The Lake Togo-Lagoon of Aného is located in the coastal zone where phosphorite mining is carried out. This mining discharges all kinds of waste such as fuel oil into the surrounding environment without prior treatment. Moreover, the hydrosystem receives runoff and river inputs after having crossed and leached from mining and urban soils. This study aims to determine the polycyclic aromatic hydrocarbons (PAHs) contamination in commercially consumed fish species (Chrysichthys nigrodigitatus) from that hydrosystem and the associated health risks for consumers. For that, fish sample collection was performed during the dry season. Afterwards, their muscles, gills, and livers were cut and 12 PAHs were analyzed using gas chromatography coupled with a mass spectrometer (GC-MS). The total PAHs (tPAHs) concentrations in fish tissues ranged from 5.24 to 48.40 µg/kg with average concentration of 14.51 ± 8.95 µg/kg in muscles, from 5.90 to 28.20 µg/kg averaging 14.90 ± 5.19 µg/kg in gills, and from 43.20 to 149.00 µg/kg with an average of 80.74 ± 27.08 µg/kg in livers. The average concentrations of low molecular weight PAHs (LMW PAHs) were 10.82 ± 9.61 µg/kg in muscles, 8.25 ± 5.43 µg/kg in gills, and 47.97 ± 22.56 µg/kg in livers whereas those of high molecular weight of PAHs (HMW PAHs) were 4.10 ± 2.14 µg/kg in muscles, 7.98 ± 3.96 µg/kg in gills, and 32.77 ± 8.66 µg/kg in livers. An overall trend of decreasing concentrations with increasing fish size classes was observed for some PAHs (Naphtalene, Pyrene in muscles, for Pyrene, Benzo(a)Anthracene, Chrysene in gills and for Naphtalene, Phenanthrene in livers). The PAHs in these fish might have pyrogenic and petrogenic sources, with the dominance of pyrogenic, and all of the total hazard quotients (THQ) are less than 1. This situation must not be neglected for better planning sustainable management of the target ecosystem.
Keywords: Chrysichthys nigrodigitatus; Lake Togo; contamination; health risk; polycyclic aromatic hydrocarbons.