Plastics and recycling: a toxic relationship?

The recy­cling of the mate­ri­als that we pro­duce and con­sume has been iden­ti­fied as a major chal­lenge by the French gov­ern­ment. It is the sub­ject of a Pri­or­i­ty Research Pro­gramme and Equip­ment (PEPR) fund­ed by France 2030¹. Plas­tics, in par­tic­u­lar, are the focus of a ded­i­cat­ed research pro­gramme. The stat­ed objec­tive is to improve the knowl­edge and tech­niques that enable them to be reused, in order to pre­serve resources. Plas­tics are found every­where: in pack­ag­ing, tex­tiles, cos­met­ics, etc. They are extreme­ly ver­sa­tile and have become “inte­grat­ed into our pro­duc­tion and con­sump­tion prac­tices by pre­sent­ing them­selves as a sub­sti­tute for nat­ur­al mate­ri­als,” observes Bap­tiste Mon­sain­geon, soci­ol­o­gist and lec­tur­er at the Uni­ver­si­ty of Reims Cham­pagne-Ardenne. With the lim­i­ta­tions that we are aware of today.

To begin with, the bricks that make up plas­tics are main­ly obtained from fos­sil fuels (oil and gas) and assem­bled into a long chain: the poly­mer. Numer­ous sub­stances are used dur­ing the syn­the­sis process. Some are used to opti­mise the chem­i­cal reac­tion and are there­fore not intend­ed to end up in the fin­ished prod­uct, yet some are absorbed by the plas­tic. Oth­ers are used to give the mate­r­i­al spe­cif­ic prop­er­ties: flex­i­bil­i­ty, colour, UV or fire resis­tance, etc.

Accord­ing to the Plas­tChem report², up to 16,000 dif­fer­ent chem­i­cals can be used in plas­tic. A num­ber of them are poten­tial­ly harm­ful. “There are about 10,000 for which we lack data. And more than 4,000 that we know are dan­ger­ous,” warns Bethanie Car­ney Alm­roth, pro­fes­sor of eco­tox­i­col­o­gy at the Uni­ver­si­ty of Gothen­burg in Swe­den. “They can be car­cino­genic, dis­rupt the endocrine sys­tem, or be tox­ic to spe­cif­ic organs such as the kid­neys or the skin.”

The man­age­ment of plas­tic waste is all the more of an issue as it has per­me­at­ed our envi­ron­ment. This is what Flo­ri­an Pohl, a geo­science researcher at the Uni­ver­si­ty of Bayreuth in Ger­many, has observed when study­ing plas­tics in riv­er and marine sys­tems. “At a depth of 4,000 metres, if I take sed­i­ment from the ocean floor, I can detect microplas­tics. It’s fright­en­ing because it shows that they are lit­er­al­ly every­where,” he warns.

“Over the past 30 years, a huge amount of ener­gy and eco­nom­ic resources have been devot­ed to the devel­op­ment of recy­cling chan­nels, with the aim of rec­on­cil­ing sus­tain­abil­i­ty and eco­nom­ic growth,” sum­maris­es Bap­tiste Mon­sain­geon. In France, local author­i­ties are respon­si­ble for man­ag­ing our waste. In most cas­es, this is del­e­gat­ed to pri­vate oper­a­tors who col­lect the con­tents of our bins and waste cen­tres and send them to sort­ing cen­tres. There, the com­po­nents are sep­a­rat­ed accord­ing to their pos­si­ble use: ener­gy pro­duc­tion by incin­er­a­tion (“ener­gy recov­ery”) or recy­cling (“mate­r­i­al recov­ery”). Oth­er­wise, they are sent to landfill.

There are around twen­ty waste man­age­ment chan­nels in France. They are organ­ised on the prin­ci­ple of “extend­ed pro­duc­er respon­si­bil­i­ty³”: pro­fes­sion­als who place prod­ucts on the mar­ket (pack­ag­ing, tex­tiles, equip­ment, etc.) are respon­si­ble for financ­ing or man­ag­ing their post-con­sumer repro­cess­ing by users. “For paper, card­board and met­als, it works rather well,” says Bap­tiste Mon­sain­geon, “as for plas­tics, it is main­ly the PET in our water bot­tles that is recycled.”

In France, accord­ing to fig­ures from ADEME⁴, less than a third of post-con­sumer plas­tic waste is col­lect­ed, and only 14% of it is actu­al­ly recy­cled. Bap­tiste Mon­sain­geon points out that in 2018 “the gov­ern­ment set a tar­get of ‘100% recy­cling of plas­tic pack­ag­ing by 2025’. We are a long way from achiev­ing this.”

