Sequential digestion for measuring leachable and total lead in the same sample of dust or paint chips by ICP-MS

Abstract

House lead exposure is generally assessed using total lead, except in France, where acid-leachable lead is used for routine regulatory purposes. In order to allow an international comparison of French lead dust contamination, a sequential digestion protocol is developed to determine both leachable and total lead on the same sample with a two-step digestion stage: firstly, hydrochloric acid is added to the sample at 37°C to solubilize leachable lead; then nitric acid is added to an aliquot at 95°C to solubilize residual (i.e., non-leachable) lead. Both sample fractions are analyzed with inductively coupled plasma mass spectrometry (ICP-MS). The sum of the two fractions allows to determine total lead. This new protocol has been tested with wiped dust (n = 111) and paint chip (n = 46) samples collected in houses (n = 16). The leachability of lead ranged from 63 to 100% in dust and from 4 to 100% in paint. These findings confirm the strong variability of lead leachability in houses samples and thus the importance of considering it for lead poisoning prevention. This double determination of leachable and total lead for each wiped dust or paint sample appears to be a reproducible, simple, low-cost protocol and thus a useful tool for international comparison of house dust lead contamination.

Keywords:

• Lead poisoning
• digestion
• bioaccessibility
• household dust
• lead paint
• ICP-MS

Acknowledgments

Séverine Durand, Erwan Gilles and Gaelle Saramito from EHESP/LERES and Olivier Jacq from the Aubervilliers Public Health Service are gratefully acknowledged for their technical support throughout this study, Olivier Thomas for his comments on the manuscript, and JoAnn Cahn for revising it.