Brainstem auditory evoked responses and audiological thresholds were used as biomarkers for neuro-ototoxicity in adults with chronic lead (Pb) intoxication from long-term Pb exposure in ceramic-glazing work. Venous blood samples collected from 30 adults (15 men and 15 women) indicated a mean blood Pb level of 45.1 μg/dL (SD, 19.5; range, 11.2 to 80.0 μg/dL) and in excess of the World Health Organization health-based biological limits (men, 46.2 μg/dL; SD, 19.6; range, 18.3 to 80.0 μg/dL; women, 44.0 μg/dL; SD, 20.1; range,11.2 to 74.2 μg/dL). Mean auditory thresholds at frequencies susceptible to ototoxicity (2.0, 3.0, 4.0, 6.0, and 8.0 kHz) revealed sensory-neural hearing loss in men, which may be attributable to occupational noise exposure in combination with Pb intoxication. Bilateral brainstem auditory evoked response tests on participants with elevated blood Pb levels (mean, 47.0 μg/dL) showed delayed wave latencies consistent with sensory-neural hearing impairment. The results suggest that environmental noise exposure must be considered an important factor in determining sensory-neural hearing status in occupationally Pb-exposed adults.
From the Department of Neurology, Massachusetts General Hospital, Harvard Medical School, The Biological Laboratories, Cambridge (Dr Counter); and the Audiology Department, Harvard University Health Services, Shriver Center UAP LEND Program, Waltham (Dr Buchanan); Massachusetts.
Address correspondence to: Dr. S. Allen Counter, Harvard University, The Biological Laboratories, 16 Divinity Avenue, Cambridge, MA 02138; firstname.lastname@example.org.