Prevalence and health risk evaluations of mycotoxins in drinking water sources in Nigeria

Mycotoxins in drinking water are neglected pollutants that have serious health implications when ingested. Common mycotoxins with health concerns include deoxynivalenol (DON), ochratoxin A (OTA), and zearalenone (ZEN). This study considers the distribution and apparent health risks of these mycotoxins in drinking water sources (groundwater, surface water, bottled water, sachet water) in three Southwest Nigeria States: Osun, Oyo, and Lagos States, using the UHPLC-ESI-QTOF. ZEN and DON were found in all 95 water samples across all three states. ZEN in sachet water samples has the highest mean concentrations, with those from Osun, Oyo, and Lagos States having concentrations of 14.96 ± 4.46, 8.59 ± 3.86, and 10.56 ± 2.84 μg L^-1, respectively. In contrast, the mean concentrations of all three mycotoxins (± Standard Error of Mean) in bottled water samples are the lowest across the three States. The mean concentrations of OTA in sachet water samples (2.93 ± 0.79, 1.24 ± 0.40, and 3.01 ± 1.50 μg L^-1) are slightly higher than those in bottled water (1.47 ± 0.28, 1.53 ± 0.31, and 0.75 ± 0.31 μg L^-1) for Osun, Oyo, and Lagos States, respectively. Groundwater samples across the three States had the lowest average pH values, below the WHO's lowest limit of 6.5. Principal Component Analysis studies indicate that all three mycotoxins in water samples are closely associated by source. Possible human exposure values for ZEN suggest some health concerns, especially with the use of sachet water type based on the estrogenicity of this mycotoxin. However, OTA values for all water samples analyzed, are much lower than the tolerable daily intake (TDI) of 4.73 μg kg^-1 bw per day provided by European Food Safety Auhtority (EFSA). The levels of DON in all water sample types were of no serious health concern. However, human exposure levels to all three mycotoxins in bottled water fall within safe limits of health-based guidance values (HBGV) indicating that this drinking water type is better treated, unlike sachet water. Nevertheless, stakeholders need to re-examine water quality with respect to these mycotoxins and adopt stringent guidelines and new water treatment strategies to provide consumers with safe drinking water in line with the UN SDG #6.