A community outreach lead screening program using capillary blood collected on filter paper

Area of Science:

• Environmental Health
• Pediatric Toxicology
• Clinical Chemistry

Background:

• Environmental lead contamination poses significant health risks, particularly to children.
• Accurate and accessible screening methods are crucial for early detection and intervention.
• Traditional venous blood sampling can be invasive and challenging in field settings.

Purpose of the Study:

• To evaluate the efficacy of fingerstick blood collection onto filter paper as an alternative screening method for lead exposure.
• To assess the accuracy of filter paper blood lead level (BLL) measurements compared to venous blood samples.
• To determine the suitability of this method in high-risk environments with potential lead contamination.

Main Methods:

• Paired venous and capillary blood samples were collected from 120 children (6 months to 6 years) in high-risk Detroit neighborhoods.
• Blood lead content was analyzed using graphite furnace atomic absorption spectrometry.
• Concordance, sensitivity, specificity, and predictive values were calculated for filter paper samples against venous samples at various cutoffs.

Main Results:

• Filter paper samples showed high concordance (0.96) with venous samples at a cutoff of 0.48 micromol/L (10 microg/dL).
• Sensitivity (94%) and specificity (99%) were excellent at the 0.48 micromol/L cutoff, with a positive predictive value of 97%.
• Accuracy decreased at higher cutoffs (0.72 micromol/L), with underreporting observed, though specificity remained high.

Conclusions:

• Capillary filter paper sampling is an accurate and practical alternative to venous sampling for blood lead screening, particularly at the 0.48 micromol/L cutoff.
• The method is highly specific for lead detection across tested cutoffs.
• Further investigation is needed to understand the discrepancies in reporting higher lead levels (≥0.72 micromol/L).