An estimated 2.2 million tons of microplastics can be generated in the course of a decade from plastic waste traded internationally each year. The annual volume of global plastic waste trade totals 14 million tons; in some regions, up to 60% of this amount is bound to get incinerated, dumped in open landfills or processed without proper environmental monitoring. Such was the conclusion made by an international team of researchers from the UK Centre for Ecology & Hydrology, Texas A&M University, the Indian Institute of Tropical Meteorology and other scientific organizations.
International plastic waste trade allows high-consumption countries to send some of their used plastic abroad for processing. Although China had long been one of the largest recipients, it imposed tight restrictions on the import of plastic waste in 2018. As a result, a significant share of these waste flows was redirected to Southeast Asia, as well as to Turkey, Africa and Latin America. However, many recipient countries lack the capacities to safely process even their own domestic waste, which means that additional imports put a heavier burden on their waste management systems.
Plastic left in open landfills gradually degrades due to exposure to sunlight, water, temperature fluctuations and mechanical stress. As a result, it breaks down into microplastics, or particles smaller than 5 mm in size which can enter soils and waterways or be transmitted through air. The researchers used an estimated degradation rate of about 3% per year. At this rate, some 26% of improperly disposed plastic turns into microplastics over a ten-year period. Based on the upper estimate of 8.4 million tons of plastic waste, it could eventually yield about 2.2 million tons of microplastics. It is, however, a rough estimate: the degradation rate depends largely on the type of plastic and environmental conditions.
Pollution is caused not only by landfills and open burning but also by the recycling process itself. The process of shredding and washing plastic waste produces fine particles that, without effective filtration, enter wastewater and the air. According to estimates cited in the study, mechanical recycling accounted for about 3.1% of global microplastic emissions in 2017. This is why waste exports can effectively shift part of the environmental burden associated with waste processing and subsequent degradation to other countries.
Once in the environment, microplastics can spread far away from their point of origin. They have been found in rivers and seas, soils and the atmosphere, including in remote mountainous and Arctic regions. However, the scientists do not posit that particles originating from imported waste are more dangerous than other microplastics. The biggest issue has to do with the redistribution of pollution: while plastic is primarily used in some countries, the consequences of waste management can be concentrated in other countries with limited capacities for safe recycling.
The researchers believe that the problem cannot be solved by recycling alone: currently, only about 9% of global plastic waste is recycled, and reducing plastic leakage to 2010 levels solely through improved waste management would require the proper collection and processing of more than 99% of waste. This is why they suggest focusing on reducing plastic waste and reusing products while also tightening controls on international trade and cutting microplastic emissions during recycling.
