Grantee Research Project Results
1998 Progress Report: Development of Biomarkers for haloacetonitriles-induced cell injury in Peripheral Blood
EPA Grant Number: R825955Title: Development of Biomarkers for haloacetonitriles-induced cell injury in Peripheral Blood
Investigators: Ahmed, Ahmed Elsayed
Institution: The University of Texas Medical Branch - Galveston
EPA Project Officer: Hahn, Intaek
Project Period: October 1, 1997 through September 30, 2000 (Extended to November 10, 2002)
Project Period Covered by this Report: October 1, 1997 through September 30, 1998
Project Amount: $485,147
RFA: Drinking Water (1997) RFA Text | Recipients Lists
Research Category: Drinking Water , Water
Objective:
Drinking waters are contaminated with a mixture of halogenated hydrocarbons that are disinfection byproducts. Among those are haloacetonitriles. Our objective is to develop unique biomarkers, in peripheral blood, for exposure and HAN-induced cellular injury, which may result from HAN-induced alkylative or oxidative damage to cellular molecules.Progress Summary:
The water disinfectant byproduct dichloroacetonitrile (DCAN) is a mutagen and known to induce DNA strand breaks in cultured human lymphoblasts. The effect of DCAN in cultured mouse peritoneal macrophages (MPM, RAW 264.7) was explored (see Figure 1). MPMs were exposed to various concentrations (100 µM- 400 µM) of DCAN for 4 hours. The phagocytic activation of MPMs was characterized by the production of reactive oxygen intermediates (ROI) and secretion of TNF-a. The ratios of intracellular GSH/GSSG were assessed and used as an indicator of oxidative stress. Electrophoretic detection of DNA degradation and light microscopy were utilized for the characterization of DCAN-induced apoptosis. LDH leakage and trypan blue exclusion were used as markers of the necrotic effects of DCAN.Following treatment with DCAN, GSSG was increased (135 percent of control, P< 0.05). DCAN activation of MPMs was observed by elevated levels of ROI (190-250 percent of control, P<0.05) and increased secretion of TNF-a (450 percent of control, P<0.05). Electrophoresis of DNA of treated MPMs indicated a dose dependent increase in the degradation of genomic DNA. This information combined with morphological studies indicated that exposure of MPMs to lower levels of DCAN (100 µM and 200 µM) incites apoptic cell death. At 400 µM DCAN cellular necrosis was observed as indicated by increased LDH leakage and decreased viability (45 percent of control, P< 0.05).
These studies suggest that the dose dependent DCAN-induced apoptosis or necrosis in MPMs is due to the disturbance in GSH/GSSG ratio and initiation of ROI mediated oxidative damage mechanisms. Our studies should provide the basis for the development of regulatory guidelines and policies governing the tolerance levels for chronic human exposure to HAN.
Future Activities:
We will focus on the characterization and quantitative determination of alkylative (DNA and Hemoglobin adducts) and oxidative damage to cellular macromolecules.Journal Articles:
No journal articles submitted with this report: View all 23 publications for this projectSupplemental Keywords:
drinking water disinfection, disinfection byproducts, haloacetonitriles, biomarkers of exposure, peripheral blood, DNA adducts, hemoglobin adducts, cyanomethyl guanine, cyanomethyl valine., RFA, Scientific Discipline, Water, Health Risk Assessment, Environmental Chemistry, Biochemistry, Drinking Water, community water system, toxicity, carcinogenicity, dose response, treatment, haloacetonitriles, animal model, dermal exposure, drinking water system, drinking water contaminants, exposure, halogenated hydrocarbons, chemical byproducts, halogenated disinfection by-products, peripheral blood, disinfection byproducts (DPBs), human health effects, public water systems, cell injury, DBP exposure, biomarkers, inhalationProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.