Occurrence, seasonal variation and human exposure to pharmaceuticals and personal care products in surface water, groundwater and drinking water in Lagos State, Nigeria

The occurrence of 28 pharmaceuticals and personal care products (PPCPs) was investigated in 17 surface water samples (rivers, canals, and lagoons), 12 groundwater samples (wells and boreholes, which can also be consumed for drinking) and 8 drinking water samples (bottles and sachets) during dry and rainy seasons in Lagos state, Nigeria. The most prevalent compound detected in all samples was amoxicillin (an antibiotic) at median concentrations of 1614, 238 and 358 ng/L in surface water, ground water and drinking water, respectively. This is of concern due to potential impact on development of antibiotic-resistant microbial strains. Other frequently-detected compounds include acetaminophen, nicotine, ibuprofen, and codeine with detection frequencies of more than 70%. Investigation of seasonal variability revealed that glyburide, caffeine, naproxen and diclofenac concentrations were significantly (P < 0.05) higher during the dry season (winter), while Nicotine and Codeine levels were higher during the rainy season (summer). The factors influencing such seasonal variability include: dilution by extensive rainfall, agricultural activity (for nicotine) and usage patterns of pharmaceuticals among the local community. Measured concentrations in drinking water samples were used to assess inadvertent human exposure to PPCPs in Nigerian adults. Results revealed average daily exposures of 81, 14 and 3 ng ƩPPCPs/kg BW/day via drinking borehole, sachet water and bottled water, respectively. While there exists no health-based limit value (HBLV) for chronic exposure to mixtures of PPCPs, our results raise concern and warrant further investigation of the potential health implications of such unintended PPCPs exposure.