Table 2.

Studies assessing the possible synergetic/antagonistic effect of persistent organic compounds (POPs) combined with MPs.

MP Type	MP Size	Chemical Sorbate	Exposure Concentrations	Exposure Time	Organism	Toxicological Assessment	Highlight Results	Ref.
PS-divinilbenzene	97 μm	Pyrene	Pyrene alone [Pyrene] = 0.1 µM MPs alone [MPs] = 100 particles/L MPs + Pyrene 100 nM pyrene + 100 particles/L MPs	24 h	Tropical fish juveniles (Lates calcarifer)	Mortality rate Juveniles behaviour Predatory performance Size differences	Individuals exposed to both pollutants were the most affected group, but the negative impact was relatively small	[126]
PE	< 100 µm	Pyrene	MPs alone [MPs]= 20 g/L MPs + pyrene Before the experiment, a solution of PE or PS were incubated with pyrene (50 µg/L) for 6 days	7 days	Marine mussel (Mytilus galloprovincialis)	Histological analysis (gills and digestive glands) Gene transcription analyses Genotoxic effects Immunological alterations Neurotoxic responses Oxidative stress Antioxidant defences	Clear separation between control and MPs exposed mussels Biological variations were influenced by the typology of polymer (PE vs PS) Only genotoxic responses separated virgin from pyrene- contaminated polymers	[107]
PS
PE	1–5 µm	Pyrene	Pyrene alone [Pyrene]= 20 and 200 µg/L MPs alone [MPs]= 0, 18.4 and 184 µg/L MPs + Pyrene 0 µg/L pyrene-18.4 µg/L MPs 200 µg/L pyrene-184 µg/L MPs 200 µg/L pyrene-184 µg/L MPs	96 h	Juveniles of the common Goby (Pomatoschitus microps)	Protein content AChE, IDH, GST activities - LPO levels Bile samples were analysed for pyrene metabolites	The presence of MPs was found to delay the pyrene-induced mortality Enhanced concentration of pyrene-metabolites was detected in co-exposure treatments Results suggest toxicologically relevant interactions between both pollutants	[130]
PE	10–90 µm	Fluoranthene (Flu.)	Flu. alone [Flu]= 100 µg/L MPs alone [MPs]= 1000 particles/mL MPs + Flu. Flu – PE/PHB co-exposure or incubation at the same concentrations tested in single exposures (incubation during overnight)	96 h	Blue Mussel (Mytilus edulis)	Protein content in the cytosol The cytosolic concentration of GSH SOD, CAT, GPx and SeGPx activities	In co-exposure and incubation treatments, biochemical responses were generally comparable with those exerted MPs only Apparent absence of combined effects of MPs with the pollutant.	[5]
PHB	10–90 µm
PE	10–90 µm	Fluoranthene (Flu.)	Flu. alone [Flu]= 50 and 100 µg/L MPs alone [MPs]= 100 and 1000 particles/mL MPs+ Flu. 50 µg/L Flu.-100 particle/mL 100 µg/L Flu.-1000 particle/mL (For both mixtures, co-exposure and incubation experiments (incubation during overnight))	96 h	Blue mussel (Mytilus edulis)	Total GSH + 2GSSG levels SOD, CAT, GPx and SeGPx activities	No synergistic or antagonistic effect was seen in the co-exposure or the incubation experiments	[131]
PS	Mix of 2 and 6 µm	Fluoranthene (Flu.)	Flu. alone [Flu]= 30 µg/L day MPs alone [MPs]= 32 mg/L day MPs + Flu. 30 µg/L day Flu.-32 mg/L day PS	7 days (+ 7 days of depuration)	Marine mussel (Mytilus spp.)	Morphological and functional analyses of hemocytes Hemocyte mortality Circulating hemocytes concentration Phagocytosis activity Histopathological assessment (digestive tract and intestine) ROS production Levels of LPO SOD, CAT, GR and GST activities Gene expression analysis	Increase in the total histopathological lesions/ abnormalities was demonstrated in co-exposure treatments After depuration, a higher fluoranthene concentration was detected in mussels exposed to the mixture of MPs and Flu Results suggested that MPs led to modulated fluoranthene kinetics and toxicity in marine mussels.	[132]
PS	500 nm 30 µm	Benzo[a]pyrene (B[a]P) 17β-estradiol (E2)	B[a]P alone [B[a] P] = 5 and 50 mg/L E2 alone [E2] = 0.1 and 1 mg/L MPs alone [MPs]= 1 mg/L MPs + Pollutant Combination of individual concentrations of MPs of both sizes and the organic contaminants	4 days	Bivalve specie (Tegillarca granosa)	Analysis of total counts, cell-type composition, and phagocytic activity of haemocytes ROS and Ca2+ concentration from haemocytes LZM content and activity Gene expression of three major types of genes	POPs toxicity was aggravated by smaller MPs and mitigated by larger MPs The deleterious impacts of B[a]P or E2 were mitigated by the presence of larger sized MPs and aggravated smaller ones	[8]
