Seasonal distribution of organochlorine pesticides and polychlorinated biphenyls in three fish species and their implications for human health risk: The case of Al Massira Reservoir, Morocco

Title : Seasonal distribution of organochlorine pesticides and polychlorinated biphenyls in three fish species and their implications for human health risk: The case of Al Massira Reservoir, Morocco

Abstract:

Fish represent a major pathway for the transfer of persistent organic pollutants (POPs) to humans, due to their lipophilic affinity and resistance to degradation. This study assessed the distribution of eight organochlorine pesticides (OCPs: α-HCH, γ-HCH, β-HCH, aldrin, dieldrin, DDD, DDE, DDT) and four polychlorinated biphenyls (PCBs: PCB28, PCB52, PCB101, PCB180) in the muscle tissue of Nile tilapia (Oreochromis niloticus), common carp (Cyprinus carpio), and pikeperch (Sander lucioperca) from the Al Massira Reservoir, Morocco, sampled monthly over one year and analyzed by gas chromatography.

Pikeperch, as the top trophic-level predator among the three species, accumulated markedly higher levels of both OCPs and PCBs than common carp and Nile tilapia, consistent with a biomagnification pattern along the trophic chain. Pollutant levels also varied significantly across sampling months, with several compounds ,notably dieldrin, γ-HCH, aldrin, PCB52, and α-HCH ,showing clear seasonal fluctuations linked to climatic and hydrological conditions in the reservoir.

Health risk assessment indicated that OCP levels remained below international safety thresholds, pointing to negligible risk for consumers. In contrast, PCB levels, although comparatively low, exceeded the theoretical long-term cancer risk threshold for regular fish consumers, with children found to be more vulnerable than adults. These findings underline the need for reinforced environmental monitoring of POPs in Moroccan aquatic ecosystems and for sustainable management strategies to protect both biodiversity and public health.

Keywords: organochlorine pesticides, PCBs, seasonal distribution, biomagnification, health risk assessment, Al Massira Reservoir, Morocco

Biography:

Dr. Loubna Ferraj holds a PhD in Biology, specializing in Ecotoxicology and Aquaculture, from Sultan Moulay Slimane University, Béni Mellal, Morocco (2025). Her research focuses on the growth, feeding ecology and contamination of freshwater fish by organochlorine pesticides, PCBs and heavy metals, and the associated human health risks, with the Al Massira Reservoir as her main study site. During her doctoral training at the National Laboratory for Pollution Studies and Monitoring (LNESP, Rabat), she gained expertise in pollutant extraction and GC-MS analysis. She has co-authored 18 scientific publications and presented more than 20 communications at international conferences. She currently teaches practical courses in biology, biochemistry and toxicology as a contract instructor at the Faculty of Sciences and Techniques of Béni Mellal.