Grantee Research Project Results
2004 Progress Report: Biomarkers for Air Pollutants: Development of Hemoglobin Adduct Methodology for Assessment of Exposure to Butadienes and Polycyclic Aromatic Hydrocarbons, SEER project of SIP: Experimental Program To Stimulate Competitive Research (EPSCoR) From The Commonwealth Of Kentucky
EPA Grant Number: R829419E02Title: Biomarkers for Air Pollutants: Development of Hemoglobin Adduct Methodology for Assessment of Exposure to Butadienes and Polycyclic Aromatic Hydrocarbons, SEER project of SIP: Experimental Program To Stimulate Competitive Research (EPSCoR) From The Commonwealth Of Kentucky
Investigators: Hurst, Harrell E. , Myers, Steven R.
Institution: University of Louisville
EPA Project Officer: Chung, Serena
Project Period: October 1, 2002 through September 30, 2004 (Extended to September 30, 2005)
Project Period Covered by this Report: October 1, 2003 through September 30, 2004
Project Amount: $219,287
RFA: EPSCoR (Experimental Program to Stimulate Competitive Research) (2000) RFA Text | Recipients Lists
Research Category: EPSCoR (The Experimental Program to Stimulate Competitive Research)
Objective:
The objective of this research project is to develop methodology that will measure systemic exposures to chloroprene (2-chloro-1,3-butadiene, CAS 126-99-8) and selected polycyclic aromatic hydrocarbons (PAHs)—fluoranthene (CAS 205-44-0) and benzo(a)pyrene (CAS 50-32-8). The methods involve detection and measurement of covalent adducts to the abundant blood protein hemoglobin (Hb) as biomarkers of exposure. The postulated adducts are formed by electrophilic epoxide metabolites of these compounds. Analysis involves synthesis of derivatives of chloroprene epoxide adducts through Edman cleavage of globin N-terminal valine adducts or hydrolysis of PAH adducts bound at other more labile sites. Quantification of adducts derived from chloroprene is accomplished by selected ion monitoring gas chromatography/mass spectrometry (SIM-GC/MS) using stable isotope internal standards. Adducts from PAH exposure are analyzed after acid hydrolysis of labile PAH-Hb carboxylate adducts.
Progress Summary:
During Year 3 of this project, research focused on refinement of working assays for measurement of Hb adducts. SIM-GC/MS methods have been developed for assay of Hb adducts formed from (1-chloroethenyl)oxirane, also known as chloroprene epoxide or CEO. The adduct detection methods rely on sequential Edman cleavage and trimethylsilylation reactions. Limits of detection and quantification of analytical methods of CEO-valine adducts are of the order of 1 and 10 picomoles of adduct per mg globin. These limits are anticipated to be inadequate to use this assay for chloroprene human exposure assessment at parts-per-billion levels in ambient air, but exposure levels in the parts-per-million range should be detectable. Insight has been gained into the mechanism of detoxification of the toxicologically significant metabolite of chloroprene. Reactions of CEO with N-terminal valines in mouse red cell Hb have been characterized kinetically. Additionally, a method was developed to resolve chromatographically the R- and S-enantiomers of (1-chloroethenyl)oxirane. The methods were used to explore a glutathione-dependent mechanism of degradation of (1-chloroethenyl)oxirane, an active metabolite of chloroprene. From the latter work, enantiomeric selectivity in the destruction of chloroprene epoxide was discovered using a red blood cell incubation system in vitro. This discovery led to formulation of the hypothesis that the enantiomeric selectivity results from glutathione S-transferase mediated degradation of the S-enantiomer of chloroprene epoxide.
Future Activities:
Future efforts will use the SIM-GC/MS method to examine the extent of formation of adduct from the epoxides following treatment of red blood cells with compounds that deplete glutathione and examine differential mechanisms associated with increased persistence of the R-enantiomer of chloroprene epoxide.
Journal Articles:
No journal articles submitted with this report: View all 14 publications for this projectSupplemental Keywords:
exposure, ambient air, carcinogen, chloroprene, chloroprene epoxide adducts, biomarkers, Hb adducts, pollution prevention, human health biomarkers, ecosystem protection, environmental exposure and risk, Kentucky, KY,, RFA, Health, Scientific Discipline, Geographic Area, Ecosystem Protection/Environmental Exposure & Risk, Sustainable Industry/Business, cleaner production/pollution prevention, Environmental Chemistry, Health Risk Assessment, amphibians, State, Risk Assessments, Biochemistry, EPA Region, pollution prevention research, biomarkers, population decline, amphibian decline, clean technology, hazardous emissions, Region 3, animal model, exposure, alternative materials, air pollution, PAH, butadiene, human exposure, amphibian bioindicator, causal mechanisms, air emissions, pollution prevention, Kentucky (KY), biomarker based exposure inference, biomarker, biomarker measurements, exposure assessmentRelevant Websites:
http://www.louisville.edu/~hehurs01/ Exit
Progress 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.