Pollution and Risk Assessment of Phenolic Compounds in Drinking Water Sources in South-Western Nigeria

Abstract This study reports the occurrence and risk assessment of 2,4- Dinitrophenol (2,4-DNP), Phenol (PHE), and 2,4,6- Trichlorophenol (2,4,6-TCP) in drinking water sources in three South western States in Nigeria (Osun, Oyo and Lagos). Groundwater (GW) and surface water (SW) were collected during dry and wet seasons of a year. The detection frequency of the phenolic compounds followed the trend: Phenol > 2,4-DNP > 2,4,6- TCP. The mean concentrations of 2,4-DNP, Phenol, and 2,4,6-TCP in GW/SW samples from Osun State were 639/553 µg L − 1 , 261/262 µg L − 1 , and 169/131 µg L − 1 respectively, during the rainy season and 154/7 µg L − 1 , 78/37 µg L − 1 , and 123/15 µg L − 1 during the dry season. In Oyo state, the mean concentration were 165/391 µgL − 1 for 2,4-DNP and 71/231 µgL − 1 for Phenol in GW/SW samples respectively, during rainy season. Generally, in the dry season, these values decreased. In any case, these concentrations are higher than those previously reported in water from other countries. The concentration of 2,4-DNP in water posed serious ecological risks to Daphnia on the acute scale while it was Algae on the chronic scale. Estimated daily intake and hazard quotient calculations suggests that 2,4-DNP in water pose serious toxicity concern to humans. Additionally, the concentration of 2,4,6-TCP in water from Osun State in both seasons pose significant carcinogenic risk to persons ingesting water from this State. Every exposure group were at risk from ingesting these phenolic compounds in water. However, this decreased with increasing age of the exposure group. Results from the Principal Component Analysis indicate that 2,4-DNP in water samples is from an anthropogenic source different from that for Phenol and 2,4,6-TCP. There is a need to treat these GW and SW before drinking while maintaining regular assessment of these water sources.