title: Increased ERG a- and b-wave amplitudes in 7- to 10-year-old children resulting from prenatal lead exposure.
abstract: OBJECTIVE
  To determine the dose-response relationship between blood lead concentration ([PbB]) and scotopic ERG amplitude in 7- to 10-year-old children with lifetime lead exposure.
  
  
  METHODS
  Full-field flash scotopic ERGs were recorded over a 4-log-unit range in 45 dark-adapted children with normal visual acuity. [PbB] was measured throughout pregnancy and postnatal development, and the subjects' [PbB] levels were grouped at each age by tertiles.
  
  
  RESULTS
  The median [PbB] during pregnancy was, from lowest to highest tertile, 2.5 to 5.0, 7.5 to 9.0, and 14.0 to 16.5 microg/dL, and after birth was 4.0 to 8.0, 6.0 to 14.5, and 7.5 to 21.0 microg/dL. Only maternal [PbB] at 12 weeks of pregnancy showed a significant dose-response relationship with the ERG measures, so that with increasing [PbB] there were significant increases in leading-edge a-wave amplitude, peak a-wave amplitude, and b-wave amplitude and sensitivity, with no changes in implicit times. Data analyses showed that children whose mothers had [PbB] of 10.5 microg/dL or more at 12 weeks of pregnancy had relatively increased a- and b-waves.
  
  
  CONCLUSIONS
  Lead exposure during the first trimester of pregnancy produces dose-dependent increases in scotopic a- and b-wave amplitudes in 7- to 10-year-old children. The results suggest that the increases in a- and b-wave amplitudes originate from rods; however, the increased b-wave amplitude and sensitivity may also originate in the inner retina. These alterations occurred at maternal [PbB] at or below currently accepted safe levels. These novel findings reveal that the developing retina is a sensitive target for lead and suggest that lead-exposed children be examined for possible future visual system deficits.
authors.affiliation: National Institute of Public Health, Cuernavaca, Mexico.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Rothenberg
authors.forename: Lourdes
authors.initials: L
authors.lastname: Schnaas
authors.forename: Manuel
authors.initials: M
authors.lastname: Salgado-Valladares
authors.forename: Esther
authors.initials: E
authors.lastname: Casanueva
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Geller
authors.forename: H Kenneth
authors.initials: HK
authors.lastname: Hudnell
authors.forename: Donald A
authors.initials: DA
authors.lastname: Fox
mesh_terms: D002648:Child; D004305:Dose-Response Relationship, Drug; D004596:Electroretinography / Q000187:drug effects*; D005260:Female; D006801:Humans; D007501:Iron / Q000097:blood; D007854:Lead / Q000009:adverse effects* / Q000097:blood; D008297:Male; D018811:Maternal Exposure / Q000009:adverse effects*; D010775:Photic Stimulation; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D011446:Prospective Studies; D012160:Retina / Q000187:drug effects* / Q000502:physiology; D014801:Vitamin A / Q000097:blood; D015032:Zinc / Q000097:blood
chemical_list: D014801:Vitamin A; D007854:Lead; D007501:Iron; D015032:Zinc