Hearing loss in humans drinking tube well water with high levels of iron in arsenic\u2013polluted area

Tingchao He,Masashi Kato,Nobutaka Ohgami,Reina Negishi-Oshino,Nazmul Ahsan,Kyoko Ohgami,Anwarul Azim Akhand,Yoko Kato,Huadong Xu,Xiang Li,Ichiro Yajima

doi:10.1038/s41598-019-45524-1

Tingchao He, Masashi Kato + Show 9 more

Open Access

https://doi.org/10.1038/s41598-019-45524-1

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Journal: Scientific Reports	Publication Date: Jun 21, 2019
Citations: 11	License type: open-access

Affiliation: Nagoya University, University of Dhaka

Abstract

Well water for drinking with increased levels of iron in arsenic-polluted areas has been reported worldwide. Oral exposure to arsenic has been shown to be associated with hearing loss, while there is no evidence for an association between excessive exposure to iron and hearing loss in humans. In this study, we determined iron and arsenic levels in biological samples and hearing levels by pure tone audiometry (PTA) in subjects in a control area and an arsenic-polluted area in Bangladesh. The iron level in well water in the arsenic-polluted area was significantly higher than that in piped supply water in the control area. Subjects in the polluted area (n = 109), who had higher iron and arsenic levels in hair and toenails than those in subjects in the control area (n = 36), had an increased risk of hearing loss at 8 kHz and 12 kHz after adjustments for age, gender, smoking and BMI. Significant associations of the exposure group with hearing loss at 8 kHz and 12 kHz remained after further adjustment for arsenic levels in toenails and hair. Thus, this pilot study showed that excessive exposure to iron via drinking water is a potential risk for hearing loss in humans.

Highlights

Well water for drinking that is contaminated with toxic elements including arsenic has been reported worldwide[1,2,3]
Another study showed that insulin resistance due to dietary iron overload reduced the number of ribbon synapses that led to auditory brain response (ABR) threshold elevations[12], suggesting that excess exposure to iron might affect hearing levels in experimental animals
There is no information about the association between excessive exposure to iron in drinking water and hearing loss in humans, oral exposure to arsenic has been shown to be associated with hearing loss in humans[15]

Summary

Introduction

Well water for drinking that is contaminated with toxic elements including arsenic has been reported worldwide[1,2,3]. We compared iron and arsenic levels in toenails and hair in a control group drinking piped supply water and an exposure group drinking tube well water contaminated with arsenic in Bangladesh.

Results

Conclusion