OPS (Organo Psycho Syndrome) or painter's disease is caused by prolonged and frequent exposure to the fumes of solvents such as turpentine. The risk for the oil painter many times lower than in other paint-related professions. The paint itself contains no solvent and the little bit of white spirit to rinse the brushes is in no proportion to the above quantities. Of course, it is good to ventilate the work area (regularly). Incidentally, it has not been proven that turpentine, unlike white spirit, contributes to the risk of OPS. The harmful effects of turpentine are more likely to involve skin disorders and allergies, while when ingested by mouth, a dose of 120 - 180 ml is even fatal. More on the background in "Health - more on painter's disease"