Polyhalogenated carbazoles induce hepatic metabolic disorders in mice via alteration in gut microbiota

Polyhalogenated carbazoles(PHCZs)have been widely accepted as emerging pollutants,whereas their ecological and health risks remain uncertain.Herein,female and male Sprague-Dawley(SD)mice were treated with four typical PHCZs to investigate their negative consequences,along with alternations in gutmicrobiota to indicate underlyingmechanisms.In female mice,the relative liver weight ratio increased after four PHCZs exposure;2-bromocarbazole(2-BCZ)increased urine glucose level;3-bromocarbazole(3-BCZ)decreased the glucose and total cholesterol levels;3,6-dichlorocarbazole(3,6-DCCZ)decreased glucose level.The only disturbed biochemical index in male mice was the promoted alkaline phosphatase(ALP)level by 3,6-DCCZ.We also found that the differential blood biochemical indices were correlated with gut microbiota.3-BCZ and 3,6-DCCZ altered Bacteroidetes and Proteobacteria phyla in female and male mice,which were correlated with metabolic disorders.Our findings demonstrated the correlation between PHCZs induced potential hepatotoxicity andmetabolic disordersmay be due to their dioxin-like potentials and endocrine disrupting activities,and the gender differences might result from their estrogenic activities.Overall,data presented here can help to evaluate the ecological and health risks of PHCZs and reveal the underlying mechanisms.

PM_(2.5)-bound polyhalogenated carbazoles(PHCZs)in urban Beijing,China:Occurrence and the source implication

Polyhalogenated carbazoles(PHCZs)are recently raising much attention due to their toxicity and ubiquitous environmental distribution.However,little knowledge is known about their ambient occurrences and the potential source.In this study,we developed an analytical method based on GC-MS/MS to simultaneously determine 11 PHCZs in PM_(2.5) from urban Beijing,China.The optimized method provided low method limit of quantifications(MLOQs,1.45–7.39 fg/m^(3))and satisfied recoveries(73.4%–109.5%).This method was applied to analyze the PHCZs in the outdoor PM_(2.5)(n=46)and fly ash(n=6)collected from 3 kinds of surrounding incinerator plants(steel plant,medical waste incinerator and domestic waste incinerator).The levels of Σ_(11)PHCZs in PM_(2.5) ranged from 0.117 to 5.54 pg/m^(3)(median 1.18 pg/m^(3)).3-chloro-9H-carbazole(3-CCZ),3-bromo-9H-carbazole(3-BCZ),and 3,6-dichloro-9Hcarbazole(36-CCZ)were the dominant compounds,accounting for 93%.3-CCZ and 3-BCZ were significantly higher in winter due to the high PM_(2.5) concentration,while 36-CCZ was higher in spring,which may be related to the resuspending of surface soil.Furthermore,the levels of11PHCZs in fly ash ranged from 338 to 6101 pg/g.3-CCZ,3-BCZ and 36-CCZ accounted for 86.0%.The congener profiles of PHCZs between fly ash and PM_(2.5) were highly similar,indicating that combustion process could be an important source of ambient PHCZs.To the best of our knowledge,this is the first research providing the occurrences of PHCZs in outdoor PM_(2.5).