Date of Award
Background and Significance. Interior dust lead loadings on floors and windowsills are reliable predictors of a child’s blood lead level and an important predictor in “clearance testing” of residences. The traditional method of determining dust lead levels on surfaces is to send dust wipe samples to a laboratory for analysis. These laboratory analyses are expensive and analysis reports typically take up to 2 weeks to complete. The portable X-ray fluorescence device has been touted as a technique that can provide fast, accurate, and precise results regarding the presence of dust lead hazards in residences but needs to be further evaluated for comparability with laboratory analyses.
Methods. Dust wipe samples (n=109) collected from 13 homes were tested by means of X-ray fluorescence (XRF) analysis and subsequently analyzed for lead using Inductively Coupled Plasma Mass Spectrometry (ICPMS). Samples were collected from floors and interior windowsills and included blank samples and samples with known concentrations for quality control.
Results. Considering ICPMS as the “gold standard,” the XRF produced an average false negative rate of 5.6% at the new EPA dust lead hazard standards of 10μg/ft2 for floors and 100μg/ft2 for windowsills. Interestingly, there were no false positive results from the XRF device at the new dust lead hazard standards. A Bland Altman analysis showed that 96.3% of the data points were within the lower and upper acceptable limits of agreement. Results of a Mann-Whitney U test showed that lead concentration in windowsill dust wipe samples were significantly higher than floor dust wipe samples as reported by the ICPMS device (U=475.50μg/ft2, p<0.001).
Conclusion. The results of the study suggested that the XRF device has a good agreement with the ICPMS device at lower lead concentrations and may be appropriate for measuring lead concentrations in field dust wipe samples from homes where lead concentrations are not high. It can also be concluded that XRF device may be used as a positive and negative screen for lead dust hazards in the homes of children. Additional studies are needed to further evaluate the accuracy and comparability of XRF devices at the new EPA dust lead hazard standards.
Received from ProQuest
Alexander Boakye Obeng
Obeng, Alexander Boakye, "Validity Of A Portable X-Ray Fluorescence Device For Analyzing Field Dust Wipe Samples For Lead" (2020). Open Access Theses & Dissertations. 3114.