Assessment of Heavy Metal Contamination in Urban Water Sources and Its Health Risks

Thesis Abstract

Heavy metal contamination in urban water sources poses a significant public health challenge, particularly in rapidly urbanizing regions where infrastructure and environmental management may be inadequate. The persistent presence of heavy metals such as lead, cadmium, mercury, arsenic, and chromium in drinking water supplies can lead to severe health risks including neurological disorders, renal damage, carcinogenicity, and developmental issues in vulnerable populations. This study aims to comprehensively assess the levels, spatial distribution, and potential health risks associated with heavy metal contamination in urban water sources within the metropolitan area. The specific objectives are to quantify concentrations of selected heavy metals using atomic absorption spectrophotometry (AAS), determine contamination sources through spatial analysis, evaluate the health risk indices for different demographic groups, and establish correlations between heavy metal levels and socio-economic as well as environmental factors. A cross-sectional analytical research design was adopted, examining water samples from 150 locations across the urban district, including household taps, wells, and surface water bodies. The population encompasses residents relying on these water sources, with a sample size determined via stratified random sampling to ensure representative coverage of diverse socio-economic zones. Data collection involved both field sampling and structured questionnaires to ascertain water usage practices, awareness levels, and potential exposure pathways. The field samples were processed and analyzed for heavy metal content utilizing atomic absorption spectrophotometry (AAS), adhering to standardized preparation protocols to ensure accuracy and repeatability. Validity and reliability of analytical instruments were established through calibration with certified reference standards and repeated measurements, with a detection limit sufficient to identify trace levels of metals. The study employed descriptive statistics to summarize concentration data, while inferential analyses, including regression models and Analysis of Variance (ANOVA), were used to identify significant determinants of contamination and differentiate between sources. Health risk assessments were conducted using the calculation of hazard quotient (HQ) and carcinogenic risk indices based on the EPA guidelines, applying exposure parameters tailored to local consumption rates and demographic profiles. Expected findings include elevated concentrations of heavy metals exceeding permissible limits set by the World Health Organization (WHO) in certain water sources, with industrial discharge areas showing higher contamination levels. Spatial mapping is anticipated to reveal hotspots correlating with proximity to waste disposal sites and industrial zones. The risk assessment is projected to indicate potential non-carcinogenic and carcinogenic health risks for residents exposed via ingestion and dermal contact, especially among children and low-income communities. This research contributes to the existing body of knowledge by providing region-specific data on heavy metal contamination and associated health risks, filling gaps related to urban water quality in developing cities. The findings will inform policymakers, environmental agencies, and public health programs regarding targeted interventions, regulatory enforcement, and community awareness campaigns. Additionally, the study offers a framework for integrating spatial analysis and health risk assessments in urban water quality monitoring. In conclusion, the study underscores the urgent need for continuous water quality surveillance and stricter pollution control measures to safeguard public health in urban environments. Recommendations include the implementation of regular monitoring programs employing advanced analytical techniques, upgrading of waste management practices, development of sustainable urban planning policies, and community-based awareness initiatives aimed at reducing exposure to contaminated water. Future research should explore longitudinal studies to assess temporal variations in contamination levels and evaluate the effectiveness of remediation strategies over time.