Polylactic Acid Microplastics Do Not Exhibit Lower Biological Toxicity in Growing Mice Compared to Polyvinyl Chloride Microplastics

Biomicroplastics (BMPs) will be produced during bioplastic degradation (i.e., polylactic acid), although bioplastics have been widely used for food packaging. Like conventional microplastics (MPs), BMPs would be mistakenly ingested into the body through diet or drinking water, but their health risks in vivo are poorly understood. Here, we deeply compared the toxicity difference between irregularly shaped polylactic acid (PLA-MPs, 16–350 μm) and polyvinyl chloride (PVC-MPs, 40–300 μm) MPs in growing mice. After six weeks of exposure, PLA-MP exposure resulted in more severe inhibition of the mice’s weight gain than PVC-MPs did. Both PLA- and PVC-MPs significantly elevated the levels of oxidative stress. Moreover, significant changes including altered transcriptional profiles and significantly differentially expressed genes in liver and colon transcription levels were observed in the PVC- and PLA-MP groups. Compared with PVC-MPs, PLA-MPs have a stronger effect on lipid metabolism and digestive systems. PLA-MPs also caused gut microbiota dysbiosis, significantly interfering with the relative abundance of microbiota and altering microbial diversity. These findings indicated the toxicities of PLA-MPs in growing mice were not significantly reduced compared to PVC-MPs, which would also provide new insights for re-examining bioplastic safety

Metagenomic and Metabolomic Analysis of the Toxic Effects of Trichloroacetamide-Induced Gut Microbiome and Urine Metabolome Perturbations in Mice

Disinfection byproducts (DBPs) in drinking water have been linked to various diseases, including colon, colorectal, rectal, and bladder cancer. Trichloroacetamide (TCAcAm) is an emerging nitrogenous DBP, and our previous study found that TCAcAm could induce some changes associated with host–gut microbiota co-metabolism. In this study, we used an integrated approach combining metagenomics, based on high-throughput sequencing, and metabolomics, based on nuclear magnetic resonance (NMR), to evaluate the toxic effects of TCAcAm exposure on the gut microbiome and urine metabolome. High-throughput sequencing revealed that the gut microbiome’s composition and function were significantly altered after TCAcAm exposure for 90 days in Mus musculus mice. In addition, metabolomic analysis showed that a number of gut microbiota-related metabolites were dramatically perturbed in the urine of the mice. These results may provide novel insight into evaluating the health risk of environmental pollutants as well as revealing the potential mechanism of TCAcAm’s toxic effects

Polystyrene Microplastics Affect the Reproductive Performance of Male Mice and Lipid Homeostasis in Their Offspring

The potential health risks of microplastics (MPs) to humans and other mammals have attracted global attention. However, whether long-term exposure to environmentally relevant doses of MPs could impair the reproductive functions of mammals and cause transgenerational effects on their offspring remains largely unclear. Our study revealed that long-term (i.e., 21 weeks) exposure to environmentally relevant doses of polystyrene MPs (40–100 μm) not only significantly decreased testicle relative weight but also decreased sperm quality (i.e., decreased sperm number and changed sperm phenotype), thus affecting the reproductive performance of male mice. The exposure also dysregulated lipid metabolism in their F1 offspring by altering 17 of 23 lipid classes. In particular, three lipid classes were closely related to non-alcoholic fatty liver disease; i.e., levels of alkylphosphatidylcholine, alkenylphosphatidylcholine, and alkenylphosphatidylethanolamine were significantly increased in the liver and plasma of F1 offspring. The lipid metabolism disruption also exhibited a dose-, gender-, and tissue-specific pattern. Our findings demonstrate for the first time the in vivo evidence of the male reproductive effects of exposure to environmentally relevant doses of MPs on terrestrial mammals and transgenerational effects on their offspring

Evaluation of the Toxic Effects of Municipal Wastewater Effluent on Mice Using Omic Approaches

