Polychlorinated dibenzo-p-dioxin/dibenzo furans (PCDD/Fs) contamination in sediments and fish from Msimbazi river in Dar es Salam-Tanzania: patterns, sources and their exposure to humans

Abstract Results of a GCXGC-TOFMS determination of PCDD/Fs in sediments and cat fish samples collected from Msimbazi river, are presented here. PCDD/Fs congeners in sediments ranged from 2.0 to 393.0 and 0.7 to 654.8 pg/g in the dry and wet season respectively. 1,2,3,4,,7,8,9-HepCDF was detected at the highest concentration but all were lower than the United States of America (USA) action level of 1000 pg/g. Toxicity for each of the sampling points ranged from 19.7 to 36.5 with a mean concentration of 27.0 pg WHO 2005-TEQ g-1in the dry season and 2.0 to 38.7 with a mean concentration of 20.7 pg WHO 2005-TEQ g−1 in the wet season. Analysis of variance (ANOVA) showed that there was no significance difference between PCDD/Fs TEQ during the dry and the wet season, (P=0.08), α=0.05). The highest TEQ value was estimated at Jangwani in the wet season. Toxicity of PCDD/Fs in cat fish collected from Msimbazi river ranged from 9.3 to 145.2, with a mean of 61.2 pg WHO2005-TEQg-1. Tetrachlorodibenzo dioxin (2,3,7,8-TCDD), was detected in all fish samples and ranged from 3.5 to 12.7 with a mean of 8.1 pg/g.