Astrid, a quick search found this comment at the
Art Materials Information and Education Network
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Mike,
Thanks for posting.
Let everyone be aware that "English Distilled Turpentine" is no safer than any other gum Turpentine. In general, all the turpentines present serious health risks on the order of higher organic solvents, principally in its risk for skin damage and allergic reactions to the vapors. Avoid it. Use a conservator's services unless you can protect your health. "
In relation to the 'mad artists', there may be more concerns to them in the old days because of lead and the glues they used. Hatters and milliners (makers of female hats) also suffered as they used mercury, hence the term "mad as a hatter".
Little
more info in the Wikipedia