Grantee Research Project Results
1999 Progress Report: Inhalation and Dermal Exposure to Disinfection By-Products of Chlorinated Drinking Water
EPA Grant Number: R825953Title: Inhalation and Dermal Exposure to Disinfection By-Products of Chlorinated Drinking Water
Investigators: Weisel, Clifford P. , Laskin, Jeffrey
Institution: University of Medicine and Dentistry of New Jersey , Environmental and Occupational Health Sciences Institute
Current Institution: Environmental and Occupational Health Sciences Institute , University of Medicine and Dentistry of New Jersey
EPA Project Officer: Hahn, Intaek
Project Period: October 1, 1997 through September 30, 2000
Project Period Covered by this Report: October 1, 1998 through September 30, 1999
Project Amount: $539,069
RFA: Drinking Water (1997) RFA Text | Recipients Lists
Research Category: Drinking Water , Water
Objective:
The overall goal of the project is to determine the potential inhalation and dermal exposure to haloacetic acid, haloketones, haloacetonitriles, and chlorohydrate from showering, bathing, and the use of humidifiers. These will be determined in vivo from measurements of urinary and breath levels of these DBPs and their metabolites following exposures to known concentrations in bath and shower water. In vitro measurements of aerosol air concentrations from showers and humidifiers will be made. In vitro dermal fluxes of characteristic DBPs will be made using a Franz cell.Progress Summary:
During the second year, biomarker measurements of several haloacetic acids (HAAs), chlorohydrate (CH), and haloacetonitriles (HANs) were made following dermal or ingestion exposure to water concentrations of 20 µg/l (CH and HANs) and 10 to 100 µg/l (HAAs). In vitro studies using skin tissue have been run using monobromoacetic acid at two pH values, pH 2 and 7. Particle size measurements have been made for several different shower head and temperature configurations.Levels of the chlorinated acetic acids were higher in the urine following the ingestion, however, monobromoacetic acid was not detected in urine following exposure. This is probably due to the more efficient metabolism of brominated compounds by the body and complete metabolism of MBA following ingestion. Small increases in the excretion rate dichloroacetic acid (DCAA) but no detectable levels of urinary dibromoacetic acid were observed following dermal exposure to a mixture of these two compounds. Dichloroacetic acid was present in the participants' urine prior to exposure even though the subject did not ingest chlorinated water during the week prior to the experiment. This variation makes it difficult to quantify the amount of DCAA excreted that is associated with the dermal exposure, but the quantity was no greater than tens of nanograms. The in vitro studies also indicated that at pH 7 little dermal absorption occurs for the HAAs. Somewhat more penetration of the skin was observed at pH 2, with flux rates being estimated at 0.84 µg/cm2/hr. At pH 7, a greater portion of the HAAs is ionized and the skin is an effective barrier for ionic compounds. At pH 2, the unionized moiety can penetrate through the skin. This indicates that dermal absorption will not be a major exposure route to increasing the body burden of these compounds.
Haloacetylnitriles were not measurable in the urine either before or following either dermal or ingestion exposure, again suggesting that these compounds are metabolized prior to being excreted. The major metabolite is thiocyanide. We currently are examining the feasibility of using a spectrometric method for its analysis. In addition, breath analysis for the haloacetylnitriles is being optimized for use with both dermal and inhalation studies. Haloacetylnitriles have sufficient volatility to be present in the vapor phase, while the haloacetic acids are only expected to be present in the aerosol of showers. In vitro testing currently is underway for chloroacetonitrile, for which commercially available radiolabeled compound can be purchased.
Chlorohydrate also was not found in the urine following dermal exposure; however, its metabolites dichloroacetic acid and trichloroacetic acid were elevated in the urine. Dermal exposure studies with chlorohydrate are continuing to determine the amount of the associated internal dose excreted as its metabolites. In addition, breath analysis will be conducted for chlorohydrate to obtain a time profile.
Turning on of a shower increases the number of aerosols in the submicron size range, with smaller increases above 2 µm. The majority of the aerosol mass and number were observed 0.3 meters from the floor with lower amounts in the breathing zone, 1.5 to 2 meters from the floor.
Future Activities:
The major emphasis during the next reporting period will be to determine the feasibility of using urinary thiocyanate as a biomarker of halogenated acetonitrile exposures and to continue the in vivo and in vitro dermal studies. One additional emphasis being considered is to establish the variability in urinary dichloroacetic and trichloroacetic acids with defined ingestion exposures to these compounds.Journal Articles:
No journal articles submitted with this report: View all 13 publications for this projectSupplemental Keywords:
drinking water, indoor air, human exposure, risk, metabolism, dose-response, VOC, DBP, disinfection, chlorination, urinary biomarkers, exhaled breath., RFA, Health, Scientific Discipline, Air, ENVIRONMENTAL MANAGEMENT, Water, air toxics, Environmental Chemistry, Health Risk Assessment, Chemistry, Epidemiology, Risk Assessments, Drinking Water, Risk Assessment, monitoring, dermal exposure, public water systems, microbial risk assessment, exposure and effects, human health effects, trihalomethanes, chemical byproducts, disinfection byproducts (DPBs), dose response, exposure, community water system, residential water usage, treatment, human exposure, urinary biomarkers, chlorine-based disinfection, inhalation, chloramines, metabolism, drinking water contaminants, DBP exposure, drinking water system, DBP effects, exposure assessmentRelevant Websites:
http://www.eohsi.rutgers.edu/ 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.