Dangers in the studio
Here's a review of some of the dangers and toxins that can be encountered with oil painting. The good news is that they are mostly avoidable!
Disclaimer: I am not an expert and I encourage you to do your own research and act accordingly. This is just a brief review of information that can be easily gathered.
Turpentine and mineral spirits:
These are perhaps the most toxic things in the studio. Turpentine is quite bad to breath but is no used much these days, being replaced by odorless mineral spirits. Mineral spirits and odorless mineral spirits are also unhealthy to breath. If you use these products, be sure to have a well ventilated studio.
Are Odorless Mineral Spirits (OMS) safe? The short answer is "no". While they have less odor and may be somewhat less toxic that standard mineral spirits, their fumes are still toxic.
Safer alternatives to odorless mineral spirits:
Eco-Solve: I currently use this and really like it. It is soy-based, its fumes are non-toxic and it has practically no odor. It costs a bit more than Gamsol OMS, but is a direct replacement.
Turpenoid Natural: This is a non-toxic brush cleaner. It can be used as a thinner only in very small quantities so generally you would use something else if you wanted to paint a thin wash for example. It's a bit thicker than OMS. I tried it but I prefer Eco-Solve.
Paints: some paints such as cadmiums and lead white can be toxic if ingested. Generally you will not be ingesting paint but take care to wash hands before eating and don't eat while painting. Also if you happen to sand a dry painting, take great care not to inhale any of the dust. Do this outdoors and wear a respirator.