Sampling for lead in drinking is easier said than done. There are scientific and technical issues that complicate sampling and interpretation of testing results. It is important to understand that the purpose of sampling for lead under the USEPA lead rule is not exposure assessment. The primary goal is to confirm whether or not the water system is practicing optimal corrosion control. Seems to me that we are at a critical juncture in regulating lead in drinking water and some innovative thinking is needed to develop and move forward with a regulatory approach that will be effective in reducing lead exposure.
Goovaerts P. Monitoring the aftermath of Flint drinking water contamination crisis: Another case of sampling bias? Sci Total Environ. 2017 Mar 2. pii: S0048-9697(17)30440-0. doi: 10.1016/j.scitotenv.2017.02.183.
The delay in reporting high levels of lead in Flint drinking water, following the city’s switch to the Flint River as its water supply, was partially caused by the biased selection of sampling sites away from the lead pipe network. Since Flint returned to its pre-crisis source of drinking water, the State has been monitoring water lead levels (WLL) at selected “sentinel” sites. In a first phase that lasted two months, 739 residences were sampled, most of them bi-weekly, to determine the general health of the distribution system and to track temporal changes in lead levels. During the same period, water samples were also collected through a voluntary program whereby concerned citizens received free testing kits and conducted sampling on their own. State officials relied on the former data to demonstrate the steady improvement in water quality. A recent analysis of data collected by voluntary sampling revealed, however, an opposite trend with lead levels increasing over time. This paper looks at potential sampling bias to explain such differences. Although houses with higher WLL were more likely to be sampled repeatedly, voluntary sampling turned out to reproduce fairly well the main characteristics (i.e. presence of lead service lines (LSL), construction year) of Flint housing stock. State-controlled sampling was less representative; e.g., sentinel sites with LSL were mostly built between 1935 and 1950 in lower poverty areas, which might hamper our ability to disentangle the effects of LSL and premise plumbing (lead fixtures and pipes present within old houses) on WLL. Also, there was no sentinel site with LSL in two of the most impoverished wards, including where the percentage of children with elevated blood lead levels tripled following the switch in water supply. Correcting for sampling bias narrowed the gap between sampling programs, yet overall temporal trends are still opposite.
Zhong B, Giubilato E, Critto A, Wang L, Marcomini A, Zhang J. Probabilistic modeling of aggregate lead exposure in children of urban China using an adapted IEUBK model. The Science of the total environment. 2017 Feb 7. pii: S0048-9697(16)32629-8. doi: 10.1016/j.scitotenv.2016.11.164.
Lead, a ubiquitous pollutant throughout the environment, is confirmed to be neurotoxic for children by pulmonary and oral routes. As preschool children in China continue to be exposed to lead, we analyzed the available biomonitoring data for preschool children in urban China collected in the period 2004-2014 through a literature review. To identify apportionment of lead exposure sources for urban children in China, we modified the IEUBK model with a Monte Carlo module to assess the uncertainty and variability of the model output based on limited available exposure data and compared the simulated blood lead levels with the observed ones obtained through literature review. Although children’s blood lead levels in urban China decreased statistically over time for the included studies, changes in blood lead levels in three economic zones and seven age groups except for two age-specific groups were no longer significant. The GM-predicted BLLs and the GM-observed BLLs agreed within 1μg/dL for all fourteen cities. The 95% CIs for the predicted GMs and the observed distribution (GM±GSD) overlapped substantially. These results demonstrated the plausibility of blood lead prediction provided by the adapted IEUBK model. Lead exposure estimates for diet, soil/dust, air, and drinking water were 12.01±6.27μg/day, 2.69±0.89μg/day, 0.20±0.15μg/day, and 0.029±0.012μg/day, respectively. These findings showed that the reduction of lead concentrations in grains and vegetables would be beneficial to limit the risk of dietary lead exposure for a large proportion of preschool children in urban China.
Pieper KJ, Tang M, Edwards MA. Flint Water Crisis Caused By Interrupted Corrosion Control: Investigating “Ground Zero” Home. Environmental science & technology. 2017 Feb 1. doi: 10.1021/acs.est.6b04034.
Flint, Michigan switched to the Flint River as a temporary drinking water source without implementing corrosion control in April 2014. Ten months later, water samples collected from a Flint residence revealed progressively rising water lead levels (104, 397, and 707 μg/L) coinciding with increasing water discoloration. An intensive follow-up monitoring event at this home investigated patterns of lead release by flow rate-all water samples contained lead above 15 μg/L and several exceeded hazardous waste levels (>5000 μg/L). Forensic evaluation of exhumed service line pipes compared to water contamination “fingerprint” analysis of trace elements, revealed that the immediate cause of the high water lead levels was the destabilization of lead-bearing corrosion rust layers that accumulated over decades on a galvanized iron pipe downstream of a lead pipe. After analysis of blood lead data revealed spiking lead in blood of Flint children in September 2015, a state of emergency was declared and public health interventions (distribution of filters and bottled water) likely averted an even worse exposure event due to rising water lead levels.
Tyrrell JB, Hafida S, Stemmer P, Adhami A, Leff T. Lead (Pb) exposure promotes diabetes in obese rodents. J Trace Elem Med Biol. 2017 Jan;39:221-226. doi: 10.1016/j.jtemb.2016.10.007.
BACKGROUND: Pb (lead) exposure occurs at elevated frequency in urban inner city populations that also have high rates of obesity and diabetes.
OBJECTIVES: To determine if Pb can promote the development of diabetes in a setting of obesity, we examined the effect of Pb exposure on glucose metabolism in a rodent model of obesity.
