Associations of prenatal exposure to lead and mercury with auditory function in infants

Résumé fourni par la source

PURPOSE: This study examined the association between lead (Pb) and mercury (Hg) exposure during early brain development with auditory function in infants. METHODS: Auditory function of six-month-old infants from the Maternal-Infant Research on Environmental Chemicals-Infant Development (MIREC-ID) cohort was assessed with minimal auditory response levels (MRLs) to warble tones and speech in soundfield, tympanometry, and otoacoustic emissions (OAEs; transient - TEOAEs; and distortion product - DPOAEs). Pb and total Hg concentrations in blood samples were obtained at three time points: maternal blood samples at the first and third trimesters of pregnancy, and umbilical cord blood samples at birth. RESULTS: Higher maternal blood Pb concentrations during pregnancy were significantly related with low OAEs. The associations were stronger for TEOAEs, in particular TEOAE reproducibility, than DPOAEs, and were stronger in the left ear compared with the right ear for TEOAEs. Pb was barely associated with MRLs. No clear evidence of association between Hg exposure and auditory function (OAEs and MRL) was found. CONCLUSIONS: Developmental exposure to low Pb concentrations are associated with a reduction of outer hair cells responses to sounds, suggestive of a decrease in inner ear function. Further studies are needed to verify these results in a larger sample of infants.

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