Delayed brainstem auditory evoked potential latencies in 14-year-old children exposed to methylmercury.
OBJECTIVE
To determine possible exposure-associated delays in auditory brainstem evoked potential latencies as an objective measure of neurobehavioral toxicity in 14-year-old children with developmental exposure to methylmercury (MeHg) from seafood.


METHODS
Prospective study of a birth cohort in the Faroe Islands, where 878 of eligible children (87%) were examined at age 14 years. Latencies of brainstem evoked potential peaks I, III, and V at 20 and 40 Hz constituted the outcome variables. Mercury concentrations were determined in cord blood and maternal hair, and in the child's hair at ages 7 and 14.


RESULTS
Latencies of peaks III and V increased by about 0.012 ms when the cord blood mercury concentration doubled. As seen at age 7 years, this effect appeared mainly within the I-III interpeak interval. Despite lower postnatal exposures, the child's hair mercury level at age 14 years was associated with prolonged III-V interpeak latencies. All benchmark dose results were similar to those obtained for dose-response relationships at age 7 years.


CONCLUSIONS
The persistence of prolonged I-III interpeak intervals indicates that some neurotoxic effects from intrauterine MeHg exposure are irreversible. A change in vulnerability to MeHg toxicity is suggested by the apparent sensitivity of the peak III-V component to recent MeHg exposure.
Murata
Katsuyuki
K
Division of Environmental Health Sciences, Akita University School of Medicine, Akita, Japan.
Weihe
Pál
P
Budtz-Jørgensen
Esben
E
Jørgensen
Poul J
PJ
Grandjean
Philippe
P
D000293:Adolescent; D001299:Audiometry; D002648:Child; D015331:Cohort Studies; D003718:Denmark; D004781:Environmental Exposure / Q000009:adverse effects*; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects* / Q000502:physiology; D005260:Female; D005312:Fetal Blood / Q000737:chemistry; D005506:Food Contamination; D006197:Hair / Q000737:chemistry; D006801:Humans; D008297:Male; D020262:Mercury Poisoning, Nervous System / Q000503:physiopathology*; D008767:Methylmercury Compounds / Q000032:analysis / Q000633:toxicity*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D017747:Seafood / Q000009:adverse effects
D008767:Methylmercury Compounds