Season 01:Episode 07:

The Poison Paradigm

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The Poison Paradigm

On a daily basis, we are exposed to thousands of toxic chemicals. This is no accident; it is by design. They are everywhere – coating our consumer products, in our food packaging, being dumped into our lakes and sewers, and in countless other places. However, for the most part, regulators say that we need not worry.

That assessment is based on a simple 500-year-old adage, “the dose makes the poison.” The logic is simple: anything is poisonous, depending on how large a dose.  Dosing yourself with a miniscule amount of lead will cause no harm; while drinking an enormous amount of water will kill you. Regulators then try to find safe exposure levels for these chemicals—and they assume a simple, direct relationship (less is fine, more is worse). So, no matter how toxic the chemical, you only need to worry if it passes a certain exposure threshold.

However, what if their approach is all wrong? A revolutionary group of scientists are challenging this 500-year-old paradigm. They argue that some chemicals behave in erratic and unpredictable ways, and they can mess with us even at miniscule doses. If they’re right, then the chemicals around us are causing irreparable harm, and everything must change. We sort out this battle of paradigms through one of their most-hated chemicals, BPA.


  • Frederick “Fred” vom Saal is a reproductive biologist and a Curators' Distinguished Professor Emeritus at the University of Missouri-Columbia.
  • Patricia Hunt  is a Meyer Distinguished Professor in the School of Molecular Bioscience and Center for Reproductive Biology at Washington State University.
  • Earl Gray Jr. is a Research Biologist for the Environmental Protection Agency
  • Heather Patisaul is the Associate Dean for Research int he department of biological sciences at NC State University
  • Linda Birnbaum is the former  director of the National Institute for Environmental Health Sciences. She retired in 2019.
  • Theo Colborn was the Founder and President Emerita of The Endocrine Disruption Exchange. She died in 2014.

Key References

The Scientist Magazine®. “A Landmark Study On BPA Leaves Scientists at Odds.” 

Advancing Risk Assessment Science: Human Health (20 Sept, Part 6). Accessed June 22, 2020.

Arambula, Sheryl E., Dereje Jima, and Heather B. Patisaul. “Prenatal Bisphenol A (BPA) Exposure Alters the Transcriptome of the Neonate Rat Amygdala in a Sex-Specific Manner: A CLARITY-BPA Consortium Study.” Neurotoxicology 65 (March 2018): 207–20. 

American Scientist. “Assessing Risks from Bisphenol-A,” February 6, 2017..

Biedermann, Sandra, Patrik Tschudin, and Koni Grob. “Transfer of Bisphenol A from Thermal Printer Paper to the Skin.” Analytical and Bioanalytical Chemistry 398, no. 1 (September 2010): 571–76.

Bushnik, Tracey, Douglas Haines, Patrick Levallois, Johanne Levesque, Jay Van Oostdam, and Claude Viau. “Lead and Bisphenol A Concentrations in the Canadian Population.” Health Reports 21, no. 3 (September 2010): 7–18.

Call for Ban on Baby Bottle Chemical. Accessed June 22, 2020.

Camacho, L., S. M. Lewis, M. M. Vanlandingham, G. R. Olson, K. J. Davis, R. E. Patton, N. C. Twaddle, et al. “A Two-Year Toxicology Study of Bisphenol A (BPA) in Sprague-Dawley Rats: CLARITY-BPA Core Study Results.” Food and Chemical Toxicology: An International Journal Published for the British Industrial Biological Research Association 132 (October 2019): 110728. 

Canada, Health. “Bisphenol A (BPA).” Education and awareness. aem, April 16, 2013.

Colborn, Theo, Dianne Dumanoski, and John Peterson Myers. Our Stolen Future: Are We Threatening Our Fertility, Intelligence, and Survival?--A Scientific Detective Story. NY: Dutton, Penguin Books, 1996.

Diamanti-Kandarakis, Evanthia, Jean-Pierre Bourguignon, Linda C. Giudice, Russ Hauser, Gail S. Prins, Ana M. Soto, R. Thomas Zoeller, and Andrea C. Gore. “Endocrine-Disrupting Chemicals: An Endocrine Society Scientific Statement.” Endocrine Reviews 30, no. 4 (June 2009): 293–342. 

Fagin, Dan. “Toxicology: The Learning Curve.” Nature 490, no. 7421 (October 25, 2012): 462–65. 

Gerona, Roy, Frederick S vom Saal, and Patricia A Hunt. “BPA: Have Flawed Analytical Techniques Compromised Risk Assessments?The Lancet Diabetes & Endocrinology 8, no. 1 (January 2020): 11–13. “Government Study Of BPA Backs Its Safety, But Doesn’t Settle Debate.” 

Hinterthuer, Adam. “Just How Harmful Are Bisphenol A Plastics?” Scientific American.

Hunt, Patricia A., Kara E. Koehler, Martha Susiarjo, Craig A. Hodges, Arlene Ilagan, Robert C. Voigt, Sally Thomas, Brian F. Thomas, and Terry J. Hassold. “Bisphenol a Exposure Causes Meiotic Aneuploidy in the Female Mouse.” Current Biology: CB 13, no. 7 (April 1, 2003): 546–53. 

Krimsky, Sheldon. Hormonal Chaos: The Scientific and Social Origin of the Environmental Endocrine Hypothesis. Baltimore, Md.: Johns Hopkins University Press, 2000.

