title: Hearing thresholds in children exposed to mercury in the prenatal period.
abstract: OBJECTIVE
  To evaluate hearing thresholds in children with a history of exposure to mercury during the prenatal period.
  
  
  METHODS
  Participants were 90 children of both genders with ages from 8 to 10 years, divided into two groups according to prenatal mercury exposure levels. The study group was composed by 57 children who had mercury levels in the umbilical cord equal or above 8 µg/L, and the comparison group comprised 33 children who had mercury levels in the umbilical cord below 8 µg/L. Investigation procedures included the application of a questionnaire, pure-tone audiometry, speech reception threshold, and mercury level analysis in cord blood collected at birth.
  
  
  RESULTS
  The study group showed a median mercury level in the umbilical cord of 14.63 µg/L, and the median threshold for 500 Hz, 1 kHz and 2 kHz in pure-tone audiometry was 10 dB for both ears. The comparison group had a median cord blood mercury level of 4.88 µg/L, and the median threshold for 500 Hz, 1 kHz and 2 kHz in pure-tone audiometry was 10 dB for both ears. When the hearing thresholds were compared, both by the tritonal mean and by each frequency separately, there were no significant differences between groups.
  
  
  CONCLUSIONS
  The children had hearing thresholds within normal limits and there was no significant difference between the hearing thresholds of children exposed and not exposed prenatally to mercury.
authors.affiliation: Institute of Public Health Studies, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil. lenadutra@uol.com.br
authors.forename: Marilene Danieli Simões
authors.initials: MD
authors.lastname: Dutra
authors.forename: Marcia
authors.initials: M
authors.lastname: Cavadas
authors.forename: Iracina Maura de
authors.initials: IM
authors.lastname: Jesus
authors.forename: Elisabeth Oliveira
authors.initials: EO
authors.lastname: Santos
authors.forename: Evelyn Almeida da
authors.initials: EA
authors.lastname: Silva
authors.forename: Volney de Magalhães
authors.initials: Vde M
authors.lastname: Câmara
mesh_terms: D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold / Q000187:drug effects*; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D034381:Hearing Loss / Q000175:diagnosis; D006801:Humans; D008297:Male; D008628:Mercury / Q000009:adverse effects* / Q000097:blood; D008630:Mercury Poisoning / Q000150:complications*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000139:chemically induced*
chemical_list: D008628:Mercury