If you read MSDS's you will get the impression that virtually everything is toxic and should be avoided?and in a way they should be.
Since I've worked in the composites industry for about 40 years, I do have some experience with these products and right now I work for a company that manufactures polyesters.
Styrene odor, which is much of the "smell" that people complain about, is something you should limit your contact with, but it can be detected by your nose at very low concentrations. It can easily be detected at levels far below what's allowed in the workplace and these levels are based on what a person can be in contact with on a daily basis. So just because you can smell it, doesn't mean you're being exposed to harmful levels.
Styrene (polyesters), unlike other chemicals in the coatings industry don't have the problem of people becoming sensitized and then having serious health complications from brief or incidental contact at a later date like some types of paints and epoxies do.
As I said before, in 40+ years I?ve never met anyone that has had health related issues from polyesters and that covers thousands of people (there must be some people out there though). Yet I know many people that have problems related to paints and epoxy. So when someone puts polyesters in the same or worse class than some epoxies I feel it can be very misleading.
.....lol