Drugs

Many drugs can be taken accidentally or in an attempt at suicide, and the most common ones are sedatives such as sleeping tablets and tranquillizers, including barbiturates and drugs like diazepam. These drugs usually produce a gradual onset of unconsciousness which may last for a prolonged period. Breathing may become slow and shallow, and in severe cases it may stop completely. In cases of barbiturate poisoning, unconsciousness may continue for several days, although most patients eventually recover. Simple painkillers such as acetylsalicylic acid and paracetamol may also be taken in overdose. Acetylsalicylic acid causes vomiting, ringing in the ears, and deep rapid breathing, and in severe overdose it can cause bleeding in the stomach, leading to vomiting of bright red blood. Paracetamol usually does not produce immediate symptoms except occasional vomiting, but it can cause serious liver damage after two or three days if more than twenty to thirty tablets are consumed. Neither of these drugs typically causes unconsciousness.

Disinfectants

Many disinfectants such as carbolic acid, cresol, and bleaching solutions are toxic. Carbolic acid and cresols can cause severe skin irritation when in dilute form and painless white burns when concentrated. If swallowed, they cause burns in the mouth, severe vomiting, collapse, unconsciousness, and sometimes convulsions. Bleaches, which usually contain sodium hypochlorite, can irritate the skin and are poisonous if swallowed. The affected person may experience a burning sensation in the mouth and stomach and feel generally unwell. When bleaches come into contact with acids, they release fumes that irritate the lungs, causing coughing, breathlessness, and a burning sensation in the throat, although these fumes are usually not highly toxic and symptoms tend to subside quickly.

Solvents, Petroleum Products, and Fuel Oils

These substances mainly cause symptoms when their vapours are inhaled accidentally. The symptoms include drowsiness, dizziness, nausea, and sometimes vomiting. In cases of severe exposure, the person may become unconscious. If these substances are swallowed, they produce similar effects, but nausea and vomiting are usually more severe.

Cyanide

Cyanide, including hydrogen cyanide gas and solid forms, is extremely poisonous and acts very rapidly. It causes a burning sensation in the mouth and abdomen if swallowed, but its main effect is general poisoning. The person will experience shortness of breath, anxiety, and rapid loss of consciousness, and convulsions may occur. Death can take place within a few minutes.

Carbon Dioxide

Carbon dioxide is an odourless gas that can cause suffocation when it replaces oxygen in the air. This situation may occur during fires in ship holds, fermentation of grain, or in refrigerated cargo spaces. A person exposed to high levels of carbon dioxide may feel giddy, experience difficulty in breathing, and develop a headache, eventually collapsing and losing consciousness. Since the gas is heavier than air, it tends to accumulate in lower areas.

Carbon Monoxide

Carbon monoxide is an odourless and highly poisonous gas found in fires, engine exhausts, and explosions. Even small amounts can be dangerous. A person affected by carbon monoxide may feel giddy, weak, and may quickly become unconscious. In severe cases, the lips may appear bright red and the skin may take on a pink colour. Oxygen therapy is essential and should be administered as soon as possible.

Refrigerant Gases

Refrigerant gases such as ammonia can cause severe irritation when inhaled. In low concentrations, ammonia causes eye irritation and watering, but in high concentrations it can lead to severe breathing difficulty, collapse, and death. Carbon dioxide is also present in refrigerants and may cause suffocation. Methyl chloride is a colourless gas with an ether-like smell that can cause drowsiness, confusion, nausea, vomiting, convulsions, coma, and death, and it is also highly explosive, so no open flames should be present. Freon is generally harmless but can become dangerous in high concentrations because it reduces oxygen levels, leading to faintness, staggering, collapse, and unconsciousness.

Poisonous Gases from Refrigerated Cargo

Certain refrigerated cargoes such as fruits, vegetables, and cheese naturally produce carbon dioxide during storage. If refrigeration fails, additional dangerous gases such as carbon monoxide, ammonia, hydrogen sulfide, and hydrogen may be produced. These gases can be extremely toxic and sometimes explosive, so strict safety precautions must be followed to prevent poisoning and fire hazards.

Other Gases

Trichloroethene, also known as trilene or “trike,” is a volatile anaesthetic gas used medically and as a cleaning agent. It can cause drowsiness, confusion, nausea, vomiting, coma, and even death. Some individuals misuse it by inhaling it deliberately, which is highly dangerous.