Aluminum dialkyl phosphinates (ADPs) are a promising class of chemicals offering superior flame retardance. However, knowledge on their behavior in vivo is scarce. Hydrolysis has been suggested as one of the major routes of environmental degradation of ADPs. Herein, aluminum methylcyclohexyl phosphinic (AMHP), a kind of ADPs with industrial production in China, and its hydrolysate methyl cyclohexyl phosphinic acid (MHPA) were continuously exposed to Sprague Dawley (SD) rats for 28 days in this study. The same ratio of MHPA in organs to serum and the same daily excretion of MHPA were observed for AMHP exposure group and MHPA exposure group, suggesting the hydrolysis of AMHP in vivo. The hydrolysis of AMHP to MHPA was further confirmed by in vitro simulated human gastric intestinal juice. Therefore, both AMHP and MHPA distributed in liver, kidney and even brain in the form of MHPA. More than 80% of AMHP and MHPA could be excreted by feces and urine. Feces are the main route of excretion of AMHP and MHPA. The denseness of the inflammatory cell in the hepatic portal area and biochemical indexes showed the obvious dose-effect relationship. However, the toxicity of AMHP and MHPA was quite low even with exposure level up to 100 mg/kg dw/day. The low cumulative ability and mild toxicity indicated AMHP as a promising substitute for brominated flame retardant.

Because most chickens are reared in intensive farms, where a range of feed additives are used routinely, concerns have been raised on the potential public health risk of chicken product consumption. This study was conducted to characterize the contents of trace metals in fresh chicken tissues (354 samples) on the food markets in Guangdong province of southern China, a major region of chicken production with heavy per capita chicken consumption, and to assess the public health risk from chronic dietary exposure to the trace metals through chicken consumption. With the exception of Cr, Ni, and Pb, the contents of trace metals were generally higher in the chicken giblets (livers, gizzards, hearts, and kidneys) compared to muscles (breasts and drumsticks). Chicken tissues from the urban markets generally contained higher levels of As, Cu, Mn, and Zn than those from the rural markets, while the contents of Pb were typically higher in the chicken muscles from the rural markets. Results of statistical analyses indicate that Cu, Zn, and As in the chicken tissues derived mainly from the feeds, which is consistent with the widespread use of Cu, Zn, and phenylarsenic compounds as feed supplements/additives in intensive poultry farming. No non-carcinogenic risk is found with the consumption of fresh chicken meat products on the food markets, while approximately 70% of the adult population in Guangzhou and 30% of those in Lianzhou have bladder and lung cancer risk above the serious or priority level (10⁻⁴), which arises from the inorganic arsenic contained in the chicken tissues. These findings indicate that the occurrence of inorganic arsenic at elevated levels in chicken tissues on the food markets in Guangdong province poses a significant public health risk, thus the use of phenylarsenic feed additives in China's poultry farming should be significantly reduced and eventually phased out.

To assess hepatotoxicity and to determine the underlying mechanisms of carbamazepine (CBZ) toxicity in fish, histopathology and the liver proteome were examined after Chinese rare minnow (Gobiocypris rarus) were exposed to 1, 10, and 100 μg/L CBZ for 28 days. Histopathological changes included disruption of spatial structure, pyknotic nuclei, cellular vacuolization and deformation of cell nuclei, in addition to marked swelling of hepatocytes in all treatment groups. Protein analysis revealed that there were gender-specific responses in rare minnow following exposure, and there were 47 proteins in females and 22 proteins in males identified as differentially abundant following CBZ treatments. Pathway analysis revealed that cellular processes affected by CBZ included apoptosis, cell differentiation, cell proliferation, and the respiratory chain, indicating impaired energy homeostasis. Noteworthy was that 15 proteins identified as different in abundance were associated with carcinogenicity. Relative mRNA levels for select transcripts were consistent with the changes of proteins N-myc downstream regulated gene (NDRG), Tropomyosin 2-Beta (TPM2) and annexin A4 (ANXA4). Protein pyruvate kinase, liver and RBC (PKLR) were increased at 1 and 100 μg/L CBZ without significant difference in transcript levels. These findings characterize molecular responses and histological changes in the liver that generate new insights into CBZ hepatotoxicity in Chinese rare minnow.

