Commentary on the regulatory implications of noise-induced cochlear neuropathy.

OBJECTIVE

A discussion on whether recent research on noise-induced cochlear neuropathy in rodents justifies changes in current regulation of occupational noise exposure.

DESIGN

Informal literature review and commentary, relying on literature found in the authors' files. No formal literature search was performed.

STUDY SAMPLE: Published literature on temporary threshold shift (TTS) and cochlear pathology, in humans and experimental animals, as well as the regulations of the US Occupational Safety and Health Administration (OSHA).

RESULTS

Humans are less susceptible to TTS, and probably to cochlear neuropathy, than rodents. After correcting for inter-species audiometric differences (but not for differences in susceptibility), exposures that caused cochlear neuropathy in rodents already exceed OSHA limits. Those exposures also caused "pathological TTS" (requiring more than 24 h to recover), which does not appear to occur with human broadband noise exposure permissible under OSHA.

CONCLUSION

It would be premature to conclude that noise exposures permissible under OSHA can cause cochlear neuropathy in humans.