Heavy Metals Exposure, Noise and Hearing Loss Among E-waste Workers in Accra, Ghana

Research Trainee: Krystin Carlson, PhD Candidate, Dept. of Environmental Health Sciences at the University of Michigan

Faculty Researcher: Richard Neitzel, PhD, CIH, Assistant Professor of Environmental Health Sciences at the University of Michigan

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Surrounding market and environment. Waste site is to the right and behind the market street.

Hearing loss (HL) is a debilitating but often overlooked disease that has a profound impact on human health and quality of life. Individuals with HL suffer adverse social, psychological, educational, and occupational outcomes. While HL from noise has been recognized for hundreds of years, recent research has identified an association between environmental and occupational exposure to nonessential heavy metals- including lead (Pb) and cadmium (Cd)- and hearing loss. Our study was designed to provide much-needed information about heavy metals exposures associated with electronic waste (e-waste), an increasingly important potential source of heavy metals exposure for many communities worldwide. To address this issue, our study team worked with colleagues in the University of Ghana’s School of Public Health to assess metal and noise exposures in the Agbogbloshie e-waste recycling site in Accra, Ghana. We recruited 57 male workers from the e-waste site to participate in the study. At a clinic near the e-waste site, we obtained a variety of measurements from each subject, including a hearing test, a comprehensive occupational health and exposure survey, a physical examination, and collection of a blood sample. We also asked workers to wear a personal noise dosimeter for up to 24 hours to evaluate noise exposures.

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Many types of metals and parts are separated: copper, iron, aluminum, and lead.

Our subjects were primarily young, low income, and Muslim, and had worked in e-waste activities and lived near Agbogbloshie for approximately 6 years on average. Average occupational noise exposures were just below the 85 decibel Recommended Exposure Limit in the US. We found elevated concentrations of lead and cadmium in subjects’ blood samples, and the levels in some workers exceeded the recommended levels. The pattern of the hearing loss across different hearing test frequencies was consistent with noise-induced hearing damage; more than half of subjects were found to have a “noise notch” at the frequencies most vulnerable to damage from noise. Our statistical analyses indicated that smoking and greater task diversity had adverse impacts of hearing outcomes, as did higher blood levels of lead, cadmium, and selenium, and a greater number of years living near Agbogbloshie. Unexpectedly, higher blood levels of iron had a protective effect against hearing loss, as did average noise exposure and blood mercury level.

This global collaboration has resulted in an increased understanding of the relationships between heavy metals, noise, and HL. Given the ubiquitous nature of noise exposure in the US, the results of this study are highly relevant to US workers with occupational exposures to heavy metals, including e-waste recycling workers employed in US-based recycling facilities.

Project Abstract

Publications resulting from this project:
Burns KN, Sun K, Fobil JN, Neitzel RL. Heart Rate, Stress, and Occupational Noise Exposure among Electronic Waste Recycling Workers. International Journal of Environmental Research and Public Health. 2016;13(1):140. doi: 10.3390/ijerph13010140. PMCID: PMC4730531.