Toxicity of halogenated hydrocarbons in pretreated rats — an experimental model for the study of integrated permissible limits of environmental poisons

Summary

The heavy use and the severe toxicity of several halogenocompounds render these pollutants very important agents in occupational and environmental pathology. Both the biological conditions and the environment by itself might influence their metabolism and then the degree of the resulting toxic effects.

The present investigation extends the most significant parameters in toxicity studies to a number of largely diffused halogenocompounds, with special regard to a possible potentiation through the coexistence of other pollutants or by inducing treatments, such as isopropanol or phenobarbital administration.

Chloroform by itself elicits toxic effects which are influenced by isopropanol challenge. Halothane and trichloroethylene appear devoid of any intrinsic poisonous action on the liver, and cause hepatic injury only in phenobarbital treated rats. In our experimental conditions, bromobenzene, fluobrene® and dichloromethane do not produce any detectable alteration in the liver. On the contrary, both isopropanol and phenobarbital render the rat particularly susceptible to the toxic effects of CCl₄. In fact, treatment with alcohol reduces by two orders of magnitude the vapour concentration of the poison which causes liver necrosis and fatty infiltration, while dosing with barbiturate reduces to one tenth the effective dose of CCl₄. which leads to fatty liver.

These data underline the importance of the possible interaction between the halogenocompounds and the environmental factors or individual habits. Further, they clearly suggest the necessity of taking into account these experimental conditions in setting the maximum permissible limits (MAC or TLV) of halogenocompounds in the environment.