Combined Toxicity Of PAEs Or PPCPs: A Special Reference To Endocrine Disrupting Perspective

Combine toxicological assessment is an imperative and realistic approach for evaluating the nature of chemical interactions and the associated health risks.Regulatory authorities have also recognized the mixture effects as a major concern in the environmental risk assessment of chemicals.Phthalate esters(PAEs)are the priority pollutants classified by the United States Environmental Protection Agency(US EPA)due to their endocrine disruption properties.Moreover,US EPA categorized pharmaceuticals and personal care products(PPCPs)as the emerging contaminants that pose serious health risks in the aquatic environment.PPCPs belong to a large group of pollutants,which include antibiotics,non-steroidal anti-inflammatory drugs(NSAIDs)and personal care products(PCPs).In addition,the published studies are limited to highlight the in-depth toxic implications of chemical mixtures.Therefore,this study was the first robust study to probe the toxicogenetic concerns of the individual and combined mixtures of phthalate esters(PAEs)and pharmaceuticals and personal care products(PPCPs)using in vitro and in vivo bioassays.Furthermore,the combined toxicogenetic effects were further confirmed using the Combination index(CI),Independent action(IA),and Molecular docking(MD)models.The main findings are as follows:Among the investigated PAEs and Sulfonamides(SAs),di-(2-ethylhexyl)phthalate(DEHP)and sulfamethoxazole(SMX)were found as chemicals with higher in vitro/vivo toxicity.Compared to individual compounds,binary mixtures of PAEs or SAs induced the elevated developmental toxicity and perturbations to the detoxification pathway and hypothalamic gonadal axis(HPG)pathway in zebrafish.Importantly,exposure to the binary mixtures of PAEs,particularly the C2-C6 and C11-C15,displayed the increased level of apoptosis.Moreover,for the SAs,the CI and IA models forecasted greater synergistic effects at Fa= 0.5 and the maximum antagonistic effects for PAEs at Fa=0.5 on the growth inhibition of Acinetobacter sp.Tox2.Conversely,the IA model predicted the joints effects of SAs and PAEs with the order of additive > antagonistic > synergistic and additive > synergistic > antagonistic on the regulation of pharmaceuticals detoxification pathway and the HPG axis pathway in zebrafish,implying the different mode of action(Mo A)for chemicals to induce in vivo combined toxicity.Molecular docking for the estrogen receptor alpha and beta(ER?,ER?)of zebrafish revealed the highest binding energy scores for DEHP,and confirmed that the individual and binary mixtures of PAEs behaved as xenoestrogens in zebrafishFurther,long-term joint exposure to the non-steroid anti-inflammatory drug(NSAIDs),antibiotics,and personal care products(PCPs)was performed,and the toxicity of reproductive potential was determined using zebrafish after exposure to the pollutants at environmentally relevant concentrations(ERCs).The results were further confirmed using in silico MD prediction model.In the male and female zebrafish,the developmental indexes(K,GSI,and HSI)and histological alterations(late-vitellogenic oocytes and mature spermatids)were significantly reduced,compared to control.Moreover,the significant upregulated levels of the steroid hormone receptors(er?,and ar),gonadotropin receptors(fsh ?,fshr,lhr,and lh ?),and steroidogenic enzymes(cyp11a,cyp17,star,17?hsd,and 3?hsd)were observed in the females.However,in the males,the expression levels of vtg,cyp17 and 17 ?hsd genes were significantly downregulated and the inhibited fecundity of zebrafish was also observed.In silico molecular docking of the zebrafish steroid hormone receptors confirmed that NSAIDs(DIC,IBU),antibiotics(ERY,SMX,CBZ)and PCPs(triclosan)possessed the strongest binding energy of SMX(-9.33 kcal/mol),CBZ(-10.45 kcal/mol),and TRI(-14.78 kcal/mol)with ER?,ER? and AR and proved as xenoestrogens.In a nutshell,the elevated combined toxicities,especially the endocrine disruption ability of PAEs and PPCPs(SAs,antibiotics,NSAIDs,and PCPs),are worthy of exploration in comparison with individual compounds to simulate the real-time environmental scenarios.