barcelona Institute for Global Health (ISGlobal), a centre promoted by the "la Caixa" Foundation, which has been carried out on the basis of the monitoring of nearly 400 children in Menorca from the prenatal stage until they reach the age of majority.

Persistent organic pollutants (POPs) are toxic chemical substances that, being resistant to degradation, remain in the environment. Some examples are pesticides or organochlorine insecticides (DDT, etc.). These substances are harmful to health and the environment and their use is regulated worldwide.

Prenatal exposure to these substances has been linked to cardiometabolic risk factors in childhood, but there are no studies assessing whether these associations continue into adolescence, a period of relevant changes in the endocrine system and rapid increases in body mass.

The research, carried out within the framework of the INMA-Childhood and Environment Project, set out to study the relationship between prenatal exposure to POPs and body mass index (BMI) and other markers of cardiometabolic risk in adolescence. To do so, the scientific team followed 379 children in Menorca: POP levels were measured in umbilical cord blood samples from their mothers and their children were monitored periodically from the age of 4 to 18 years. At different visits as they grew older, their Body Mass Index (BMI), body fat percentage, and blood pressure were recorded. In addition, at the age of 14, various biomarkers of cardiometabolic risk (cholesterol, triglycerides, glucose, etc.) were analysed in their blood.

The results, published in the journal Environment International, showed a link between exposure during pregnancy to POPs and a higher Body Mass Index (BMI) in adolescence, particularly in the case of hexachlorobenzene (HCB) - a substance used as a fungicide - and dichloro diphenyl trichloroethane (DDT) - an insecticide compound.

In addition, these two substances - HCB and DDT - were associated with higher blood pressure in childhood and adolescence, as well as higher cardiometabolic risk at age 14.

Núria Güil-Oumrait, first author of the study and researcher at ISGlobal, explains that "this is the first longitudinal study to analyse the relationship between persistent organic pollutants and cardiometabolic risks throughout childhood and adolescence". The findings show that "the association between these substances and childhood BMI persists later in adolescence, and prenatal exposures are associated with major risk factors for metabolic syndrome in adulthood, a condition that now affects one in four people worldwide," he adds.

On the mechanisms that explain this association, Güil-Oumrait notes that "it is thought that POPs could interact with hormone receptors or with the generation of free radicals, and the main problem is that they accumulate in the fatty tissues of living organisms, where they persist for years, even decades".

Martine Vrijheid, coordinator of the study and head of ISGlobal's Children and the Environment programme, points out that "some of these substances could be considered endocrine disruptors and have the capacity to alter hormone regulation". "More studies are needed in this field, especially during childhood and adolescence, critical stages of vulnerability", she concludes.

Nuria Güil-Oumrait, Damaskini Valvi, Raquel Garcia Esteban, Monica Guxens, Jordi Sunyer, Maties Torrent, Maribel Casas, Martine Vrijheid. Prenatal exposure to persistent organic pollutants and markers of obesity and cardiometabolic risk in Spanish adolescents. Environment International. March 2021. https://doi.org/10.1016/j.envint.2021.106469