Maximum Permissible Urinary Concentrations: Their Relationship to Atmospheric Maximum Allowable Concentrations

There are two approaches to the determination of maximum permissible concentrations in urine (M.V.C.'s). The first is the direct method of comparing the concentration of toxic substances with the incidence of symptoms of intoxication. The second is the indirect approach of considering the worker as a sampling device and relating the urinary excretion to the atmospheric concentration to which the worker is exposed. In this case the M.V.C. will, in general, be the urinary concentration which corresponds to the atmospheric maximum allowable concentration (M.A.C.). I will employ this second approach. Let us consider briefly three factors: (I) collection of sample; (2) calculation of results; (3) relationship of M.V.C.'s to M.A.C.'s.