Table 1.

Studies discussing the cytotoxic effects of polystyrene (PS) particles.

Study	Model	Sample size	Survey	Intervention	Duration	Result
(20)	5 week-old male mice	12 mice in each group	Nasal and lung microbial dysbiosis	10 μL MP/NP suspension (containing 100 μg PS MP or PS NP)	5 weeks	Airborne PS MPs and PS NPs could alter the nasal microbiota in mice, and MPs had a stronger effect on the lung microbiota than NPs. Nasal Staphylococcus, lung Roseburia, lung Eggerthella and lung Corynebacterium were associated with both MPs and NPs, which could be biomarkers of MP and NP-induced airway dysbiosis in mice.
(33)	HKC (renal tubular epithelial cell line) HL-7702 (human derived liver cell line)	–	Cytotoxicity	80 nm diameter − 50 and 100 μg/mL PS NP	0.5 to 36 h	Most of the differential proteins and metabolites were enriched in various metabolic pathways, glycolysis, citrate cycle, oxidative phosphorylation, and amino acid metabolism, suggesting the potential effects of PS NPs on ga lobal cellular metabolic shift in human cells. Altered energy metabolism induced by PS NPs was further confirmed. mTORC1 signaling, a central regulator of cellular metabolism, was inhibited by nanoplastic exposure, likely serving as a link between lysosome dysfunction and metabolic defects.
(67)	Wild-type zebrafish	10 fish in each group	Immunotoxicity and effect on intestinal microbiota	50 μm diameter − 100 μg/mL PS MP 50 μm diameter − 1,000 μg/mL PS MP 100 nm diameter − 100 μg/mL PS NP 100 nm diameter − 1,000 μg/mL PS NP	14 days	PS particles caused damage to intestinal epithelium, altered the normal flora composition of GI tract, induced oxidative damage, and also interfered with immune responses.
(68)	Immature Crucian carp	10 fish in each group	Toxicity effects on gut microbiota	100 μg/L aged PS MPs 100 μg/L roxithromycin +100 μg/L aged PS MPs	28 days	Aging of PS MPs enhanced their binding to roxithromycin, and the combined administration of these two substances had a more pronounced effect on inducing inflammation as well as inhibition of amylase and lipase; the combined administration also altered the composition of normal flora of GI tract; aged PS MPs were also able to induce antibiotic resistance in gut microbiota.
(23)	4 week-old C57BL/6 J male mice	7 mice in each group	Hematopoietic damages	PS MPs (5 μm and 10 μm) as well as PS NPs (80 nm) at a concentration of 60 μg/day	42 days	Alterations in serum cytokines were detected which may be explained by dysbiosis, and pathologic changes in the bone marrow, i.e., elevation of lipids and inhibition of differentiation of hematopoietic stem cells.
(69)	6 week-old male C57-BL/6 mice	8 mice in each group	Intestinal immune imbalance	PS MPs (500 μg/L)	28 days	PS MPs caused a more pronounced inflammatory response (local and systemic) in mice with dysbiotis compared to normal flora, and also aggravated the dysbiosis.
(68)	Nile tilapia (Oreochromis niloticus)	40 fish in each group	Immunotoxicity and disturbance of intestinal microbiota	PS MPs (1 mg/L) alone or in combination with Cu2+ (0.5, 1, and 2 mg/L)	14 days	PS MPs aggravated the toxic effects of Cu2+ including: hepatic infiltration, pathologic changes in hepatic, intestinal, and gill tissues, oxidative damage, impaired immunity, as well as dysbiosis.
(33)	Juvenile grouper	40 fish in each group	Toxic effects on digestive system	PS NPs (300 and 3,000 μg/L)	14 days	PS NPs accumulated in the liver and intestinal tissues, weakened the digestive ability of the GI tract, induced dysbiosis, and hampered the growth of the fish.
(70)	Zebrafish	20 fish in each group	Effects on the intestinal tissue and its normal flora	1 mg/L of commercial MPs (CMPs) or realistic MPs (RMPs) given alone or in combination with 0.5 μg/L enrofloxacin	28 days	Dysbiosis caused by CMPs was more severe than RMPs, and they both induced resistance to enrofloxacin in th egut microbiota.
