Browsing by Author "Wenaty, A. N."
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Item Persistent organic pollutants in water, sediments and fish from Lake Victoria and implications to human health risks(Sokoine University of Agriculture, 2019) Wenaty, A. N.Lake Victoria is an important freshwater resource in Tanzania and its neighbouring countries namely Uganda, Kenya, Rwanda, Burundi and Democratic Republic of Congo (DRC). Millions of people dotted around the lake depend on it as a major source of household and industrial water supply, irrigation, transport and provides for fishing as a main source of animal derived protein as well as income. In Tanzania, the lake provides employment opportunities to more than four million people engaged directly or indirect with fishing activities. The frequently fished and consumed fish species that are of commercial interest include; Nile perch (Lates niloticus), Nile tilapia (Oreochromis niloticus) and the freshwater sardines (Rastrioneobola argentea) commonly known as dagaa in Tanzania. The fish are further processed to feed the domestic, regional and international markets. Current estimates from the lake put the annual contribution of the fisheries sector to the Tanzanian Gross Domestic Product (GDP) up to 2.5%. There have been unsubstantiated claims that despite using agrochemicals such as pesticides in agriculture, some fisher folks have been using such chemicals for fishing and preservation of fish products during storage. The same organochlorine pesticides are still in use in agricultural activities within the lake basin and there is a possibility that they accumulate in water, sediments and fish. Furthermore, there have been incinerations of medical wastes, discharge of electronic wastes and untreated wastewaters from industrial establishments in water bodies that tend to increase the loading of polychlorinated biphenyls (PCBs) in water, sediments and fish. It is likely that human beings will get exposed to these chemicals through drinking water and eating fish from the lake. The present study overall objective was therefore to assess fish consumersꞌ eating habits and the prevalence, levels and human health risks of indicator PCBs and OCPs in water, sediments, fish and fish products from Lake Victoria in Tanzania. The specific objectives of the study were: i. To establish levels of indicator PCBs and OCPs in water, sediments and fish from Lake Victoria. ii. To determine the prevalence and quantify residual levels of indicator PCBs and OCPs in processed fish products from Lake Victoria. iii. To assess fish consumersꞌ eating habits. iv. To evaluate the probable human health risks associated with consumption of persistent organic pollutants (POPs) contaminated fish and fish products from Lake Victoria. Water and sediment samples were collected from twelve nationally designated sampling points (considered as important hotspots). Thirty six samples of both water and sediments (a total of 72 samples) were collected for analysis. A total of 162 fresh fish samples were collected from nine selected landing sites and 480 samples of processed fish products from Kirumba Fish Market for analysis of POPs. Extraction of the samples was done using a QuEChERS method and POPs analysis using a gas chromatography equipped with electron capture detectors (GC-ECDs) and a gas chromatography equipped with mass spectrometry (GC-MS). A questionnaire was also administered to 122 fish consumers to assess the fish consumption habits and patterns. The main focus of administering the questionnaire was to identify the types of fish species consumed, frequencies of fish consumption, quantities of fish consumed and factors affecting fish consumption in the population around the lake. The results showed that some organochlorine compounds were present in water, sediments, fish and fish products from Lake Victoria in Tanzania. This is likely due to human anthropogenic activities being undertaken along the lake, long range atmospheric transport and environmental persistence of the compounds. For water samples, the ∑PCBs ranged between 0.95 and 2.24 μg/L while for sediments the range was between