Tag Archives: Lead

Galvanic Corrosion of Lead by Iron

Trueman BF, Sweet GA, Harding MD, Estabrook H, Bishop DP, Gagnon GA. Galvanic Corrosion of Lead by Iron (Oxyhydr)oxides: Potential Impacts on Drinking Water Quality. Environmental science and technology. 2017 May 30. doi: 10.1021/acs.est.7b01671.

Lead exposure via drinking water remains a significant public health risk; this study explored the potential effects of upstream iron corrosion on lead mobility in water distribution systems. Specifically, galvanic corrosion of lead by iron (oxyhydr)oxides was investigated. Coupling an iron mineral cathode with metallic lead in a galvanic cell increased lead release by 531 µg L-1 on average-a nine-fold increase over uniform corrosion in the absence of iron. Cathodes were composed of spark plasma sintered Fe3O4 or α-Fe2O3 or field-extracted Fe3O4 and α-FeOOH. Orthophosphate immobilized oxidized lead as insoluble hydroxypyromorphite, while humic acid enhanced lead mobility. Addition of a humic isolate increased lead release due to uniform corrosion by 81 µg L-1 and-upon coupling lead to a mineral cathode-release due to galvanic corrosion by 990 µg L-1. Elevated lead in the presence of humic acid appeared to be driven by complexation, with 208Pb and UV254size-exclusion chromatograms exhibiting strong correlation under these conditions (R2average = 0.87). A significant iron corrosion effect was consistent with field data: lead levels after lead service line replacement were greater by factors of 2.3 – 4.7 at sites supplied by unlined cast iron distribution mains compared with the alternative, lined ductile iron.

Lead, Legionella in US Drinking Water Supplies

Rosen MB, Pokhrel LR, Weir MH. A discussion about public health, lead and Legionella pneumophila in drinking water supplies in the United States. The Science of the total environment. 2017 Jul 15;590-591:843-852. doi: 10.1016/j.scitotenv.2017.02.164.

Lead (Pb) in public drinking water supplies has garnered much attention since the outset of the Flint water crisis. Pb is a known hazard in multiple environmental matrices, exposure from which results in long-term deleterious health effects in humans. This discussion paper aims to provide a succinct account of environmental Pb exposures with a focus on water Pb levels (WLLs) in the United States. It is understood that there is a strong correlation between WLLs and blood Pb levels (BLLs), and the associated health effects. However, within the Flint water crisis, more than water chemistry and Pb exposure occurred. A cascade of regulatory and bureaucratic failures culminated in the Flint water crisis. This paper will discuss pertinent regulations and responses including their limitations after an overview of the public health effects from Pb exposure as well as discussion on our limitations on monitoring and mitigating Pb in tap water. As the Flint water crisis also included increased Legionnares’ disease, caused by Legionella pneumophila, this paper will discuss factors influencing L. pneumophila growth. This will highlight the systemic nature of changes to water chemistry and public health impacts. As we critically analyze these important aspects of water research, we offer discussions to stimulate future water quality research from a new and systemic perspective to inform and guide public health decision-making.

Evaluating bias in lead sampling, Flint, Michigan

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.

Lead in Urban Children, China

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.

Flint Michigan Crisis Caused by Interrupted Corrosion Control

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.

Lead exposure and diabetes

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.

Flint Michigan Lead Levels Since Returning to Detroit Water

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.