Masters Thesis
Fish remains to be an important source of proteins in developing countries including
Tanzania. Fish processing methods like smoking aim at improving the shelflife of smoked
fish as well as taste and aroma. During smoking, smoke by-products from different
materials used as source of heat are deposited on the fish. The deposited by-products
include the carcinogenic polyclic aromatic hydrocarbons (PAHs) and heavy metals.
Benzo(a)pyrene has been used as a marker for the occurrence of carcinogenic PAHs. The
purpose of this study was to assess the different materials that are used in fish smoking
practices, determine the levels of benzo(a)pyrene, mercury, cadmium and lead in smoke
Lates niloticus and Oreochromis niloticus from different fish smoking areas in Mara and
Mwanza regions. A total of 32 fish smokers were interviewed to identify the materials
used and how they use them to smoke their fish. This was followed by collection of 32
smoked fish samples from Mara and Mwanza regions for laboratory analysis of heavy
metals (Mercury, Cadmium and Lead) and concentration of benzo(a)pyrene . The findings
of the study indicated that people engaged in smoking fish in the study areas are mostly
using firewood and charcoal as their main source of heat. There were no cases of the use
of plastic materials. The laboratory results indicated that mercury and cadmium were not
detected in all fish species while lead was detected at a mean concentration level of 0.28
μg/kg which is below the recommended level of 0.3 μg/kg as set by the EU. This
indicated that smoked fish from Mara and Mwanza did not contain heavy metals to a
harmful level. The mean benzo(a)pyrene concentration detected was 4.79 μg/kg. This
amount is higher than a level of 2 μg/kg set by the EU in 2014. There is therefore, a need
for people who smoke fish to use other improved methods which will lower the levels of
benzo(a)pyrene. This could be achieved by the government to have a continuous
monitoring plan for these contaminants and train the fish smokers to use improved
smaoking methods.