Reuse is sub­ject to a num­ber of tech­ni­cal lim­i­ta­tions. The fin­ished prod­ucts are com­plex assem­blies of dif­fer­ent mate­ri­als that can­not always be sort­ed. “Mechan­i­cal” recy­cling requires plas­tics to be sep­a­rat­ed into sim­i­lar poly­mers. They must then be washed and crushed into flakes, which are melt­ed down into gran­ules to make new plas­tic. Over time, this caus­es degra­da­tion of the poly­mers. “This long chain of mol­e­cules can break and start to short­en as it is heat­ed and melt­ed. The qual­i­ty of the mate­r­i­al dete­ri­o­rates, so new plas­tic must be added to main­tain it,” explains Bethanie Car­ney Alm­roth. “Ulti­mate­ly, there can be an increase in the amount of tox­ic sub­stances in plas­tics as they are recy­cled⁵⁶” she adds.

“Chem­i­cal” recy­cling, mean­while, offers meth­ods for chem­i­cal­ly sep­a­rat­ing poly­mers or break­ing them down into basic mol­e­cules, which can be used to recre­ate plas­tic. “Some of them have been shown to be effec­tive, but only on a small scale, on pre-indus­tri­al waste that is much pur­er than that from con­sumer waste,” she adds. They are there­fore not viable from an eco­nom­ic and envi­ron­men­tal point of view for mixed plastics.

Final­ly, there are plas­tics that we don’t know how to recy­cle prop­er­ly. “The chan­nels do not cov­er the entire waste deposit in France,” explains Bap­tiste Mon­sain­geon. “Some play­ers are there­fore look­ing to export, pri­mar­i­ly to Europe.” This can be a first step in the tran­sit of plas­tic mate­r­i­al flows: “Turkey, for exam­ple, is a place where plas­tic waste is export­ed, more or less legal­ly,” he says.

How­ev­er, while it may be vir­tu­ous, the repro­cess­ing of plas­tics remains a source of pol­lu­tion. “We know that recy­cling plants release microplas­tics and chem­i­cals when frag­ment­ing or shred­ding this waste⁷,” empha­sis­es Bethanie Car­ney Alm­roth. Not to men­tion that a lot of plas­tic ends up in land­fill. “This can obvi­ous­ly lead to con­t­a­m­i­na­tion of the envi­ron­ment, but also of humans,” she con­cludes, adding that “80% of glob­al recy­cling pass­es through the hands of waste pick­ers, the vast major­i­ty of whom work with­out pro­tec­tion against this expo­sure⁸.”

Poor waste man­age­ment also con­tributes to the spread of plas­tic in the envi­ron­ment. Due to open-air stor­age, at the mer­cy of the wind, or even dur­ing trans­port, as Flo­ri­an Pohl describes: “Some plas­tic gran­ules used as raw mate­r­i­al can end up in riv­er water⁹.” Car­ried along by the cur­rents, they are abrad­ed by the sed­i­ments and bro­ken down into ever small­er frag­ments. This increas­es the dif­fu­sion sur­face: the addi­tives escape from it more and more rapid­ly. “More and more plas­tic is end­ing up in the envi­ron­ment, and we don’t real­ly know the con­se­quences: how quick­ly do the sub­stances they con­tain release them­selves and what are the effects?” A ques­tion at the cen­tre of his research.

For Bap­tiste Mon­sain­geon: “Believ­ing in recy­cling is a bit like believ­ing in a promise: that of con­tin­u­ing to con­sume with a clear con­science.” How­ev­er, “it is pos­si­ble to restore it to its right­ful place with­out mak­ing it a mag­ic solu­tion,” he says. Start­ing with reduc­ing the types of plas­tic used to those that we know how to recy­cle, and lim­it­ing the num­ber of chem­i­cals used. “Addi­tives pro­vide func­tion­al­i­ty, but we can reduce them to a much small­er num­ber, avoid dan­ger­ous sub­stances, and strength­en leg­is­la­tion,” sug­gests Bethanie Car­ney Almroth.

This is a field that calls for inno­va­tion, to devel­op more sus­tain­able and safer mate­ri­als. How­ev­er, it is not a ques­tion of sim­ply replac­ing one mate­r­i­al with anoth­er, but of reduc­ing the pro­duc­tion of vir­gin plas­tic. “This is the con­sen­sus of the inter­na­tion­al sci­en­tif­ic com­mu­ni­ty, regard­less of the dis­ci­pline,” empha­sis­es Bap­tiste Monsaingeon.

This involves, in par­tic­u­lar, the imple­men­ta­tion of new infra­struc­tures to make reuse more acces­si­ble with reusable and refill­able con­tain­ers. “In France, a num­ber of com­pa­nies are work­ing in this field¹⁰¹¹,” com­ments Bethanie Car­ney Alm­roth. “This shows that there is scope for the imple­men­ta­tion of new eco­nom­ic mod­els,” beyond recy­cling and the unbri­dled pro­duc­tion of plastic.

Mikaël Mayorgas