Thank you Thomas Backhaus and Martin Wagner for this really interesting debate! I’ve been following the debate and meaning to add some thoughts to it for a while but then other things got in the way as I intended to write a more elaborate comment. To avoid that it once again slips my mind – here goes.
I absolutely agree that we need to be more balanced when communicating risks related to MPs and that we need to avoid hyperboles. I also think that it is important, as Liboiron recently pointed out in “The Conversation”, that we avoid averaging risk . That also means that, as much as possible, we should avoid averaging risk for different types of organisms, particle sizes, types of materials, shapes- essentially we should avoid extrapolating too much. That, however, leaves us with a lot of question marks. Your debate covers a wide range of subtopics but eventually it reaches the final “to act or not to act” on microplastics (MPs).
As I see it the answer is, and should be, it depends. It especially depends on what kind of action that we are talking about. The first steps to aim for should probably not be the most costly or technically advanced. It should also not be to stop using plastics entirely, since it’s a very useful material and preventive actions do needs to be put in context of its societal benefits. The first steps to aim for are, however, quite basic and could even come with some other positive side effects such as; better waste management, decreased material consumption and better designs that aim at maintaining as much material and energy value as possible for as long as possible.
In many cases, big important steps towards limiting the release of MPs into the environment are relatively easily implemented. Take for example industrial spills. It may be hard to reach a zero-pellets-released but great improvements could be achieved with introducing regular sweepings on the ground where pellets are stored and handled as well as the installation of filters for the runoff (these preventive measures should then be implemented for all actors involved in handling plastic pellets).
If we instead look at the bulk of MPs in the environment a lot of them are estimated to be fragments of bigger pieces of plastic litter. That means that one of the most effective ways of addressing microplastics would be to prevent litter in general. And it seems that most people, including the both of you as I understand it, agree that the macrolitter is something that we should take action on. And true, here it is not MPs that should be the driving force for change. The fragmentation of bigger pieces of litter into MPs that are subsequently found all over the world is just one more reason, in the midst of many, as to why we need to address inadequate waste management. Earlier this year we could for example read news-articles about a trash mountain that fell over houses nearby and killed 17 people in Mozambique , the year before that it was a trash-landslide in Ethiopia that killed 46 persons . Aside from these massive tragic events, uncollected solid waste contributes, especially on a local level, to respiratory ailments, dengue fever, diarrhoea, air pollution and flooding .
Maybe those examples are too simple? We could instead focus on a smaller source; MPs in personal care products (PCPs). I would maybe argue that this has received a disproportionate amount of focus, considering that it is not likely to be a major source. However, as Thomas points out - even if MPs in PCPs are not be a big contribution it still makes sense since to change to more sustainable alternatives since MPs in PCPs have limited societal benefits. So maybe we could also consider turning the debate around? People’s reactions towards MPs in PCPs show us that many are opposed to the thought of adding things to PCPs that that are 1) not necessary 2) take a long time to mineralize and 3) could potentially maybe have negative effects on the environment and/or human health. As an environmental scientist this reaction actually makes me cautiously optimistic. Since plastics are tangible and relatable, it makes sense that it would evoke a stronger reaction than a chemical that is not only hard to relate to but that also has a name that most people cannot even pronounce. Maybe instead of communicating “microplastics aren’t actually so bad compared to x” we should consider communicating “yes, plastic particles are added to products without any true understanding of what happens with it afterwards, other than it will take a long time for it to degrade. In fact, a lot of things, for example x, y and z, are added to PCPs, even though they have limited societal benefits and even though we are not sure that it is safe”. And then we can revisit the discussion as to whether that is something that we want to continue doing?
Another complex issue is car tires. We need car tires to be safe but car tires are known to release a lot of particulate pollutants, since by design approximately 30% of them disappear during their period of usage. Considering that transport is linked to several other environmental problems this knowledge could, however, also be seen as yet another reason as to why we need to improve public transport and sustainable transport alternatives. Taking care of runoff from bigger roads also seems like something that we would want to investigate since it would be beneficial in more ways than one.
Monitoring is indeed trickier; it does take resources but since we know so little about the sources/pathways it seems reasonable to allocate some monitoring effort to microplastic pollution. That monitoring also helps us to better understand other types of microlitter in the marine environment better.
In conclusion; the way that I see it, it is not so much a question as to whether we should or shouldn’t act but instead a question of which actions we should prioritize. And in order to make those priorities I think that, moving forward, we need to become better at communicating how closely linked these issues are to other sustainability challenges.Because MPs and other particulate pollutants are quite often connected to other sustainability challenges. Solutions should not be decided upon in a vacuum but instead we do need to become better at exploring the links between the different problems and solutions.
 Hoornweg, D. and P. Bhada-Tata, What a waste: a global review of solid waste management. 2012.