Legacy Substances in Recycled Materials: The Circular Economy's Chemistry Problem

Recycled materials carry the chemistry of the products they came from. Post-consumer streams contain yesterday's additives: brominated flame retardants from electronics-era plastics, legacy plasticisers, mineral oil hydrocarbons from printed paper, PFAS from treated articles, heavy-metal pigments from older production. Article 5's duties apply to packaging as placed, regardless of whether the substance arrived via virgin or recycled input - while Article 7 simultaneously mandates recycled content for plastics. The two duties are reconciled not by choosing one but by input quality: the content target is met with streams clean enough to meet the substance duties, which is why stream selection and decontamination are the system's critical technologies.

This is the circular economy's real chemistry problem, and the regulation's structure - targets plus thresholds, with no blanket recycled-content defence - states it without flinching.

Some legacy substances are not a minimisation question at all. The POPs Regulation sets concentration limits for persistent organic pollutants in waste and articles - certain brominated flame retardants among them - above which material must be destroyed rather than recycled, and below which recycling is managed within limits. Recyclers' sorting technology (density, spectroscopic identification of bromine-bearing plastics) exists to police exactly this boundary at stream level. A packaging manufacturer's incoming specification should reference the floor expressly for relevant streams (recycled engineering plastics above all): the recyclate supplier's POPs position, the sorting evidence, and the batch testing rhythm. Food-contact lines sit behind the additional safety gate of the contact-sensitive guide - authorised processes only - which is the system's structural answer for the most sensitive uses.

The recycled-board and mineral-oil story is the mature example of the pattern. Newsprint-derived recovered fibre carries mineral oil hydrocarbons from printing inks; these migrate through board into dry foods; member-state measures and industry migration barriers (functional barrier layers, inner bags, cleaner fibre selection) developed over a decade in response. The lessons generalise: the contaminant is managed by a stack - source selection, barrier design, migration testing - not by a single control; and the management is documented as a position in the file, revisited as limits and methods develop. Businesses meeting the pattern for the first time in another stream (PFAS in recycled moulded fibre, plasticisers in recycled PVC-adjacent streams) should copy the stack rather than improvise one.

For food-grade recycled plastics, authorised super-clean processes - deep washing, vacuum and thermal decontamination, validated by challenge tests - are the technology that lets a post-consumer stream re-enter contact use lawfully. Their existence is why the content targets for contact-sensitive PET are set where they are: the legislator mandated at the level the decontamination infrastructure can serve, and the 2040 step assumes its growth. Buyers of food-grade recyclate are buying a process as much as a material, and the evidence pack should name the process and its authorisation alongside the polymer - a discipline the contact-sensitive guide prescribes and this guide explains the reason for.

The practical synthesis is a single incoming-goods specification per recycled input, with four quadrants: content credentials (post-consumer share, certification), substance limits (Article 5 thresholds and the POPs floor, by stream risk), process credentials (authorisation where contact is intended), and change notification (stream source changes are specification changes). One document, owned jointly by procurement and compliance, tested on a rhythm proportionate to stream risk. Businesses that hold the four quadrants together find the two mandates stop appearing to conflict: the conflict was an artefact of specifying content in one department and chemistry in another.

Stream testing obeys risk economics: the broader and more variable the source stream, the denser the testing; the tighter and more controlled the loop, the more the evidence shifts to process audit. A closed deposit loop can be governed largely by certification and periodic verification; an open mixed-plastic stream needs batch-level screening for the restricted families. Price the testing into the input's comparison - a cheap recyclate with an expensive testing shadow is not cheap - and write the rhythm into the supply agreement so the cost sits in the open, where it can be managed, rather than in the audit, where it cannot.