Black plastics: Linear and circular economies, hazardous additives and marine pollution

Abstract

Black products constitute about 15% of the domestic plastic waste stream, of which the majority is single-use packaging and trays for food. This material is not, however, readily recycled owing to the low sensitivity of black pigments to near infrared radiation used in conventional plastic sorting facilities. Accordingly, there is mounting evidence that the demand for black plastics in consumer products is partly met by sourcing material from the plastic housings of end-of-life waste electronic and electrical equipment (WEEE). Inefficiently sorted WEEE plastic has the potential to introduce restricted and hazardous substances into the recyclate, including brominated flame retardants (BFRs), Sb, a flame retardant synergist, and the heavy metals, Cd, Cr, Hg and Pb. The current paper examines the life cycles of single-use black food packaging and black plastic WEEE in the context of current international regulations and directives and best practices for sorting, disposal and recycling. The discussion is supported by published and unpublished measurements of restricted substances (including Br as a proxy for BFRs) in food packaging, EEE plastic goods and non-EEE plastic products. Specifically, measurements confirm the linear economy of plastic food packaging and demonstrate a complex quasi-circular economy for WEEE plastic that results in significant and widespread contamination of black consumer goods ranging from thermos cups and cutlery to tool handles and grips, and from toys and games to spectacle frames and jewellery. The environmental impacts and human exposure routes arising from WEEE plastic recycling and contamination of consumer goods are described, including those associated with marine pollution. Regarding the latter, a compilation of elemental data on black plastic litter collected from beaches of southwest England reveals a similar chemical signature to that of contaminated consumer goods and blended plastic WEEE recyclate, exemplifying the pervasiveness of the problem.

Identification, origin and characteristics of bio-bead microplastics from beaches in western Europe

“…Here, data are discriminated by location but most data-points, including those from the SWT plant, lie within 20% of the best-fit regression line forced through the origin. Significantly, the gradient of the best-fit line (Br-Sb = 1.45) is lower than that defining pre-and post-RoHS EEE plastics (Br-Sb = 2.92) and as determined by portable XRF and reported by Turner (2018b). Given that different types of polymer may require different kinds and quantities of halogenated flame retardant and synergist for protection (Papazoglou, 2004), the discrepancy in gradients may be partly attributed to the apparent use of recycled polyethylene in bio-beads compared with the use of a multitude of polymers in EEE (including polystyrene, polypropylene and acrylonitrile butadiene styrene).…”

“…This observation, coupled with the use of combinations of brominated compounds, Cd, Pb and Sb in electronic plastic as contaminants or in order to engender flame retardancy to heat-generating articles (Turner and Filella, 2018), suggests that many bio-beads are, or have been, manufactured, directly or indirectly, from end-of-life waste electrical and electronic equipment (WEEE). Potentially harmful chemicals are supposed to be removed from the WEEE stream but poor or inefficient practices have resulted in contamination of recycled consumer goods (Turner, 2018b). This is a particular problem for black products because domestic waste plastic coloured in this way is difficult to identify and recycle at municipal sorting facilities (Rozenstein et al, 2017) and, being inherently black, most electrical equipment casings afford a convenient and cheap alternative recyclate.…”

“…On this basis, we may assert that bio-beads from Texel, for example, where restricted chemicals are abundant and, in the case of Br, frequently exceed RoHS limits, are older than ones from the Scillies or the northern coast of France. That said, however, recent studies into contemporary consumer goods suggests that contamination of black plastic is a long-term but highly variable problem and that once contaminants are introduced and blended into the recyclate are difficult to eliminate (Turner, 2018b).…”

Cadmium pigments in consumer products and their health risks

“…Small quantities of Cd appear to be heterogeneously dispersed among consumer plastics, an effect 538 that may be attributed to the recycling and blending of electronic waste and PVC. While typical 539 concentrations reported are within the most recent regulatory limits and are unlikely to pose a 540 significant risk to consumers, the widespread occurrence of the metal highlights the poor and 541 inefficient practices involved in sorting and managing end-of-life products, and in particular plastic 542 housings of electronic equipment (Turner, 2018c). 543…”

Verkenning verwerkingsopties bedrijfsmatig gemengd kunststofverpakkingsafval

“…Een specifiek probleem zijn de broomhoudende vlamvertragers. Deze komen breed voor in plastics die voor elektronische apparatuur gebruikt worden en inmiddels in zo'n 20% van de zwarte gerecyclede kunststoffen [Turner 2018]. Deze broomhoudende vlamvertragers zullen dus ook aanwezig zijn in de zwarte kunststof-niet-verpakkingen die aanwezig zijn in ingezameld kunststof verpakkingsmateriaal en mogelijk zelfs ook in zwarte verpakkingen voor non-food-artikelen.…”