Hearing threshold shifts, white-cell count and smoking status in working men

The association between cardiovascular risk factors and high-frequency hearing loss (HFHL) was examined using medical records from 699 employees with low workplace noise exposure. High-frequency hearing (averaged frequencies of 4000, 6000 and 8000 Hz) was significantly associated with white-blood-cell (WBC) count, smoking status, mean corpuscular volume and the globulin/albumin ratio, especially in men < or = 40 years old. The association with WBC count remained significant after controlling for smoking, cholesterol, blood pressure, and determinants of blood viscosity. An increase in WBC count of 10(3)/mm3 was associated with a 1.9 decibel (dB) decline in hearing (95% Cl: 0.9, 3.0). Controlling for WBC count reduced the association between high-frequency hearing loss and smoking. Ever-smokers (former and current) compared with never-smokers demonstrated a 6.8 dB decline in hearing (95% Cl: 2.4, 11.1). Associations between HFHL and cardiovascular risk factors are most apparent in younger adults with less cumulative noise exposure. HFHL may be a population marker for susceptibility to cardiovascular and cerebrovascular disease.