Microfiber fallout during dining and potential human intake

The pervasiveness of microfibers, including fibrous microplastics indoors and outdoors, has drawn attention. However, some places such as the dining environment that are closely related to human diet and health have been neglected. Here, we characterized short-term microfiber fallout in different dining spots and conducted long-term monitoring in a college cafeteria. The results showed that the microfiber abundance of restaurants during the peak hour of dinnertime (75 ± 19 MFs/plate/meal) was approximately two times that of households (36 ± 23 MFs/plate/meal). The high microfiber abundance was positively correlated with strong human activities (i.e., sitting rate of people) in restaurants, which was verified by the kinetics data of the cafeteria (R² =0.871, p = 0.000). Cotton (63%), polyester (17%), and rayon (14%) were the top three detected microfibers via μ-FTIR, and cloth friction can aggravate fiber shedding significantly. Moreover, high hairiness and short staple yarn style were likely to increase the formation of microfibers. Additionally, room structure can obviously influence microfiber abundance that households without separate dining rooms showed three times higher microfiber abundance (66 MFs/plate/meal) than those (21 MFs/plate/meal) with separate dining rooms, because partition walls were verified to effectively reduce fiber transport. Collectively, microfiber fallout during dining deserves our great attention, which may induce human intake of 63–232 MFs/person/d.