Abstract
The Allium cepa biomarker was applied to assess the cytotoxic and genotoxic effects of drinking water from different sources (tap water, bottled water and distribution network water) in Saudi Arabia. Waters samples were collected randomly from different locations in Yanbu city to evaluate the mitotic index and the chromosome aberrations on root meristematic cells of Allium cepa. The study was conducted during the four seasons to estimate possible seasonal influences on DNA damage. A significant statistical decline in the mitotic index (MIs) in root-tip meristematic cells of Allium cepa was only observed for tap water samples collected from two regions: Yanbu Al-Balad and Yanbu AL-Sinaiiya. The decreases of the MIs in cells germinated in the local water distribution network samples did not have any statistical significance (p>0.05). Root cells germinated in bottled water samples (local and imported brands) exhibited acceptable values of MIs. The study of chromosome abnormalities caused by the exposure to the tested drinking water samples was considered as the frequencies of chromosome aberrations (CAs). The highest inductions of CAs were identified in plants grown in tap water samples and only one of the distribution network water samples, mainly during the summer and spring seasons. Relatively low values of CAs were found for bottled drinking water and water samples from D2 and D3. The predominant chromosome aberrations detected in the present study were: vagrant chromosomes, stickiness and anaphase bridges.