Background: Alterations in the methylation levels of tumor suppressor genes are considered as one of the essential aspects of malignancies. The present study explored the association of O6-methylguanine- DNA methyltransferase (MGMT) gene promoter methylation, as a tumor suppressor, with some organochlorine pesticides (OCPs) in primary brain tumor (PBT) patients. Methods: The present study was conducted on a total of 73 PBT patients. The patients’ serum was analyzed using gas chromatography for seven OCP derivatives. The methylation-specific PCR (MSP) method was also used to determine the methylation status of the MGMT promoter. Results: The current findings demonstrated that the methylation of MGMT promoter occurred in 22 out of 34 glioma cases (64%), but in only one out of 35 meningioma cases. No MGMT promoter methylation was observed in other PBT, hemangioma, and anaplastic medulloblastoma stages. Besides, there were significant associations between MGMT methylation and γ-HCH (odds ratio [OR]: 1.50; 95% CI: 1.03- 2.40, P= 0.04), 4,4DDE (OR: 1.44; 95% CI: 1.01- 2.05, P= 0.02), 2,4 DDT (OR: 1.23; CI: 1.04- 1.45, P= 0.03), and 4,4DDT (OR: 1.46; CI: 1.23- 2.15, P= 0.02) in glioma patients. Conclusion: The results of the study suggested that the hypermethylation of the MGMT promoter in glioma patients is associated with increased OCPs in their serum, especially γ- HCH, 4,4DDE, 2,4DDT, and 4,4DDT. Moreover, it may lead to the hypermethylation of the MGMT promoter gene. Hence, it can be concluded that exposure to OCPs may potentially induce glioma.

Background: Water quality deterioration is becoming a serious challenge for water utility corporations supplying treated water through the use of a centralized distribution system. After water leaves the treatment plant and enters the distribution system, it is subjected to numerous complex physical, chemical, and biological changes. This study aimed to investigate the major physical factors deteriorating water quality in an aged distribution system. Methods: Deterioration modeling was undertaken using an EPANET computer program. For model calibration processes, data collected from field measurements were used. Descriptive statistics were employed to analyze the data. Water age and residual chlorine were selected parameters to investigate the deterioration level. The identification of major factors posing water quality changes was undertaken by examining distinct physical and operational settings.
Results: The maximum water-age variation obtained between two extreme water-use periods was 21.97%. In the same way, the maximum residual chlorine concentration variation obtained was 11.68%. On the contrary, with tested extreme pipe sizes in the study, the maximum water-age variation obtained was only 0.93%. Whereas, the obtained maximum residual chlorine concentration variation between the two extreme pipe sizes was 21.03%. Conclusion: Water use variation poses more water quality degradation than pipe geometry. Water age in aged distribution is rarely influenced by conditions of pipe geometry.