Bertil Nlend, Dan Lapworth, Michaela Cashman, Melissa Lenczewski

Among the emerging contaminants, microplastics (1-5,000 µm) are becoming an important issue due to their ubiquity in the environment. However, research on this emerging contaminant has been conducted mainly in marine surface waters while microplastics (MPs) are now being found in even the most remote parts of the environment. For example, in groundwater which is the primary water source which supply the world, scientists are just starting to gather evidence on risks to groundwater and dependent ecosystems. This paper reviews the current understanding of plastic contamination in groundwater, summarizes methods that can be used for sampling and detection of plastics as well as the status of environmental regulation of plastics. From the handful of published studies, MPs origins in groundwater are mainly from wastewater effluent, road runoff, agricultural activities, and landfill leachate. The relevant nature of these contaminants are related to their high specific surface area and hydrophobicity allowing co-contamination with various hazardous chemicals such as PCBs, PAHs, BPA, PBDEs, heavy metals and antibiotics. Related to this issues of co-contamination in groundwater, there are potential risks to human health and wider ecosystems that are poorly understood and there has been almost no research undertaken on the occurrence of nanoplastics (<1 m) in groundwater systems. MPs can potentially contribute to cardiovascular diseases, skin irritation, cancer, reproductive effects, and respiratory and digestive problems. In addition, soil and groundwater contamination can be detrimental to aquatic micro-organisms. There is an urgent need to develop a better understanding of the risks MP and associated co-contaminants pose and advance national and regional regulations to restrict microplastic contamination of groundwater.