Organochlorines in Chrysichthys nigrodigitatus and Liza grandisquamis from Lagos Lagoon and Agboyi Creek, Nigeria

Catfish (Chrysichthys nigrodigitatus) and mullet (Liza grandisquamis) were sampled from Lagos\udLagoon and Agboyi Creek and analysed for alpha-BHC, beta-BHC, lindane, delta-BHC, heptachlor, heptachlorepoxide\ud(B), aldrin, dieldrin, endrin, endrin aldehyde, endrin ketone, cis-chlordane, trans-chlordane, endosulfan 1,\udendosulfan 11, endosulfan sulphate, methoxychlor, p,p´-DDE, p,p´-DDD and p,p´-DDT. Sampling was conducted\udfour times at the designated sites during the dry season months of December 2008 and February 2009 and the wet\udseason months of May and September 2009. The muscle tissues and organs of the finfishes were subjected to cold\udextraction with petroleum ether/acetone (1:1 v/v) mixture and clean-up on silica gel adsorbents. A gas\udchromatograph coupled with electron capture detector (GC-ECD) was used to detect and determine the\udorganochlorines. The residue levels of the fishes were higher in the Lagos Lagoon than in Agboyi Creek while a\udhigher concentration of the residues was observed during the dry season. The female fishes accumulated higher\udorganochlorines than the male fishes. The order of residue accumulation in the organs of the fishes was gills >\udlivers > large intestines > small intestines > kidneys > muscles. The dietary surveys indicated that the amount of\udfishes consumed ranged from 20 to 200 g/day, with a mean value of 40 g/day. The estimated daily intakes of the\udorganochlorines were within the acceptable daily intakes while the levels of residues in the fishes were within the\udpermissible residue limits