The danger of microplastics

P plas­tics have colonised the planet thanks to their re­silience and abil­ity to dis­perse. En­vi­ron­men­tal­ists have long warned about the im­pact of plas­tics on the en­vi­ron­ment, but they also af­fect human health, in the form of mi­cro­scopic par­ti­cles that get into our bod­ies.

Re­searchers from Spain’s Na­tional Re­search Coun­cil (CSIC), have re­cently dis­cov­ered that tak­ing in mi­croplas­tics through food re­duces and al­ters the bac­te­r­ial di­ver­sity of the gut mi­cro­biota. Also called in­testi­nal flora, the gut mi­cro­biota is made up of var­i­ous bac­te­ria and mi­croor­gan­isms that are ben­e­fi­cial for our health. Some ex­perts even con­sider gut mi­cro­biota to be an­other organ be­cause of its im­por­tance for our im­mune sys­tems.

The study pub­lished in Sci­en­tific Re­ports shows that in­gest­ing PET (poly­eth­yl­ene tereph­tha­late) mi­croplas­tics – mainly used to make water bot­tles – de­creases the abun­dance of ben­e­fi­cial bac­te­ria in the in­testines while caus­ing mi­cro­bial groups re­lated to the ap­pear­ance of dis­eases to in­crease. Al­ter­ations in the human mi­cro­biota have been linked to con­di­tions as di­verse as asthma, chronic in­flam­ma­tory dis­eases and liver prob­lems.

“Given the pos­si­ble chronic ex­po­sure to these mi­croplas­tic par­ti­cles through our diet, the re­sults ob­tained sug­gest that their con­tin­ued in­take could alter the in­testi­nal bal­ance and, there­fore, health,” says Vic­to­ria Moreno, a re­searcher at CSIC’s In­sti­tute of Re­search in Food Sci­ences (CIAL).

The re­searchers re­spon­si­ble for the study in­sist that know­ing where these mi­croplas­tic ma­te­ri­als end up within the body and the con­se­quences they may have in the short, medium and long term is vital. It is es­ti­mated that an av­er­age per­son could in­gest be­tween 0.1 and 5 grams of mi­croplas­tics a week through their food and drink. In ad­di­tion, the study showed for the first time that these mi­croplas­tics can un­dergo trans­for­ma­tions along the gas­troin­testi­nal tract and reach the colon in a struc­turally dif­fer­ent form than when they were in­gested.

Re­search in this field is still new and it is not known ex­actly in which tis­sues and or­gans these mi­croplas­tics are ac­cu­mu­lat­ing. The as­sump­tion is that if the par­ti­cles are large enough the body will expel them, but those that are smaller – the small­est are nanoplas­tics – may pass into the blood­stream and thus reach dif­fer­ent or­gans. Al­though there are still no large-scale stud­ies, traces of plas­tic have been found in sam­ples of human pla­centa, as well as lungs, kid­neys, liver and spleen. Ex­perts agree that more re­search is needed on what ef­fects these traces may have and also on how ex­actly they get into our di­ges­tive sys­tem. It seems clear that many mi­croplas­tics are in­gested through the con­sump­tion of fish and shell­fish, as the oceans are heav­ily pol­luted by plas­tic prod­ucts.

De­spite ef­forts to re­cy­cle plas­tic, the amount of plas­tic that ends up in the ocean is huge. Ac­cord­ing to the IUCN (In­ter­na­tional Union for Con­ser­va­tion of Na­ture), the total amount is at least 14 mil­lion tonnes a year, mak­ing plas­tic the main waste ma­te­r­ial to be found in the oceans. Plas­tic has even been found at a depth of 10,000 me­tres and trapped in Arc­tic ice.

There is talk of the planet’s oceans turn­ing into “plas­tic soup”, and we know of five huge is­lands of plas­tic that have been cre­ated due to the con­ver­gence of sea cur­rents and winds. Two of them are in the At­lantic (North and South), two more are in the Pa­cific (also North and South) and one is in the In­dian Ocean.

With the Mediter­ranean Sea being a largely en­closed body of water with a lot of tourist ac­tiv­ity on its shores, the pres­ence of mi­croplas­tics here is es­pe­cially wor­ry­ing. Ac­cord­ing to Green­peace, be­tween 21% and 54% of all plas­tic par­ti­cles scat­tered in the planet’s seas and oceans are to be found in the Mediter­ranean.

It is es­ti­mated that the plas­tic float­ing or de­posited on shores ac­counts for only 15% of all the plas­tic in the oceans. Much more plas­tic is in sus­pen­sion. Over time, the ac­tion of water and the sun break the plas­tics down into ever smaller pieces that are then scat­tered through­out the ma­rine ecosys­tems. It is when they reach a size of less than 5 mil­lime­tres that they are con­sid­ered mi­croplas­tics and this is when it be­comes easy for them to enter the food chain, via fish, birds and ma­rine mam­mals.

In 2020, sci­en­tists from the Uni­ver­sity of Hull in the UK pub­lished a re­view of 50 stud­ies done over the pre­vi­ous six years on lev­els of mi­croplas­tic con­t­a­m­i­na­tion in fish and shell­fish in dif­fer­ent parts of the world. The re­searchers found that mol­lusks (such as clams, mus­sels, oys­ters and scal­lops) con­tained the high­est lev­els. They also found that the most pol­luted an­i­mals were col­lected off the coast of Asia.

As for de­f­i­n­i­tions, there is a dis­tinc­tion be­tween mi­croplas­tics gen­er­ated from the frag­men­ta­tion of larger pieces, those that from the wear and tear of fab­ric – mi­crofibers – and those that are called pri­mary, which get into the en­vi­ron­ment in the form in which they were orig­i­nally syn­the­sised. These are mi­cros­pheres, spher­i­cal par­ti­cles so small they pass through fil­ters and pu­ri­fiers. These tiny par­ti­cles are used in ex­fo­li­at­ing gels or de­ter­gents, for ex­am­ple. Green­peace has launched a cam­paign to raise aware­ness of mi­cros­pheres and coun­tries such as the US and the UK have en­acted re­stric­tions.

fea­ture health