Prevalence of lead poisoning and unique lead sources in Bhutan: Findings from a nationally representative survey 2024

Lead is a toxic element causing devastating consequences in children and affecting health throughout life. One in three children globally are estimated to have a blood lead level (BLL) of 5 µg/dL or higher, and lead causes harm at even lower levels. Low-level lead poisoning is pervasive. However, few low- and middle-income countries have national BLL prevalence or local lead source data. A nationally representative cross-sectional BLL survey in children 1–6 years old was conducted in Bhutan in 2024. Risk factors were surveyed, and BLLs were tested with LeadCare II analyzers. Convenience sampling of children less than 13 years old in monastic institutions and purposive sampling of pregnant/breastfeeding women were conducted. Targeted environmental lead source testing was conducted using portable Evident/Olympus Vanta X-ray fluorescence (XRF) analyzers. Two BLL cutoffs were analyzed for comparison with global data. In nationally representative sampling of 1–6-year-old children, 2,246/2,959 (75.9% [95% CI 74.0-77.7]) had a BLL ≥ 3.5 µg/dL, and 1,518/2,959 (51.3% [95% CI 49.0-53.6]) had a BLL ≥ 5 µg/dL. The mean (SD) BLL was 5.3 (3.2) µg/dL. Among monastic children and pregnant/breastfeeding women, 178/207 (86.0%) and 73/124 (58.9%) respectively, had a BLL ≥ 3.5 µg/dL. These two populations were not nationally representative. Lead poisoning prevalence was high across all ages, rural/urban locations, and income quintiles. Taking Jinlab Mendrup (blessed religious substance) in the previous 15 days was associated with having a BLL ≥ 3.5 µg/dL, aOR=1.94 (1.34-2.70, p = 0.009). XRF source testing identified lead above reference thresholds in 44.2% (339/767) of Jinlab Mendrup samples, 22.4% (15/67) of spices, and 21.5% (143/665) of kitchen items. Lead poisoning prevalence was pervasive in young children in Bhutan and in other groups tested. Numerous potential lead sources were identified, including Jinlab Mendrup and items unique to Bhutan. Urgent action is needed to address the high prevalence of lead poisoning.