TABLE 5 |.

Effects of microplastics in cell viability and uptake.

End-point	Polymer type	Exposure time	Size	Concentration range	Assay	Cell type	Outcome	Ref
Cell viability	Polystyrene (PS)	12 h	0.1 and 5 um	1–200 ug/ml	CCK-8 kit	Caco-2 cells	No effect was observed	Wu et al.(2019)
		24 h, 48 h	1.72 ± 0.26 um	1–1,000 ug/cm2	Trypan blue	BEAS-2B	Viability decreased to 60–70% at 1,000 ug/cm2 after 24 h exposure and all the concentrations above 10ug/cm2 after 48 h exposure	Dong et al. (2020)
			1, 4 and 10 um	1–1,000 ug/ml	CTB and MTT	Caco-2 cells	CTB: 24 h 48 h exposures decrease the viability to 0% only after 1um PS exposure. MTT: Showed the same, results and additionally cell viability decreased to 80% and 70% after 24h and 48 h exposure to 4um	Stock et al. (2019)
			5 um	0.00001–100 ug/ml	MTT	Caco-2 cells	No effect was observed	Wu et al. (2020),
		24 h	10 um	0.05–10 mg/L	Hoechst 33258	T98G and HeLa cells	No effect was observed	Schirinzi et al., (2017)
	COOH-modified polystyrene (PS)	24 h	0.5 um	0.01–100 ug/ml	WST-1	GIT co culture model	Intestinal cells: PS decreased the metabolic activity only at 0.01 μg/ml. Placental cells: PS increased mitochondrial activity only at concentrations from 0.01–10 μg/ml	Helser et al.,(2019)
					MTS	BeWo b30 cells
	Polyethylene (PE)	24 h	3–16 um	0.05–10 mg/L	Hoechst 33258	T98G and HeLa cells	No effect was observed	Schirinzi et al., (2017)
	Polypropylene (PP)	48 h	20 and 25–200 um	In DMSO 10–1000 ug/ml and in powder 0.1–4.5 mg	CCK-8 colorimetric kit	HDF	HDF cells: only the 20 um PP (in DMSO) caused a reduction in viability (20%) at the highest concentration 1000 ug/ml	Hwang et al., (2019)
Intracellular localization	Polystyrene (PS)	12 h	0.1 and 5 um	1–80 ug/ml	ABC transporter activity (CAM cell probe)	Caco-2 cells	Inhibition of ABC transporter was observed for 0.1 um PS concentrations >20 ug/ml and 5 um PS only at 80 ug/ml	Wu et al., (2019)
		24 h	1, 4 and 10 um	108/ml (1 and 4 um), 3×106/ml (10 um)	Fluorescence microscopy	Caco-2 cells, mucus co-culture1 model and M-cell model2	4 um PS were absorbed the most in Caco-2 cells (3.8%), M cell model and mucus model 4.8%). 1 um PS were significantlyabsorbed by the M cell mode (5.8%)*	Stock et al.,(2019)
		24 h, 72 h	1, 4 and 10 um	100,000/ml (1 um), 250,000/ml (4 um), 60,000/ml (10 um)	Fluorescence microscopy	THP-1 cells derived macrophages	Macrophages contained intracellular 4 um PS (40–80%) and 1 um and 10 um in lower extent	Stock et al., (2019)
	COOH-modified	24 h	0.5 um	100 ug/ml	Confocal microscopy	GIT barrier3 and placental barrier coculture4 models	In the GIT barrier coculture, PS were internalized by intestinal cells and in the placental barrier model the placental cells	Hesler et al., (2019)
	Fluorescent polystyrene (PS)	12 h	0.1 um and 5 um	20 ug/ml	Confocal microscopy	Caco-2 cells	Overlap between lysosomes and microplastics. Level of 5 um entering into cells lower than 1 um	Wu et al. (2019)
	Polystyrene (PS) and arsenic (As)	12 h	0.1 and 5 um	PS: 20 ug/ml (0.1 um), 80 ug/ml (0.5 um). As: 150 mg/L	Intracellular arsenic by ICP-MS	Caco-2 cells	0.1 um PSs at 20 ug/ml increased the intracellular concentration of As	Wu et al. (2019)

^*extrapolated from the graph. Abbreviations: Polystyrene PS, Polyethylene PE, Polypropylene PP.

¹Caco-2 cells and HT29-MTX-E12 cells

²Caco-2 and RajiB transwell coculture

³Caco-2 and HT29-MTX-E12 cells

⁴BeWo b30 and HPEC-A2 cells.