DEAR DR. ROACH: How much mercury is safe? — A.C. ANSWER: The chemical element mercury exists in three forms: elemental mercury, which is the kind in thermometers; inorganic mercury, especially mercuric chloride; and organic mercury, including methyl and ethyl mercury. All of these have toxicities, but the types of toxicities are different for each, and … Continue reading TO YOUR GOOD HEALTH: Less mercury in flu shot than in can of tuna