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 minuscule 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 minuscule 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 the lens of one of their most-hated chemicals, BPA.

———-CREDITS———-

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.