PhD defence M.A. (Michiel) van den Dries

During pregnancy, women are universally exposed to phthalates, bisphenols, and organophosphate pesticides (OPs), commonly present in consumer products. Animal studies have linked prenatal exposure to these chemicals to adverse effects on neurodevelopment. Epidemiological studies investigating these associations are suggestive, but overall inconclusive. We examined the association between these chemicals and neurodevelopment in children by studying the determinants of the exposure, exploring the associations with neurodevelopment in children, and investigating the effect of exposure to these chemicals on potential mediators such as thyroid function, brain structure, and fetal growth.

These aims were explored using data from the Generation R Study which is characterized by a large sample size and three repeated measures of exposure during pregnancy (early, mid, and late).

OPs concentrations were higher than those observed in most other studies and fruit was the main dietary source of exposure to OPs. Early pregnancy exposure to phthalates and late pregnancy exposure to OPs were associated with lower IQ. No consistent association with IQ was observed for exposure to these chemicals during other periods, or for bisphenol exposure. No association was observed with behavioral outcomes. Regarding the mediators, we found no association between prenatal OPs exposure and thyroid function. However, there was some suggestion that prenatal exposure to phthalates and OPs was associated with altered brain structure and reduced fetal weight. 

Taken together, these results demonstrate that prenatal exposure to phthalates and OPs may be associated with neurodevelopment, but more research is needed to confirm our results.

Due to corona, the PhD defences do not take place publicly in the usual way in the Senate Hall or in the Professor Andries Querido Room. The candidates will defend their dissertation either in a small group or online.