Microplastic-mediated transport of PCBs? A depuration study with Daphnia magna

Abstract

The role of microplastic (MP) as a carrier of persistent organic pollutants (POPs) to aquatic organisms has been a topic of debate. However, the reverse POP transport can occur if relative contaminant concentrations are higher in the organism than in the microplastic. We evaluated the effect of microplastic on the PCB removal in planktonic animals by exposing the cladoceran Daphnia magna with a high body burden of polychlorinated biphenyls (PCB 18, 40, 128 and 209) to a mixture of microplastic and algae; daphnids exposed to only algae served as the control. As the endpoints, we used PCB body burden, growth, fecundity and elemental composition (%C and %N) of the daphnids. In the daphnids fed with microplastic, PCB 209 was removed more efficiently, while there was no difference for any other congeners and ΣPCBs between the microplastic-exposed and control animals. Also, higher size-specific egg production in the animals carrying PCB and receiving food mixed with microplastics was observed. However, the effects of the microplastic exposure on fecundity were of low biological significance, because the PCB body burden and the microplastic exposure concentrations were greatly exceeding environmentally relevant concentrations.

Microplastic Intake, Its Biotic Drivers, and Hydrophobic Organic Contaminant Levels in the Baltic Herring

“…In the European pilchard (Sardina pilchardus), Digka et al (2018) analyzed the presence of anthropogenic microparticles (1.2-5,000 µm) in the fishes' gastrointestinal tract using hydrogen peroxide digestion and found ∼75% of the particles to be in the size range of the natural food, further supporting primary ingestion as the main route for microplastic uptake in clupeids. Moreover, given the short residence time (Grigorakis et al, 2017) of ingested particles and the slow desorption kinetics of many HOCs, the lack of correlation between the MP and organic contaminants is rather expected and in line with other reports for fish and other aquatic animals (Herzke et al, 2016;Kleinteich et al, 2018;Gerdes et al, 2019).…”

“…A commonly held paradigm states that MP ingestion can lead to decreased nutritional status (Cole et al, 2015;Ogonowski et al, 2016) and bioaccumulation of hydrophobic organic chemicals (HOCs) (Rochman et al, 2013;Wardrop et al, 2016) that sorb to the MP particles in the water and desorb in the gut lumen (Rochman et al, 2014). However, some experimental and modeling studies indicate that plastic polymers could also have a net cleaning effect acting as passive samplers while in the digestive system and thereby relieve the animals of HOCs (Gouin et al, 2011;Gerdes et al, 2019;Mohamed Nor and Koelmans, 2019). The relative importance of microplastics as vectors for contaminant transport remains unresolved, possibly also due to the lack of field data linking HOC concentrations in biota to ingested MP in ecologically relevant settings.…”

Microplastic contamination of drinking water: A systematic review

“…Determining exposure levels is key in formulating a risk assessment framework for this emerging environmental contaminant. Health effects will be caused by: their physical attributes, the chemical properties of the polymers, the plasticisers, or other chemicals added in the manufacturing process, and the chemicals they can absorb in nature as well as the microbes that can grow on their surface [40][41][42].…”

Weight of Evidence for the Microplastic Vector Effect in the Context of Chemical Risk Assessment

“…One approach is to assess this via measurement. This requires assessment of chemical concentrations in plastic, water and ingested food throughout the experiment (e.g., Besseling et al 2017;Rehse et al 2018;Gerdes et al 2019b). Many studies have interpreted data based on nominal concentrations of chemicals on plastic, which however is not fully reliable.…”