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Ecotoxicology and Human Environmental Health
Lead levels at the tap and consumer exposure from legacy and recent lead service line replacements in 6 utilities Elise Deshommes, Benjamin Trueman, Ian Douglas, Daniel Huggins, Laurent Laroche, Jeff Swertfeger, Abby Spielmacher, Graham A. Gagnon, and Michèle Prévost Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.8b02388 • Publication Date (Web): 20 Jul 2018 Downloaded from http://pubs.acs.org on July 24, 2018
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Lead levels at the tap and consumer exposure
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from legacy and recent lead service line
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replacements in 6 utilities
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Elise Deshommes*, a, Benjamin Truemanb, Ian Douglasc, Dan Hugginsd, Laurent
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Larochee, Jeff Swertfegerf, Abby Spielmacherg, Graham A. Gagnonb and Michèle
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Prévosta
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*
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4711 (2236), fax number: (+1) 514-340-5918
Corresponding Author, e-mail:
[email protected], phone number: (+1) 514-340-
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a
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Montreal, Quebec, H3T 1J4, Canada
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b
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Scotia, B3H4R2, Canada
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c
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d
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e
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f
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g
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Canada
Department of Civil, Geological and Mining Engineering, Polytechnique Montreal,
Department of Civil and Resource Engineering, Dalhousie University, Halifax, Nova
City of Ottawa, Drinking Water Services, Ottawa, Ontario, K1P 1J1, Canada City of London, Water Operations, London, Ontario, N6A 4L9, Canada
City of Montreal, Technical Expertise Division, Montreal, Quebec, H8N 2K2, Canada
Greater Cincinnati Water Works, Cincinnati, Ohio, 45232, USA City of Guelph, Water Services, Environmental Services Guelph, Ontario, N1E 6P7
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KEYWORDS: lead service line replacement, flushing, profile sampling, corrosion
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control, exposure
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TOC/GRAPHICAL ABSTRACT
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ABSTRACT
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Profile, regulatory, and investigative sampling were completed in six utilities to study the
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impact of partial and full lead service line replacements (LSLRs) on water lead levels
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(WLLs) and consumer’s exposure. As compared to households with no replacement, lead
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release after partial LSLR (PLSLR) was generally greater in the short-term (3-50 days),
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comparable or lower in the medium (2 years). This was
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mainly explained by insufficient time elapsed to stabilize scales after disturbances to the
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service line. One utility showed sustained lead release over 18 months after PLSLR.
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Moreover, the reduction in WLLs was small when analyzing results for the same
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households. As a comparison, full LSLR decreased WLLs drastically and immediately.
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The occurrence of low (0-5 µg/L) to high (≥50 µg/L) WLLs in the profiles varied between
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households and reflected the variability of exposure amongst households in the same
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system. Using this probability of occurrence, the distribution of WLLs of exposure was
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estimated for households with or without a PLSLR, and used to model young children
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blood lead levels (BLLs) for both groups of households. The range of modeled BLLs 2 ACS Paragon Plus Environment
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decreased slightly for households with PLSLR, but still overlapped the range estimated
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for households with no replacement. This analysis suggests that, in a system, PLSLRs do
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not reduce young children blood lead levels except in a fraction of households.
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INTRODUCTION
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Lead service lines (LSLs) contribute to increased water lead levels (WLLs) and
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ultimately to increased blood lead levels (BLLs) of young children1-3. While corrosion
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control is applied in the United States and in Ontario (Canada) for systems exceeding the
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Action Levels of 15 µg/L and 10 µg/L respectively4,5, the lead crises in Flint, MI, and
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Washington, DC, are stark reminders that the legacy of LSLs combined with human error
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represents a serious risk for lead exposure through water1,2. Corrosion control may also
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be insufficient to achieve the recently proposed Canadian health-based value of 5 µg/L6.
