Sentinel lead pipe racks quantify orthophosphate’s dose-response in drinking water

Le résumé fourni par la source

Orthophosphate is used to minimize lead contamination of tap water, but its benefits are difficult to quantify since lead concentrations are plumbing-dependent. Homes serviced by lead pipe are ideal for monitoring orthophosphate treatment, but best practices dictate the removal of lead once identified, which complicates sampling plans. Here we explore an alternative: recovered lead pipe racks supplied with distributed drinking water at various locations within a water system. We also propose a strategy for analyzing the data based on the generalized additive model, which approximates time series as a sum of smooth functions. In this study, geometric mean lead release from pipe racks exhibited a pronounced dose-response, falling by 54% after an increase from 1 to 2 mg PO4 L-1, and then climbing by 55% after a decrease to 1.5 mg PO4 L-1. Data from nine sentinel homes were consistent with those from pipe racks: geometric mean lead at the high orthophosphate dose was 60% of that at the low dose. Our results demonstrate sentinel pipe racks as a viable alternative to at-the-tap sampling for non-regulatory corrosion control monitoring. They also provide a Bayesian framework for quantifying orthophosphate’s effect on lead release that can incorporate information from multiple sources.

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