The BCEOHRN Spotlight: Glenys Webster

Newsletter Feature – The BCEOHRN Spotlight!

Our next researcher in the spotlight is Glenys Webster.  

Please describe your general research interests for the BCEOHRN membership:
I am interested in the connections between environmental chemical exposures and human health, especially during pregnancy and early childhood. I am currently investigating whether exposures to PFAS stain repellents and PBDE flame retardants in the womb are associated with ADHD-related behaviours in US and Canadian children. These chemicals are found in many household products and in the blood of nearly all Canadians. Other interests include autism, thyroid disruption, understanding how people are exposed to environmental chemicals, pondering how to model chemical mixtures and science communication.

What was the impetus behind this study:
This study examines the thyroid disrupting effects of PFASs in US adults. It follows up on previous findings from the Vancouver-based (and BCEOHRN-funded) CHirP Study (, in which PFASs were associated with thyroid hormones in pregnant women, but only in those who also had elevated levels of TPOAb – a marker of an autoimmune thyroid condition called Hashimoto’s disease. We proposed a “multiple hits hypothesis” to explain these findings, postulating that people with multiple stressors to the thyroid system might be more vulnerable to PFAS-induced thyroid disruption than others. The current study tests this hypothesis in the US adult population.

How was the study funded?
My work was funded by postdoctoral fellowships through the Michael Smith Foundation of Health Research and CIHR.

What was the key result?
As hypothesized, we found PFASs were associated with thyroid hormones in US adults, but only in the subgroup with joint exposure to both high TPOAb and low iodine levels – 2 indicators of thyroid system stress. Approximately 1.3% of the US adult population, or 3 million adults, fall into this potentially-vulnerable subgroup.

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What impact do you hope it will have?
We hope this work will contribute to ongoing policy discussions about the regulation of PFASs and their replacement chemicals. More broadly, we hope it stimulates further thinking about how combinations of stressors affect vulnerability. Our findings suggest that there may be physiological “tipping points” beyond which the body is unable to compensate for the additional thyroid stress of PFASs. This idea may be applicable to other exposures, other sets of stressors, and other outcomes.

Who were your collaborators in BC and elsewhere?
The study team included Scott Venners, Bruce Lanphear and Nathalie Ste Marie (Simon Fraser University), Andre Mattman (St Paul’s Hospital), and Stephen Rauch (University of California, Berkeley).

What is your #1 networking tip for others working in this field?
Work on questions that excite you and don’t be shy! Reach out, share your ideas and enthusiasm with others, be curious, and listen well. There are many people who would be happy to help you.

What’s next for you?
I have just moved to Victoria and am excited to join the local research community and to help build further capacity for environmental health research in this beautiful city. I have many projects on the go, and am actively seeking a place to call my long-term research “home” (….speaking of networking!)