(52)	Swiss mice	12 mice in each group	Neurotoxic, biochemical and genotoxic effects	PS NPs (14.6 ng/kg) Intraperitoneal administration	3 days	PS NPs accumulated in the brain resulting in elevated levels of NO, thiobarbituric acid reactive species, and acetylcholine, which impaired cognitive function of the mice; DNA damage in erythrocytes and hyperlipidemia were also observed.
(71)	Ctenopharyngodon idella (grass carp) juveniles	21 fish in each group	Biochemical, genotoxic, mutagenic and cytotoxic effects	PS NPs (-I group 0.04 and 34 ng/L, 34 μg/L)	20 days	PS NPs caused mutagenic effects, oxidative damage, and morphological changes in erythrocytes; infiltration into hepatic and brain tissues was also observed.
(56)	6 week old male C57 mice	Total of 50 mice	Biochemical, metabolomics and histopathological analysis of the liver	PS MPs (5 μm, 500 μg/L) Oral administration (in distilled water)	28 days	PS MPs caused a proinflammatory response as well as altered metabolic activity of the liver in mice, whether normal or with colitis; the elevated fat content of hepatocytes was only significant in mice with colitis.
(59)	8 week old male C57BL/6 J mice	12 mice ineach group	Hepatotoxicity	PS MPs (5 μm, 0.1 mg/day) Oral administration (in distilled water)	90 days	Increased ER stress in hepatocytes by PERK activation.
(60)	6 week old female Wistar rats	8 mice in each group	Ovarian toxicity	PS MPs (0.5 μm) at doses of 0.015, 0.15 and 1.5 mg/kg/d Oral administration (in distilled water)	90 days	Increased oxidative stress in granulosa cells resulting in more apoptosis, and fewer ovarian follicles.
(60)	4–5 week old ICR male mice	10 mice in each group	Testicular toxicity	PS MPs (5 μm) at concentrations of 100 and 1,000 μg/L, and 10 mg/L Oral administration (in distilled water)	35 days	Testicular sperm showed an accelerated apoptotic rate due to increased inflammatory cytokines in testicular tissue. Epididymal sperm showed a decreased number and more dysmorphic changes.
(62)	6 week old C57BL/6 male mice	10 mice in each group	Skeletal muscle toxicity	PS MPs (10 mg/L) at two size ranges: 1–10 μm and 50–100 μm	30 days	Increased oxidative damage inhibited the rhabdomyocytes ability to proliferate and repair the muscle tissue. Furthermore, PS MPs prevented MAPK from being phosphorylated, while activating NF-κB to drive myocyte differentiation into adipocytes.
(58)	5 week old C57BL/6 male mice GES-1 cells	6 mice in each group	Cytotoxicity	PS NPs at a concentration of 50 μg/mL Oral gavage (in double distilled water)	3 days	In mice, PS NPs infiltrated into gastric, intestinal, as well as hepatic tissue PS NPs were endocytosed into GES-1 cells in vitro to induce apoptosis.
(72)	6 week old C57BL/6 J mice	15 mice in each group in the 24 h experiment 10, 15, or 25 mice in each group in the 28 day experiment	Intestinal barrier dysfunction	PS particles with three sizes: 50, 500, and 5,000 nm; dose range of 2.5 to 500 mg/kg/day	24 h 28 days	In 24 h experiment: the PS NPs and MPs infiltrated into intestinal epithelial cells, infiltration was higher when NPs and MPs were co-administered; infiltration induced apoptosis in intestinal epithelial cells to interfere with their barrier function; infiltration of PS particles was also detected in various other tissues. The 28 day experiment: confirmed the disruption of barrier function.
(66)	Raji-B and TK6 cells (lymphocytic cell lines) THP-1 cells (monocytic cell line)	–	Human hematopoietic cell toxicity	PS NPs about 50 nm size and a concentration range up to 200 μg/mL	3 to 48 h	The monocytic cell line internalized the more NPs, but the oxidative and mutagenic effects were not significant; the lymphocytic cell lines internalized fewer NPS, but the toxic effects were more pronounced.
(73)	Caco-2 cells	–	Intestinal toxicity	PS particles and transformed PS particles with two sizes: 5 and 100 nm, and two concentrations: 1 and 20 μg/mL	96 h	Model digestive fluid (designed to simulate the human GI tract) was added to PS particles, which developed a corona on their surface, but did not alter their chemical composition; these corona PS particles were called transformed. This transformation reduced the oxidative damage and penetration of particles through the epithelial layer, but promoted the inflammatory response.