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LSL replacements (LSLRs) are frequent in distribution systems upgrading their water
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mains, they are also conducted proactively. Considering the legal constraints related to
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dual ownership, and the lack of funding, utilities are however usually unable to complete
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full LSLRs (FLSLRs)7. Partial LSLRs (PLSLRs) can increase WLLs due to the
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disturbances caused to the LSL scales during replacement work. Moreover, galvanic
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corrosion deposits have been observed at the copper-lead junction of field-collected
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LSLs, and related to increased WLLs over the long-term in pilot studies7-12. Full-scale
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monitoring in Halifax and Montreal measured acute particulate lead release immediately
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after PLSLR; however, after two years the WLLs were generally lower than before
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replacement13,14. Nonetheless, 61% of the samples exceeded 10 µg/L short- and long-
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term (>2 years) after PLSLR in Montreal, while about 25% of the samples collected six
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months post-PLSLR were >15 µg/L in Halifax13. In these studies, the post-LSLR flushing
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procedure, the type of LSLR, and the water main material and corrosion state were
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evidenced as key parameters driving lead release following LSLR13-16.
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Regulated lead sampling includes the collection of the first draw after overnight
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stagnation without any pre-flush in the US (Lead and Copper Rule or LCR)4; two liters
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after 30 minutes of stagnation preceded by a pre-flush in Ontario (regulation 170/03)5;
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one liter after 5 minutes of flushing in Quebec17; and a random daytime sample in
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Europe18. The US and European protocols aim to evaluate system-wide corrosion control
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efficiency, although the latter can estimate consumer exposure at the system level. The
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Ontario protocol is a compromise because it includes a pre-flush that limits the
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probability of capturing water originating from the LSL and particulate lead. Its shorter
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stagnation time is however more typical of water use intervals in households18. Finally,
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the Quebec protocol aims to identify worst-case households >10 µg/L after flushing, but
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also underestimates the consumer’s exposure18,19. Profile (sequential) sampling consists
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of collecting consecutive samples (typically four or more samples) at the tap after
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stagnation. The volume collected covers the piping volume from the tap to the main19,20.
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Profile sampling has been used to detect lead sources in the piping, to quantify WLL
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variability, to measure corrosion control efficiency, and to evaluate galvanic corrosion in
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PLSLRs13,19-21. Although informative, profile sampling is not realistically applicable at
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large scale. Nonetheless, WLLs measured from profile sampling have been successfully
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linked to those measured after flushing, indicating that a few profiles may be sufficient to
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evaluate consumers’ potential risk of exposure in a full-scale system14,19.
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The main objective of this study was to investigate and document the impacts of PLSLR
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and FLSLR over short- and long-term for many water qualities, using full-scale results
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from profile and regulatory sampling. Based on the probability of occurrence of WLLs in
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the profiles, plausible exposure scenarios are drawn to better understand the impact of
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LSLR on exposure assessment.
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MATERIAL AND METHODS
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Utilities and monitoring design. Sampling for WLLs was completed at the kitchen tap
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of 3460 households before and/or after LSLR in five Canadian utilities (three provinces)
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and one US utility. Among these utilities, utilities A, B, and F are regulated using a 90th
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percentile action level of 10 µg/L after flushing and 30 minutes of stagnation (1st and 2nd
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liter); utilities C and E are regulated using a maximum acceptable concentration of 10
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µg/L after 5 minutes of flushing; utility D is regulated using a 90th percentile action level
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of 15 µg/L and a 1st draw sample collected after at least 6 hours of stagnation. Moreover,
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as the impact of PLSLR has been extensively studied for utilities C and E13,14,19, it will
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not be detailed in this paper. Corrosion control consisted in pH adjustment for utilities A
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and D and resulted in WLLs below the action level; the other utilities did not have
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corrosion control or not an optimized one as WLLs exceeded the local regulation. Table 1
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presents the main water quality parameters for the utilities studied and their monitoring
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design.
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The configurations of the households monitored included full LSLs (100% Pb), PLSLRs
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and FLSLRs (100% Cu). The effect of LSLR was evaluated over time after recent
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PLSLRs and FLSLRs. Moreover, old PLSLRs present in the distribution system were
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sampled. For purposes of this study, old PLSLRs are defined as legacy PLSLRs of
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greater than two years, while recent PLSLRs are PLSLRs of less than two years (0-50
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days in utility A, 3 days to 6 months in utility E, 0-1 year in utility D; 3 days to 2 years in
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other utilities; Table 1). Households monitored were all single-family homes except for a
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subsample of nineteen multi-unit homes. Finally, PLSLRs consisted of a copper pipe on
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the public side of the service line and a lead pipe on the private side, except a fraction of
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old PLSLRs in utilities C and F (lead on the public side, copper on the private side).
