Chemical Quality of Tap Water versus Bottled Water: Evaluation of Some Heavy Metals and Elements Content of Drinking Water in Dakhlia Governorate - Egypt

摘要

Water is essential to sustain life, and a satisfactory safe supply must be made available to consumers. Many different chemicals may occur in drinking water. The problems associated with chemical constituents of drinking water arise primarily from their ability to cause significant human health risks after prolonged periods of exposure; of particular concern are contaminants that have cumulative toxic properties, such as heavy metals. This study was done to clarify concerns about chemical quality and safety of drinking tap water in Dakhlia governorate. For comparison, selected samples from three common commercial bottled water were analyzed. Atomic absorption Spectrometry technique was used to measure lead, cadmium, arsenic, mercury, zinc, selenium, calcium, magnesium and sodium in 65 samples of tap water and nine samples of bottled water. The mean concentrations of the metals in drinking water obtained in this study were within the acceptable levels of the World Health Organization (WHO,2004) guidelines and lower than maximum contaminated levels (MCL) established by the United States Environmental Protection Agency (USEPA,2004). Tap water showed slightly higher levels of lead, arsenic, cadmium, zinc, and selenium. Introduction Safe drinking water is a basic need for human development, health and well-being, it is an internationally accepted human right (WHO, 2001 ). Chemical contaminants of drinking water are often considered a lower priority than microbial contaminants, as adverse health effects from chemical contaminants are generally associated with long-term exposures, whereas the effects from microbial contaminants are usually immediate. Nonetheless, chemicals in water supplies can cause very serious problems (WHO, 2007).The abundance of toxic chemicals in drinking water may cause adverse effect on the human health such as cancer and chronic illness (IKem et al., 2002). Epidemiological studies have indicated a strong association between the occurrence of several diseases in humans, particularly cardiovascular diseases, kidney-related disorders, neurocognitive effects and various forms of cancer and the presence of many metals such as cadmium, mercury and lead (Al –Saleh and Al- Doush, 1998).Water may contain toxic metals like mercury, lead, cadmium, arsenic and selenium. These metals can cause acute or chronic poisoning and should be eliminated from drinking water, if possible. Several metal ions such as sodium, calcium and magnesium are essential to sustain biological life. Other additional metals are also essential for optimal growth, development and reproduction like zinc which is in small enough quantities to be considered trace element. Trace metals function mostly as catalysts for enzymatic activity in human bodies; however, their accumulation in the human body cause harmful effects (Tayyeb et al., 2004).So, this study aims to assess drinking water chemically to determine whether it is capable of meeting the health-based targets and as it is neither physically nor economically feasible to test for all chemical constituents in drinking water, monitoring efforts were directed at significant parameters. Material And Methods SamplingWater samples were randomly collected from private residencies at different 13 locations “districts” of Dakhlia Governorate (L1: El-Mansoura, L2: Talkha, L3: Bilqas, L4: Dekernis, L5: Sherbin, L6: El-Sinbillawin, L7: Minyat El-Nasr, L8: El-Manzala, L9: El-Gamalia, L10: Mit-Salsil, L11: TemiEl-Amdid , L12 : Aga , L13: Mit Ghamr). Of each location, five water sampling were taken from different houses. Chemical studies were performed for 65 household tap water samples collected from November to December 2006. These samples represent indoor tap water after passing in the plumbing of each building.Tap water was kept in sealed glass bottles, refrigerated and transferred to the laboratory for analysis. All samples were analyzed within 7 days from the time of collection. No preservatives were added