Assessment of possible sources of endocrine disruptors and microbial pathogens and their impacts in the Lake Victoria Basin in the East African Region.

Abstract

This study was conducted from August 2008 to May 2009 in Mwanza (Tanzania), Jinja (Uganda) and Kisumu, Homabay and Suba (Kenya) to establish the sources of pollutants in particular endocrine disruptors and microbial pathogens in water and fish. A sociological study was undertaken using qualitative and quantitative methods. Microbial contamination of water and fish in the lake was assessed in 14 water and 60 fish samples in Mwanza. In Jinja, assessment of microbial contamination was carried out in 100 water and 26 fish samples. A total of 80 Nile tilapia were collected from Kisumu, Homabay and Suba and examined for gross pathological lesions using standard necropsy techniques. Findings from the sociological studies indicated that, the knowledge and awareness on endocrine disruptors in the region is low. Pollutants that find access into the lake and have potential for disrupting the endocrine systems exist in all cities and originate from point and non-point sources. Human, industrial, agricultural, hospital and domestic wastes are the main sources of pollutants likely to contain endocrine disruptors. These pollutants are handled poorly and most of them are disposed off into the lake without treatment. In Mwanza, contamination of water with faecal material at various landing sites was observed in 85.7%, 78.6% and 35.7% of the samples determined using Total Viable Counts, Total Coliform Counts and Total Faecal Coliform Count. All water samples were negative for Salmonella spp, Vibrio spp, Cryptosporidia spp and Giardia spp. In Jinja, microbial contamination was observed in all sampling sites as determined by aerobic plate count (APC), Total Coliform Count (TCC) and Escherichia coli count. There was no significant difference in microbial load between sampling sites (P > 0.05). The gross pathological lesions were generalized hyperemia, liver changes (paleness, grey spots and hemorrhages), cystic urinary bladder, atrophied testis and kidneys, eye opacity, degenerated ovaries, grey patches on the stomach, clear cysts in the testis, deformed dorsal fin and ulcers on the lateral side of the body. Further studies are underway to confirm the likely causes of the observed lesions and the impact of the observed pollutants and microbial pathogens.