Plastic as a Carrier of POPs to Aquatic Organisms: A Model Analysis

Abstract

It has been hypothesized that persistent organic pollutants (POPs) in microplastic may pose a risk to aquatic organisms. Here we develop and analyze a conceptual model that simulates the effects of plastic on bioaccumulation of POPs. The model accounts for dilution of exposure concentration by sorption of POPs to plastic (POP "dilution"), increased bioaccumulation by ingestion of plastic-containing POPs ("carrier"), and decreased bioaccumulation by ingestion of clean plastic ("cleaning"). The model is parametrized for the lugworm Arenicola marina and evaluated against recently published bioaccumulation data for this species from laboratory bioassays with polystyrene microplastic. Further scenarios include polyethylene microplastic, nanosized plastic, and open marine systems. Model analysis shows that plastic with low affinity for POPs such as polystyrene will have a marginal decreasing effect on bioaccumulation, governed by dilution. For stronger sorbents such as polyethylene, the dilution, carrier, and cleaning mechanism are more substantial. In closed laboratory bioassay systems, dilution and cleaning dominate, leading to decreased bioaccumulation. Also in open marine systems a decrease is predicted due to a cleaning mechanism that counteracts biomagnification. However, the differences are considered too small to be relevant from a risk assessment perspective.

Persistence of Plastic Litter in the Oceans

“…This is a particular concern as it involves the lower echelons of the marine food web, where any adverse impact may affect the entire food chain and potentially the global fish supply (Betts 2008). Others have suggested that this transfer pathway is likely of limited importance under equilibrium conditions (Gouin et al 2011;Koelmans et al 2013Koelmans et al , 2014. At least in the lugworm Arenicola marina, conservative modeling suggests that the transfer of POPs (Bisphenol A and nonylphenol) from microplastics into the organism yields concentrations below the global environmental concentration of these chemicals (Koelmans et al 2014).…”

Focal plane array detector-based micro-Fourier-transform infrared imaging for the analysis of microplastics in environmental samples

“…[32][33][34][35][36] Hence, when microplastics, because of their minuteness, enter marine food webs at low trophic levels they simultaneously harbour the risk of potentially propagating these toxic substances up the food chain. [37,38] This issue is discussed controversially in recent research and although several studies suggest it being of minor importance from a risk assessment perspective [39,40] microplastics have the potential to transport POPs to human food. [33] In addition, because of their material properties many microplastic particles are buoyant and their durability enables them to travel long distances.…”

Microplastics present pollution puzzle

“…And at a chemical level, an organism's intake of toxic substances from microplastic may be dwarfed by the inputs from its food and water, according to modeling studies by Bart Koelmans, an aquatic ecologist and chemist at Wageningen University in The Netherlands (20,21). Koelmans's model predicts the fate of different pollutants ingested in food, water, and plastic particles, based "This is only the start of thinking about the problem in a rigorous way," says Kara Lavender Law.…”