الفهرس 
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Abstract
This study was conducted in the laboratories of the Department of Genetics, Faculty of Agriculture, Ain Shams University, and the Medical Genetic Center, Faculty of Medicine, Ain Shams University. The study aimed to evaluate the potential genotoxic effect of treated wastewater to study the relationship between environmental pollution and changes in the genetic material of living organisms.
This study targeted the Al-Jabal Al-Asfar farm, which has been irrigated with treated and untreated wastewater for more than 90 years. This farm is considered a model for the environmental stress role in causing genetic variation in the population and organisms that live in this region. Therefore, the importance of studying the environment and public health in this region emerged under conditions of soil, water, and crop pollution. Accordingly, the current study was concerned to study the genetic effects resulting from the use of wastewater for long periods, which may reach all living systems in the ecosystem. To achieve our goal, this study was carried out on two different biological systems to evaluate the genetic effect resulting from the irrigation of wastewater. Allium Cepa was used as an example for plants, while albino mice were used as an example for animals.
The study was conducted on four groups of water, the first group represented untreated wastewater (RWW), the second group represented treated wastewater for plant irrigation (IWW), the third group represented treated wastewater for drinking (DWW), and the fourth group represented the control and was taken from Shubra.
The main results of this study were:
1- The results of wastewater analysis showed that the first group (RWW) had the highest concentration of heavy metals and EC value, followed by the second group (IWW), then the third group (DWW) compared to the control group. Iron (Fe) was high in IWW and RWW while Mn was high only in RWW which may negatively affect the health of plants, animals, and humans.
2- Allium Cepa was used for cytological analysis to determine the chromosomal changes and measure the MI rate. Exposing onion roots to different groups of water showed different chromosomal changes that depend strongly on the degree of water contamination. RWW and IWW treatments had a significant effect on the aberrant mitosis rate, while DWW treatment gave a non-significant effect on chromosomal aberrations. Whereas the mitotic activity significantly decreased in RWW and IWW-treated root tips (49.65% and 64.15% respectively) compared to normal control (81.8%). Whereas the decrease in the DWW treatment (75.9%) wasn’t significant. The results showed that untreated water has a great potential to cause defects in the spindle fiber, due to its high content of heavy metals, which are responsible for the genotoxic effects that have been seen from chromosomal retardation, chromosomal stickiness, chromosomal bridges at the dissociation stage, as well as chromosomal fragments.
3- The histological examination of albino mice liver after treatment with the different forms of wastewater demonstrated that RWW caused severe hydropic degeneration of the tissues of the mice and irregular hepatic cords. On the other hand, the IWW and DWW caused mild and few hydropic degenerations of the tissues respectively.
4- Total structural chromosomal abnormalities in bone marrow cells of male mice generated by various forms of wastewater treatments illustrated that only RWW, IWW, and DWW (8.4 ± 2.16, 7.8 ± 2.11, and 3.2 ± 1.24 respectively) were significantly changed than negative control (1.6 ± 0.75). Meanwhile, the total numerical chromosomal aberrations in bone marrow cells of male mice showed only significant differences in the RWW and IWW treatment (4.6 ± 0.68 and 3.4 ± 0.68 respectively) compared to negative control (1.4 ± 0.45). The mitotic activity decreased significantly in MMC, RWW, and IWW treatment (54%, 78%, and 66% respectively) compared to negative control. Meanwhile, the decrease in the DWW treatment wasn’t significant.
5- The expression levels of the apoptosis-related genes P53, BAX, and Bcl-2 in the liver of mice were assessed by quantitative real-time PCR to determine the ability of wastewater to induce apoptosis in liver cells. The results supported our study in terms of damage caused by wastewater to animal cells. The expression level of the P53 and Bax gene was downregulated by increasing the water pollution compared to mitomycin, whereas the Bcl-2 gene was upregulated.
Finally, the result of this study concluded that all the wastewater forms contained toxic chemicals and heavy metals above the permissible limits, which cause mutations. Therefore, it is recommended the necessity of developing a good system to get rid of heavy elements from the wastewater before release into the environment. So, the estimates of genotoxicity and mutagenic potential must be taken into account in testing programs and assessment of water quality to get rid of the harmful mutational effects present in water waste.