Styrene ototoxic effect depends mainly on the exposure level.
Tanaka-C; Chen-G-D; Henderson-D
Abstr 31st Midwinter Res Meet 2008 Feb; 31:52-53
Campo and colleagues (Campo et al., Hear. Res., 154, 170-180, 2001) reported that styrene-induced hearing loss did not increase with exposure duration. In this experiment, the issue of whether the total dose or the distribution is a key for determining extent of hearing loss was evaluated. Experimental animals (Long-Evans rats) were divided into 4 groups (n=6 rats in each group) to be exposed by gavage to styrene at a dose of 800 mg/kg once a day for 5 days per week for 3 weeks (3w-800 group), at 400 mg/kg for 6 weeks (6w-400 group), at 200 mg/kg for 12 weeks (12w-200 group), and at 100 mg/kg for 24 weeks (24w-100 group). The 3w-800-mg-group developed an up to 35-dB permanent threshold shift (PTS) and an up to 60% OHC loss in the middle turn. the 6w-400 group showed an up to 15-dB PTS and an up to 40% OHC loss, which were slightly higher than those induced by a 3-week-exposure at a dose of 400 mg/kg. The 12w-200 group showed less than 10% OHC loss and less than 10-dB PTS. The 24w-100 did not show significant damage, although the animals received the same amount of styrene as the other animals. The data indicate that exposure level is critical for styrene ototoxicity and that the ear's propensity to accumulate the toxic styrene is limited. A clinical implication of this research is that short, transient, high-level styrene exposure can be ototoxic.
Noise-exposure; Exposure-levels; Noise-induced-hearing-loss; Noise-exposure; Noise; Hearing; Hearing-disorders; Hearing-loss; Laboratory-animals; Animals; Styrenes; Exposure-levels
Abstracts of the 31st Midwinter Research Meeting
Washington University, St. Louis