In this study, the levels of organochlorine pesticide residues in the Densu basin have been
investigated using fish sam ples as a case study. Six fish species namely Heterotis niloticus, Channa obscura,
Hepsetus odoe, Tilapia zilli, Clarias gariepinus and Chrysichthys nigrodigitatus were collected from the
sampling towns, Weija and Nsawam along the Densu river basin in the Greater Accra Region of Ghana.
Composite samples w ere homogenized, freeze dried and ground to obtain powdered samples. The powdered
samples were extracted by soxhlet extraction procedure using (3:1) hexane: acetone mixture. The extracts were
cleaned-up using florisil adsorbent and characterized for organochlorine content using Gas Chromatography
(GC) equipped with Electron Capture Detector (ECD). The GC recoveries of spiked samples were between
80 to 96%. Fourteen organochlorines (OCs) namely gamma-HCH, delta-HCH, heptachlor, aldrin, gammachlordane,
p,pí-DDE, alpha-endosulfan, dieldrin, endrin, endrin-aldehyde, endosulfan-sufate, p,pí-DDT, endrinketone
and methoxychlor were identified and quantified. A 100% incidence was recorded for gamma-HCH,
delta-HCH, heptachlor, aldrin, gamma-chlordane, alpha-endosulfan, dieldrin and p,pí-DDT, while 75%
incidence was recorded for the metabolites, p,pí-DDE and endosulfan-sulfate. The concentrations of OCs
ranged from 0.3 to 71.3 :g/kg and were however, below the Australian Maximum Residue Limits (MRL) of
50 to 1000 :g/kg for fresh w ater fish.