Evidence of microplastic accumulation on the surface of lettuce and analysis of contamination sources

Microplastic (MP) pollution has emerged as a significant environmental concern. Microplastics land on vegetable surfaces with airborne deposition and agronomic activities. However, research on the sources of microplastics on vegetable surfaces is limited by the lack of monitoring of microplastics in the growing environment. Therefore, we detected microplastics on lettuce surfaces, in air, and in pesticides to determine the correlation between them. In addition, this study compared microplastics on the surface of different types of lettuce to explore their differences. The results showed that the content, in descending order, was old leaves of leaf lettuce > new leaves of leaf lettuce > nodular lettuce. A total of 19 polymers, mainly polyamide polyethylene and polypropylene, were detected on the surface of the lettuce. The contribution of microplastics on the surface of lettuce was air and pesticides in descending order of origin. Microplastic risk assessment index was determined that the risk level of microplastics on lettuce surfaces could be classed as level IV, indicating a high dietary health risk. The results presented here will enable scientific assessments of the exposure pathways of MPs in fresh vegetables and their potential harm to human health.