Waterborne microcystin-LR (MC-LR) has been reported to disrupt sex hormones, while its estrogenic potency remains controversial. We hypothesized that MC-LR could induce estrogenic effects via disrupting sex hormone synthesis, and verified this hypothesis by in vitro and in vivo assays. Effects of MC-LR (1, 10, 100, 500, 1000 and 5000 μg/L) on steroidogenesis were assessed in the H295R cells after 48 h. The contents of 17β-estradiol (E2) and testosterone (T) increased in a non-dose-dependent manner, which showed positive correlations with the expression of steroidogenic genes. In the in vivo assay, adult male zebrafish were exposed to 0.3, 1, 3, 10 and 30 μg/L MC-LR for 30 d. Similarly, E2 and T contents in the testis were increased, accompanied by extensive up-regulation of steroidogenic genes, especially cyp19a. Meanwhile, the percentage of spermatid in the testis declined. In the liver, the vtg1 gene was significantly up-regulated while both the transcriptional and protein levels of the estrogenic receptor (ER) declined. These results indicate that MC-LR induced non-dose-dependent estrogenic effects at environmental concentrations, which may result from steroidogenesis stimulation via a non-ER-mediated pathway. Our findings support a paradigm shift in the risk assessment of MC-LR from traditional toxicity to estrogenic risk, particularly at low concentrations, and emphasize the potential threat to the male reproductive capacity of wildlife in bloom areas.

The aryl hydrocarbon receptor (AhR) plays an important role in mediating dioxins toxicity. Currently, genes of P450 families are major research interests in studies on AhR-mediated gene alterations caused by dioxins. Genes related to other metabolic pathways or processes may be also responsive to dioxin exposures. Amino acid transporter B0AT1 (encoded by SLC6A19) plays a decisive role in neutral amino acid transport which is present in kidney, intestine and liver. However, effects of dioxins on its expression are still unknown. In the present study, we focused on the effects of dioxin and dioxin-like compounds on SLC6A19 expression in HepG2 cells. We identified SLC6A19 as a novel putative target gene of AhR activation in HepG2 cells. 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD) increased the expression of SLC6A19 in time- and concentration-dependent manners. Using AhR antagonist CH223191 and/or siRNA assays, we demonstrated that certain AhR agonists upregulated SLC6A19 expression via AhR, including TCDD, 1,2,3,7,8-pentachlorodibenzo-p-dioxin (1,2,3,7,8-PeCDD), 2,3,4,7,8- pentachlorodibenzofuran (2,3,4,7,8-PeCDF) and PCB126. In addition, the expression of B0AT1 was also significantly induced by TCDD in HepG2 cells. Our study suggested that dioxins might affect the transcription and translation of SLC6A19 in HepG2 cells, which might be a novel putative gene to assess dioxins' toxicity in amino acid transport and metabolism in liver.

Tributyltin is a biocide used in nautical paints, aiming to reduce fouling of barnacles in ships. Despite the fact that many effects of TBT on marine species are known, studies in mammals have been limited, especially those evaluating its effect on the function of the hypothalamus-pituitary-thyroid (HPT) axis. The aim of this study was to investigate the effects of subchronic exposure to TBT on the HPT axis in female rats. Female Wistar rats received vehicle, TBT 200 ng kg−1 BW d−1 or 1000 ng kg−1 BW d−1 orally by gavage for 40 d. Hypothalamus, pituitary, thyroid, liver and blood samples were collected. TBT200 and TBT1000 thyroids showed vacuolated follicular cells, with follicular hypertrophy and hyperplasia. An increase in epithelial height and a decrease in the thyroid follicle and colloid area were observed in TBT1000 rats. Moreover, an increase in the epithelium/colloid area ratio was observed in both TBT groups. Lower TRH mRNA expression was observed in the hypothalami of TBT200 and TBT1000 rats. An increase in Dio1 mRNA levels was observed in the hypothalamus and thyroid in TBT1000 rats only. TSH serum levels were increased in TBT200 rats. In TBT1000 rats, there was a decrease in total T4 serum levels compared to control rats, whereas T3 serum levels did not show significant alterations. We conclude that TBT exposure can promote critical abnormalities in the HPT axis, including changes in TRH mRNA expression and serum TSH and T4 levels, in addition to affecting thyroid morphology. These findings demonstrate that TBT disrupts the HPT axis. Additionally, the changes found in thyroid hormones suggest that TBT may interfere with the peripheral metabolism of these hormones, an idea corroborated by the observed changes in Dio1 mRNA levels. Therefore, TBT exposition might interfere not only with the thyroid axis but also with thyroid hormone metabolism.