LD-PE	20–25 µm	Benzo(a)pyrene (B[a]P)	B[a]P alone [B[a] P] = 150 µg/L MPs alone [MPs]= 10 mg/L MPs+ B[a]P 15 µg/g B[a]P-10 mg/L MPs (To reach this B[a]P sorbed concentration, 2 days of incubation was performed)	7, 14 and 28 days	Marine mussel (Mytilus galloprovincialis)	Immunological alterations of hemocytes Neurotoxic responses in hemocytes and gills Oxidative stress Antioxidant defences, Genotoxic effects Transcriptional responses	The overall evaluation provided a clear separation between times and typologies of exposure Significant alterations measured on the immune system Results suggested that the toxicological risk of MPs for marine organisms is probably low, but not negligible	[133]
PE	212–250 µm	Phenanthrene (Phe.) Anthracene	Phe. alone [Phe.] = 0.12 µM Anthracene alone [Anthracene] = 0.14 µM MPs alone [MPs]= 0.02 and 0.2 g/g sediment MPs + Phe. / Anthracene Lower dose of PE combined with pollutants preloaded for 96h	2 weeks	Bacterial community of sediments	Gene expression assessment	The presence of MP reduced the effect of the two PAHs on microbial community composition and the degradation of these organic compounds	[134]
LD-PE non-uniformly shaped	< 60 µm	Phenanthrene (Phe.)	Phe. alone [Phe.] = 10 and 100 µg/L MPs alone [MPs]= 50 and 500 µg/L MPs + Phe. Combination of individual concentrations of MPs the organic contaminant	96 h	African catfish (Clarias gariepinus)	Histopathological analysis (liver and gill) Glycogen stores of the liver Biomarkers responses of AST, ALT, LDH, ALP, γGT Contents of total protein, total albumin, lipase, glucose, lactate, direct bilirubin, HDL, LDL, TG and cholesterol Gene expression analysis	Changes in biomarker responses of co-exposure treatment might be due to the facilitated transportation of Phe into the fish body Findings suggested toxicologically relevant interactions between MPs and Phe	[135]
PE	50 nm 500nm 5 µm 10 µm 15 µm	Phenanthrene (Phe.)	Phe. alone [Phe.] = 0, 0.05, 0.1, 0.2, 0.4, 0.8 and 1.2 mg/L MPs alone [MPs]= 0, 2.5, 5, 10 and 50 mg/L NPs alone [NPs]= 0, 2.5, 5, 8.5, 11 and 14.5 mg/L MPs/NPs + Phe. Combination of the individual concentrations tested for both pollutants	48 h	Daphnia magna	Immobilization rate of the daphnids	Enhanced immobilization of daphnia was observed in co-exposure treatments (especially for NPs) The presence of NPs inhibited the dissipation of phenanthrene of the environment	[61]
LD-PE	125–250 µm	α-HBCD 2,4,6-tribromophenol PBDEs mix (PBDE 47, 99, 153, 154) PCB congeners (28, 52, 101, 118, 138, 153, 180) methyl mercury PFOS PFOA PFOSA PFNA	Feed A: Basic feed (control) Feed B: Basic feed + contaminants sorbed to MPs before the incorporation of 2% into pellets (incubation for overnight) Feed C: Basic feed + contaminants without MPs Feed D: Basic feed + contaminants and clean MPs	80 days (+ 51 days of depuration)	European seabass (Dicentrarchus labrax)	Growth factors Feeding rates Gene expression analysis	Results indicated that MPs inhibit or induce detoxification in the liver and influence the lipid distribution Gene expression results also indicated that MPs might indeed potentiate the adverse effect of some chemical contaminants	[105]
LD-PE	125–250 µm	Methylmercury Perfluoroctanesulfonate Perfluorooctanoat PFOSA PFNA α-HBCD 2,4,6-Tribromphenol PBDE 47 PBDE 99 PBDE 153 PBDE 154 PCB 28 PCB 52 PCB 101 PCB 118 PCB 138 PCB 153 PCB 180	Feed A: Basic feed Feed B: Basic feed + 4% of clean MPs Feed C: Basic feed + 2% of MPs with sorbed POPs Feed D: Basic feed + POPs	3 weeks	Zebrafish (Danio rerio)	Visual observation (microscopic level and Hispathological analysis) Evaluation of differential gene expression of some selected biomarkers	Feed C produced the most evident effects, especially on the liver Combined effects of MPs and chemicals significantly altered the homeostasis in greater manner respect both pollutants alone	[136]
LD-PE	marine exposition: 3 mm feed exposition: 0.5 mm	PAHs, PCBs and PBDEs congeners	Feed A: Basic feed Feed B: Basic feed + virgin LD-PE Feed C: Basic feed + marine-plastic treatment (LDPE deployed in San Diego Bay for 3 months)	2 months	Japanese medaka (Oryzias latipes)	Histopathological analysis (gonads) Gene expression analysis on selected liver’s genes and biomarkers for endocrine disruption	Results show early- warning signs of endocrine disruption in fish exposed to a mixture of plastic and sorbed contaminants	[127]
LD-PE	marine exposition: 3 mm feed exposition: 0.5 mm	PAHs, PCBs and PBDEs congeners	Feed A: Basic feed Feed B: Basic feed + virgin LD-PE Feed C: Basic feed + marine-plastic treatment (LDPE deployed in San Diego Bay for 3 months)	2 months	Japanese medaka (Oryzias latipes)	Histopathological analysis (gonads) Gene expression analysis on selected liver’s genes and biomarkers for endocrine disruption	Hepatic stress in medaka exposed to the combination of plastic and sorbed contaminants was demonstrated No significant differences in the expression of CYP1A were found between treatments	[31]

* Shadowed cells represent environmental relevant concentrations.