Project description:Although drinking water disinfection has proved to be an effective strategy to eliminate most waterborne pathogens, bacterial pathogens can still show disinfection tolerance in drinking water distribution systems (DWDSs), posing a great threat to drinking water safety and human health. Despite stress signals such as starvation and low temperature were reported to increase disinfection tolerance of E. coli, it is unclear whether the stress-induced disinfection tolerance was conserved in different bacterial species.
Project description:Human cell toxicogenomic analysis links reactive oxygen species to the toxicity of monohaloacetic acid drinking water disinfection byproducts
Project description:In this study we linked the biological end point of genomic DNA damage from our quantitative, comparative disinfection by-product (DBP) database, with toxicogenomic analysis using a Super Array RT2 Profiler™ PCR Array containing primers for 84 genes related to human DNA damage and repair and 84 genes whose expression level is indicative of stress and toxicity.
Project description:The monohaloacetic acids (monoHAAs) are generated as byproducts during the disinfection of drinking water and are cytotoxic, genotoxic, mutagenic, and teratogenic. Iodoacetic acid (IAA) toxicity was mitigated by antioxidants, suggesting the involvement of oxidative stress. Other monoHAAs may share a similar mode of action. Human oxidative stress and antioxidant defense gene arrays (SA biosciences) were used to evaluate changes in transcriptome profiles in the human intestinal epithelial cell line FHS 74 INT generated by three compounds, chloroacetic acid (CAA), bromoacetic acid (BAA) and IAA at two time points (30 min and 4 h).
Project description:Here we investigated the longterm carryover effects of dichloroacetic acid (DCA), a common by-product of drinking water chlorination, on hepatic tumorigenesis in mice. Our findings demonstrate that postnatal exposure to a common drinking water contaminant results in longterm carryover effects on tumorigenesis, potentially via epigenetic events altering cellular respiration and metabolism.
Project description:Ozone has been proposed for water disinfection because it is more efficient than chlorine for killing microbes and results in much lower levels of carcinogenic trihalomethanes than does chlorination. Ozone leads to formation of hypobromous acid in surface waters with high bromine content and forms brominated organic by-products and bromate. The carcinogenicity and chronic toxicity of potassium bromate (KBrO3) [CAS:7758-02-3;CHEBI:32030] was studied in male B6C3F1 mice and F344/N rats to confirm and extend the results of previous work. Mice were treated with 0, 0.08, 0.4, or 0.8 g/L KBrO3 in the drinking water for up to 100 wk, and rats were provided with 0, 0.02, 0.1, 0.2, or 0.4 g/L KBrO3. Animals were euthanatized, necropsied, and subjected to a complete macroscopic examination. Selected tissues and gross lesions were processed by routine methods for light microscopic examination. The present study showed that KBrO3 is carcinogenic in the rat kidney, thyroid, and mesothelium and is a renal carcinogen in the male mouse, KBrO3 was carcinogenic in rodents at water concentrations as low as 0.02 g/L (20 ppm; 1.5 mg/kg/day). These data can be used to estimate the human health risk that would be associated with changing from chlorination to ozonation for disinfection of drinking water.
Project description:Perfluoroalkyl acid carboxylates and sulfonates (PFAAs) have many consumer and industrial applications. The persistence and widespread distribution of these compounds in humans have brought them under intense scrutiny. Limited pharmacokinetic data is available in humans; however, human data exists for two communities with drinking water contaminated by PFAAs. Also, there is toxicological and pharmacokinetic data for monkeys, which can be quite useful for cross-species extrapolation to humans. The goal of this research was to develop a physiologically-based pharmacokinetic (PBPK) model for PFOA and PFOS for monkeys and then scale this model to humans in order to describe available human drinking water data. The monkey model simulations were consistent with available PK data for monkeys. The monkey model was then extrapolated to the human and then used to successfully simulate the data collected from residents of two communities exposed to PFOA in drinking water. Human PFOS data is minimal; however, using the half-life estimated from occupational exposure, our model exhibits reasonable agreement with the available human serum PFOS data. It is envisioned that our PBPK model will be useful in supporting human health risk assessments for PFOA and PFOS by aiding in understanding of human pharmacokinetics.
Model is encoded by Ruby and submitted to BioModels by Ahmad Zyoud
Project description:The process of drinking water disinfection forms compounds known as disinfection byproducts (DBPs). Studies have shown that DBPs can be harmful to human and animal health. Iodoacetic acid (IAA) is a non-regulated DBP that is cytotoxic and genotoxic to mammalian cells. In addition, IAA has been shown to be an ovarian toxicant in vitro and in vivo. However, the mechanisms of action underlying IAA toxicity on ovarian follicles in vivo remain unclear. In this study, we determined whether IAA exposure alters gene expression patterns in ovarian antral follicles in mice. Adult female CD-1 mice were dosed with water or IAA (10 or 500mg/L) in the drinking water for 35-40 days. Antral follicles were dissected from the ovaries based on size (220–400 μm). Sera were collected to measure estradiol levels. RNA-sequencing was applied to uncover the global gene expression of the antral follicles in response to IAA exposure. RNA-sequencing analysis identified 410 and 653 differentially expressed genes (DEGs) in the 10 and 500mg/L IAA treatment groups (FDR < 0.1), respectively, compared to controls. Gene Ontology Enrichment analysis showed that DEGs were involved with RNA processing and regulation of angiogenesis (10mg/L) and the cell cycle, cell division, and mitotic nuclear division (500mg/L). In addition, Pathway Enrichment analysis showed that DEGs were involved in the phosphatidylinositol 3-kinase and protein kinase B (PI3K-Akt) signaling pathway, gonadotropin-releasing hormone (GnRH) signaling pathway, estrogen signaling pathway, and insulin signaling pathway (10mg/L). In the 500mg/L group, Pathway Enrichment analysis showed that DEGs were involved in the oocyte meiosis signaling pathway, GnRH signaling pathway, and oxytocin signaling pathway. In addition, RNA-sequencing analysis identified 809 DEGs when comparing the 10 and 500mg/L IAA groups (FDR < 0.1). DEGs were related to ribosome, translation, mRNA processing, oxidative phosphorylation, chromosome, cell cycle, cell division, protein folding, platelet activation, and the oxytocin signaling pathway. Moreover, IAA exposure significantly decreased estradiol levels (500mg/L) in serum compared to control. This study identified key candidate genes and pathways involved in IAA toxicity that could help to further understand the molecular mechanisms of IAA toxicity in ovarian follicles.
Project description:Here we investigated the longterm carryover effects of dichloroacetic acid (DCA), a common by-product of drinking water chlorination, on hepatic tumorigenesis in mice. Our findings demonstrate that postnatal exposure to a common drinking water contaminant results in longterm carryover effects on tumorigenesis, potentially via epigenetic events altering cellular respiration and metabolism. The gene expression study followed a stop-promotion design in which 7d male B6C3F1 mice received the following treatments: deionized water alone (dH2O, control); 0.06% phenobarbital (PB), a rodent liver mitogen and tumor promoter; or DCA (3.5g/L) for 10 weeks followed by dH2O for 90 weeks.