Assessing Environmental Lead Exposure in Resource-Constrained Settings
This tool is the third tool in the Toolkit to End Childhood Lead Poisoning. This tool aims to familiarize readers with key concepts of a lead risk assessment, providing a foundation for conducting investigations in resource-constrained settings where children have been identified with elevated blood lead levels (BLLs).
Assessing Environmental Lead Exposure in Resource-Constrained Settings is a technical note and does not itself constitute adequate guidance for the development and implementation of environmental risk assessments. Rather, key considerations are outlined and a preliminary list of possible actions is presented.
This tool is organized sequentially, proceeding from background research to design and execution and finally to interpretation and communication of results. Some additional detail on sampling methods and estimating BLLs is presented in the annexes of the report.
The process flow chart below presents the overall organization of this tool.
Lead risk assessment process
Comparison of various analytical techniques used in lead risk assessment
Method of analysis | Qualitative or | Cost | Field | Medium | US EPA | Limitations |
| Sodium rhodizonate swabs | Qualitative | Low (approx. US$0.30 per test) | Y | Leachable surfaces | N | Not US EPA recognized; colorimetric nature may diminish utility with yellow or red materials |
| Colorimetric water tests | Qualitative | Low (approx. US$15–US$30 per kit) | Y | Water | N | Not US EPA recognized |
| LeadCheck™ | Qualitative | Low (approx. US$5–US$10 per test) | Y | Leachable surfaces | Y | Difficult to integrate into exposure assessment; colorimetric nature may diminish utility with yellow or red materials; currently discontinued by manufacturer |
| D-Lead® paint test | Semiquantitative | Low (approx. US$10 per test) | Y | Paint | Y | Difficult to integrate into exposure assessment; colorimetric nature may diminish utility with yellow or red materials |
| pXRF | Quantitative | Moderate to high (approx. US$30,000 instrument; nil cost per sample) | Y | Multiple solid media | Y | May require laboratory confirmation to ensure the validity of findings |
| Field sampling with lab analysis (ICP-MS, ICP-OES, GFAAS, GFAES) | Quantitative | High (approx. US$100,000 instrument; approx. US$25–US$50 per test) | N | Multiple media (liquid or solid) | Y | Not logistically feasible for a large number of samples; level of precision not always necessary for exposure assessment |
© UNICEF/UN0626461/Wilander
Avoiding tunnel vision: South Asia
A research team conducted a regional survey of point-source pollution from informal battery recycling sites. The sites all exhibited similar characteristics: high soil-lead contamination at a point source attenuating steeply after 10–20 m. Elevated blood lead levels (BLLs) correlated with soil contamination, prompting a targeted intervention of the known pollution source (battery processing) and documented route of exposure (incidental ingestion of contaminated soil). Typically, when exposure is discontinued, human BLLs typically decline at a predictable rate of halving every 28 days. In this intervention, while BLLs initially declined as expected, they eventually plateaued, leading to further investigation. This revealed an unexpected source of lead exposure: turmeric adulterated with lead chromate. Addressing this newly identified source finally allowed BLLs to decline predictably, highlighting the importance of comprehensive exposure assessments in mitigation efforts.
