الفهرس 
Background and stating of the problemOnly 14 pages are availabe for public view
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Abstract
Research has clearly established environmental pollution from the presence of organic micropollutants in drinking water, groundwater and surface water. Organic micropollutants affect water quality and cause adverse health and environmental effects. These pollutants come from various sources and enter the bodies of water by different pathways.
The main goal of this study is to monitor the occurrence and levels of some groups of organic micropollutants in the tap drinking water of Egypt. The study focused on the disinfectant by-products such as trihalomethanes (THMs), and haloacetic acids (HAAs). Also, the study checked the compliance of the observed concentrations of trihalomethanes, and haloacetic acids to the Egyptian guidelines for drinking water and World Health Organization (WHO) guidelines.
In the first part of this thesis, the occurrence of disinfectant by-products in desalinated drinking water in Egypt was studied. Seawater desalination is the technology of choice in many countries worldwide. In Egypt, the technology of reverse osmosis (RO) seawater desalination is used in coastal areas along the Mediterranean and Red Sea. The presence of disinfection by-products (DBPs) in drinking water remains a great threat to human’s health. This study reported for the first time the levels of trihalomethanes, haloacetic acids, total organic carbon (TOC), and total organic halogen (TOX) in desalinated drinking water. Water samples were collected from desalination plants (DPs) located in Marsa Matrouh and Red Sea governorates. Since the water characteristics play a key role in determining the type and quantity of generated DBPs, the inorganic parameters were measured as well. The values of trihalomethanes and haloacetic acids were far below their maximum permissible limits set by the Egyptian Standards. The inorganic parameters were complying with the Egyptian Standards except for a case of pH and chloride.
The second part of this thesis, was concerned with investigating the multi-exposure human health risk assessment of trihalomethanes exposure in drinking water of Egypt. The study aimed to calculate and evaluate the probable lifetime cancer risks and non-cancer risks of trihalomethanes through ingestion, dermal contact, and inhalation exposure to Egypt’s drinking water. A total of 1667 samples were collected from twenty-three Egyptian governorates over a period of three years.
The concentrations of total trihalomethanes were ranging between 29.07 and 86.01 μg/L, with an average of 53.62 µg/L. These concentrations are lower than the maximum recommended by the Egyptian standards (100 μg/L). The most prominent trihalomethanes compounds were chloroform and bromodichloromethane (BDCM), while bromoform was rarely detected.
Cancer risk assessment results showed that inhalation is the pathway that impose the highest cancer risk relative to the other two pathways. Of the studied trihalomethanes, bromodichloromethane (BDCM) had the highest impact to cancer (69%), followed by chlorodibromomethane (CDBM, 28%), while chloroform had the highest contribution to non-cancer risk. On the other hand, the highest cancer risk value was calculated for Matrouh governorate (42.2×10-6) and the lowest was in Minia governorate (1.0×10-6). Average total lifetime cancer risk was 13.1×10-6, which is higher than the minimum or negligible risk level defined by the USEPA (1.0×10-6). Most of the governorates exceeded the general guidance risk value of USEPA, only Minia governorate was equal to it. Thus, these higher values of cancer risk may cause several diseases among the population.
Ingestion pathway led to higher HI values in comparison with dermal pathway. Trihalomethanes species follows the order of chloroform> bromodichloromethane> chlorodibromomethane>bromoform. The average hazard index for both routes was far lower than unity demonstrating that there would be negligible non-cancer risk.