On June 10, 2021, the peer-reviewed journal Nature Sustainability published an analysis harmonizing litter inventories in aquatic environments from around the world. Carmen Morales-Caselles, of the University of Cadiz and European University of the Seas, and her colleagues gathered information from scientific surveys and civil society networks around the world to create a comprehensive aquatic litter database of over 12 million items. They defined seven river and marine environments and found “take-out consumer items made up the largest share across all environments (from 50% to 88%), except for the open ocean, where most of the items resulted from ocean-based activities.” The authors write that while locally litter types other than packaging may be more noticeable, “our global analysis clearly points to consumer activities as the main sources of marine litter, followed by sea-based activities.”
The database of identified litter only considered macro-litter pieces larger than 3cm in diameter. However, Morales-Caselles et al. also looked at the size distribution of plastic debris between half a millimeter and 1 meter in diameter. They found that through wave action larger, more buoyant pieces of plastic litter tend to stay near-shore where high temperatures and the mechanical stress of the waves “accelerate the cracking and fragmentation of plastic litter… resulting in the generation of the small fragments that are then likely to be transported offshore.” Considering that shorelines temporarily capture many microplastic items, these environments may be “key areas to intercept microplastic loads” before the particles can reach the open ocean.
Because the four most common macro-litter items were primarily consumer food packaging (single-use bags, bottles, food containers, and wrappers, making up 44% of total litter), the authors provide three considerations for researchers and policy-makers: (i) life cycle assessments of top litter products compared to more degradable products should account for all life-cycle impacts on ecosystems, (ii) regulatory bans on avoidable items should be the preferred action in the management of take-out items, and (iii) in addition to extended-producer responsibilities (FPF reported), an extended consumer responsibility on essential take-out products, such as through a deposit–refund levy, “may be justified on the basis of the extra risk of leakage to the environment of these particular products.”
Morales-Caselles, C., et al. (June 10, 2021). “An inshore–offshore sorting system revealed from global classification of ocean litter.” Nature Sustainability
Damian Carrington (June 10, 2021). “Takeaway food and drink litter dominates ocean plastic, study shows.” The Guardian
Packaging Gateway (June 10, 2021). “Report finds rise in food packaging litter on Canada shorelines.”
Ocean Wise (June 2021). “Great Canadian Shoreline Cleanup – 2020 Annual Report.” (pdf)