METHODS: Adult female ZDF rats were exposed to Pb in drinking water for 24 weeks. Fasting blood glucose, insulin, and glucose tolerance were measured at regular intervals. Expression of hepatic gluconeogenic genes was measured in exposed and control animals and in cultured hepatoma cells treated with Pb.
RESULTS: Pb exposure induced fasting hyperglycemia after 8 weeks and glucose intolerance after 12 weeks of exposure. In addition, Pb-exposed animals showed elevated hepatic triglyceride levels and increased expression of the gluconeogenic genes PEPCK and glucose-6-phosphatase. In cultured rat hepatoma cells treatment with Pb stimulated PEPCK and glucose-6-phosphatase gene expression, suggesting a possible direct effect of Pb on hepatic gluconeogenic gene expression.
CONCLUSIONS: In the setting of obesity, Pb exposure is prodiabetic, causing fasting hyperglycemia and glucose intolerance in rats. A contributing factor to the metabolic effects of Pb may be the direct stimulation of hepatic gluconeogenic gene expression.
Goovaerts P. The drinking water contamination crisis in Flint: Modeling temporal trends of lead level since returning to Detroit water system. The Science of the total environment. 2016 Oct 5. pii: S0048-9697(16)32137-4. doi: 10.1016/j.scitotenv.2016.09.207.
Since Flint returned to its pre-crisis source of drinking water close to 25,000 water samples have been collected and tested for lead and copper in >10,000 residences. This paper presents the first analysis and time trend modeling of lead data, providing new insights about the impact of this intervention. The analysis started with geocoding all water lead levels (WLL) measured during an 11-month period following the return to the Detroit water supply. Each data was allocated to the corresponding tax parcel unit and linked to secondary datasets, such as the composition of service lines, year built, or census tract poverty level. Only data collected on residential parcels within the City limits were used in the analysis. One key feature of Flint data is their collection through two different sampling initiatives: (i) voluntary or homeowner-driven sampling whereby concerned citizens decided to acquire a testing kit and conduct sampling on their own (non-sentinel sites), and (ii) State-controlled sampling where data were collected bi-weekly at selected sites after training of residents by technical teams (sentinel sites). Temporal trends modeled from these two datasets were found to be statistically different with fewer sentinel data exceeding WLL thresholds ranging from 10 to 50μg/L. Even after adjusting for housing characteristics the odds ratio (OR) of measuring WLL above 15μg/L at non-sentinel sites is significantly >1 (OR=1.480) and it increases with the threshold (OR=2.055 for 50μg/L). Joinpoint regression showed that the city-wide percentage of WLL data above 15μg/L displayed four successive trends since the return to Detroit Water System. Despite the recent improvement in water quality, the culprit for differences between sampling programs needs to be identified as it impacts exposure assessment and might influence whether there is compliance or not with the Lead and Copper Rule.
Posted in Lead
Tagged Lead, Michigan
Mona Hanna-Attisha, Jenny LaChance, Richard Casey Sadler, and Allison Champney Schnepp. Elevated Blood Lead Levels in Children Associated With the Flint Drinking Water Crisis: A Spatial Analysis of Risk and Public Health Response. American Journal of Public Health. 2016;106:283–290. doi:10.2105/AJPH.2015.303003
Objectives. We analyzed differences in pediatric elevated blood lead level incidence before and after Flint, Michigan, introduced a more corrosive water source into an aging water system without adequate corrosion control.
Methods. We reviewed blood lead levels for children younger than 5 years before (2013) and after (2015) water source change in Greater Flint, Michigan. We assessed the percentage of elevated blood lead levels in both time periods, and identified geographical locations through spatial analysis.
Results. Incidence of elevated blood lead levels increased from 2.4% to 4.9% (P < .05) after water source change, and neighborhoods with the highest water lead levels experienced a 6.6% increase. No significant change was seen outside the city. Geospatial analysis identified disadvantaged neighborhoods as having the greatest elevated blood lead level increases and informed response prioritization during the now-declared public health emergency.
Conclusions. The percentage of children with elevated blood lead levels increased after water source change, particularly in socioeconomically disadvantaged neighborhoods. Water is a growing source of childhood lead exposure because of aging infrastructure.
Posted in Lead
Tagged Lead, Michigan
Deshommes E, Andrews RC, Gagnon G, McCluskey T, McIlwain B, Doré E, Nour S, Prévost M. Evaluation of exposure to lead from drinking water in large buildings. Water Research. 2016 Apr 22;99:46-55. doi: 10.1016/j.watres.2016.04.050.
Lead results from 78,971 water samples collected in four Canadian provinces from elementary schools, daycares, and other large buildings using regulatory and investigative sampling protocols were analyzed to provide lead concentration distributions. Maximum concentrations reached 13,200 and 3890 μg/L following long and short stagnation periods respectively. High lead levels were persistent in some large buildings, reflected by high median values considering all taps, or specific to a few taps in the building. Simulations using the Integrated Uptake Biokinetic (IEUBK) model and lead concentrations after 30 min of stagnation in the dataset showed that, for most buildings, exposure to lead at the tap does not increase children’s blood lead levels (BLLs). However, buildings or taps with extreme concentrations represent a significant health risk to young children attending school or daycare, as the estimated BLL far exceeded the 5 μg/dL threshold. Ingestion of water from specific taps could lead to acute exposure. Finally, for a few taps, the total daily lead intake reached the former World Health Organization (WHO) tolerable level for adults, suggesting potential health risks.
Posted in Lead
Tagged Canada, Lead