Effectiveness of Prevailing Flush Guidelines to Prevent Exposure to Lead in Tap Water

Abstract

Flushing tap water is promoted as a low cost approach to reducing water lead exposures. This study evaluated lead reduction when prevailing flush guidelines (30 s–2 min) are implemented in a city compliant with lead-associated water regulations (New Orleans, LA, USA). Water samples (n = 1497) collected from a convenience sample of 376 residential sites (2015–2017) were analyzed for lead. Samples were collected at (1) first draw (n = 375) and after incremental flushes of (2) 30–45 s (n = 375); (3) 2.5–3 min (n = 373), and (4) 5.5–6 min (n = 218). There was a small but significant increase in water lead after the 30 s flush (vs. first draw lead). There was no significant lead reduction until the 6 min flush (p < 0.05); but of these samples, 52% still had detectable lead (≥1 ppb). Older homes (pre-1950) and low occupancy sites had significantly higher water lead (p < 0.05). Each sample type had health-based standard exceedances in over 50% of sites sampled (max: 58 ppb). While flushing may be an effective short-term approach to remediate high lead, prevailing flush recommendations are an inconsistently effective exposure prevention measure that may inadvertently increase exposures. Public health messages should be modified to ensure appropriate application of flushing, while acknowledging its short-comings and practical limitations.

Influence of surface copper content onStenotrophomonas maltophiliabiofilm control using chlorine and mechanical stress

“…Tabrez Khan et al (2013) also observed a decrease in EPS production after exposure to CuNP at 50 g l À1 for 16 h, observing that copper had a greater influence on protein production than on polysaccharide production. Contradicting the present results, Katner et al (2018) and Miao et al (2017) found that exposure to copper was associated with an increase in EPS production by anaerobic ammonia-oxidizing bacteria and by wastewater activated sludge, respectively. Therefore, the effects of copper exposure on EPS production is non-consensual.…”

Under-Sink Activated Carbon Water Filters Effectively Remove Lead from Private Well Water for over Six Months

“…Thus, these households represent a different type of Pb release than previously characterized by private well water profile sampling, where semi-random increases in Pb concentrations in the profile were predominantly in the particulate form [23]. Otherwise, this finding confirms what has been shown elsewhere that flushing can reduce Pb levels at the tap, but not ensure that the water is consistently safe for consumption [52,53]. The observed long-term effectiveness of the filters for Pb removal may be attributable in part to relatively low water usage and Pb loading at the kitchen tap.…”

“…On a mass basis, the total Pb mass in profiles without the filter was approximately 49.1-155 µg compared to 2.1-23.9 µg with the filters, representing a mass reduction of 66-98% (85% on average) in the first 17-23 L of flushed water after a 6-h stagnation time. Thus, even with additional risks due to the faucet, the use of an under-sink filter reduces the total amount of Pb at the tap by (a) mitigating Pb release from distant plumbing sources, ensuring that users are not inadvertently exposed to higher concentrations of Pb in the flushed water [53], and (b) improving the effectiveness of flushing by requiring less flushing time to reach Pb levels below 1 µg/L. Installing a filter in conjunction with flushing the faucet for one minute after long periods of non-use will thus ensure the greatest Pb exposure reduction.…”

Disparity in Risk Factor Severity for Early Childhood Blood Lead among Predominantly African-American Black Children: The 1999 to 2010 US NHANES

“…Data on parental occupation that can result in take-home contamination [103], proximity to lead-emitting industry, leaded household plumbing, or Pb intake from drinking water are not examined by the NHANES. However, it can be reasonably assumed that most of the affected households with Pb-contaminated drinking water involve older homes built before 1978 [104], given that bans on leaded household plumbing began in 1986. Recent renovation or removal of old paint, leaded paint hazards in the house, and household Pb dust measurements were not included in our analyses as a result of reporting only until 2004.…”