Bringing to light vinyl chloride oligomers, a class of polychlorinated alkanes differing from chlorinated paraffins

Polyvinyl chloride (PVC) is one of the most widely used polymers, which contrasts with the low amount of literature on the leaching of associated additives and in particular unintended oligomers, a class of non-intentionally added substances (NIAS). This study sheds light on the occurrence of vinyl chloride oligomers (VCOs) in a variety of PVC analytical standards (n = 4), PVC items employed for construction, medical or food contact applications (n = 14), as well as in foodstuffs and environmental matrices (n = 10). Samples were analysed by liquid chromatography coupled to high-resolution mass spectrometry hyphenated with chloride-enhanced electrospray ionisation. Series of saturated (⁰VCO), monounsaturated (¹VCO), diunsaturated (²VCO) and triunsaturated (³VCO) VCOs were revealed. The dominant series remained ¹VCOs of the general formula C_2nH_3nCl_n, accounting for ∼80 % of VCOs in PVC standards. A risk of signal overlap was found between ⁰VCOs of the general formula C_2nH_3n+1Cl_n+1 (accounting for ∼8 % in PVC standards) and polychlorinated alkanes making up chlorinated paraffins, given that they share the same chemical formulas. A methodology for discriminating between signals arising from VCOs and chlorinated paraffins has been proposed. VCOs were detected in 88 % of the samples analysed (other than standards), and in particular in some foodstuffs and environmental matrices, suggesting that VCOs have the capacity to leach out of PVC materials, and thus contaminate food and the environment. Overall, these results call for greater attention to be paid to vinyl chloride oligomers and raise the question of whether they pose a risk to living organisms.