Distribution and health risk assessment of cadmium, lead, and mercury in freshwater fish from the right bank of Senegal River in Mauritania Mohamed Salem El Mahmoud-Hamed & Sarah Montesdeoca-Esponda & Angelo Santana-Del Pino & Mohamed Lemine Zamel & Mohamed Brahim & Hasni T’feil & José Juan Santana-Rodiguez & Zeinebou Sidoumou & Mohamed Sidi’Ahmed-Kankou Received: 18 June 2019 /Accepted: 1 July 2019 # Springer Nature Switzerland AG 2019 Abstract Clarias gariepinus (African catfish) and Oreochromis niloticus (Tilapia fish) from the right North bank of the Senegal River in Mauritania (Rosso, Boghé, and Kaédi) were sampled during 1-year moni- toring and tested for lead (Pb), cadmium (Cd), and mercury (Hg) levels. Fishing from the Senegal River is an essential source of food for the local population and these two species are the most common. Muscle pre- sents higher Hg concentrations than liver and gills for both species. Gill Hg concentrations from Kaédi are higher than Boghé and Rosso for both species. The Cd levels measured in gills were low in the different loca- tions and revealed high variation throughout the 1-year study. No significant differences were observed between concentrations of Cd in Clarias gariepinus and Oreochromis niloticus parts. Statistical treatment did not show a considerable variation of Pb concentration between the different parts, revealing lower levels in gills from Boghé than the ones from Kaédi and Rosso. The associated human health risk was calculated from the concentration levels using the target hazard quotient (THQ) approach. Even though all the THQ values and the hazard index were lower than 1 for the determined trace metals when the exposure frequency was not greater than three times a week, eating frequency in the studied locations sometimes is greater than five, thus posing a health risk, especially at Kaédi and Boghé. Keywords Clarias gariepinus . Oreochromis niloticus . Trace metals . Senegal River . Mauritania . Human health risk Introduction The Senegal River is one of the largest drainage basins in the world (Potter et al. 2004). It is located in the western part of Africa between latitudes 10° Environ Monit Assess (2019) 191:493 https://doi.org/10.1007/s10661-019-7627-5 M. S. El Mahmoud-Hamed : M. Sidi’Ahmed-Kankou Unité de recherche Eau, Pollution et Environnement (EPE), Département de chimie, faculté des sciences et techniques (FST), Université de Nouakchott Al-Aasriya (UNA), campus universitaire de Nouakchott, 880, Route de Nouadhibou, Nouakchott, Mauritania M. S. El Mahmoud-Hamed (*) : M. L. Zamel : M. Brahim : H. T’feil Département chimie microbiologie et suivi du milieu aquatique (DCM-SMA), office national d’inspection sanitaire des produits de la pêche et de l’aquaculture (ONISPA), 1416 Nouadhibou, Mauritania e-mail: imouh84@yahoo.fr S. Montesdeoca-Esponda : J. J. Santana-Rodiguez Instituto de Estudios Ambientales y Recursos Naturales (i-UNAT), Universidad de Las Palmas de Gran Canaria, 35017 Las Palmas de Gran Canaria, Spain A. Santana-Del Pino Departamento de Matemáticas, Universidad de Las Palmas de Gran Canaria, Campus Universitario de Tafira, s/n, 35017 Las Palmas de Gran Canaria, Spain H. T’feil : Z. Sidoumou Unité de recherche Ecobiologie marine et environnement (EBIOME), département biologie , faculté des sciences et techniques (FST), Université de Nouakchott Al-Aasriya (UNA), campus universitaire de Nouakchott, 880, Route de Nouadhibou, Nouakchott, Mauritania