Exposure to indoor residual spraying insecticides and obesity and pubertal development in South African children participating in the VHEMBE study

In recent decades, a dramatic increase in childhood obesity rates and an acceleration of pubertal development have been observed worldwide. Although changes in diet and physical activity may have influenced these trends, evidence suggests that exposure to endocrine-disrupting chemicals may play a role. More than 50 countries use indoor residual spraying (IRS), the application of insecticides to the interior walls of homes, to control malaria, resulting in significant exposure to endocrine-disrupting chemicals such as DDT and pyrethroids. DDT has an estrogenic effect, increases body fat, and accelerates puberty in female rodents, while its metabolite, DDE, is an antiandrogen and delays puberty in males. Currently no studies have investigated the impact of DDT or pyrethroid exposure on the initiation or timing of puberty in peripubertal African children.

This study will provide data that will enable policymakers to better understand the determinants of the dramatic increase in obesity rates and the acceleration of puberty in South Africa and other developing countries. It will also provide critical information on the potential unintended consequences of IRS to malaria-endemic countries and international agencies so they can develop safe and sustainable malaria control methods.

The proposed study will use data from the Venda Health Examination of Mothers, Babies and their Environment (VHEMBE), a birth cohort of 752 mother-child dyads living in a region where IRS is practiced annually. In this ongoing cohort, participants visit the research office every 9 months between the ages of 8 and 11 years for a structured maternal interview, anthropometric measurements, puberty assessment based on Tanner stages, and blood and urine sample collection. Exposure is estimated based on the measurement of pyrethroid and DDT metabolites in maternal perinatal and infant samples. Duo Zhang will consider temporal variation in IRS insecticide exposure, adiposity, puberty, and covariates by applying longitudinal models and assess mediation of the relationship by obesity by applying causal inference methods. Zhang will also evaluate the interaction between insecticides using mixture models.

Project details

Impact of Interventions
Vector Control

May 2025 — Apr 2029

$69,824

South Africa