Krishnan, A. V., P. Stathis, S. F. Permuth, L. Tokes, and D. Feldman. “Bisphenol-A: An Estrogenic Substance Is Released from Polycarbonate Flasks during Autoclaving.” Endocrinology 132, no. 6 (June 1993): 2279–86. 

Lang, Iain A., Tamara S. Galloway, Alan Scarlett, William E. Henley, Michael Depledge, Robert B. Wallace, and David Melzer. “Association of Urinary Bisphenol A Concentration With Medical Disorders and Laboratory Abnormalities in Adults.” JAMA 300, no. 11 (September 17, 2008): 1303–10.

The Pitch. “Missouri Biologist Frederick Vom Saal and His Team Exposed the Dangers of Bisphenol A — and Earned the Wrath of the Plastic Industry.,” April 24, 2008. 

“National Toxicology Program (NTP) - 2018 - NTP Research Report on the CLARITY-BPA Core Study.Pdf.” Accessed June 22, 2020. 

“Plastic Additives in Consumer Products | C-SPAN.Org.” Accessed June 22, 2020.

Saal, Frederick S. vom. “Flaws in Design, Execution and Interpretation Limit CLARITY-BPA’s Value for Risk Assessments of Bisphenol A.Basic & Clinical Pharmacology & Toxicology 125, no. S3 (2019): 32–43. 

Saal, Frederick S. vom, Benson T. Akingbemi, Scott M. Belcher, Linda S. Birnbaum, D. Andrew Crain, Marcus Eriksen, Francesca Farabollini, et al. “Chapel Hill Bisphenol A Expert Panel Consensus Statement: Integration of Mechanisms, Effects in Animals and Potential to Impact Human Health at Current Levels of Exposure.” Reproductive Toxicology (Elmsford, N.Y.) 24, no. 2 (2007): 131–38.

Sartain, Caroline V., and Patricia A. Hunt. “An Old Culprit but a New Story: Bisphenol A and ‘NextGen’ Bisphenols.” Fertility and Sterility 106, no. 4 (September 2016): 820–26.

Tarapore, Pheruza, Jun Ying, Bin Ouyang, Barbara Burke, Bruce Bracken, and Shuk-Mei Ho. “Exposure to Bisphenol A Correlates with Early-Onset Prostate Cancer and Promotes Centrosome Amplification and Anchorage-Independent Growth In Vitro.” PLOS ONE 9, no. 3 (March 3, 2014): e90332.

Vandenberg, Laura N. “Non-Monotonic Dose Responses in Studies of Endocrine Disrupting Chemicals: Bisphenol A as a Case Study.Dose-Response 12, no. 2 (October 7, 2013): 259–76. 

Vandenberg, Laura N., Patricia A. Hunt, and Andrea C. Gore. “Endocrine Disruptors and the Future of Toxicology Testing — Lessons from CLARITY–BPA.” Nature Reviews Endocrinology 15, no. 6 (June 2019): 366–74. 

Vandenberg, Laura N., Gail S. Prins, Heather B. Patisaul, and R. Thomas Zoeller. “The Use and Misuse of Historical Controls in Regulatory Toxicology: Lessons from the CLARITY-BPA Study.” Endocrinology 161, no. 5 (May 1, 2020).

Vijaykumar, Tushara, Dipty Singh, Geeta R. Vanage, Rohit V. Dhumal, and Vikas D. Dighe. “Bisphenol A-Induced Ultrastructural Changes in the Testes of Common Marmoset.” The Indian Journal of Medical Research 146, no. 1 (July 2017): 126–37. 

Vogel, Sarah A. “The Politics of Plastics: The Making and Unmaking of Bisphenol A ‘Safety.’” American Journal of Public Health 99, no. Suppl 3 (November 2009): S559–66. 

Zimmermann, Lisa, Georg Dierkes, Thomas A. Ternes, Carolin Völker, and Martin Wagner. “Benchmarking the in Vitro Toxicity and Chemical Composition of Plastic Consumer Products.” Environmental Science & Technology 53, no. 19 (October 1, 2019): 11467–77. 


This episode was produced by Irina Zhorov. Editing from Acey Rowe and Gordon Katic. Franklynn Bartol was our research assistant, with fact checking from Polly Leger.

Our theme song and original music is by our composer, Mike Barber. Dakota Koop is our graphic designer. Our production manager is David Tobiasz, and executive producers are Gordon Katic and Sam Fenn.

Special thanks to the scientists who helped us understand this story, including: Laura Vandenberg, Daniel Dietrich, Rich Giovane and Savannah Johnson.

This episode was funded in part by the Social Science and Humanities Research Council. It’s part of a larger project that examines the roles of values in science, lead by Professor Gunilla Oberg at the University of British Columbia. Professor Oberg also provided research guidance to the project, though this episode does not necessarily reflect the view of Professor Oberg or her project

Cited is produced out of the Centre of Ethics at the University of Toronto, which is on the traditional land of Mississaugas of the Credit, the Anishnabeg, the Chippewa, the Haudenosaunee and the Wendat Peoples. Cited is also produced out of the Michael Smith Laboratories at the University of British Columbia -- that’s on the unceded territories of the Musqueam, Squamish, and Tsleil-Waututh Nations.