Identifying the most significant contributors to child blood lead levels (BLL) in Dhaka, Bangladesh
Identifying the most significant contributors to child blood lead levels (BLL) in Dhaka, Bangladesh
Objectives
1. Assess the prevalence of elevated blood lead levels among children 24-48 months old
2. Explore sources and pathways of lead exposure
3. Identify Lead sources and pathways that contribute to child blood lead levels
Rationale
Exposure to lead during early childhood has a negative, irreversible, and long-term effect. Globally, 1 in 3 children, or more than 800 million children, have elevated blood lead levels. Most child lead exposure occurs in lower income countries because there are more sources of lead and more contamination than in higher income countries. With insufficient capacity to develop and maintain protective regulations and infrastructure, the use of lead in industry persists in resource-limited countries like Bangladesh.
Our proposed study focuses on Dhaka, the capital of Bangladesh, because the lead burden is high and the dominant exposure sources have not been identified. Our first research gap we are addressing is the prevalence of elevated child blood lead levels among young children 24-48 months.
There are no adequate therapies or treatments for lead-poisoned children. To focus attention and limited resources on eliminating and preventing lead exposures, we must first identify lead sources that contribute most to children’s burden. The lack of clarity on the sources of child lead exposure in Dhaka and their relative contributions to child blood lead levels are additional research gaps we are addressing.
Several possible lead sources have been suggested but not thoroughly investigated in Dhaka, including contaminated air or soil from battery recycling, legacy lead from gasoline, as well as the use of decorative paints in homes, and the consumption of indigenous medicines and turmeric.
Project Dates
2022-2024
Stage of Work
We have enrolled all 500 children and conducted exposure surveys, collected environmental samples, and collected and analyzed blood samples. The median blood lead level for these children was 6.7 μg/dL with a maximum of 36 μg/dL. 98% of the children exceeded the CDC’s threshold of 3.5 μg/dL.
There is a strong spatial clustering of children with elevated blood lead levels. Initial regression analyses suggest that blood lead level is correlated with socioeconomic status, along with living within 500 meters of risky industries (battery recycling or metal alloy factories). Soil lead levels are lower than expected, with none exceeding the EPA 400 ppm threshold for play soil. Nonetheless, there is a slight positive association between elevated soil lead level and BLL. Less than 5% of turmeric samples had detectable lead, with a maximum of 67 ppm.
The field team is now conducting household re-visits among a subset of participants with high and low blood lead levels. The re-visit protocol involves asking questions about the occupations of individuals working outside the home, the behavior and habits of children, and assessing lead levels among potential sources like paint, cookware, amulets, and jewelry. At the same time, the team is conducting more comprehensive air and soil sampling around industries and selected households.
People
Primary Contact: Jenna Forsyth
Stanford University
. Stephen Luby, (PI)
. Jenna Forsyth (Oversees project)
. Scott Fendorf (Laboratory Advisor)
. Ali Namayandeh (Leads laboratory work)
. Christlee Elmera (Data Manager)
International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b)
. Mahbub Rahman (Local PI)
. Jesmin Sultana (Oversees fieldwork)
Funding