Table 1.

Impact of halogenated compounds on gut microbiota and host (where applicable).

Compound, concentration and duration of use	Compound type	Study model	Impact on gut microbiota	Impact on host	References
2,3,7,8-tetrachlorodibenzofuran, 24 μg/kg for 5 days	POP	C57BL/6J mice (Ahr+/+) and C57BL/6J congenic mice (Ahr−/−)	Decreased Firmicutes/Bacteroidetes ratio; enriched Butyrivibrio spp. and depleted Oscillibacter spp. in cecal contents; production of short chain fatty acids like butyrate	Altered bile acid metabolism; significant inflammation and host metabolic disorders as a result of activation of bacterial fermentation; altered hepatic lipogenesis, gluconeogenesis and glycogenolysis in an Ahr-dependent manner	(Zhang L. et al., 2015)
Polychlorinated biphenyls (PCB) congeners (PCB153, PCB138, and PCB180) total dose of 150 μmol/kg for 2 days	POP	C57BL/6 mice	Decreased overall abundance of bacterial species; decreased levels of Proteobacteria; exercise attenuated PCB-induced alterations of gut microbiota composition; abundant Lactobacillales and depleted Erysipelotrichaceae bacterium C11_K211 (Tenericutes phylum) in the exercised group	Exercise provided protection against PCB-induced changes in the gut microbiota than sedentary mice.	Choi et al., 2013
2,3,7,8-tetrachlorodibenzo-p-dioxin, 0-30 μg/kg every 4 days for 28 and 92 days	POP	C57BL/6 mice	Significant increase of fourteen antimicrobial resistance genes and mobile genetic elements genes typically observed in Enterobacteriaceae	Increased hepatic fat accumulation; depletion of immune cell expression and populations of macrophage and dendritic cells in the intestinal lamina propria	Fader et al., 2015; Stedtfeld et al., 2017
2,3,7,8-tetrachlorodibenzo-p-dioxin, biweekly with a dose of 6 μg 2,3,7,8-tetrachlorodibenzo-p-dioxin /kg for 26 weeks	POP	CD-1 mice	Increased Firmicutes/Bacteroidetes ratio; increased Lactobacillaceae and Desulfovibrionaceae, and decreased Prevotellaceae and ACKM1	Liver toxicity, polydipsia (excessive thirst), polyphagia (increased appetite) and prediabetes	Lefever et al., 2016
Chlorpyrifos, 1 mg everyday for 30 days	Pesticide	Human Intestinal Microbial Ecosystem (SHIME)	Compositional change in the microbial community; increased numbers of Enterococcus and Bacteroides spp. and decreased numbers of lactobacilli and bifidobacteria		Joly et al., 2013
0.3 or 3 mg chlorpyrifos/kg bodyweight/day or for 9 weeks in rats fed a normal (NF) or high fat (HF) diet	Pesticide	Wistar rats	Reduced relative abundance of Aerococcus, Brevundimonas, and Trichococcus in NF-fed rats, and Olsenella, Clostridium sensu stricto 1, Amphibacillus, Enterorhabdus, and Alloprevotella in HF-fed rats	Pro-obesity phenotype in NF-fed rats; significantly reduced serum insulin, C-peptide, and amylin concentrations in NF- and HF-fed rats; no impact on serum glucose and lipid profiles	Fang et al., 2018
1 mg chlorpyrifos /kg bodyweight in corn oil once daily for 30 days	Pesticide	Mus musculus mice	Decreased Firmicutes/Bacteroidetes ratio; reduced relative abundance of Lactobacillaceae and increased relative abundance of Bacteroidaceae	Alterations of urine metabolites related to the metabolism of amino acids, energy, short chain fatty acids, phenyl derivatives and bile acids	Zhao et al., 2016
Chlorothalonil, 10 μg/L in a 30% sucrose solution for 6 weeks	Pesticide	Honey bees (Apis mellifera)	Perturbed bacterial communities but not fungal communities; reduced relative abundance of Lactobacillaceae and increased relative abundance of Enterobacteriaceae and Caulobacteraceae; increased putative genes for oxidative phosphorylation and declined genes for sugar metabolism and peptidase		Kakumanu et al., 2016
Pentachlorophenol, 0–100 μg/L for 28 days	Pesticide	Goldfish (Carassius auratus)	Decreased Firmicutes/Bacteroidetes ratio; increased relative abundance of Bacteroides and decreased relative abundance of Chryseobacterium, Microbacterium, Arthrobacter and Legionella	Accumulation of PCP in the fish intestinal tract in a time- and dose-dependent manner; reduced fish body weight and liver weight; antioxidant system disturbance	Kan et al., 2015
Triclosan at 0.05 mg/kg body weight, administration through milk until 28 days and afterwards through oral gavage three times a week till day 181	PPCP	Sprague Dawley rats	Decreased Firmicutes /Bacteroidetes ratio; increased Deltaproteobacteria and Lactobacillus, increased Lachnospiraceae	Reduction in the bodyweight in adolescent rats	Hu et al., 2016
Triclosan in water solution (2 mg/L) for 13 weeks	PPCP	C57BL/6 mice	Decreased alpha diversity; depletion of Turicibacteraceae, Christensenellaceae and Clostridiales; enrichment of gut bacterial genes related to triclosan resistance, stress response, antibiotic resistance and heavy metal resistance		Gao et al., 2017
Triclocarbon, supplemented in feed (0.1% w/w) for 12 days	PPCP	Sprague Dawley rats	Significantly reduced phylogenetic diversity of gut among exposed dams and neonates during gestation and lactation; dominance of Enterobacteriaceae		Kennedy et al., 2016
Commercially available wash products either containing or not containing triclosan for 1 year	PPCP	Humans: 39 pairs of mothers and babies	No global reconstruction or loss of microbial diversity of either infant or maternal gut microbiotas; broadly antibiotic-resistant species from the phylum Proteobacteria were enriched in stool samples from mothers		Ribado et al., 2017
Triclosan-containing PPCP (4 months) and non-triclosan-containing PPCP (4 months)	PPCP	Humans (16 persons)	No differences in microbiota composition, species richness and overall diversity of the stool, molar, or incisor	Higher urinary concentrations of triclosan in all volunteers during the triclosan period; no differences in metabolic or endocrine markers, or weight	Poole et al., 2016
Chloroacetate, bromoacetate, dichloroacetate, dibromoacetate, trichloroacetate, tribromoacetate, or bromochloroacetate; 1 gm/ml of each compound in selective gorwth media	DBP	Incubations of CDF rat cecal microbiota	Toxic impacts on cecal microbiota especially to the enterococci; increased activities for β-glucuronidase, β-galactosidase, β-glucosidase, azoreductase, nitroreductase, dechlorinase, and dehydrochlorinase that can affect the biotransformation of co-exposed compounds		Nelson et al., 2001
Trichloroacetamide, 50, 500 and 5000 μg/l for 90 days	DBP	Mus musculus mice	Decreased Firmicutes/Bacteroidetes ratio with an increase in the concentration of trichloroacetamide; Increased relative abundance of Bacteroidaceae, Porphyromonadaceae, Sphingobacteriaceae, Aerococcaceae, and Erysipelotrichaceae and decreaseed relative abundance of Bacillaceae, Heliobacteriaceae, Syntrophomonadaceae	Disruption of the host metabolism, weight loss, altered choline metabolites in urine samples; decreased urine tyrosine and intestinal lesions; disordered amino acid and lipid metabolism, alterations in the serum metabolome, including altered choline, trimethylamino oxide, as well as hepatotoxicity and cytotoxicity	(Zhang et al., 2013; Zhang Y. et al., 2015)