How and Why the Dose (And Your Genes) Make the Poison

Or why I’m not afraid of fava beans, but 500 million people around the world should.

Would you like some Chianti with those fava beans? (Photo by amirmasoud on Unsplash)

While waiting for a radio interview on the case for fluoridation in potable water, I looked at the bottle of water I had with me. I read the ingredients and chuckled because the brand claims to be “pure water.” The label mentions that the water is “enhanced with minerals for a crisp taste.” So I looked at the ingredients: Purified water, less than 0.5% of calcium chloride, sodium bicarbonate, and magnesium sulfate.

I wasn’t scared of those chemicals, of course. Less than 0.5% means the 500 mL of water contained less than 2500 milligrams (about 0.09 ounces) of those chemicals. (Correct my math in the comments if I got that wrong, please.) Not only that, but those chemicals are not exactly poisons at that concentration in the half liter of water. They probably occur at higher concentrations in other products.

A Quick Chemistry Lesson

For the uninitiated, calcium chloride is a salt used for road de-icing, in home dehumidifiers, and in some foods. Much of it probably enters your groundwater if you’re in a location where it is used in copious amounts to de-ice roads. And you’ve probably gotten some of it on your hands if you…