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Brainstem auditory evoked potentials in children with lead exposure
Katia de Freitas Alvarenga1, Thais Catalani Morata2, Andrea Cintra Lopes1
1Department of Speech Therapy and Audiology, Faculdade de Odontologia de Bauru, Universidade de São Paulo (FOB-USP), Bauru, SP, Brazil.
Insights
This study found no auditory effects from low chronic lead exposure in children. Comprehensive hearing tests revealed no association between blood lead levels and auditory function, suggesting safety at these low exposure levels.
Area of Science:
- Environmental Health
- Pediatric Audiology
- Toxicology
Background:
- Previous research indicates lead exposure can affect children's hearing.
- Further investigation into the impact of low-level, chronic lead exposure is necessary.
Purpose of the Study:
- To assess the auditory system's response to low chronic lead exposure in children.
- Utilized auditory electrophysiological tests to evaluate hearing function.
Main Methods:
- A cross-sectional cohort study involving 130 children (18 months to 14 years).
- Evaluated participants using tympanometry, audiometry, transient evoked otoacoustic emissions, and brainstem auditory evoked potentials.
- Monitored blood lead levels over 35.5 months.
Main Results:
- The average cumulative blood lead index was 12 microg/dL.
- All children demonstrated normal hearing thresholds and transient evoked otoacoustic emissions.
- No correlation was found between cumulative lead levels and auditory pathway nerve signal timing.
Conclusions:
- Chronic low-level lead exposure did not show evidence of toxic effects on children's auditory function.
- Findings suggest the auditory system in children is resilient to the low chronic lead exposures studied.
Introduction:
Earlier studies have demonstrated an auditory effect of lead exposure in children, but information on the effects of low chronic exposures needs to be further elucidated.
Objective:
To investigate the effect of low chronic exposures of the auditory system in children with a history of low blood lead levels, using an auditory electrophysiological test.
Methods:
Contemporary cross-sectional cohort. Study participants underwent tympanometry, pure tone and speech audiometry, transient evoked otoacoustic emissions, and brainstem auditory evoked potentials, with blood lead monitoring over a period of 35.5 months. The study included 130 children, with ages ranging from 18 months to 14 years, 5 months (mean age 6 years, 8 months ± 3 years, 2 months).
Results:
The mean time-integrated cumulative blood lead index was 12 microg/dL (SD ± 5.7, range: 2.433). All participants had hearing thresholds equal to or below 20 dBHL and normal amplitudes of transient evoked otoacoustic emissions. No association was found between the absolute latencies of waves I, III, and V, the interpeak latencies I-III, III-V, and I-V, and the cumulative lead values.
Conclusion:
No evidence of toxic effects from chronic low lead exposures was observed on the auditory function of children living in a lead contaminated area.
