June 17, 2026

expert reaction to cohort study looking at gestational exposure to 10 classes of environmental chemicals and birth outcomes

A cohort study published in JAMA Network Open looks at gestational exposure to environmental chemicals and birth outcomes. 

Prof Oliver Jones, Professor of Chemistry, RMIT University, said:

“I can see this study being reported as chemicals are harming our children or similar, but there are several factors that need to be taken into account when assessing the results.

“While the analytical method used is good, the problem is that the authors measured the concentrations of various chemicals in urine at a single time point; This is not best practice and can give misleading results. This is because concentrations of things in urine vary throughout the day depending on a range of factors. For example, if you just happened to take the measurement when you hadn’t drunk a lot of water, you may get a much higher concentration of the chemical than if you had drunk a lot of water. The more accurate way to test is to collect all patients’ urine over 24 hours and then analyse the combined sample for the compound(s) of interest. Even then, a single test does not tell us much about chemical exposure over the entire pregnancy.

“The authors also assume that the concentration of a chemical in urine is a reliable proxy for its concentration in the mother’s blood/tissue and/or the children, but there is no reason to think this is correct. In any case, if it is in the urine, you have excreted it, and it can’t be doing harm.

“The mere detection of a compound does not automatically mean it is causing harm. Modern analytical equipment is so sensitive that you can detect almost anything anywhere, but it is the dose that makes the poison.

“Finally, the study reports an association between environmental chemicals and birth outcomes, but an association is not causation. It is more likely that the results described in this paper are due to the third factor, which affects both blood chemical concentrations and birth outcomes. For example, someone at a socioeconomic disadvantage might be exposed to more chemicals (with no effect) and have a lower-quality diet and less access to healthcare, but it would be the diet and healthcare access are more likely to affect birth outcomes.

“So, while the data are interesting, the results don’t prove anything directly and need to be interpreted in context. I don’t think people need to panic”.

‘Gestational Exposure to 10 Classes of Priority Chemicals and Birth Outcomes in the ECHO Cohort’ by Jessie P. Buckley et al. was published in JAMA Network Open at 16:00 UK Time on Wednesday the 17th of June 2026. 

DOI: 10.1001/jamanetworkopen.2026.18883

Declared interests

Prof Oliver Jones: “My research group is active in research on environmental pollutants and their effects on biological systems. I have previously received research funding from various water utilities and the Environment Protection Authority Victoria. I am a member of the Australian National Health and Medical Research Council (NHMRC) Water Quality Advisory Committee.”