The Dose Makes the Poison?
We Know Better Now
March 15

When I was working on my keynote talk for the Sustainable Cosmetics Summit, I got to thinking about the paradigm shifts in science that are changing the business of beauty. To sum it up: We didn’t used to know what we know now about the health risks posed by toxic chemicals. So, now that we know, what are we going to do about it?

We know, for example, that chemicals don’t act in the predictable ways once assumed. You’ve probably heard the old adage “the dose makes the poison” — the idea coined by Paracelsus in the 1500s (and oft repeated by beauty industry execs) that toxic substances are harmless in small enough doses, while harmless substances can be deadly if over-consumed.

Science has come a long way in that past five centuries. Now we know: it’s not the dose that makes the poison, but also the timing of the dose, the size of the person and the toxicity of chemical mixtures — factors that aren’t considered in typical risk assessments.

We know that even very low doses of some chemicals can have a profound effect on health, especially if exposures occur to the developing fetus. And there’s far too much we don’t know. Consider the following equation for risk assessment:

Risk = Hazard x Exposure

Makes sense, except that we have a regulatory system that encourage ignorance on all parts of the equation. You can’t figure out the answer (risk) if you don’t have good information about hazard and exposure — and unfortunately, there are no requirements for cosmetics companies to assess the hazard of the chemicals they use or understand how much their customers are being exposed.

It reminds me of the time the Cosmetics Ingredients Review panel tried to determine the risk of phthalates in cosmetics by calculating exposure numbers on the back of a lunch napkin. (See Chapter 2 of my book for more on that story.) The bottom line is, they don’t know the aggregate exposure, and to understand risk, you would have to know how much people are being exposed to a particular chemical as well as to other substances that have similar biological mechanisms of action.

Clearly, we need new chemical policies and new cosmetic laws that bring our regulatory framework and scientific assessment methods into the 21st century.

Meantime, companies have a choice about how to respond to new knowledge from current science. Many good companies are choosing to avoid hazardous chemicals in the first place. And then there are those who insist it’s safe for products like baby shampoo to contain low levels of known carcinogens mixed with various other toxins. What are they thinking? Calvin & Hobbes offer some insight:

Thanks to all the companies that are willing to get informed, act on new knowledge and make the best choices — these companies have my business and will continue to grow as more people become aware of the facts. And to all the rest:  Ignorance may be easier but it’s not particularly smart!

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