Investigation of factors affecting the accumulation of vinyl chloride in polyvinyl chloride piping used in drinking water distribution systems

Abstract

Plastic piping made of polyvinyl chloride (PVC), and chlorinated PVC (CPVC), is being increasingly used for drinking water distribution lines. Given the formulation of the material from vinyl chloride (VC), there has been concern that the VC (a confirmed human carcinogen) can leach from the plastic piping into drinking water. PVC/CPVC pipe reactors in the laboratory and tap samples collected from consumers homes (n = 15) revealed vinyl chloride accumulation in the tens of ng/L range after a few days and hundreds of ng/L after two years. While these levels did not exceed the EPA's maximum contaminant level (MCL) of 2 μg/L, many readings that simulated stagnation times in homes (overnight) exceeded the MCL-Goal of 0 μg/L. Considerable differences in VC levels were seen across different manufacturers, while aging and biofilm effects were generally small. Preliminary evidence suggests that VC may accumulate not only via chemical leaching from the plastic piping, but also as a disinfection byproduct (DBP) via a chlorine-dependent reaction. This is supported from studies with CPVC pipe reactors where chlorinated reactors accumulated more VC than dechlorinated reactors, copper pipe reactors that accumulated VC in chlorinated reactors and not in dechlorinated reactors, and field samples where VC levels were the same before and after flushing the lines where PVC/CPVC fittings were contributing. Free chlorine residual tests suggest that VC may be formed as a secondary, rather than primary, DBP. Further research and additional studies need to be conducted in order to elucidate reaction mechanisms and tease apart relative contributions of VC accumulation from PVC/CPVC piping and chlorine-dependent reactions.

Occurrence and Assessment of Chemical Contaminants in Drinking Water in Tunceli, Turkey

“…Some other chemical pollutants that are also monitored in drinking water according to EU Directive 98/93 on drinking water have the following guideline values: benzene (1.0 g/L), which is widely used in products containing plastics, rubber, resins, and synthetic fabrics like nylon and polyester; epichlorohydrin (0.1 g/L), which is used for making glycerine, plastics, and other polymers, some of which are used as coagulant aids in water treatment; vinyl chloride (0.5 g/L), which is used in polyvinyl chloride piping in drinking water distribution systems [35]; and acrylamide, which is used in acrylamide based polymeric coagulant aids used in water treatment (0.1 g/L)-all of which are suspected to be human carcinogens [3]. The EPA's maximum contamination level goals in drinking water for benzene, vinyl chloride, epichlorohydrin, and acrylamide are zero [14].…”

Abiotic degradation of chlorinated ethanes and ethenes in water

“…VC can be leached from PVC piping (Walter et al 2011). Their improper use and disposal leads to unintentional releases to the environment.…”

A Perspective on the Global Pandemic of Waterborne Disease

“…Piping used after 1977 should not leach vinyl choride, a known carcinogen, but it is not clear whether the research is as yet conclusive [20], or the US EPA entirely agrees [21] (EPA 2012). The other problem is that organic chemicals such as gasoline weaken PVC and can even permeate the piping.…”