INTEGRATED RISK ASSESSMENT USING CHRYSICHTHYS NIGRODIGITATUS: A CASE STUDY OF NEW CALABAR RIVER BASIN (Published)
The aim of this study was to assess human and ecological risk posed by water and sediment quality of New Calabar New (NCR) using Chrysicthys Nigrodigitatus. For this study, chemical- and bio-monitoring assessments were carried out in three sampling stations (Choba, Ogbogoro and Iwofe) of NCR. A Fish Consumption Survey (FCS) was also implemented to assess the risk of exposure of subsistence fishers from host communities of the sampling stations of NCR. Using data from FCS, mathematical models were used to charactconsumptionerize risk due to the consumption of fish. Chemical monitoring involved the assessment of pysico-chemical variables of water with an evaluation ofEnvironmental Water Quality Index (EWQI) and sediment quality. Biomonitoring involved the assessment of the edible part of fish tissue (skin and muscle) for chemicals of potential concern (COPC). Physico-chemical water analysis and set against SON benchmarks, results showed that temperature, pH, conductivity and dissolved oxygen values were abnormal, while heavy metals and PAH were normal. The evaluated EWQI was marginal for NCR. Sediment quality showed slightly elevated PAH level at Ogbogoro station while heavy metals remain normal. Fish edibility study set against RfD benchmarks of USEPA, indicated a slightly elevated PAH, hence fish from NCR was unsafe for consumption. The FCS showed that an average of 1.2kg/day/ of C. Nigrodigitatus was consumed by respondent from NCR basin, with an age group range of 18-34 forming the highest consumers. HQ<1 for COPC, meaning their levels in the edible part of tissue are not acutely hazardous on consumption, but PAH, a carcinogenicchemicalforming part of the assessed COPC, showed a carcinogenic risk characterization of 1.4E-04, 1.3E-04 and 1.3E-04 respectively for subsistent fishers from Choba, Ogbogoro and Iwofe.