Animal Breath Data for Estimating the Exposure of Humans to Chlorinated Hydrocarbons

The analysis for various chlorinated hydrocarbons in the breath of workers is useful in determining the extent of exposure. Interpretation of this information requires prior data which relate the quantity of the chemical in the breath to the time after exposure to a known quantity of the compound. Such rate-of-decay curves on human subjects are difficult to obtain; here we have attempted to construct such curves from animal data. A comparison of such data using trichloroethane and tetrachloroethylene showed that it was necessary to establish the relationship between the concentration of the compound, the time of exposure, and the amount exhaled in the breath. Nine rate-of-decay curves for four concentrations and five exposure times have been constructed. The results show that a change in concentration from 100 to 1000 ppm results in an equivalent shift in the quantity of the compound in the breath. A change in the time of a 350-ppm exposure from 1 to 20 hours resulted in only a small change of the compound in the breath. The significance of this and the correlation with human data are discussed.