Association between blood lead levels and environmental exposure among Saudi schoolchildren in certain districts of Al-Madinah

Mohammed Adnan Zolaly¹, Manal Ibrahim Hanafi^2,3, Nashaat Shawky⁴, Khalid el-Harbi¹, Ahmed M Mohamadin^5,6
1Pediatric Department, ²Family and Community Medicine Department, Medical College, Taibah University, Al-Madinah Al-Munawwarah, Saudi Arabia; ³Community Medicine Department, Faculty of Medicine, Alexandria University, Alexandria, Egypt; ⁴Ophthalmology Department, Medical College, ⁵Chemistry for Health Sciences Department, Deanery of Academic Services, Taibah University, Al-Madinah Al-Munawwarah, Saudi Arabia; ⁶Biochemistry Department, Faculty of Pharmacy, Al-Azhar University, Cairo, Egypt

Introduction: Both occupational and environmental exposures to lead remain a serious problem in many developing and industrializing countries. When humans are exposed to high levels of lead, there is damage to almost all organs and organ systems (most importantly, the central nervous system, kidneys, and blood), which often culminates in death.
Objective: To estimate the prevalence of blood lead levels (BLLs) and to identify the sources of environmental exposure and potential risk factors for elevated BLLs among Saudi schoolchildren.
Methods: A cross-sectional survey was conducted from March to May 2010. The study population included 557 Saudi school students of both sexes. A multistage random sampling technique was used. Information about socioeconomic status, house and school construction, and parents' education and employment was collected using questionnaires. Lead was analyzed in a blood sample using an atomic absorption technique and hemoglobin was measured using a Sysmex hematological analyzer.
Results: The mean BLL was 4.94 ± 3.38 µg/dL (range 0.45–26.3 µg/dL). A total of 19% had BLLs <1.0 µg/dL, 16% had BLLs <2.5 µg/dL, 15% had BLLs <5.0 µg/dL, 20% had BLLs <7.5 µg/dL, 25% had BLLs <10.0 µg/dL, and about 6% had BLLs >10.0 µg/dL. Analysis of odds by controlling all risk factors (adjusted odds ratio [OR]) that affect BLLs (≥10 µg/dL) indicated that using cosmetics (OR = 18.5, confidence interval [CI] = 14.4–19.8), putting colored toys in mouth (OR = 15.7, CI = 3.6–16.2), eating canned food (OR = 9.8, CI = 7.0–10.1), and using newspaper during food preparation (OR = 7.6, CI = 6.3–8.2) are risk factors. There were significant correlations between BLLs and family habits (r = 0.225, P = 0.000), personal habits (r = 0.321, P = 0.000), eating habits (r = 0.128, P = 0.002) and school building characteristics (r = 0.469, P = 0.000). There was a significant correlation between BLLs and anemia in age group 6 < 12 years (P = 0.000) and age group 12 to less than 18 years, among males (P = 0.000) and females (P = 0.041).
Conclusion: The BLLs of children are affected by multiple factors. Female students have higher BLLs and lower hemoglobin concentration than males. The possible sources of lead exposure were use of toothpaste, use of kohl, putting colored toys in the mouth, use of both canned food and canned juice, use of lip gloss in females, and different methods of handling newspaper while preparing food.

Keywords: blood, lead, exposure, cosmetics, schoolchildren, anemia