Chemical burns causing systemic toxicity.

Chemical burns can cause severe local pain and tissue damage which require specialized treatment. They account for one patient in six admitted to a bums unit after an industrial accident (Herbert & Lawrence, 1989). Strong acids and alkalis are the commonest cause. The initial treatment of nearly all such burns is to drench the affected area with water, remove contaminated clothing and continue dre-nching. There is however a theoretical danger of explosion if water is used to remove certain alkali metals (sodium, potassium, rubidium and caesium) because they liberate hydrogen gas and heat. Strong acids and alkalis also evolve heat when water is added, but the heat is dissipated rapidly if sufficient water is used. The local effects of chemical tissue destruction can be very severe and may distract attention from the dangers of systemic toxicity, which are greatest for burns due to yellow (white) phosphorus, hydrofluoric acid and phenols. Yellow phosphorus is an important intermediate in the production of phosphorus pentoxide, phosphoric acid and phosphorus chloride and sulphide. It is also used in tracer bullets. It ignites in air to produce the acid gas phosphorus pentoxide. Wounds should therefore be drenched and then left immersed in water or covered with wet dressings. The phosphorus particles can be removed with forceps and stored under water. They are easier to see if washed or swabbed with a 1% copper sulphate solution, when black copper sulphide is formed, followed by 1% sodium bicarbonate solution to neutralize any phosphoric acid. Only dilute copper sulphate solution should be used, to avoid systemic absorption of copper ions, which may result in haemolysis (Summerlin et