Abstract
Lead (Pb) exposure is a major public health problem worldwide. Although high levels of Pb in blood in Bangladesh have been documented, the dominant Pb sources contributing to human exposure in rural Bangladesh have not been determined. Here, we first obtained blood from pregnant women from three rural Bangladeshi districts who were previously assessed by a case-control and sampling study, and we then conducted semistructured in-depth interviews to understand Pb exposure behavior and finally collected samples of the suspected Pb sources. We measured the Pb isotopic composition of both potential Pb sources and 45 blood samples in order to understand which of three sources predominate: (1) food from Pb-soldered cans, (2) turmeric, or (3) geophagous materials (clay, soil, or ash). The Pb isotope ratios of the three sources are distinct (p = 0.0001) and blood isotope ratios are most similar to turmeric. Elevated lead and chromium (Cr) concentrations in turmeric and a yellow pigment used in turmeric processing are consistent with reported consumption behavior that indicated turmeric as a primary contributor to blood Pb. The Pb isotopic composition analyses combined with a case-control and sampling approach provides evidence that turmeric adulterated with the yellow Pb-bearing pigment is the main Pb exposure source in these districts and illustrates the need to assess drivers and practices of turmeric adulteration, as well as the prevalence of adulteration across South Asia.
Highlights
Exposure to lead (Pb) during the prenatal period and early childhood has an irreversible negative effect on cognitive outcomes later in life.[1,2] A pooled analysis of data from 1333 children indicated that those with blood Pb levels (BLLs) between 2.4 and 10 μg/dL had subsequent IQ scores 3.9 points lower than children with BLLs < 2.4 μg/dL.[3]
Bangladesh phased out Pb in gasoline in 1999 but elevated BLLs greater than 5 μg/dL persist.[8−15] Since 2012, studies of over 1200 children in three districts found that 54−78% of children have high BLLs compared to less than 3% in the United States.[10,12,16]
We find that individual sources are characterized by statistically significant differences among Pb isotope ratios, whereas blood Pb isotope ratios fall within a discrete range, allowing us to decipher the most likely source of Pb in prenatal blood samples
Summary
Exposure to lead (Pb) during the prenatal period and early childhood has an irreversible negative effect on cognitive outcomes later in life.[1,2] A pooled analysis of data from 1333 children indicated that those with blood Pb levels (BLLs) between 2.4 and 10 μg/dL had subsequent IQ scores 3.9 points lower than children with BLLs < 2.4 μg/dL.[3]. In many low- and middle-income countries, Pb exposure remains high despite a worldwide reduction in BLLs due to the transition to unleaded gasoline.[6,7] For example, Bangladesh phased out Pb in gasoline in 1999 but elevated BLLs greater than 5 μg/dL persist.[8−15] Since 2012, studies of over 1200 children in three districts found that 54−78% of children have high BLLs compared to less than 3% in the United States.[10,12,16] The reduction in IQ from these elevated BLLs in Bangladesh costs an estimated 16 billion dollars per year in lost lifetime productivity or 6% of gross domestic products.[17]
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