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Journal of Environmental Pathology, Toxicology and Oncology
Factor de Impacto: 1.241 Factor de Impacto de 5 años: 1.349 SJR: 0.356 SNIP: 0.613 CiteScore™: 1.61

ISSN Imprimir: 0731-8898
ISSN En Línea: 2162-6537

Journal of Environmental Pathology, Toxicology and Oncology

DOI: 10.1615/JEnvironPatholToxicolOncol.v28.i4.40
pages 283-302

Prenatal and Postnatal Lead Exposure and Early Cognitive Development: Longitudinal Study in Saudi Arabia

Iman Al-Saleh
King Faisal Specialist Hospital & Research Centre
Michael Nester
Departments of Neuroscience, King Faisal Specialist Hospital & Research Centre, Riyadh
Abdullah Mashhour
Biological & Medical Research Department, King Faisal Specialist Hospital & Research Centre, Riyadh
Lina Moncari
Departments of Neuroscience, King Faisal Specialist Hospital & Research Centre, Riyadh
Neptune Shinwari
Biological & Medical Research Department, King Faisal Specialist Hospital & Research Centre, Riyadh
Gamal El-Din Mohamed
Biostatistics, Epidemiology & Scientific Computing Department, King Faisal Specialist Hospital & Research Centre, P.O. Box: 3354, Riyadh
Abdullah Rabah
Department of Pediatrics, King Khalid Hospital, Al-Kharj

SINOPSIS

The goal of this study was to assess the effect of prenatal and postnatal lead exposure on early cognitive development of infants using the Bayley Scale of Infant Development (BSID-I) at the age of 6, 12, 18, and 24 months in a longitudinal study. Based on the results of 653 cord blood lead levels, infants were classified into three groups for neuropsychological assessments: low lead risk (<10th percentile) and high lead risk (>10th percentile) of the distribution of cord blood lead level were designated as low (≤ 1.045 μg/dL) and high (≥ 3.466 μg/dL) lead risk groups. Blood lead levels in between the <10th and >90th percentile were designated as mid lead risk group. A total of 66 infants were supposed to be selected from each group for a follow-up study. Of these, only 106 participated 6 months after the study. During the follow-up study, the dropout was very high with attrition rates of 74.5%, 52.8%, and 39.6% during the 12, 18, and 24 months. Mean blood lead levels increased from 3.36 to 4.45 μg/dL between the ages of 6 and 24 months, but the standardized Mental Development Index (MDI) and Psychomotor Development Index (PDI) decreased from 99.26 and 98.13 (6 months old) to 93.29 and 82.52, respectively (24 months old). Due to the high rate of attrition, most of the infants in the low group were lost. Therefore, we used the 75th percentile of blood lead levels as a cutoff in the statistical analyses. After adjustment for a large number of confounding variables, prenatal lead exposure was found to be signifi cantly associated with the standardized MDI and PDI scores at the age of 6 months old with a P value of 0.02 for both. A borderline signifi cant effect of prenatal lead exposure was also seen on standardized PDI scores at the age of 24 months (P = 0.09). On the other hand, no relationship was seen between postnatal blood lead levels and concurrent cognitive development scores. Such an observation is not conclusive because of low statistical power due to small sample size. Our results provide additional evidence for low prenatal lead exposure effects on cognitive development in Saudi infants living in a rural area.