Study in Progress
Review of DoD's Proposed Occupational Exposure Limits for LeadBoard on Environmental Studies and Toxicology
Statement of Task
An ad hoc committee will review the scientific and technical basis of the occupational exposure limits (OELs) for airborne lead developed by the US Department of Defense (DoD). Specifically, the committee will evaluate whether the physiologically-based pharmacokinetic model (DoD-O'Flaherty model) used to derive airborne concentrations from blood lead levels was appropriate. Consideration will be given to whether an appropriate model was chosen, whether modifications to the model were appropriately justified, and whether the assumptions in and inputs to the model were reasonable. The committee will not recommend specific OEL values.
The committee will provide an overall summary conclusion on DoD's selected approach and the application of the approach for derivation of lead OEL values. The committee will address the following specific topics:
-- Was the DoD-O'Flaherty model selection, parameterization, and validation appropriate, given the intended purpose - to develop OELs for DoD civilian and military workers?
-- Were the inhalation rates used within the DoD-O?Flaherty model appropriate to represent DoD workers (military and civilian) who are occupationally exposed to lead?
-- Were background levels of lead in air appropriately accounted for within the DoD-O'Flaherty model and representative of DoD workers who are occupationally exposed to lead?
-- Is particle size variation appropriately accounted for within the DoD-O'Flaherty model and representative of lead absorption within the DoD workers (military and civilian) who are occupationally exposed to lead?