title: Acoustic stapedius muscle reflex in mercury-exposed Andean children and adults.
abstract: CONCLUSIONS
  The results suggested mercury (Hg)-induced anomalies in the brainstem-mediated acoustic stapedius muscle reflex in children.
  
  
  OBJECTIVE
  Hg exposure has been associated with hearing impairment and brainstem anomalies. Acoustic stapedius reflex (ASR) thresholds, growth functions, decay/adaptation times, and behavioral auditory thresholds were used to screen Andean children and adults for Hg-induced auditory brainstem and facial nerve impairment.
  
  
  METHODS
  Fifty-one participants, which included 22 children (aged 6-17 years) and 29 adults (aged 19-83 years) living in gold mining areas of Ecuador where Hg is widely used in amalgamation, were screened using ASR immittance procedures.
  
  
  RESULTS
  Mean blood mercury (HgB) level in the children was 15.6 μg/L (SD, 21.3; median, 7 μg/L; range, 2.0-89 μg/L), and in the adults 8.5 μg/L (SD, 7.1; median, 6 μg/L; range, 2.0-32 μg/L). Mean contralateral ASR thresholds (ASRT) for the screening frequency of 2000 Hz in the children (39 ears) was 92.9 dB HL (SD, 6.1; range, 80-105 dB HL), and in the adults (53 ears) 90.0 dB HL (SD, 6.4; range, 65-105 dB HL). The ASRT in the children increased significantly with HgB level (rho = 0.433; p = 0.008).
authors.affiliation: Department of Neurology, Harvard Medical School/Harvard Biological Laboratories, Cambridge, MA 02138, USA. allen_counter@harvard.edu
authors.forename: S Allen
authors.initials: SA
authors.lastname: Counter
authors.forename: Leo H
authors.initials: LH
authors.lastname: Buchanan
authors.forename: Fernando
authors.initials: F
authors.lastname: Ortega
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001309:Auditory Threshold / Q000187:drug effects / Q000502:physiology*; D002648:Child; D004484:Ecuador / Q000453:epidemiology; D004781:Environmental Exposure / Q000009:adverse effects*; D018876:Environmental Illness / Q000139:chemically induced / Q000453:epidemiology / Q000503:physiopathology*; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008628:Mercury / Q000009:adverse effects*; D008875:Middle Aged; D008906:Mining; D012022:Reflex, Acoustic / Q000187:drug effects / Q000502:physiology*; D055815:Young Adult
chemical_list: D008628:Mercury