ANNOUNCEMENTS
Persistent organic pollutants (POPs) are among the group of anthropogenic and man-made chemical pollutants. These chemical substances have toxic properties, resist degradation in the environment, bioaccumulate through food chains and are transported long distances through moving air masses, water currents and migratory species, within and across international boundaries. India has been categorized as a hot spot of POP exposure. Beyond the presence of active primary sources, the Indian environment may be sensitive to the influence of releases from various environmental repositories (including soil, vegetation, and glaciers). POP outflow from melting glacier which is under the threat of climate change, for example, has been pointed out as a relevant source for freshwater ecosystems. However, little is known on the modality and relevance of this relationship. Furthermore, lack of baseline studies, hampers forecasting of future regional exposure scenarios.
This thesis contributes to fill these gaps by developing a research framework for the Ganges River basin which receives 30 to 40% of water driven from glacier melting. The thesis aimed at increasing the holistic understanding on fate and distribution of legacy and emerging POPs in the Ganges River basin, and their implication on human health. Four scientific publications, which have been brought out from this study, are included in this thesis. Research Paper 1 presents the first systematic review considering all available past data on POP occurrence in India and examine the distribution pattern of POPs in multi-compartment environment and human samples, meta-analysis of time trends in exposure levels to environment and humans, and cross country comparison of POP contamination with China. Results from this paper concluded that the Indian environment and human population were highly contaminated by DDTs and HCHs. While comparing contamination levels between India and China, tendency towards decline in POP contamination is visible in China, unlike India. Research Paper 2 reviews the policy and legal and non-regulatory schemes set in place in this country during the last decades to manage chemical risk and compares them with those in developed nations. Findings of this research paper suggests that overlapping of jurisdictions and retrospectively approached environmental policy and risk management currently adopted in India are out of date and excluding Indian economy from the process of building and participating into new, environmentally-sustainable market spaces for chemical products. Research Paper 3 presents the analysis of legacy POPs levels in air, deposition and river water in several sections along the Ganges River and its major headwaters. It elucidates that melting Indian Himalayan glaciers can be major contributors of polychlorinated biphenyls (PCBs) and high-molecular-weight polycyclic aromatic hydrocarbons (PAHs) for surface water in the Gangetic plain during the dry season. Research Paper 4 assesses the distribution of emerging POPs like perfluorooctane sulfonic acid (PFOS) from perfluoroalkyl substances (PFAS) group in river and groundwater (used in this region as drinking water) from several locations along the Ganges River and estimates direct emissions, specifically for PFOS and PFOA. It also assesses daily PFAS exposure intakes for local population through contaminated drinking water consumption. This study finds the prevalence of short-chain PFAS in the river and groundwater, which indicates that the effects of PFOA and PFOS substitution from the global market are visible in Indian environment. Concentrations and trends of PFAS in groundwater were generally similar to those observed in the Ganges River water, suggesting the aquifer was contaminated by wastewater receiving river water.
Outcomes of this thesis open up a wide space for policy makers and researchers to plan and conduct future research on fate and dynamics of POPs and similar pollutants and their management in transitional economies such as India
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