Fire is dangerous, and we know it kills a bunch of people.
Fire retardants may be dangerous, they may harm a bunch of people, but we're not sure how many, nor how they are harmed. Research is sometimes conducted poorly, or good research is interpreted poorly by reporters.
We need to balance risk and cost. People dying in fires is bad. People getting a bunch of diseases is also bad. We need to find out which is more likely.
Perhaps my tone came across as snarky because the person providing the TL;DR actually "assailed" me for asking for a TL;DR. Sorry about that.