PRENATAL BLOOD AND BONE LEAD EFECTS ON INFANT OCULOMOTOR FUNCTION

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The project will investigate the role of prepregnancy maternal bone lead and prenatal maternal blood lead upon alterations in infant saccadic and smooth pursuit eye movements. The project will study a traditionally underserved, primarily Latino and African-American inner city population in South Central Los Angeles at the King/Drew Medical Center. The target population has higher blood lead levels than the national average. The study seeks to determine if maternal blood lead during specific periods of pregnancy, representing different phases of fetal development, are more highly correlated with altered oculomotor function than maternal blood lead at other periods of pregnancy. It will determine if the effects of prenatal lead exposure can be measured from six months to two years of age. It will also see if postnatal blood lead levels predict altered oculomotor function. The study will determine if maternal bone lead contributes to altered oculomotor development with or without influence upon maternal blood lead level during pregnancy. It will determine which of the two lead exposure indices better predict developmental deficit. Mothers will be recruited near the end of one pregnancy and followed until their next pregnancy to obtain a prepregnancy bone lead. Maternal blood lead will be measured in the interpregnancy interval and during pregnancy while maternal bone lead will be measured only during the interpregnancy interval. Infant blood lead will be measured every 6 months from birth. Blood lead will be measured by atomic absorption spectrometry with graphite furnace. Bone lead will be measured by K-band X-ray fluorescence with 109Cd source, fast spectroscopy amplifier and advanced spectral analysis algorithms. Oculomotor function will be measured by infrared pupil-corneal reflection television scanner with automatic head tracking. Saccade parameters of latency and accuracy will be measured, along with smooth pursuit parameters of velocity gain using step-ramp horizontally displaced visual targets. Multiple regression techniques will be used to control for confounding and control variables, such as nutrition, illness and injury, in order to test the effects of the lead measures upon oculomotor function. Oculomotor function is a vital behavior that allows the infant to orient itself to acquire visual information. This function is primary to adequate development of the child. The tests are culture- free and validation of lead effect upon them will permit their wider use in any population. Bone lead measurements may supplement traditional blood lead measurements in determining exposure limits for regulatory purposes.