The Relationship Between Inhalation Exposure And Renal Excretion Of Some Chemicals.
A simple mathematical model for determining the relationship between exposure concentrations and elimination rates of rapidly excreted chemicals was described. A linear one compartment model was utilized. The treatment was based on the assumption that under steady state conditions the renal administration rate equals the pulmonary uptake rate. The model was valid under the following conditions: the chemical had similar solubility in water and in fat, the chemical had only one major elimination pathway, elimination was governed by first order kinetics, and the elimination rate was rapid so that no significant accumulation occurred over the work week. The model used two parameters, elimination halftime and retention under steady state conditions which could be easily determined experimentally. The method was applied to phenol (108952). For a worker exposed to 5 parts per million phenol, the current standard, the predicted elimination rate at the end of an 8 hour exposure averaged 15.5 milligrams (mg) per hour. The experimental value was 15.3mg/hour. The amount of phenol eliminated after an 8 hour exposure amounted to 98 percent of the total amount eliminated and to 50 percent of the amount absorbed. The authors conclude that only negligible accumulation of phenol over the work week is predicted. This conclusion agrees with experimental data.
NIOSH-Author; Inhalants; Air-monitoring; Air-sampling; Respiration; Ventilation; Chemical-analysis;
Division of Biomedical and Behavioral Science, NIOSH, U.S. Department of Health and Human Services, Cincinnati, Ohio, 13 pages, 3 references