Environmental impacts of plastics: Moving beyond the perspective on waste

The United Nations have introduced the term "triple planetary crisis" to describe the interlinked global crises of climate change, biodiversity loss and environmental pollution. The UN is using this term to highlight the interdependence and mutual impact of these crises on ecosystems, societies and economies. However, while the contribution of plastics on environmental pollution appears to be well researched, biodiversity and climate change have received comparatively little attention. "Scientific understanding of the interactions of these crises with regard to plastics is currently patchy and unevenly distributed," concludes author and UFZ hydrogeologist Dr Christian Schmidt.

The UFZ researchers operate over a wide range of disciplines from hydrology, toxicology, microbiology and environmental chemistry to social sciences and are part of the UFZ's Microplastics Competence Cluster. They evaluated more than 19,000 scientific studies in preparing this article. The findings are very clear: 17,463 of the evaluated studies address the negative impacts of plastics and associated chemicals on environmental pollution, only 1,279 consider the impacts on climate change and a scant 652 focus on the impacts on biodiversity. "There is an extremely divergent drift in the available knowledge," summarizes Prof Annika Jahnke, author and UFZ environmental chemist.

A comprehensive knowledge base is available for environmental pollution, particularly concerning the plastics life cycle. Since the 1950s, approximately 9,200 million tons of plastics have been produced around the world. Of this, 2,900 million tons are currently in use, comprising 2,700 million tons of primary plastics and roughly 200 million tons of recycled material. 5,300 million tons have ended up in landfills and 1000 million tons have been incinerated. It is also known that between 1,750 and 2,500 million tons are considered "mismanaged", meaning that they can leak into the environment in an unplanned manner. The hazards that plastic-associated chemicals pose to humans and environmental organisms and the impact of plastics on oceans, soils and freshwater ecosystems are also regarded as well researched. However, going further into detail reveals knowledge deficits here as well, which in turn correspond to research gaps: How are plastics in the environment transported further by wind and water? How much plastics reach the oceans? Where do plastics accumulate in the environment? What are the effects of UV radiation, temperature differences or mechanical stress on plastics and the chemicals they contain? Furthermore, only a paucity of studies deal with the effects of plastics on the atmosphere and the cryosphere, which is that part of the Earth's surface where water is present as snow or ice. Nanoplastics have also generally been the subject of less research than microplastics. There are significantly more studies on microplastics, as the particles are larger and could therefore be studied by a large number of institutions for some time. The chemical composition of the plastics is also largely unknown, as they contain many added chemicals in addition to the polymer. Examples of these are UV stabilizers, plasticizers or associated processing aids that can be used to facilitate processing of the plastics or to lend them specific desired properties. To date, roughly 640 million tons of additive chemicals have been added to plastic products. "But little is known about how they are released and what consequences they have for people and the environment," explains Annika Jahnke.

Research on the effects of plastics on climate change is also limited. For example, there is the question of the extent to which greenhouse gas emissions are caused by plastics production, the extent to which plastics affect biogeochemical cycles in the global oceans or how plastics change the albedo, i.e. how much solar radiation is reflected back from the earth's surface. Similarly few studies have been published on the effects of plastic pollution on biodiversity. There are a few studies, such as on the toxicity of plastics, changes in habitats and ecosystems and rafting of species. "We aim to shift the focus away from viewing plastics as merely a waste problem Not only do plastics cause a disposal and waste management problem, but the entire life cycle must be considered, starting from the extraction of raw materials," says Christian Schmidt. Plastics also contribute to exacerbation of climate change and biodiversity loss through various mechanisms. Environmental pollution, climate change and biodiversity loss must therefore be considered comprehensively. "We need a broader perspective."

The UFZ researchers therefore see the need for a strongly overarching focus on international regulations to achieve the necessary shift in perspective towards comprehensive global solutions. "We now know that plastics contain roughly 16,000 chemicals. Of these, it is known that over 4,200 are persistent in the environment, accumulate in living organisms, are transported over long distances or pose a potential hazard," says Annika Jahnke. Current regulations cover only a very few of these chemicals. Many of these substances could be replaced by less problematic ones that fulfil the same function. Together with UFZ ecotoxicologist Dr Dana Kühnel and as part of the network known as the "Scientists' Coalition for an Effective Plastics Treaty", Annika Jahnke intends to contribute recommendations such as these to the negotiations on the global UN plastics treaty, which will be conducted in Busan (South Korea) from 25 November to 1 December. In the final meeting, the international community plans to adopt a global agreement with objectives including reducing the production of new plastics and reducing hazardous plastics chemicals. "Because of the broad impacts of plastics, it is important to also harmonise future agreements with legislation protecting the climate and biodiversity. This necessitates the regulation of plastics and associated chemicals," says Dana Kühnel.