Hearing loss, lead (Pb) exposure, and noise: a sound approach to ototoxicity exploration

ABSTRACT

To determine the state of the research on ototoxic properties of Pb, evaluate possible synergistic effects with concurrent noise exposure, and identify opportunities to improve future research, we performed a review of the peer-reviewed literature to identify studies examining auditory damage due to Pb over the past 50 years. Thirty-eight studies (14 animal and 24 human) were reviewed. Of these, 24 suggested potential ototoxicity due to Pb exposure, while 14 found no evidence of ototoxicity. More animal studies are needed, especially those investigating Pb exposure levels that are occupationally and environmentally relevant to humans. Further investigations into potential interactions of Pb in the auditory system with other hazards and compounds that elicit ototoxicity are also needed in animal models. To better assess the effects of Pb exposure on the human auditory system and the possibility of a synergism with noise, future epidemiological studies need to carefully consider and address four main areas of uncertainty: (1) hearing examination and quantification of hearing loss, (2) Pb exposure evaluation, (3) noise exposure evaluation, and (4) the personal characteristics of those exposed. Two potentially confounding factors, protective factors and mixtures of ototoxicants, also warrant further exploration.

KEYWORDS:

• Ototoxicity
• hearing loss
• lead (Pb)
• noise
• exposure mixtures

Acknowledgments

The authors wish to thank Marie O’Neil for her support and feedback regarding this review, and Stephanie Sayler for assistance in formatting and editing.

Disclosure

The authors declare no conflicts of interest related to this research.

Additional information

Funding

This work was supported by aUniversity of Michigan Rackham Merit Fellowship and a Environmental Toxicology and Epidemiology Program fellowship funded by the National Institute of Environmental Health Sciences [T32 ES007062].