Application of Assessment Models for Health Risk and Pollution from Surface Water from Okumpi River in Nwangele, Imo State, Nigeria

The mean and standard deviation of pH value in the present study during the wet and dry seasons varied from 6.21±0.22 - 5.75±0.41. The mean and standard deviation of EC in the current study ranges between 219.15±12.20 - 193.30±14.81 μS/cm for wet and dry seasons which are found to be in line with the WHO standard used. The mean and standard deviation of DO for this study during the wet and dry seasons were found to be 10.03±0.58 - 6.47±0.41 (mg/L). TDS for wet and dry seasons ranges from 374.79 ±5.33 - 121.65 ±6.33 mg/L. The nitrate [9.05 ±1.08 - 8.09 ±1.57], sulphate [3.91 ±0.51 – 3.73 ±0.46] and phosphate [82.78 ±3.86 - 81.76±3.32] in this present study for wet and dry season were all found to be below the standard. The Hazard quotient via ingestion and Hazard quotient via dermal has a reduction in the order of lead > nickel > iron > manganese > copper > zinc and lead > zinc > nickel > copper > iron > manganese > cadmium, in cooperation in children and adults in wet season, correspondingly. The Hazard quotient via ingestion and Hazard quotient via dermal has a decrease in the following order of nickel > lead > manganese > copper > iron > zinc and lead >zinc > nickel > copper > manganese > iron > for both children and adults in dry season, respectively. Lead possess carcinogenic risk for the inhabitants of this area due to the value of the carcinogenic risk n wet season of 4.05E-4 in adult and 1.55E-3 in children, in dry season of 2.57E-4 in adult and 9.88E-4 in children, against the standard set by the USEPA of 10-6 – 10-4. The surface water is not suitable for drinking as seen by the high water quality index of > 300. Lead possess carcinogenic risk for the inhabitants.