Project 3: Modeling spatial patterns of drinking-water contamination

Mayuri Bhatia, Aaron J Specht, Vallabhuni Ramya, Dahy Sulaiman, Manasa Konda, Prentiss Balcom, Elsie M Sunderland, and Asif Qureshi. 2021. “Portable X-ray Fluorescence as a Rapid Determination Tool to Detect Parts per Million Levels of Ni, Zn, As, Se, and Pb in Human Toenails: A South India Case Study.” Environ Sci Technol, 55, 19, Pp. 13113-13121. Publisher's VersionAbstract
Chronic exposure to inorganic pollutants adversely affects human health. Inductively coupled plasma mass spectrometry (ICP-MS) is the most common method used for trace metal(loid) analysis of human biomarkers. However, it leads to sample destruction, generation of secondary waste, and significant recurring costs. Portable X-ray fluorescence (XRF) instruments can rapidly and nondestructively determine low concentrations of metal(loid)s. In this work, we evaluated the applicability of portable XRF as a rapid method for analyzing trace metal(loid)s in toenail samples from three populations (n = 97) near the city of Chennai, India. A Passing-Bablok regression analysis of results from both methods revealed that there was no proportional bias among the two methods for nickel (measurement range ∼25 to 420 mg/kg), zinc (10 to 890 mg/kg), and lead (0.29 to 4.47 mg/kg). There was a small absolute bias between the two methods. There was a strong proportional bias (slope = 0.253, 95% CI: 0.027, 0.614) between the two methods for arsenic (below detection to 3.8 mg/kg) and for selenium when the concentrations were lower than 2 mg/kg. Limits of agreement between the two methods using Bland-Altman analysis were derived for nickel, zinc, and lead. Overall, a suitably calibrated and evaluated portable XRF shows promise in making high-throughput assessments at population scales.

Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS)

Elsie Sunderland's Biogeochemistry of Global Contaminants lab at the Harvard SEAS is the home of MEMCARE-SRC's Project 3. Dr. Sunderland's lab develops and evaluates environmental models of and factors controlling spatial and temporal variability in trace metals and organic chemicals. Chemical analysis of water samples for Project 3 will also be conducted at Harvard SEAS.