(74)	Single cell organisms: bacteria (E. coli, S. aureus, V. fischeri), yeast (S. cerevisiae wild type and end3Δ strains), algae (Raphidocelis subcapitata), and protozoa (Tetrahymena thermophila) Multicellular oraganisms: Daphnia magna, Heterocypris incongruens, and Chironomus riparius THP-1 cells (derived from human monocytes)	–	Cytotoxicity	Commercial PS NPs with two sizes: 26 and 100 nm, and doses up to 100 mg/L	30 min to 6 days	Cytotoxic effects were only observed in V. fischeri, R. subcapitata, and D. magna; further evaluation showed that even this toxicity may not be caused by the PS NPs, but may be partially attributed to NaN3, a cytotoxic additive present in commercial preparations of PS NPs.
(75)	HepG2 cells	–	Cytotoxicity	PS NPs (50 nm) at three doses: 10, 50, and 100 μg/mL	24 h	PS NPs with carboxyl and amine groups on their surface induced more oxidative damage.
(76)	Human peripheral blood mononuclear cells KATO III cells HeLa cells Human dermal fibroblasts	–	Cytotoxicity	PS particles with random shapes from 5 to 200 μm size, three different concentrations: 10, 100, and 1,000 μg/mL	1 and 4 days	Oxidative damage in all cell lines; these particles were also able to physically rupture the cellular membrane.
(77)	5–6 week-old Balb/c male mice	10 mice in each group	Reproductive toxicity	PS MPs (5.0–5.9 μm) at three different doses: 0.01, 0.1, and 1 mg/day N-acetylcysteine (anti-oxidant) and SB203580 (inhibitor of MAPK) were also co-administered Oral gavage	42 days	PS MPs induced oxidative damage in testicular tissue through MAPK activation, which resulted in reduced sperm numbers, which were dysmotile and dysmorphic;,the testosterone level in plasma was also decreased; administration of N-acetylcysteine or SB203580 was able to alleviate these effects.
(78)	Human mast cell line1 Peripheral blood mononuclear cells Human dermal fibroblasts Sheep RBCs	–	Cytotoxicity	PS particles with six diameters: 460 nm, 1 μm, 3 μm, 10 μm, 40 μm, and 100 μm, and doses of 1, 10, 100, 500, and 1,000 μg/mL	–	In general, the PS particles did not cause notable cytotoxicity in human cell lines, but could damage RBCs through direct contact; inflammatory cytokine profile was also altered.
(79)	Mus musculus mice	5 mice in each group	Biodistribution	PS particles with two diameters: 5 and 20 μm, and three doses: 0.01, 0.1, and 0.5 mg/day. Oral administration	28 days	PS particles accumulated in intestinal, hepatic, and renal tissues with subsequent oxidative damage, which may be affected by the particle size.
(80)	Caco-2, HT29, Raji B, and THP-1 cell lines Male Hmox1 reporter mice	5 mice in each group	Cytotoxicity	1, 4, and 10 μm PS particles at doses of (4.55 × 107 particles), (4.55 × 107 particles) and (1.49 × 106 particles), respectively	In vitro study: 24 or 48 h In vivo study: 28 days	Neither in vitro nor in vivo studies showed notable cytotoxic effects attributable to PS particles; the ability of THP-1 cells to differentiate into different types of macrophages was also preserved.
(81)	6–8 week-old male Wistar rats	6 rats in each group	Neurobehavioral assessment	PS particles with two diameters: 25 and 50 nm, and doses of 1, 3, 6, and 10 mg /kg /day Oral administration	35 days	No notable neurobehavioral dysfunction.
(82)	Oysters	40 oysters per tank	Reproductive toxicity	2 and 6 μm PS MPs at a concentration of 0.023 mg/L	60 days	Reduced number of oocytes and motility of sperm; developmental progress of offspring was slower.
(83)	AGS gastric cancer cell line	–	Cytotoxicity	PS particles with diameters of 44 nm and 100 nm and doses of 1, 2, and 10 μg/mL	1 and 24 h	Both NP sizes accumulated in gastric cancer cells; the effects on cellular viability were paradoxical; but they both upregulated IL-6 and IL-8.