Abstract
Purpose
Arsenic is a toxic metalloid that carries number of potential risks to human health, although there is little evidence of the ototoxic effect of arsenic. The aim of this study was to identify the relationship between arsenic exposure and hearing loss by measuring blood arsenic concentrations and hearing among miners.
Materials and methods
This research is a retrospective case control study. Included in the study were miners employed in a single silver mine whose blood arsenic concentrations were high. A comparison was made on the pure tone audiometry measurements taken from miners exposed only to arsenic (Group 1), those exposed to both arsenic and noise (Group 2) and a control group exposed to neither arsenic nor noise (Group 3).
Results
It was found that for both ears at all frequencies, the hearing level of Group 3 was better than the hearing levels of both Group 1 and Group 2. There was no correlation between the blood arsenic levels and hearing levels in both ears.
Conclusion
This study has revealed the ototoxic effects of arsenic. As blood arsenic concentrations do not reflect long-term exposure, no correlation was identified between blood arsenic concentrations and hearing levels. Further studies will be needed to clarify the mechanisms involved in the effect of arsenic on hearing. This paper represents the largest study to date focusing on the isolated effects of arsenic on hearing through the use of a clinical auditory test.
1
Introduction
Arsenic is a toxic metalloid that is found in soil, water, air and rocks, with inorganic arsenic compounds being the most prevalent and toxic. Arsenic leaches from rock formations into water sources, and arsenic pollution of the groundwater is a common problem around the world. Exposure to arsenic occurs via oral, respiratory or dermal routes, and is an important issue in public health. The toxicity of arsenic poses a number of potential risks to human health, and there have been numerous studies reporting various health effects of arsenic toxicity, including carcinogenicity, neurotoxicity, diabetes, hematologic disorders, gastrointestinal disorders, cardiovascular disorders and pregnancy complications .
Although in most of the cases exposure to arsenic occurs via the groundwater, occupational exposure is also common. The US Environmental Protection Agency (EPA) determined the permitted concentration of arsenic in water as 10 μg/L (10 ppb) .
In Turkey, the Simav Plain is one of the regions in which concentrations of arsenic are high, being situated in an area with active tectonics. In a study of the area, it was found that the average total arsenic concentrations in samples collected from local groundwater was 99 ppb, with a maximum of 561 ppb . In another study in which soil samples were analyzed for total arsenic content, an average value of 49 ppm and a maximum of 833.9 ppm were found. Based on the knowledge that the world average value for arsenic content in soil is 1.5 ppm, the arsenic content of the soil in this region can be considered extremely high . The region contains a silver mine, and so high levels of arsenic can be expected in miners.
Previous research has suggested that arsenic may be ototoxic in humans, although there is little evidence available charting the association between arsenic and hearing. Studies into the effect of arsenic exposure on hearing function are very limited, and so it is the aim of this study to clarify the relationship between arsenic exposure and hearing loss by measuring blood arsenic concentrations and hearing among the miners employed at the above-mentioned mine.
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