Pesticide Residues in Coastal Dar Es Salaam

This paper reports on the levels of organochlorine pesticide residues in edible biota from the coastal area of Dar es Salaam city, Tanzania. Samples were collected from the Msimbazi and Kizinga rivers and from the coastal marine environment receiving waters from these rivers. The samples were analysed for various organochlorine pesticide residues using GC-ECD and the results confirmed with GC-MS. Dieldrin, p,p'-DDT, p,p'-DDE, p,p'-DDD, o,p'-DDT and γHCH were the only organochlorines detected at concentrations above the method detection limits (MDL). The samples showed significant differences in levels of residues depending on location, mode of feeding and age/size of analysed biota. p,p'-DDT to total DDT ratios in biota indicated recent contamination of DDT. Biota from mangrove areas showed highest level of residues followed by those from fresh water while lowest concentrations were detected in biota from marine coastal water. In spite of concerns on the adverse effects to humans posed by pesticide residues in sediments reported from previous studies, edible biota from the examined water bodies are safe for human consumption.