Interview with Dr. Shanna Swan
WT: Dr. Swan, you have summarized your research findings on endocrine disruptors in the video, After Skool.
What are endocrine disruptors?
Swan: Endocrine disruptors are chemicals that have the ability to interfere with the body’s endogenous (innate) hormones (the messengers of the endocrine system). Disruptions of the sex steroid hormones (such as testosterone and estrogen) are of particular concern with respect to sperm count and infertility.
WT: As a world leading environmental and reproductive epidemiologist, what has your research confirmed about sperm counts? Please refer to your 2017research paper
and the updated 2022 paper.
Swan: In our rigorous and comprehensive meta-analysis of data collected between 1973 and 2011 (published 2017) we found that among men from Western countries who were not selected on the basis of their infertility status, sperm concentration declined by more than 50% in Western countries, with no evidence of a “levelling off” in recent years.
These findings strongly suggest a significant decline in male reproductive health that has serious implications beyond fertility and reproduction, given recent evidence linking poor semen quality with a higher risk of hospitalization and death.
WT: What does the updated paper reveal and why is this significant? What are your conclusions?
Swan: The recent (2022) paper is the first to report a decline in sperm count among unselected men from South/Central America, Asia, and Africa, in contrast to our previous meta-analysis that was underpowered to examine those continents
These data suggest that this worldwide decline is continuing in the 21st century and at an accelerated pace.
WT: What might be plausible reasons for the decline in sperm count?
Swan: Plausible causes of sperm decline fall into two groups: lifestyle factors (smoking, obesity, stress, binge drinking etc.) and environmental chemicals (endocrine disruptors – phthalates, BPA, pesticides, PFAS) – as well as some metals – lead, for example.
There is a large amount of literature based on the adverse impact of lifestyle factors on reproductive function.
The literature on environmental chemicals is more recent but convincing for several classes of chemicals. It is hard to separate lifestyle and chemical causes since environmental chemicals also affect lifestyle factors – obesity for example.
WT: What are the devastating effects of decreased fertility?
Swan: On a personal level, the individual or couple may be unable to conceive a pregnancy if they choose to.
In addition, decreased fertility in men and women is linked to decreased longevity.
The ability to conceive is a marker of overall health – the “Sixth Vital Sign”.
On a societal level, a reduced rate implies a shift in the age distribution of the population with huge economic consequences.
WT: Are there solutions? Do we need a paradigm shift as consumers? Do we need regulatory changes?
Swan: “Yes” to all. But the solutions will remain elusive until we, as a society, commit to finding alternatives to EDCs (plastics, pesticides, PFAs and other chemicals of concern) that do not have the ability to interfere with our body’s hormone system.
Until then, we need to become far more aware of the chemicals we are continuously exposed to through our food, water, air, personal care products, and so on.
Right now, there is almost no governmental control of these chemicals.
A chemical should be tested for safety before being introduced into commerce, which is not the case in the US.
These and other solutions are discussed at length in my book, Count Down (Swan and Colino, Published by Scribner 2021)