Consequences of nano and microplastic exposure in rodent models: the known and unknown

Abstract

The ubiquitous nature of micro- (MP) and nanoplastics (NP) is a growing environmental concern. However, their potential impact on human health remains unknown. Research increasingly focused on using rodent models to understand the effects of exposure to individual plastic polymers. In vivo data showed critical exposure effects depending on particle size, polymer, shape, charge, concentration, and exposure routes. Those effects included local inflammation, oxidative stress, and metabolic disruption, leading to gastrointestinal toxicity, hepatotoxicity, reproduction disorders, and neurotoxic effects. This review distillates the current knowledge regarding rodent models exposed to MP and NP with different experimental designs assessing biodistribution, bioaccumulation, and biological responses. Rodents exposed to MP and NP showed particle accumulation in several tissues. Critical responses included local inflammation and oxidative stress, leading to microbiota dysbiosis, metabolic, hepatic, and reproductive disorders, and diseases exacerbation. Most studies used MP and NP commercially provided and doses higher than found in environmental exposure. Hence, standardized sampling techniques and improved characterization of environmental MP and NP are needed and may help in toxicity assessments of relevant particle mixtures, filling knowledge gaps in the literature.

Microplastics: research landscape, challenges, and remediation

“…82 AChE enzyme inhibition and alterations in its gene expression were noted as well. 58,82 The internal wear of implants containing plastics has been a known source of microplastic deposition in people and in other mammals such as dogs. 68 The particles induce fibrin deposition and necrosis in the nearby joint areas, while macrophages take up the polymer.…”

“…58,82 In addition, thyroid disruption was also observed. 82 AChE enzyme inhibition and alterations in its gene expression were noted as well. 58,82 The internal wear of implants containing plastics has been a known source of microplastic deposition in people and in other mammals such as dogs.…”

“…Mice are a common model organism for evaluating the health effects of potentially toxic or harmful agents in humans, and thus the effect of microplastics on them has been analyzed. 58,[80][81][82] In pooled data with zebrafish, intestinal bacteria were significantly perturbed in the presence of microplastics; populations of Chlamydia, Proteobacteria, and Firmicutes in the GI tract increased while the population of Bacteroides in the GI tract decreased. 80 5 m polystyrene particles at 1 mg/L concentrations in mice decreased intestinal mucus, perturbed the intestinal microbiome, and perturbed their livers (with decreased liver weight and altered gene expression and metabolic enzymes amounts).…”

“…81 With larger doses (15 and 20/mg/kg/d polystyrene, greater than estimates of human doses of 14-700 mg/d), oxidative stress, GI inflammation, decreased intestinal mucus, and liver toxicity were observed, though the larger doses may make the results less applicable at ordinary levels of consumption. 58,82 In addition, changes in the uterus, fibrosis, and altered gender ratio and metabolism in children were observed, indicating that microplastics may exert estrogenic effects. 58,82 In addition, thyroid disruption was also observed.…”

“…58,82 In addition, changes in the uterus, fibrosis, and altered gender ratio and metabolism in children were observed, indicating that microplastics may exert estrogenic effects. 58,82 In addition, thyroid disruption was also observed. 82 AChE enzyme inhibition and alterations in its gene expression were noted as well.…”