Generation of microplastics from the opening and closing of disposable plastic water bottles

There has recently been a significant increase in interest regarding the prevalence of microplastics in bottled water. Previous studies have shown that the composition of many of the microplastics in bottled water is consistent with the materials of the bottle and bottle cap. The focus of this study is to quantify microplastic particle generation from the cap and bottle interaction during open and close cycles. Nile Red dye was used for the detection of microplastics >4.7 μm in size. Microplastic contamination levels in the water were found to increase as the bottle cap is opened and closed repeatedly. The rate of generation of particles with bottle opening and closing cycles (553 ± 202 microplastics/L/cycle) is adequate to account for the total particle density in the water. This clearly demonstrates that the abrasion between the bottle cap and bottleneck is the dominant mechanism for the generation of microplastic contamination detected in bottled water. A large spread between the maximum and minimum levels of microplastic contamination for bottles from the same lot, regardless of the number of times the cap is opened and closed, suggests that mechanical tolerances in the manufacturing of bottles and caps might play an important role in microplastic generation.