Abstract

Few experiments have been conducted on the toxicity of solid carbonaceous combustion products. In order to obtain an estimate of the toxicity of black smoke which could be compared with similar estimates for other pollutants, the median dosage to death, (Ct)D 50, has been determined for smoke from burning tetrahydronaphthalene administered to guinea-pigs and mice. Values ranging from 147,000 mg. min./m.³ to 351,000 mg. min./m.³ were obtained at concentrations between 714 mg./m.³ and 1,140 mg./m.³. Animals allowed to associated protected one another to some extent, probably owing to their fur acting as a filter.

In mice the cause of death appears to be blockage of the air passages; deaths after removal from the smoke are unusual. In guinea-pigs haemorrhagic lesions are caused, and delayed deaths are commoner.

The action of smoke on rats resembles its action on mice.

It is pointed out that tetralin smoke is considerably more toxic to animals than is sulphur dioxide in the same concentration. This finding is discussed in relation to atmospheric pollution.