Prediction of blood lead levels in occupationally exposed workers using toxicokinetic modelling and empirically-derived size distribution data: regulatory implications.
Froines-JR; Liu-WV; Wegman-DH; Hinds-WC
Occup Hyg 1995; 1(4):279-292
The results of analyses of the ability of toxicokinetic models to predict blood lead (7439921) concentrations in occupationally exposed workers and their regulatory implications were discussed. Lead aerosol concentration and distribution data obtained during surveys of various processes in brass/bronze foundries and battery manufacturing facilities were utilized. Exposures producing air lead concentrations of 25 and 50 micrograms per cubic meter (microg/m3) were used in the Hybrid/P and Marcus toxicokinetic models and an International Commission on Radiological Protection lung deposition model to predict the blood lead concentrations in the workers. The results were compared with those predicted by OSHA in their 1978 lead standard. The OSHA standard limited lead exposures to 50microg/m3, which was assumed to be equivalent to a maximum blood lead concentration of 40microg per deciliter (microg/dl). Representative data indicated that blood lead concentrations predicted by the Marcus model assuming an air lead exposure of 25microg/m3 for the various jobs in the brass foundry varied from 13.4 to 21.3microg/m3, which were substantially less than the 34.6microg/m3 predicted in the OSHA standard. When the air lead concentrations were assumed to be 50microg/m3, the estimated percentage of workers having blood lead concentrations greater than 40microg/dl was considerably less than that estimated by the OSHA, 0 to 1.6 versus 6.0%, respectively. The percentage of workers predicted to have blood lead concentrations above 30microg/dl was large only in the furnace and pouring areas of the brass foundry, varying from 27.0 to 81.2%. The authors conclude that blood lead concentrations predicted by the simulations are lower than those predicted by the OSHA standard, suggesting that workers are better protected by the standard than previously believed. Recommendations have been made to reduce the current lead standard to provide greater health protection. Reducing the standard to an exposure that would produce a maximum blood lead concentration of 30microg/dl is feasible, but may require extensive use of respiratory protective equipment.
NIOSH-Publication; NIOSH-Grant; Grants-other; Blood-samples; Heavy-metals; Occupational-exposure; Pharmacodynamics; Mathematical-models; Industrial-hygiene; Brass-foundries; Health-standards; Simulation-methods; Health-protection; Regulations
Environmtl/occupatnl Hlth Scis University of Calfironia 405 Hilgard Ave Los Angeles, CA 90024
Other Occupational Concerns; Grants-other
University of California Los Angeles, Los Angeles, California