According to the Chemical Abstract Service, there are now over 50 million chemicals listed in their catalogues. New chemicals are being produced at the rate of 25 per minute. For the artist, here’s the problem: In order to regulate the use? of any chemical, the Environmental Protection Agency must prove the chemical poses an “unreasonable risk”, a process that can take years.  The burden of proof is on the EPA!
For artists, many of the standard materials are organic pigments which are suspected to be carcinogenic and be related to other long-term health problems, but have never been tested. For example, it was recently acknowledged that Titanium Dioxide is potentially carcinogenic if inhaled in powdered form.  This is the most common “white” pigment in use today for art materials. 
What to use?  Linseed oil is flax oil.  Don’t inhale anything in powder form. Keep it simple!