During my last couple of years working, I had the great luck to work with a Regulatory Services business that Intertek owned.  I say “great luck” for a couple of reasons: 1) this is a fascinating business that I knew very little about and I learned so much in my time working with them; and, 2) I had the pleasure of getting to know several fascinating people, including the person who inadvertently helped me write this essay and to whom it is dedicated.

This Regulatory Services business is a consultancy that assists companies in navigating a range of regulations often focused on public health.  The part of the business I worked most closely with was Chemical Services, which helps companies understand the regulations associated with chemicals in their products and how to comply with said regulations.  I had worked with this type of business in my earlier days as a bench chemist when I was developing specialty chemicals used in Industrial paints and coatings.  I, of course, felt that because I had this cursory exposure to the industry that I was “knowledgeable”.  Unsurprisingly, I found out very quickly that I was not.  Or, rather, that I knew just enough to be dangerous.  We’ve touched on this topic before.  Thanks to Karen, I know much more.  Which only seems to make me more dangerous.

The Principals in this business were very kind and patient with me.  Maybe it was because the business is located in Canada and Canadians are pathologically nice.  Maybe it was just because they were incredible people.  During one of my early trips, my host planned a half day of hookey with me.  We spent the morning in the office outside of Toronto, filling my brain.  At lunch time, we took off and headed south.  We drove through the adorable town of Niagra-on-the-Lake.  Had lunch; did a little shopping.  We drove through wine country (alas, no tastings) and down to the Canadian side of Niagra Falls (clearly more beautiful than the American side).  Karen and I talked all along the way about a zillion things, including more about the business and building my understanding.  It was during this trip that Karen fed me that immortal line that titles this essay: A chemical in and of itself is not safe or dangerous.  It’s the dose that makes the poison.  Depending on the characteristics of the chemical and how it interacts with human systems, a “safe” dose can vary.  Determining that dose, both in the acute and chronic sense, is a difficult undertaking and fraught with conflicting interpretations.  It just ain’t that simple.

That lesson clearly had a big impact on me.  It is partly about risk assessment and, in fact, this essay is a good companion to the one I wrote a few months ago on risk.  It’s a follow on that I’ve been mulling over since that writing.  This idea of “how much of something makes it a bad thing” is an idea we wrestle with daily in all aspects of our lives.  It’s further complicated by the companion question of “is the risk worth it?”  As I wrote in that essay on risk, it’s a wonder that we aren’t paralyzed daily by indecision, but we usually take these quickie risk assessments in stride. 

The aspect of this subject that I’ve been ruminating on a lot lately is this idea that some thing or person or idea is not—cannot be—all good or all bad.  It’s the dose that makes the poison.  In the realm of toxicology, Karen spoke about a few ways of looking at this.  There is the classical S-shaped response curve where something is not dangerous until you reach a critical threshold level—this is what most of us think about when we think of something as a “poison”.  There is the proverbial Goldilocks dilemma—where too little of something is bad and too much is bad, but there is a sweet spot in the middle.  Exposure to oxygen is a good example.  And there is even an instance, called hormesis, where something is beneficial in smaller doses, no more beneficial but not dangerous at some intermediate level, and then toxic above a threshold. Exercise and alcohol are good examples here.

Why am I bringing all this up (besides the fact that I love discussing this kind of thing with Karen)? Well, we’ve had a lot of mental whiplash over this past year of pandemic as the pace of new information has caused changes in the guidance we’ve gotten from experts on how to best protect ourselves and squash the spread of the virus.  (Their often-poor risk communication has not helped.)  I think as Americans (as humans?) we like to have nice, clear cut, unchangeable answers on how to address serious problems.  Mask are good or masks are worthless; the vaccines are safe or they are not; the virus lives on surfaces or it doesn’t; it’s safe to open schools or it’s not.  We just don’t like “It depends” as an answer even though we know, realistically, that’s the case most of the time.  It doesn’t help that we have the companion problem of “if a little of this is good, then a lot must be better!”  If you believe wearing masks helps reduce spread of the virus, then you want to see everyone in a mask everywhere all the time.  And if you think they don’t really help, then you never want to see one anywhere on anyone.  Absolutism helps reinforce our beliefs but it’s the dose that makes the poison.  “Never” and “always” are dangerous words.

Think about sunshine.  Nothing feels better than warm sun on winter-tired skin in springtime.  Doctors even tell us we need sunshine to manufacture Vitamin D!  But spend more than, say, 15 unprotected minutes in direct, strong sun and your skin begins to burn.  (OK, for me it’s 15 minutes; for Trish it’s about an hour.)  That doesn’t mean I should spend zero time in the sun because I will burn.  It means I need to limit the time and/or wear sunscreen.  Think about that one friend or family member who you love dearly but who drinks too much or talks too loudly or keeps bringing up that topic.  It doesn’t mean you never want to see them; it just means you can’t spend too much time together (classic risk management!).  It’s the dose that makes the poison.

I’ve struggled mightily lately with how to put this thinking to work in evaluating our societal conflicts, be they over the pandemic, racial injustice and inequality, or even (ick) politics.  My risk assessment is going to be different than yours. Remember that there are two components of this analysis:  the intrinsic danger/hazard/toxicity of what you are considering, matched against your assessment of the probability of exposure.  We often miscalculate on both!  How can I effectively respect your context and still remain true to mine?  It’s a lot of work to challenge your own assumptions and see the world through someone else’s eyes and experiences.  Even in the data-driven world of toxicology, it can be difficult to put the health risks of certain chemicals into effective safe ranges of exposure.  In our ever-fractured world, we are quick to condemn products or people or even ideas over an instance of negative impact—irrespective of the balance of good vs. bad or the probability of negative impact or even the time and context of said negativity.  We have zero tolerance (ok, now I’m getting into engineering).  But zero tolerance never works.  It’s the dose that makes the poison.