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Profile sampling was accomplished in five of the six utilities, and consisted in the
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collection of four to sixteen consecutive liters following a stagnation of either 30 minutes
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(30MS) or greater than 6 hours (6HS). Other protocols included the collection of a
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sample after 5 minutes of flushing (5MF, 5 utilities); a first-draw after 6HS according to
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the LCR (utility D), and two consecutive liters after 30MS according to Ontario 170/03
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regulation (utility F). Finally, samples were collected after 3 or 10 minutes of flushing
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(3MF, 10MF) in utility D following LSLR, while samples were collected in utility A by
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opening and closing the tap at maximum flow rate according to the particulate
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stimulation sampling (PSS) detailed in Deshommes et al.22. Samples were analyzed for
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total lead in water with ICP/MS by licensed laboratories (3450 households) according to
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the USEPA 200.8 method and Standard Method 3125 B. Finally, a subset of samples was
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analyzed with ASV analyzer23 in utility C (40 households). Collection periods were
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equally distributed to cover cold and warm seasons except for a subset of 30MS profiles
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collected in utility C (summer only), and for 6HS profiles collected in utility E
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(monitoring in summer for 100% Pb households, monitoring over time after LSLR from
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summer to winter).
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Table 1. Summary of the utilities and monitoring design. Utility and water quality parameters
A (pH 9.2; Alk. 33 mg/L as CaCO3, CSMR 0.2) B (pH 8.1; Alk. 90 mg/L as CaCO3, CSMR 0.44) C (pH 8.0; Alk. 95 mg/L as CaCO3, CSMR 1.1) D (pH 8.8; Alk. 74 mg/L as CaCO3, CSMR 0.45)
Number of households (number of samples in italics) Recent * PLSLR
Old * PLSLR
n=207 (n=1034) n=111 (n=111) n=11 (n=1195) n=1245 (n=1245) n=17 (n=170)
n=15 ǂ (n=160) n=15 (n=64) n=1 ǂ (n=63)
n=187 (n=935) n=81 (n=81) n=3 (n=405) n=506 (n=506) n=20 (n=211)
n=5 (n=132)
n=13 ǂ (n=417)
100% Pb
n=12 (n=303) n=16 (n=50)
Seasons
Sampling protocol
Summer and winter Summer and winter
5MF (1L), 30MS profile (4L)
*
Full LSLR -
PSS (1 or 2L)
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All seasons
5MF (1L), 30MS profile (8L)
-
All seasons
5MF (1L)
n=3 (n=19)
Summer
5MF (1L), 30MS profile † (≥8L)
n=7 (n=331)
n=3 ǂ (n=113)
All seasons
5MF (2L), 6HS profile ** (≥6L)
-
-
-
All seasons
Profile after 6HS (4-10L)
n=11 ǂ (n=245)
-
n=5 ǂ (n=183)
All seasons
1 draw 6HS, ǂǂ 3MF&10MF (0.75L)
-
st
E (pH 7.3; Alk. 20 mg/L as n=45 n=74 Summer to 5MF (1L), 6HS profile n=57 ǂ ǂ †† CaCO3; CSMR 1.1; 0.5 (n=225) (n=755) (n=975) Winter (4L) mg/L as OPO4) F st nd n=108 n=99 n=185 n=439 5MF (0.125L), 1 and 2 (pH 7.9; Alk. 277 mg/L All seasons L after 30MS (n=245) (n=288) (n=276) (n=1096) as CaCO3, CSMR 1.1) Notes: 5MF—5 minutes of flushing; 30MS—30 minutes of stagnation; 6HS—at least 6 hours of stagnation; PSS— Particulate Stimulation Sampling22; *PLSLR stands for partial LSLR; Recent PLSLR defined as
