INMA: “Exposure before birth to persistent organic pollutants may increase the risk of metabolic disorders in adolescence”
An INMA study investigated the association between prenatal exposure to persistent organic pollutants (POP) and markers of obesity and cardiometabolic risk.
POPs include organochlorine pesticides (e.g., p,p’-DDT, HCB), as well as industrial chemical (PCB). The production and use of these chemicals have been banned (PCBs, HCB) or restricted (p,p’-DDT) under the Stockholm Convention in 2004. However, due to their high persistence in the environment, they are still detected in human bodies, including pregnant women and children. Populations are mostly exposed by contaminated food. During pregnancy, maternal levels of POPs are transmitted to the child through the placenta, and postnatally, via breast milk.
In previous INMA studies, prenatal exposure to p,p’-DDT, HCB and PCBs have been associated with a risk for rapid weight gain in infancy and elevated body mass index (BMI) in childhood. There were no studies assessing whether such associations continue into adolescence, a developmental stage characterized by significant changes in the hormonal system and rapid increases in body mass. Moreover, most studies used indirect measures of obesity and few of them explored cardiometabolic traits.
In this new study, a total of 379 children from INMA-Menorca were included. POP levels were measured in umbilical cord blood samples and the children were then seen periodically between the ages of 4 and 18 years. At these visits, scientists recorded BMI, body fat percentage and blood pressure. When the child reached 14 years of age, biomarkers of cardiometabolic risk (cholesterol, triglycerides, glucose, etc.) were measured in blood.
The results suggest that prenatal exposure to p,p’-DDT and HCB was associated with increase BMI during childhood and adolescence. In addition, they were also associated with increased waist-to-height ratio, higher blood pressure and greater levels of serum lipids in adolescence. Finally, prenatal HCB levels were associated with higher body fat % in adolescence.
This is the first study showing that the association between prenatal exposure to POPs and BMI persist into adolescence, and that POPs are associated with risk factors for metabolic syndrome in adults. Authors say that “some of these substances could be considered endocrine disruptors, that is, chemicals that interfere with hormonal regulation”, adding that “it is thought that POPs may interact with hormone receptors or with the generation of free radicals, and the chief problem is that these pollutants accumulate in the fatty tissues of living organisms, where they can persist for years, even decades”. As one in four people is affected by metabolic syndrome worldwide, authors plead for more studies, especially in children and adolescents.
Reference: Güil-Oumrait N, Valvi D, Garcia-Esteban R, Guxens M, Sunyer J, Torrent M, Casas M, Vrijheid M. Prenatal exposure to persistent organic pollutants and markers of obesity and cardiometabolic risk in Spanish adolescents. Environ Int. 2021 Jun;151:106469.