could present a more accurate estimate of dose,
however, and eventually relate better to the health
effects of solvents than environmental monitoring of
air (1) to compensate for pulmonary ventilation due
to the workload, (2) when a solvent is absorbed
through the skin rather than or in addition to the
respiratory route, (3) when interaction of the
chemical with other environmental and workplace
chemicals may modify the rate of elimination and
thus influence the toxicity of the chemical. For
example, the concentration of toluene in blood is
increased twofold by simultaneous intake of ethanol.'
Thus monitoring of environmental concentrations
gives misleading information about the internal
exposure to toluene.