Lead level in foremilk and neurobehavioral development of neonates

Abstract

Background Recently, it has been reported that blood lead level lower than 24 μmol/L can lead to learning and cognitive deficits. Objective To investigate the relationship of lead level in foremilk and early neurobehavioral development of neonates taking lead level in foremilk as lead exposure index. Design A controlled observation. Setting Maternal and Child Health Center, Shanxi Children's Hospital. Participants Totally 128 neonates of full-term normal delivery, 76 male and 52 female, from Shanxi Provincial Maternal and Child Health Center and Jiexiu Maternal and Child Health Center were involved in this study. All the involved neonates had no peripartal ischemic/hypoxic history. The corresponding puerperants were aged (27±5)years. They had no various acute and chronic diseases during pregnancy, and family history of neurological disease as well as occupational lead exposure. Informed consents of detected items were obtained from the puerperants. Methods ▪ Determination of lead level in foremilk: Altogether 128 foremilk samples, 1 mL each, were collected between January and February 2005. The same amount of violet acid was added to each sample. After foremilk was fully dissolved, 0.2 mL solution was taken for determining lead level with atomic absorption spectrometer in graphite stove. The determined process strictly followed the internal quantity control of laboratory and was involved in the blind quality control of Institute of Environmental Health of Chinese Academy. ▪ Participants grouping: Totally 128 neonates were involved, and the normal reference value of lead level of foremilk was 0.06–0.48 μmol/L. The involved neonates were assigned into high-level lead group (≥ 0.24 μmol/L, n =60) and low-level lead group (< 0.24 μmol/L, n =68). ▪ Assessment of neurobehavioral development of neonates: Neurobehavioral development level of neonates who was born 24 to 72 hours was assessed with 20-item neonatal neurobehavioral determination method, which involved behavioral ability (6 items), passive muscular tension (4 items), active muscular tension (4 items), primitive reflection (3 items) and general evaluation (3 items). Each above-mentioned scoring had 3 scales (0,1 and 2 points). The full mark of 20 items was 40 points. Neurological behaviors of neonates might be unabnormal when scoring was < 35 points. Main outcome measures Assessment results of neurobehavioral development of neonates in high- and low-level lead neonates. Results After lead-level determination, the involved neonates in two groups participated in the final analysis. Neurobehavioral total scores of neonates of high-level lead group were lower than those in the low-level lead group [(35.9±1.3) points vs.(37.7±1.4) points, P < 0.01]. The scores of neonatal erection in high-level lead group were lower than those in low-level lead group [(1.4±0.4) points vs.(1.8±0.5) points, P <0.01], and time for head erection of neonates in the high-level lead group was shortened as compared with that in the low-level lead group [(1.8±1.7) minutes vs. (3.3±2.2) minutes, P < 0.01]. Conclusion 0.24 μmol/L lead level in foremilk has certain relationship with neurobehavioral development. The main influenced manifestations are shortened duration of neonatal head erection and actively contracted extensor, i.e. cervical curved ability is weakened.