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Updated: May 23, 2025

Long-term Behavioral and Reproductive Consequences of Embryonic Exposure to Low-dose Toxicants
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Long-term Behavioral and Reproductive Consequences of Embryonic Exposure to Low-dose Toxicants

Published on: March 6, 2018

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

Sandra Fortin1, Benoît Jutras2, Maryse F Bouchard3

  • 1École d'orthophonie et d'audiologie, Université de Montréal, Montréal, Québec, Canada.

International Journal of Pediatric Otorhinolaryngology
|May 21, 2025
PubMed

Insights

Early life lead exposure in infants is linked to reduced auditory function, specifically outer hair cell responses. Mercury exposure showed no clear association with infant hearing. Further research is recommended.

Area of Science:

  • Environmental Health
  • Neurodevelopmental Toxicology
  • Audiology

Background:

  • Early brain development is vulnerable to environmental toxicants.
  • Lead (Pb) and mercury (Hg) are common developmental toxicants.
  • Understanding their impact on infant auditory function is crucial.

Purpose of the Study:

  • To investigate the association between prenatal lead (Pb) and mercury (Hg) exposure and auditory function in infants.
  • To assess auditory function using otoacoustic emissions (OAEs) and minimal auditory response levels (MRLs).
  • To determine if early life exposure to these metals affects infant hearing.

Main Methods:

  • Auditory function was assessed in 6-month-old infants using TEOAEs, DPOAEs, and MRLs.
  • Maternal blood samples (1st/3rd trimester) and cord blood were analyzed for Pb and Hg concentrations.
  • The Maternal-Infant Research on Environmental Chemicals-Infant Development (MIREC-ID) cohort provided the study population.

Main Results:

  • Higher maternal blood lead (Pb) concentrations were significantly associated with reduced OAEs, indicating impaired inner ear function.
  • The association was stronger for transient-evoked OAEs (TEOAEs), particularly reproducibility, and more pronounced in the left ear.
  • No clear association was found between mercury (Hg) exposure and infant auditory function (OAEs or MRLs).

Conclusions:

  • Prenatal exposure to low levels of lead (Pb) is associated with reduced outer hair cell function in infants.
  • This suggests a potential decrease in inner ear function due to developmental lead exposure.
  • Larger studies are needed to confirm these findings and their implications for infant hearing health.
Abstract

Keywords:
Auditory functionInfantLeadMIREC studyMercuryPrenatal exposure

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