The study, published April 24 in the journal Environmental Science & Technology, builds on existing data models estimating how much microplastic humans unwittingly eat and inhale as a result of untreated plastic debris degrading and dispersing into the environment.
Overall, the study found that Indonesians eat about 15 grams of microplastics per month—more than any other country—with the majority of plastic particles coming from aquatic sources such as seafood. That is a 59-fold increase in daily microplastic consumption from 1990 to 2018, the date range used for the models. U.S. dietary intake of microplastics is estimated to be about 2.4 grams per month, while the lowest is Paraguay at 0.85 grams.
Data on airborne microplastic concentration, age demographics and human respiration rates were used to calculate microplastics being inhaled. Residents of China and Mongolia topped the list, breathing in more than 2.8 million particles per month. U.S. residents inhale about 300,000 particles per month. Only residents in the Mediterranean and nearby regions breathed less, with countries like Spain, Portugal and Hungary breathing about 60,000 to 240,000 particles per month.
According to the study, a 90% reduction in aquatic plastic debris could lead to substantial decreases in microplastic exposure, potentially by up to 51% in developed countries and 49% in highly industrializing regions.