| IJOMEH
![Zdjęcie](http://oldwww.imp.lodz.pl/gal_cache/tnm_e91ab88191cfdcd.jpg)
INTERNATIONAL JOURNAL OF OCCUPATIONAL MEDICINE AND ENVIRONMENTAL HEALTH
Current website - http://ijomeh.eu
Int. J. Occup. Med. Environ Health 2008;21(1):47-57 |
DOI 10.2478/v10001-008-0008-x |
HAZARDS TO HEARING FROM COMBINED EXPOSURE TO TOLUENE AND NOISE IN RATS |
SØREN P. LUND, GITTE B. KRISTIANSEN |
Abstract
Introduction: The main risk of hearing impairment from workplace
exposure to organic solvents may stem from the potentiation of effects
caused by concomitant noise exposure. The aim of the present study was
to identify the main hazards from combined long-term, low-level
exposure to noise and aromatic organic solvents, like toluene, in rats.
Material and Methods: The rats were exposed to steady-state,
wide-band noise (WBN) and 0 ppm, 100 ppm, 200 ppm and 500 ppm toluene
for 90 days. Hearing was assessed using Auditory Brain Stem Responses
(ABR) and Distortion Product Oto-Acoustic Emissions (DPOAE) eight weeks
after exposure. The impact of noise composition on the interaction
between solvent and noise exposure was investigated in rats exposed for
10 days either to 0 ppm, 500 ppm, 1000 ppm or 1500 ppm toluene and
either WBN or impulse noise. ABR and DPOAE tests were performed before
and two weeks after exposure. Results: Long-term exposure of
rats to WBN and toluene at 500 ppm or less did not show any increase in
hearing impairment compared to the rats exposed to noise only.
Synergistic interaction was demonstrated in short-term exposure to 1500
ppm toluene and both to WBN and impulse noise, but hearing impairment
was much larger when following exposure to impulse noise. Conclusion:
In combined exposure to low-levels of noise and toluene, even a
long-term exposure did not reveal a potential hazard of hearing
impairment. Synergistic interaction in combined short-term exposure to
toluene and noise was noted both with respect to WBN and impulse noise,
but the impulse noise was much more disruptive than WBN at the same
level of noise exposure. The ototoxicity of organic solvents may
primarily be a hazard also to human hearing due to the exacerbation of
hearing loss by a possible co-exposure to especially harmful noise such
as impulse noise.
Key words
Hearing, Wide Band Noise, Impulse noise, Interaction, Organic solvents, Toluene, Rat, ABR, DPOAE![](images/buttons/buynum_blue_EN.gif)