Forensic Estimates of Lead Release from Lead Service Lines during the Water Crisis in Flint, Michigan

Corrosion pipe scale samples were collected from 10 lead service lines (LSLs) in Flint, Michigan, after corrosive conditions associated with the Flint water crisis of 2014–2015 caused citywide release of lead into its drinking water. Elemental analysis of metals in the LSL scale revealed that the scale was relatively depleted of lead compared to a literature survey of LSL scale from 26 U.S. utilities. Flint LSL scale was also significantly enriched with aluminum and magnesium compared to reported literature LSL scale compositions. Using correlative associations of lead with aluminum and magnesium in Flint scale samples, and average LSL abundances of aluminum and magnesium from the literature, we estimated that at least 2.7 ± 1.5 g of lead per meter of Flint’s LSLs was released from the pipe scale during the corrosion episode. The findings provide evidence that selective dissolution of lead phosphate minerals occurred because of the absence of orthophosphate during the crisis.