A critical review of microbiological colonisation of nano- and microplastics (NMP) and their significance to the food chain

Microplastics are extremely small mixed shaped plastic debris in the environment. These plastics are manufactured (primary microplastics) or formed from the breakdown of larger plastics once they enter the terrestrial, freshwater and marine environments (secondary microplastics). Over time, a combination of physical, photochemical and biological processes can reduce the structural integrity of plastic debris to produce microplastics and even further to produce nanoplastics. NMPs have been detected in both the aquatic and terrestrial environments and can be easily spread by water, soil and air and can be ingested by a wide range of organisms. For example, NMPs have been found in the guts of fish and bivalve shellfish. Microplastics have also been detected in food and in human faeces. Therefore, NMPs are not only found in the environment, but they may contaminate the food supply chain and be ingested by consumers. There is evidence suggesting that microorganisms are able to colonise the surfaces of microplastics and aggregates of nanoplastics. However, the risk to consumers posed by NMPs colonised with microorganisms (including those that are AMR) which enter the food supply chain is currently unknown.