Is occupational noise exposure during pregnancy a risk factor of damage to the auditory system of the fetus?

In the Province of Quebec, the regulated daily noise exposure limit is 90 dBA-8h. This limit value also applies to pregnant women. Experimental studies suggest however, that this standard is not sufficiently stringent to protect the auditory system of the fetus, particularly in cases of low-frequency noise exposure. An exploratory study was undertaken to assess this possibility. A total of 131 children were examined. Their mothers had worked, while pregnant with that child, in noise conditions ranging from 65 to 95 dBA-8h. Results show a three-fold increase in the risk of having a high-frequency hearing loss in the children whose mothers were exposed to noise in the range between a LAeq,9 m of 85 to 95 dB, and a significant increase in the risk of hearing loss at a frequency of 4000 Hz when these exposures involved a strong component of low-frequency noise.