Oral arsenic exposure leads to hearing loss
Oral exposure to arsenic can cause hearing loss in young people, a new study from Bangladesh has shown.
The study included 77 healthy individuals (mean age 20.81±4.34 years) who were exposed to either control tap water (n=29; mean age 21.52±2.34 years) or tube well water contaminated with 20.6, 53.8, 221.0 and 22.2 µg/L of arsenic (n=48; mean age 20.38±5.17 years). Those who regularly used earphones or had a drinking habit were excluded from the study.
Pure tone audiometry was used to measure the hearing thresholds of the participants at frequencies of 1, 4, 8 and 12 kHz.
Participants who received tube well water had significantly higher levels of arsenic in the urine, hair and toenails (p<0.0001 for all). Similarly, hearing levels at 4 (p<0.01), 8 (p<0.0001) and 12 (p<0.0001) kHz were significantly lower in participants who received the tube well water than those in controls.
After categorizing hearing levels with the mean hearing threshold values at different frequencies (6 decibels [dB] at 1 kHz, 7 dB at 4 kHz, 19 dB at 8 kHz and 35 dB at 12 kHz), the investigators performed binary logistic regression to determine the risk of hearing loss.
Notably, those who received tube well water had significantly higher risks of hearing loss at 4 kHz (odds ratio [OR], 7.60; 95 percent CI, 1.56 to 57.88; p<0.05), 8 kHz (OR, 5.00; 1.48 to 18.90; p<0.05) and 12 kHz (OR, 8.72; 2.09 to 47.77; p<0.01) than those who received control tap water even after adjusting for body mass index, sex, age and smoking history.