Municipal wastewater effluents (MWWE) contain a lot of trace organic pollutants, which will be a threat to environmental health. However, little information is available for the mixed toxicity of MWWE on mammals. In the present study, male mice were exposed to MWWE for 90 days, and then, histopathology and clinical biochemistry determination and transcriptomic and metabolomic profiling were conducted. The results showed that MWWE exposure resulted in injuries in liver and kidney. Combined transcriptomic and metabolomic data demonstrated that MWWE exposure induced perturbations of metabolism, including lipid, nucleotide, amino acid, and energy metabolism. Furthermore, dysregulation of signal transduction processes were also identified based on differentially expressed genes. These results suggested that chronic exposure to MWWE could induce hepatotoxicity and nephrotoxicity in mice and omic approaches are of practical value to evaluate the complex toxicity of MWWE

Mice In Vivo Toxicity Studies for Monohaloacetamides Emerging Disinfection Byproducts Based on Metabolomic Methods

Haloacetamides (HAcAms) as a new class of nitrogenous disinfection byproducts (N-DBPs) have been widely detected in drinking water and reclaimed water. Cytotoxicity and genotoxicity of monoHAcAms are determined by the leaving tendency of the halogens and decrease following a rank order of iodoacetamide (IAcAm) > bromoacetamide (BAcAm) ≫ chloroacetamide (CAcAm). However, the in vivo toxicity date for monoHAcAms is limited. In this study, hepatic oxidative stress and metabolomics responses in mice corresponding to monoHAcAms exposure were investigated. Exposure to the monoHAcAms decreased the activities of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and the levels of malonaldehyde (MDA) and increased the level of 8-hydroxy-2-deoxyguanosine (8-OHdG), indicating that each exposure generated oxidative stress in mice liver. Metabolomic alterations were also induced by each monoHAcAms exposure. In addition, disruptions of metabolic pathways, related to amino acid, energy and lipid metabolism, were identified based on the significantly changed metabolites. These data, for the first time, provide a comprehensive view for the toxic effects of monoHAcAms

Uptake and Accumulation of Polystyrene Microplastics in Zebrafish (Danio rerio) and Toxic Effects in Liver

Microplastics have become emerging contaminants, causing widespread concern about their potential toxic effects. In this study, the uptake and tissue accumulation of polystyrene microplastics (PS-MPs) in zebrafish were detected, and the toxic effects in liver were investigated. The results showed that after 7 days of exposure, 5 μm diameter MPs accumulated in fish gills, liver, and gut, while 20 μm diameter MPs accumulated only in fish gills and gut. Histopathological analysis showed that both 5 μm and 70 nm PS-MPs caused inflammation and lipid accumulation in fish liver. PS-MPs also induced significantly increased activities of superoxide dismutase and catalase, indicating that oxidative stress was induced after treatment with MPs. In addition, metabolomic analysis suggested that exposure to MPs induced alterations of metabolic profiles in fish liver and disturbed the lipid and energy metabolism. These findings provide new insights into the toxic effects of MPs on fish

Q₁₀ and estimated parameters simulating relationship between flux data and T₅.

<p>Q₁₀ and estimated parameters simulating relationship between flux data and T₅.</p

The <i>P</i> values of the Mann–Whitney U Test of CO₂ flux among the four sites.

<p>The <i>P</i> values of the Mann–Whitney U Test of CO₂ flux among the four sites.</p

Correlation between ecosystem respiration and T₅ each groundwater table treatment, as well as for plateau zokor treatment.

<p>A linear equation describing the correlation between the natural logarithm of the ecosystem respiration and the soil temperature and the 95% confidence interval are shown: site LIT (<i>y</i> = 0.11<i>x</i>+0.33, <i>R</i>² = 0.83, <i>P</i><0.001); site INT (<i>y</i> = 0.10<i>x</i>+0.83, <i>R</i>² = 0.68, <i>P</i><0.001); site CON (<i>y</i> = 0.10<i>x</i>+0.92, <i>R</i>² = 0.77, <i>P</i><0.001); site HUM (<i>y</i> = 0.04<i>x</i>+1.13, <i>R</i>² = 0.46, <i>P</i><0.001).</p