Silver, such as silver nanoparticles (AgNPs), has been widely used in commercial products and may be released into the environment. The interaction between Ag deposition and biological systems is raising serious concerns because of one health consideration. Cetaceans, as the top predators of the oceans, may be exposed to Ag/Ag compounds and suffer negative health impacts from the deposition of these compounds in their bodies. In the present study, we utilized autometallography (AMG) to localize the Ag in the liver and kidney tissues of cetaceans and developed a model called the cetacean histological Ag assay (CHAA) to estimate the Ag concentrations in the liver and kidney tissues of cetaceans. Our results revealed that Ag was mainly located in hepatocytes, Kupffer cells and the epithelial cells of some proximal renal tubules. The tissue pattern of Ag/Ag compounds deposition in cetaceans was different from those in previous studies conducted on laboratory rats. This difference may suggest that cetaceans have a different metabolic profile of Ag, so a presumptive metabolic pathway of Ag in cetaceans is advanced. Furthermore, our results suggest that the Ag contamination in cetaceans living in the North-western Pacific Ocean is more severe than that in cetaceans living in other marine regions of the world. The level of Ag deposition in cetaceans living in the former area may have caused negative impacts on their health condition. Further investigations are warranted to study the systemic Ag distribution, the cause of death/stranding, and the infectious diseases in stranded cetaceans with different Ag concentrations for comprehensively evaluating the negative health effects caused by Ag in cetaceans.

Environmental chemicals originating from human activities, such as persistent organic pollutants (POPs), may interfere with the endocrine system of aquatic organisms. The effect of these chemicals on biota and human populations is of high public concern but remains poorly understood, especially in aquatic environments of South America. The aim of this study was to investigate the bioavailability of POPs and the related effects in caged male tilapia (Oreochromis niloticus) in four cascading reservoirs of the Iguaçu River, Southern Brazil. POPs including organochlorine pesticides (OCPs), polychlorinated biphenyl (PCBs), and polybrominated diphenyl ethers (PBDEs) were determined in the reservoir water and tissue samples of tilapia after two months of exposure. The PCB levels in water (14.7 ng L−1) were 14 times higher than the limits permitted by the Brazilian legislation in the Salto Santiago (SS) reservoir. Similarly, concentrations of aldrin and its metabolites (6.05 ng L−1) detected in the water sample of the Salto Osório (SO) reservoir were also above the permitted limits. RT-qPCR analysis revealed different transcript levels of cytochrome P450 enzymes (CYP1A and CYP3A) in the liver among the four groups, with induced activity in tilapia from the SS reservoir. Quantification of the CYP3A mRNA expression and catalytic activity showed higher values for fish caged at the SS reservoir. The fish from this site also had a higher number of eosinophils observed in the testes. Although overt measurements of endocrine disruption were not observed in caged fish, alteration of CYP enzymes with co-occurrence of organochlorine contaminants in water may suggest bioavailability of contaminants from agricultural sources to biota. Additional studies with feral or caged animals for a longer duration may be necessary to evaluate the risks of the waterways to humans and wildlife.

Decabromodiphenyl Ethane (DBDPE), a kind of new brominated flame retardants (NBFRs) used to replace DecaBDE, has been frequently detected in the environment and human samples. In this study, we explored its toxic effects on male mouse offspring after perinatal exposure to DBDPE. During the perinatal period, pregnant ICR mice were exposed to DBDPE (100 μg/kg body weight) via oral gavage. After weaning, male offspring were fed on a low-fat diet and a high-fat diet, respectively. We measured and recorded body weight, liver weight, and epididymis fat mass, blood biochemical markers, metabolites changes in liver, and gene expression involved in lipid and glucose homeostasis. The results showed that perinatal exposure to DBDPE increased the risk of obesity in mouse offspring and affected triglyceride synthesis, bile secretion, purine synthesis, mitochondrial function and glucose metabolism, furthermore, the use of HFD feeding may further exacerbate these effects. All of these results show that early-life exposure to low doses of DBDPE can promote the development of metabolic dysfunction, which in turn induces obesity.

Microcystin-LR (MC-LR) is the most abundant toxicant among microcystin variants produced by cyanobacteria. MC-induced toxicity is broadly reported to pose a threat to aquatic animals and humans and has been associated with the dysfunction of some organs such as liver and kidney. However, MC-induced neurotoxicity has not been well characterized after long-term exposure. This study was designed to investigate the neurotoxic effects after chronic oral administration of MC-LR. In our trial, C57/BL6 mice received MC-LR at 0, 1, 5, 10, 20 and 40 μg/L in drinking water for twelve months. Our data demonstrated that mitochondrial DNA (mtDNA) damage was evident in the damaged neurons as a result of chronic exposure. Histopathological abnormalities and mtDNA damage were observed in the hippocampus and cerebral cortex. Furthermore, MC-LR exerted distinct effects on these two brain regions. The hippocampus was more susceptible to the treatment of MC-LR compared with the cerebral cortex. However, no strong relationships were observed between the genotoxic effects and exposure doses. In conclusion, this study has provided a mtDNA-related mechanism for underlying chronic neurotoxicity of MC-LR and suggested the presence of differential toxicant effects on the hippocampus and cerebral cortex.