Brainstem auditory evoked response at five years and prenatal and postnatal blood lead.

Previous work from this laboratory demonstrated an association between higher maternal blood lead level at 20 weeks of pregnancy and increased I-V and III-V interpeak intervals in the brainstem auditory evoked response (BAER) recorded in 1-month-old infants. We repeated the BAER measurements with a larger group of children (n = 100-113) from the same study at 5-7 years. Maternal blood lead level at 20 weeks of pregnancy (geometric mean = 7.7 microg/dl; range 1-30. 5 microg/dl) was the only prenatal blood lead level significantly associated with I-V and III-V interpeak interval in a multiple regression model controlling for head circumference and age at time of testing and sex. In contrast to the findings at 1 month of age, interpeak intervals decreased as a linear function of increasing 20-week maternal blood lead. A nonlinear, orthogonal, second-order polynomial model was a significantly better fit to the data than the linear model. The nonlinear model showed I-V and III-V interpeak intervals decreased as blood lead rose from 1 to 8 microg/dl, and then increased as blood lead rose from 8 to 30.5 microg/dl. We hypothesized that the negative linear term was related to lead effect on brainstem auditory pathway length, and that the positive quadratic term was related to neurotoxic lead effect on synaptic transmission or conduction velocity. We found support for the brainstem length interpretation in the data, showing that 6-year-old head circumference in these children significantly decreased with increased maternal 20-week blood lead level. Increasing postnatal blood lead at 12 and 48 months was related only to decreased BAER conduction intervals across the entire blood lead range, suggesting only pathway length effects. Alterations in BAER at this age may indicate that the effect of prenatal lead exposure on the auditory brainstem is permanent, as response latencies reach essentially adult values by 4 years of age.

[1]  Ze D Jiang,et al.  Brainstem auditory evoked responses from birth to adulthood: Normative data of latency and interval , 1991, Hearing Research.

[2]  C W Ponton,et al.  Auditory Brain Stem Response Generation by Parallel Pathways: Differential Maturation of Axonal Conduction Time and Synaptic Transmission , 1996, Ear and hearing.

[3]  H. Lilienthal,et al.  Lead effects on the brain stem auditory evoked potential in monkeys during and after the treatment phase. , 1996, Neurotoxicology and teratology.

[4]  G. Laurell,et al.  Normal auditory brainstem and cochlear function in extreme pediatric plumbism , 1997, Journal of the Neurological Sciences.

[5]  R. Lasky,et al.  The effects of lead on otoacoustic emissions and auditory evoked potentials in monkeys. , 1995, Neurotoxicology and teratology.

[6]  P. Morse,et al.  Categorical perception for voicing contrasts in normal and lead-treated rhesus monkeys: Electrophysiological indices , 1987, Brain and Language.

[7]  S. Rothenberg,et al.  Pre- and postnatal lead effect on head circumference: a case for critical periods. , 1999, Neurotoxicology and teratology.

[8]  G. Vimpani,et al.  The Port Pirie Cohort Study: Blood lead concentrations in early childhood , 1985, The Medical journal of Australia.

[9]  J. Schwartz,et al.  Lead and minor hearing impairment. , 1991, Archives of environmental health.

[10]  G. Vimpani,et al.  Determinants of blood lead concentrations to age 5 years in a birth cohort study of children living in the lead smelting city of Port Pirie and surrounding areas. , 1992, Archives of environmental health.

[11]  S. Rothenberg,et al.  Changes in serial blood lead levels during pregnancy. , 1994, Environmental health perspectives.

[12]  A. Starr.  Auditory Brainstem Potentials: Comments on Their Use During Infant Development , 1984, Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society.

[13]  P. Yakovlev,et al.  The myelogenetic cycles of regional maturation of the brain , 1967 .

[14]  S. Rothenberg,et al.  Prenatal and perinatal low level lead exposure alters brainstem auditory evoked responses in infants. , 1994, Neurotoxicology.

[15]  D. Kleinbaum,et al.  5-year follow-up study of children with low-to-moderate lead absorption: electrophysiological evaluation. , 1985, Environmental Research.

[16]  Perinatal Maturation of the Auditory Brain Stem Response: Changes in Path Length and Conduction Velocity , 1996, Ear and hearing.

[17]  D. Rice.  Effects of lifetime lead exposure in monkeys on detection of pure tones. , 1997, Fundamental and applied toxicology : official journal of the Society of Toxicology.

[18]  S. Rothenberg,et al.  Prenatal and perinatal lead exposures alter acoustic cry parameters of neonate. , 1995, Neurotoxicology and teratology.

[19]  Jean K. Moore,et al.  Time course of axonal myelination in the human brainstem auditory pathway , 1995, Hearing Research.

[20]  A. Minkowski,et al.  Regional Development of the Brain in Early Life , 1968 .

[21]  C. Clark,et al.  The influence of social and environmental factors on dust lead, hand lead, and blood lead levels in young children. , 1985, Environmental research.

[22]  Y. Guan,et al.  Axogenesis in the human fetal auditory system, demonstrated by neurofilament immunohistochemistry , 1996, Anatomy and Embryology.

[23]  R. Keith,et al.  Lead exposure and the central auditory processing abilities and cognitive development of urban children: the Cincinnati Lead Study cohort at age 5 years. , 1992, Neurotoxicology and teratology.

[24]  T. Steinbrecher,et al.  A selective synthesis of 4-aminobiphenyl-N2-deoxyguanosine adducts. , 1994, Environmental health perspectives.

[25]  A. Salamy,et al.  Maturation of the Auditory Brainstem Response from Birth through Early Childhood , 1984, Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society.