– Gagnaire and Langlais (2005), but a NOAEL could not be derived
as only one high dose of 880 mg/kg bw/d was given.
– Chen and Henderson (2009) exposed rats to continuous noise
(100 dB SPL, 6 h/d, 5 d/week over 3 weeks) superimposed by
an impact noise (up to 110 dB SPL, duration 30 ms at a rate of
1/s). 300 or 400 mg/kg bw S were given by gavage (5 d/week
over 3 weeks). The exposure levels to S only induced a limited
loss of outer hair cells and a very small hearing loss, but a
NOAEL was not attained. Exposure to noise alone led to a clear
hearing loss while there were only slight losses of outer hair
cells. The combined exposures induced hearing and outer hair
cell losses that were greater than the sum caused by S or noise
alone. Thus, this study showed a S/noise interaction but the
high noise levels leading by themselves already to hearing loss
have to be taken into consideration.
– Yang et al. (2009) exposed rats by gavage at 400 mg/kg bw, 5 d/
week over 3 weeks. Hearing ability was impaired and there was
a clear damage of outer hair cells. A NOAEL was not established.
– The study of Chen et al. (2008) did not allow establishing a
NOAEL, but the results of Chen et al. (2007) may allow an
approximation of a NOAEL.