I put the word "chemicals" in quotation marks because, of course, everything is a chemical. I just wanted to point out that we shouldn't pick just one chemical (e.g. BPA) and heap all the blame onto it. As a society, we have to be concerned about the potential dangers of every synthetic chemical
I wouldn't put too much importance on the synthetic / natural distinction.
Lead, tobacco, and various radioactive elements (uranium, radium, thorium, and radon) are all perfectly natural. If you were harmed by chemicals in the last century, it was probably one of them.
There are also thousands of lab-made chemicals that never make the news because they're just not harmful.
The UK-based non-profit Sense About Science has produced some literature trying to combat what they call "chemophobia," the fear of man-made chemicals:
I mean, yeah, don't drink DDT. But don't try to make your drinking water "more natural" either, thank your city for treating it with a little bit of synthetic (and toxic in large doses) chlorine, and enjoy a day free of all-natural additives like cholera.
"natural" is in some ways a proxy for "understood". We know lead, tobacco, and radiation are toxic. We have hundreds of years of evidence. On the other hand brand-new man-made chemical X that was just invented yesterday has no track record whatsoever. We just don't know.
I try to read food labels, and it's exhausting trying to keep up with all the new chemicals they put in food (or in furniture, or plastics, or whatever) so rough heuristics become useful and help avoid spending six hours at the grocery store.
I'm not opposed to proxies, I just think "anti-synthetic" is a particularly bad one. Synthetics are so frequently protective that avoiding them is more likely to do harm than good.
A better heuristic might be:
Humans worry too much.
Or:
Don't invent heuristics that scientists working in the relevant field think are unnecessary.
Toxicology is full of smart people learning things on our behalf. They have models and simulations and labs to scrutinize new chemicals for us, or even just to avoid massive class action lawsuits.
Among their findings is the fact that we can't seem to make anything nearly as toxic as nature can. Even when we try we come up short by a factor of like a freaking million:
If you want simple guidelines to save time with groceries: avoid lunchmeats to reduce your risk of (natural) listeria, cook your chicken to avoid (natural) salmonella, don't can your own food to avoid (natural) botulism, and call it a day.
Or maybe don't worry about toxins at all, because they kill statistically almost no one, and instead: work out, eat some leafy greens, avoid obesity, smoking, drinking, guns, and unnecessary car trips.
At that point you're so far in the lead that if you die from a random chemical, just shake your fist at the gods and die knowing you did far more than most people. If you do die from a chemical, you didn't die from not being smart, you died from not being lucky, and could have easily been crushed by a meteor.
I think your use of it is pretty clear, but it's interesting to note that quotation marks are also used for scare quotes. Two possible usages in this case with almost entirely opposite meanings.
If it is some sort of chemical, it was introduced around 70s (later than most plastics) and is still in widespread and increasing use. Few such targets.
BPA in plastics is polymerized, but BPA in thermal paper is free molecules, which are easier absorbed. Thermal paper didn't become widespread until the 70s, so BPA is still a possible candidate.
Or the chemical had to reach a threshold concentration in the environment and/or our bodies before having a noticeable effect, which could have taken 20 years..