Grantee Research Project Results
1998 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.
Current 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, 1997 through September 30, 1998
Project Amount: $539,069
RFA: Drinking Water (1997) RFA Text | Recipients Lists
Research Category: Drinking Water , Water
Objective:
The overall project goal is to determine the inhalation and dermal exposure to disinfection by-products (DBPs) of chlorination from the multiple water uses that occur within a home. The exposures will be determined by: (1) measurements of the concentration of the DBPs or their metabolites in urine or breath following known exposures within baths or showers; (2) estimation of dermal transport coefficients using in vitro measurements across excised skin under controlled conditions; and (3) measurement of size and number distribution of residential water aerosols generated by typical water uses that result in inhalation exposures.Progress Summary:
During the first year, biomarker measurement methodologies for the targeted DBPs, haloacetic acids, haloketones, chloral hydrate, and haloacetonitriles are being optimized. These methodologies include extraction procedures from water based on EPA water methodologies adjusted to provide adequate separation of the target compounds from others present in urine as well as stability studies. A flow system is being developed to directly add DBPs to purified water that is used for showering or bathing at the upper range of concentrations measured in drinking water systems so that a known, constant exposure can be introduced. Particle size range measurements are being made of water droplets generated from showers and ultrasonic humidifiers for inhalation exposure of nonvolatile DBPs.
Optimization of the methodologies for haloacetic acids and haloketones analyses in urine have been done. The procedure being used is: a 5-mL urine sample is acidified with concentrated sulfuric acid; extracted twice with ethyl ether; centrifuged; the ether evaporated; the halogenated acids and ketones methylated at 60 C for 1 h with a 10 percent sulfuric acid/methanol mixture in methyl tertiary-butyl ether (MTBE); sodium sulfate is added; and the MTBE is analyzed by gas chromatography/electron capture detection (GC/ECD). A similar method is used for the water analysis, except that MTBE is used initially in place of ethyl ether. The mean percent recoveries based on replicate analyses of spiked samples were between 80 and 100 percent for all compounds, except dibromoacetic acid from urine, which was 67 percent. The detection limits were all <0.2 g/L from water and <0.5 g/L from urine, except bromochloroacetic acid from urine, which had a value of 1.2 g/L. A co-eluting peak to methyl bromochloroacetate has been
found in the urine extracts using a J&W DB1 column. Changing the column to DB1701 has resulted in separation of the target compound from interfering peaks.
The method for urinary haloacetonitriles and chloral nitrile being evaluated is an (MTBE) extraction based on EPA Method 551.1. Recoveries exceeding 90 percent have been obtained for all compounds except trichloroacetonitrile, which appears to be degraded. Current optimization conditions being examined for trichloroacetonitrile include pH adjustments and the addition of antioxidants.
Ingestion studies for trichloroacetic acid and dichloroacetic acid
have been conducted to evaluate the urinary analysis following an actual known
exposure. The peak excretions observed indicate dichloroacetic acid having a
shorter biological half-life than trichloroacetic acid, consistent with animal
data (see Figures 1 and 2).
Less than 10 percent of the ingested dose of both
dichloroacetic and trichloroacetic acids were excreted in urine, which has been
previously observed for chloroform in expired breath following ingestion of
water, while higher levels were measured following dermal and inhalation
exposure. The near-complete metabolism following ingestion occurs because
ingested compounds are transported directly to the liver where efficient
metabolism occurs before being distributed throughout the body in the blood
stream. Compounds inhaled or dermally absorbed from water initially circulate
throughout the bloodstream before reaching the liver. Thus, it is expected that
a smaller percentage of the ingested haloacetic acids would be excreted than
would occur from other exposure routes.
Particle size distribution of aerosols generated by a shower and an ultrasonic humidifier were determined using a Lasair Model 1002. The particle counts from showers exceeded 1 x 103 in the breathing zone with the largest fraction being 0.3?0.4 m in diameter. Assuming that spherical water droplets have a density of 1.0 g/cc, the particle mass concentration was 10 g/m3, with the majority of the mass having a particle diameter of >1 m. The ultrasonic humidifier generated in 1 x 106 particles at the exit of the system with most particles being <0.1 m. The particle counts decreased with distance from the humidifier, with a ten-fold reduction in number 1?2 m distance. Very few particles <0.7 m were generated. The aerosol concentration at the humidifier was 10 g/m3, and approximately one-half that concentration at a distance of 1?2 m from the humidifier (see Figures 3 and 4).
Future Activities:
Future activities include dermal and inhalation exposures to human subjects with the collection and analysis of urinary levels with time, and in vitro skin studies to determine the dermal flux under controlled, laboratory conditions. Additional showers and humidifiers in the homes during use to determine particle size distribution in different rooms.Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 13 publications | 5 publications in selected types | All 5 journal articles |
---|
Type | Citation | ||
---|---|---|---|
|
Kim HK, Weisel CP. Dermal absorption of dichloro-and trichloroacetic acids from chlorinated water. J Exposure Anal Environ Epidemiology 1998;8(4):555-575. |
R825953 (1998) |
not available |
Supplemental Keywords:
exposure, disinfectant by-products, dermal absorption, bathing, showering., RFA, Health, Scientific Discipline, Air, ENVIRONMENTAL MANAGEMENT, Water, air toxics, Environmental Chemistry, Health Risk Assessment, Epidemiology, Chemistry, 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.