Inhalation and Dermal Exposure to Disinfection By-Products of Chlorinated Drinking WaterEPA Grant Number: R825953
Title: 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 Amount: $539,069
RFA: Drinking Water (1997) RFA Text | Recipients Lists
Research Category: Drinking Water , Water
Description:Objectives/Hypotheses: Exposure to disinfection byproducts (DBPs) in chlorinated drinking water is multi-route. However, little information is available for the dose from non-ingestion routes of exposure to DBPs other than trihalomethanes. It is hypothesized that inhalation exposure to non and semi-volatile DBPs is a small portion of the total exposure while inhalation exposure will be significant for volatile DBPs. It is further hypothesized that the dermal exposure to DBPs that are highly ionized in water at neutral pH will be small while dermal exposure to non-ionizable lipophilic DBPs will be significant.
The overall goals are to obtain the fundamental estimates of DBPs' dermal transport across skin, and inhalation exposure and absorption across the lung during various water centered activities. The specific aims are: i) determine the dermal absorption for haloacetic acids (HAAs) (MCAA, DCAA, TCAA, MBAA, DBAA, BCAA), haloacetonitriles (HANs) (DCAN, TCAN, BCAN), haloketones (HKs) (DCP, TCP) and chloral hydrate (CH) in vitro using human cadaver skin mounted in a thermostatically controlled cell at realistic environmental concentrations and conditions; ii) confirm the methodology for human urinary and breath DBP biomarkers; iii) determine the amount of dermal absorption associated with water uses for DBPs using biomarkers; iv) determine the particle number and size distribution and DBPs concentrations in aerosols generated by different water activities within a home; v) determine the dose from inhalation exposure to humans breathing volatilized DBPs or DBPs in aerosols using biomarkers; and vi) compare the potential internal dose from the inhalation and dermal exposure identified above for each of the studied DBPs to that expected from ingestion.
The projected results will be usable for estimating realistic values for the parameters used in developing and for evaluating inhalation and dermal portions of microenvironmental exposure and pharmacokinetic models. These models are used by EPA to establish population-based exposure estimates and to determine what data is required to accurately predict the most exposed populations for risk assessment. The data obtained can be used to update the exposure factor handbook, a major resource for researchers and managers when projecting safe exposure levels to the general public. A unique set of data on the aerosol particle size and number distributions and the DBPs concentrations from different water usages will be obtained. The research will determine the relative importance of inhalation exposure and dermal absorption of DBPs compared to ingestion exposure, extending studies the researchers have previously done on THMs, for which it was found that half of the total exposure was from dermal and inhalation exposure routes. These comparisons are needed to establish safe DBPs levels in drinking water and to advise populations of safe uses of contaminated water supplies.