| Summary: | 碩士 === 中山醫學院 === 毒理學研究所 === 89 === The purpose of this thesis is to study the habits of people using water in Taiwan and evaluates the cancer risk of disinfection by-products (DBPs). Also we want to discuss the correlation between cancer occurring and DBPs. Furthermore, we want to compare the results with different ways removing DBPs in water.
The research mode referred to the cancer mortality data in Taiwan during 1992-1996, which compared with the data -the mortality of cancer caused by DBPs (bladder cancer, colon-rectum cancer, pancreas cancer), added up and then divided into four levels. From these four levels, we picked up 80 stations randomly, and gathered their water in use, including boiled and not boiled tap water, mountain spring, underground water and others such as filtering through the water-cleaner. Then we analyzed trihalomethanes (THMs), haloacetic acid (HAAs), volatile organic compounds (VOCs) and total organic carbon (TOC) in those samples. After that, we referred to the USEPA risk assessment methods by regulatory agencies, evaluated the cancer risk of DBPs in every region, and discussed the correlation between cancer mortality and DBPs.
In the analytical methods, THMs and VOCs referred to USEPA method 524.2; HAAs referred to USEPA method 552; and TOC referred to Taiwan EPA method (NIEA W530.51C.).
The results found that the concentration of THMs wrer between ND-
64.5 μg/L, and the concentrations of HAAs were between ND-37.2 μg/L.
Trans-1, 3-dichloropropene in drinking water were found in every stations and had positive correlation with THMs. Besides, in some places, 1,1-dichloroethene, trichloroethene, trans-1, 2-dichloroethene and chlorobenzene were also detected. In addition, most of TOC concen-
trations were under 2 mg/L.
The removing rate of substances, drinking water that boiled was benefit to deduct THMs and VOCs but not HAAs and TOC. Moreover, different treatments for boiling water would cause different results. We found that boiling by drinking fountain and kettle had the same effect in removing THMs and HAAs. If boiling by thermos, that was
advantage to removing THMs but adverse to HAAs. In addition, R.O. water-cleaner had better removing effect than non-R.O. water-Cleaner.
The results of drinking water use habits survey indicated that most people in metropolitan city liked to use filtered tap water, and bought mountain spring to be another drinking source. People in a mountain country liked to use mountain spring. Other rural regions were directly taking tap water to boil and drinking. In the boiling habits, most people chose kettle and when the water boiling they turned off the fire immediately. Besides, if people had the habits to boil for a while, half of them would open the kettle cover Furthermore, most people like to use R.O. water-cleaner.
In risk assessment, the lifetime cancer risk of THMs in Taiwan was higher than the USEPA acceptable risk (10-6) by about 3.5-14.1 times. And HAAs was far lower than the hazard concentration.
At last, we found that the mortality of bladder cancer, colon-rectum cancer and pancreas cancer had positive correlation with the concen-
tration of DBPs.
|
|---|
