A holistic approach to lead pipe scale analysis: Importance, methodology, and limitations

Trace elements in hair or fingernail and gastroesophageal cancers: results from a population-based case-control study

BACKGROUND

Growing evidence suggests that environmental factors probably play important roles in the development of gastroesophageal cancers (GOC), however, the effects of trace elements on GOC remain unclear.

OBJECTIVE

To assess the effect of trace elements on GOC and the effect modification by other factors.

METHODS

Hair and fingernail samples were collected from GOC cases and controls in a population-based case-control study in Taixing, China, and were used to detect the concentrations of 12 trace elements using inductively coupled plasma mass spectrometry. Unconditional logistic regression models were used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) for concentrations of 12 trace elements in association with GOC after adjusting the other factors.

RESULTS

A total of 830 hair samples (581 controls and 249 cases) and 895 fingernail samples (559 controls and 336 cases) were included. Compared to the lowest-tertile concentration, the higher tertiles of Ca, Zn, Fe, Al, Cr, Pb, Se, and V were positively associated with GOC, while the higher tertiles of Mg, Mn, Sr, and As were inversely associated with GOC. Significant interactions between the hair level of Cr and two other risk factors, including smoking (P for interaction = 0.044) and alcohol drinking (P for interaction = 0.028), were observed in association with GOC.

SIGNIFICANCE

The current study reveals that these 12 trace elements in hair and fingernails are associated with GOC to varying degrees. Further studies and animal experiments are needed to clarify the associations and explore potential mechanisms.

IMPACT STATEMENT

The role of trace elements in the development or inhibition of gastroesophageal cancers (GOC) remains unclear. In this study, we further explored the associations between 12 trace elements and GOC based on a population-based case-control study conducted in Taixing, China. Higher levels of Ca, Zn, Fe, Al, Cr, Pb, Se, and V were positively associated with increased GOC, while inverse associations between higher levels of Mg, Mn, Sr, As, and GOC were observed. Observed associations were consistent in hair and fingernail samples. Moreover, interaction effects between hair level of Cr and smoking or alcohol drinking were identified.

The Behavior of Polymeric Pipes in Drinking Water Distribution System-Comparison with Other Pipe Materials

The inner walls of the drinking water distribution system (DWDS) are expected to be clean to ensure a safe quality of drinking water. Complex physical, chemical, and biological processes take place when water comes into contact with the pipe surface. This paper describes the impact of leaching different compounds from the water supply pipes into drinking water and subsequent risks. Among these compounds, there are heavy metals. It is necessary to prevent these metals from getting into the DWDS. Those compounds are susceptible to impacting the quality of the water delivered to the population either by leaching dangerous chemicals into water or by enhancing the development of microorganism growth on the pipe surface. The corrosion process of different pipe materials, scale formation mechanisms, and the impact of bacteria formed in corrosion layers are discussed. Water treatment processes and the pipe materials also affect the water composition. Pipe materials act differently in the flowing and stagnation conditions. Moreover, they age differently (e.g., metal-based pipes are subjected to corrosion while polymer-based pipes have a decreased mechanical resistance) and are susceptible to enhanced bacterial film formation. Water distribution pipes are a dynamic environment, therefore, the models that are used must consider the changes that occur over time. Mathematical modeling of the leaching process is complex and includes the description of corrosion development over time, correlated with a model for the biofilm formation and the disinfectants-corrosion products and disinfectants-biofilm interactions. The models used for these processes range from simple longitudinal dispersion models to Monte Carlo simulations and 3D modeling. This review helps to clarify what are the possible sources of compounds responsible for drinking water quality degradation. Additionally, it gives guidance on the measures that are needed to maintain stable and safe drinking water quality.

Spherulitic Lead Calcium Apatite Minerals in Lead Water Pipes Exposed to Phosphate-Dosed Tap Water

Phosphate dosing is the principle strategy used in the United Kingdom to reduce the concentration of lead in tap waters supplied by lead water pipes. The mechanisms of phosphate-mediated lead control are not fully understood, but solid solutions of lead calcium apatite are thought to play an important role. This study investigated the microstructure of a lead pipe, supplied with high-alkalinity tap water, in which the lead calcium apatite crystals were spherulitic having rounded and dumb-bell-shaped morphologies. XRD, Fourier transform infrared spectroscopy, optical microscopy, Raman spectroscopy, scanning electron microscopy, and energy-dispersive spectroscopy showed that the lead pipe had a well-established inner layer of litharge; a middle layer containing lead calcium apatite spherulites, plumbonacrite, and some hydrocerussite; and an outer layer containing iron, lead, phosphorus, calcium, silicon, and aluminum. It was found that spherulitic lead calcium apatite could be grown in the laboratory by adding hydrocerussite to synthetic soft and hard water-containing phosphate, chloride, and citrate ions at pH 5.5 but not when the citrate was absent. This suggests that dissolved organic molecules might play a role in spherulite formation on lead water pipes. These molecules might inhibit the formation of lead calcium apatite, reducing the effectiveness of phosphate dosing in lead water pipes.

A literature review of bench top and pilot lead corrosion assessment studies

Bench top and pilot lead corrosion studies are gaining more interest, considering revisions and upcoming improvements to the Lead and Copper Rule. This literature review identified studies ranging from simpler month(s)-long bench top dump-and-fill stagnant water tests (coupon tests/standing pipe tests) to more complicated year(s)-long intermittent flow pilot studies (recirculating pipe loops/once through pipe rigs). With increasing complexity in design and operation, studies more closely approximated real plumbing conditions (e.g., by incorporating harvested lead pipes and intermittent flow regimes) at increased cost, footprint, and duration. Comparison of bench top and pilot designs (in terms of lead test piece age/dimensions/configuration/replicates, study duration, sample collection, and other factors) can assist drinking water utilities, consultants, academics, and others to select a design that matches their needs and constraints. No matter the choice, surrogate systems cannot replace actual system water testing and are best complemented by other corrosion assessment tools.

Release of Particulate Lead from Four Lead Corrosion Products in Drinking Water: A Laboratory Study Coupled with Microscopic Observations and Computational Fluid Dynamics

Particulate lead resulting from the detachment of lead corrosion products (LCPs) contributes significantly to lead contamination in drinking water. Since LCPs formed under different water chemistry possesses different crystal structures, their hydrodynamic behaviors could be significantly different in flowing water. In this study, flushing experiments and microscopic observations were employed to investigate the release of cerussite (PbCO₃), hydrocerussite (Pb₃(CO₃)₂(OH)₂), chloropyromorphite (Pb₅(PO₄)₃Cl), and lead dioxide (scrutinyite α-PbO₂/plattnerite β-PbO₂), the four LCPs commonly found in the drinking water distribution system. Under the same flow rate, particulate lead release showed the following trend: lead dioxide > cerussite ∼ chloropyromorphite > hydrocerussite. In the range of 1-10 L/min, a higher flow rate enhanced the release of cerussite, chloropyromorphite, and lead dioxide, while the release of hydrocerussite was not significantly affected, likely due to its platelike crystal structure that reduced the shear force exerted by the flowing water. The detachments of visible cerussite and chloropyromorphite particles were captured using a digital microscope at flow rates of 8.0 and 8.2 L/min, and the shear forces causing their detachments were determined to be 5.8 × 10^-11 and 3.1 × 10^-10 N, respectively, using computational fluid dynamics (CFD). Our study demonstrated that crystal structure could be an important factor affecting the detachment of LCPs and CFD could be a useful tool to characterize their hydrodynamic behaviors.