Mercury poisoning is more common in chronic form, mainly occurring during production activities, caused by long-term inhalation of mercury vapor and mercury compound dust. The main symptoms are mental-neurological abnormalities, gingivitis, and tremors. Acute mercury poisoning occurs when large doses of mercury vapor are inhaled or mercury compounds are ingested. People who are allergic to mercury can be poisoned even if mercury oil-based preparations are applied topically. Workers who are more likely to be exposed to mercury include those working in mercury mining, amalgam smelting, gold and silver extraction, mercury rectifiers, as well as vacuum pumps, lighting, instruments, thermometers, dental amalgam, fulminate of mercury, pigments, pharmaceuticals, nuclear reactor coolants, and anti-atomic radiation materials. Organic mercury compounds were previously used mainly as agricultural fungicides, but they are highly toxic and are no longer produced or used in my country.