Abstract
Background:
Dichlorodiphenyltrichloroethane (DDT) or pyrethroid insecticides are sprayed inside dwellings as part of global malaria vector control programs, resulting in high levels of exposure to millions of people, including pregnant women. These chemicals are endocrine disruptors and may affect child growth.
Objectives:
To assess the impact of gestational exposure to DDT and pyrethroid insecticides on child weight trajectories in the Venda Health Examination of Mothers, Babies and their Environment (VHEMBE) birth cohort study based in Limpopo, South Africa (n=751).
Methods:
In samples taken from mothers at delivery, DDT and its breakdown product were measured in in serum and pyrethroid metabolites were measured in urine. Child weight was measured at 1, 2, 3.5 and 5-year follow-up visits, and all available measurements since birth were abstracted from medical records. We modelled child weight trajectories using SuperImposition, Translation and Rotation (SITAR) to estimate child-specific weight over time and the timing of the infant growth spurt, then estimated associations between insecticides and SITAR parameters using marginal structural models.
Results:
The pyrethroid metabolite trans-DCCA was associated with -21g (95%CI: -40, -2) lower weight among boys per 10-fold increase, with similar magnitudes of association for cis-DBCA and cis-DCCA. Pyrethroids metabolites were also associated with earlier infant growth spurt, but confidence intervals included the null; e.g. -1.8 days (95% CI: -3.7, 0.1) earlier per 10-fold increase in cis-DBCA.
Discussion:
Inverse associations between pyrethroids and weight among boys may reflect disruption of androgen pathways. These findings support previous findings in this population and the endocrine-disrupting potential of pyrethroids.
