A poison is any chemical substance that can cause death or injury if taken in large enough quantities. Every common drug or medicine, safe in the recommended dosage, is in essence a poison; so too are apparently innocuous household substances such as salt and even water (both are fatal in excess). Most poisoning incidents needing first aid are acute cases, resulting from the immediate or short-term effects of the poison. Chronic poisoning is more likely to result from long-term exposure to a chemical. Impaired intelligence in children, for example, has been linked to the lead in traffic fumes. Acute poisoning accounts for over 20 per cent of emergency medical admissions to hospital. The poison is usually self-administered – and usually intentionally in the case of adults. Locking away all potential poisons would cut drastically the rate of accidental poisoning among toddlers and children, and ensuring they are correctly labelled would do the same among adults. First aid for a person suffering from poisoning means, first, as always, checking that you are in no danger in going to his or her aid. It is better to wait for qualified assistance than to become the next casualty. A casualty who is unconscious but breathing normally should be put in the recovery position. Have them transferred to hospital as soon as possible, together with any evidence about the possible cause of the poisoning, such as tablets or empty bottles. If the casualty has stopped breathing, clear the airway and begin artificial respiration; use the mouth-to-nose method if the person’s mouth may be contaminated by the poison. Ask conscious casualties as soon as you can what they have taken or how they were poisoned, because they may lapse into unconsciousness before reaching hospital. If their mouth appears burned, give conscious casualties a little water or milk to drink, but never try to induce vomiting. The stomach is an organ partly suited to containing corrosive chemicals because it is normally bathed by its own hydrochloric acid; so poisons are often better left there temporarily. If someone vomits a corrosive chemical this may burn and inflame the mouth and throat, possibly affecting breathing. If the casualty does vomit, however, send samples with him or her to the hospital.