exposures that result in BLLs of 40 μg/dL or below could result in material impairment of health or functional capacity in DOD firing-range workers. It is important to note that BLL generally reflects short-latency, acute health effects of recent lead exposure. However, to some extent, BLLs later in life reflect cumulative lead exposure, so the interpretation of studies of BLLs later in life is problematic with regard to defining a “threshold level” for a health effect. The committee also recognized that peak BLLs, average BLLs, and current BLLs could be expected to have different associations with health outcomes, depending on mechanism of action, latency, and other considerations.
The committee concludes that the current OSHA standard of a BLL of under 40 μg/dL is not sufficiently protective of personnel who have repeated lead exposures on firing ranges. The committee concludes that the evidence is sufficient to infer causal relationships between BLLs under 40 μg/dL and impaired neurologic, hematopoietic, renal, reproductive, and cardiovascular function. Examples of acute and chronic adverse health effects that have been reported in the literature and are relevant for DOD firing-range personnel (and their associated mean BLL, benchmark dose, or lowest observed BLLs) are1
• Reduced fetal growth and low birth weight (maternal BLL under 5 μg/dL).
• Increased cardiovascular-disease mortality (BLL 8 μg/dL or higher).
• Increased serum creatinine, an indicator of renal injury (BLL 8-12 μg/dL).
• Hearing loss (BLL under 10 μg/dL).
• Increased blood pressure (BLL under 10 μg/dL).
• Preterm birth (BLL under 10 μg/dL; evidence on this level is growing stronger).
• Altered postnatal development and growth (maternal BLL under 10 μg/dL).
• Impaired balance (BLL = 14 μg/dL, identified as a benchmark dose).
• Neuronal loss and myelin alterations (BLL = 16.9 μg/dL).
• Slowed visual evoked potentials (BLL = 17-20 μg/dL).
• Decreased psychomotor speed and dexterity and executive function (BLL = 18 μg/dL).
• Decreased erythrocyte, hematocrit, and hemoglobin concentrations (BLL = 20-30 μg/dL).
• Decreased creatinine clearance and glomerular filtration rate, indicators of renal injury (BLL = 20-30 μg/dL).
• Altered parasympathetic and sympathetic activity (BLL = 20 μg/dL or higher).
• Slowed brainstem auditory evoked potentials (BLL = 26-30 μg/dL).
1The reader is referred to Chapter 4 for additional details about individual studies.