How To Think About Safety and Toxicology

Toxicology is the science of understanding how chemicals affect humans, animals, and the environment. It helps us determine what’s safe and what’s not. A key principle is “the amount matters.” Even water can be dangerous in excess, while many other chemicals are safe even at high levels. 

How do we figure this stuff out? Right now, testing is the only way. We hope at some point AI will be able to predict what is safe and what is not, but right now, it's simply not good enough. So, we test. First, we test on single cells, then animals and then humans. I know, animal testing is horrible, but it’s the fact that any new chemical in the US still needs animal data before it can be tested in humans. In the EU, this stopped around 2013, but still occurs under a lot of situations. There are technologies now that promise to eliminate animal testing altogether, but they are still evolving. So, while a finished product, your moisturizer for example, might say “not tested on animals” or “cruelty free” or whatever, the fact is that if it contains any chemicals created in the last 80 plus years, that chemical was at some point tested on animals.

It’s important to remember that toxicology tests done in the lab, whether in cells (in vitro) or animals (in vivo), don’t always reflect what happens in the real world. For example, lab tests often use much higher doses than people would ever encounter, or test substances in ways that don’t match how we actually use them.

There are also big differences between species: aspirin is a trusted medicine for people, but can be toxic to dogs. Similarly, some chemicals that are harmful in human tests looked fine in animal tests. Environmental toxicology adds another layer of complexity. Ingredients safe for people can harm the environment if enough gets out there. A great example of a naturally occurring chemical that is safe for humans, but harmful to marine life is prymnesin, a toxin produced by the golden alga prymnesium parvum. While prymnesin does not appear to affect humans, it is highly toxic to fish causing large fish kills in lakes and rivers where the algae bloom.