Earlier this morning, I posted a new video from a scientist explaining that below certain thresholds of concentration various potential toxins are not dangerous to us.  In reply, The Vicar makes some interesting points about the difficulties in controlling how the toxins we create will concentrate in practice, even if individual products in isolation have safe levels of toxicity:

Sounds very reassuring, until you remember that the concentrations delivered by the manufacturer/supplier/whatever are not what end up showing up in daily use.

Sometimes that’s not such a big deal — a little evaporation isn’t going to put the fluoride in your water up to toxic levels because you don’t let your water stagnate long enough for that before you drink it.

But that isn’t always the case. Imidacloprid is a pesticide sold by Bayer. In the recommended dosage, lightly powdered across the crops, it’s safe for humans and benign insects such as bees, and Bayer swore up and down that it was benign, because they had tested it at that level of concentration. But one good rain and the stuff concentrates where the water collects, and it has been shown that (for example) it can quite easily kill bees who come to pollinate the crops. In fact, it has been implicated in the whole mysterious die-off of bee colonies, the ones which have scary implications for food supply and economics.

Similar stories happen with drug interactions: a drug is declared “safe” in testing, because the drug company which created it tested at a dosage which will be used as the minimum in prescription and didn’t include a significant number of subjects with high blood pressure, or pregnancy, or whatever. The FDA accepts this because here in the US we buy into the idea that drug companies have our best interests at heart so we shouldn’t get in their way with a lot of pesky regulation. (Unless, of course, they are producing something which competes with a profitable patent held by someone well-connected. Go look up Stevia in Wikipedia for a good laugh — can’t let a cheap natural sweetener compete with Monsanto’s patented and expensive aspartame, after all. Better cook up an illegally anonymous complaint to block it from commercial use for decades until the patents are about to expire!) Then two years after the “safe” drug gets to market a bunch of patients die or are made dangerously ill, there’s a huge scandal, and the drug gets pulled. How many times has that happened in the last couple of decades? I can think of at least 3 high-profile cases, and I’m not even trying hard.

So, yeah, a chemist may find that toxicity levels in things being sold are safe, but chemists don’t always consider how things will be used once they leave the packaging. SKepticism should not end just because the subject wears a lab coat and makes a good wage.

I admit right up front I am no scientist and not well versed on all the relevant factors in play in various situations.  Your Thoughts?