Transfer of PCBs from Microplastics under Simulated Gut Fluid Conditions Is Biphasic and Reversible

Abstract

The role of plastic as a vector for bioaccumulation of toxic chemicals is central to the risk assessment of microplastic for human health and the environment. However, transfer kinetics of sorbed contaminants from ingested microplastics are poorly understood. We develop and parametrize a chemical exchange model on microplastics in a gut fluid mimic of aquatic biota, and also included food to provide a better representation of contaminant dynamics when plastic and food are ingested, as would occur in nature. The transfer kinetics of 14 polychlorinated biphenyls (PCBs) were measured in gut fluid mimic systems under three environmentally relevant exposure scenarios of plastic ingestion by organisms, for low-density polyethylene (LDPE) and polyvinyl chloride (PVC), and were evaluated with the model. Chemical transfer was demonstrated to be biphasic and fully reversible, with fast exchange within hours followed by a slow transfer lasting for weeks to months. In clean gut systems, the bioavailability of plastic-associated PCBs for lugworms and cod ranged from 14 to 42% and 45−83% respectively. However, in contaminated gut systems, clean microplastic was capable of rapidly extracting ("cleaning") PCBs from food inside the gut, thus demonstrating that the effect of microplastic is context dependent. Therefore, chemical contamination and cleaning are likely to occur simultaneously due to the ingestion of microplastic.

Lifetime Accumulation of Microplastic in Children and Adults

“…For HOCs, the chemical exchange is quantified based on kinetic parameters and the concentration gradient between MPs and gut, using a previously published biphasic kinetic model for organic chemicals sorbed on MPs. 71 The chemical exchange in the fast and slow sorbing compartments is modeled as where C 1 and C 2 are chemical concentrations in the fast and slow reservoirs of the MP (μg/kg); k 1 is the fast sorption rate constant (d –1 ), k 2 is the desorption rate constant (d –1 ), and k 3 is the intrapolymer rate constant (d –1 ); and f 1 is the fast reservoir fraction (dimensionless). The rate constants for desorption into gut fluids were quantified in earlier research 71 and were rescaled to account for the diversity of particle sizes based on Fick’s law of diffusion (see the Supporting Information).…”

“…We parameterized the chemical exchange of HOCs in the present study for the case of low density polyethylene (LDPE) as it is a common polymer type 57 and has the best available information thus far. 71 The amount of chemical leached from LDPE in the gut was calculated using the MC approach and the aforementioned biphasic reversible (de-) sorption model. First, we generated 10,000 particles ( i ) with different sizes for MP in food and air, respectively, based on the aforementioned power-law exponents (i.e., α food and α air ).…”

The fate of plastic in the ocean environment – a minireview

“…22 If these are in equilibrium with the surrounding seawater, the risk of sorbed chemicals for ocean life is considered relatively low, but toxicity might become relevant under some exposure conditions. [23][24][25][26][27] It is unknown how long plastic waste remains in the environment. The durability of plastic entails slow degradation and it was believed that plastics may persists in the environment for an extended period of time, possibly exceeding centuries or even millennia.…”

Interaction of Environmental Pollutants with Microplastics: A Critical Review of Sorption Factors, Bioaccumulation and Ecotoxicological Effects

“…Therefore, MPs may play a crucial role in aquatic ecotoxicology acting as vectors for these highly toxic pollutants, becoming a potential source of lipophilic chemicals for bioaccumulation and biomagnification by facilitating their entrance to the food chain [59]. For that reason, several studies have assessed the potential bioaccumulation and bioavailability enhancement of chemicals previously sorbed on MPs [60][61][62][63][64]. Conversely, many authors have refuted the idea that MPs might have a relevant role in this bioaccumulation and biomagnification of toxic chemicals like POPs by marine animals.…”