Neurophysiologic measures of auditory function in fish consumers: associations with long chain polyunsaturated fatty acids and methylmercury.
BACKGROUND
Determining if associations exist between child neurodevelopment and environmental exposures, especially low level or background ones, is challenging and dependent upon being able to measure specific and sensitive endpoints. Psychometric or behavioral measures of CNS function have traditionally been used in such studies, but do have some limitations. Auditory neurophysiologic measures examine different nervous system structures and mechanisms, have fewer limitations, can more easily be quantified, and might be helpful additions to testing. To date, their use in human epidemiological studies has been limited. We reviewed the use of auditory brainstem responses (ABR) and otoacoustic emissions (OAE) in studies designed to determine the relationship of exposures to methyl mercury (MeHg) and nutrients from fish consumption with neurological development. We included studies of experimental animals and humans in an effort to better understand the possible benefits and risks of fish consumption.


OBJECTIVE
We reviewed the literature on the use of ABR and OAE to measure associations with environmental exposures that result from consuming a diet high in fish. We focused specifically on long chain polyunsaturated fatty acids (LCPUFA) and MeHg.


METHODS
We performed a comprehensive review of relevant studies using web-based search tools and appropriate search terms.


RESULTS
Gestational exposure to both LCPUFA and MeHg has been reported to influence the developing auditory system. In experimental studies supplemental LCPUFA is reported to prolong ABR latencies and human studies also suggest an association. Experimental studies of acute and gestational MeHg exposure are reported to prolong ABR latencies and impair hair cell function. In humans, MeHg exposure is reported to prolong ABR latencies, but the impact on hair cell function is unknown.


CONCLUSIONS
The auditory system can provide objective measures and may be useful in studying exposures to nutrients and toxicants and whether they are associated with children's neurodevelopment.
Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA.
Adam C
AC
Dziorny
Mark S
MS
Orlando
J J
JJ
Strain
Philip W
PW
Davidson
Gary J
GJ
Myers
D000818:Animals; D002648:Child; D002657:Child Development / Q000187:drug effects*; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D005260:Female; D005399:Fishes; D005506:Food Contamination; D006309:Hearing / Q000187:drug effects*; D006801:Humans; D018811:Maternal Exposure / Q000009:adverse effects*; D008767:Methylmercury Compounds / Q000633:toxicity*
D005231:Fatty Acids, Unsaturated; D008767:Methylmercury Compounds