Public Thesis Defense - LIBST

Plastic ingestion in Procellariiformes: Assessing in vitro release of plastic-associated chemicals during gastric digestion and interactions with estrogen receptors by Liesbeth VAN HASSEL

Pour l'obtention du grade académique de doctorat en Sciences agronomiques et Ingénierie biologique

Every year, millions of tons of plastic enter the ocean, threatening marine wildlife. Seabirds, especially Procellariiformes are particularly prone to plastic ingestion due to their infrequent regurgitation and unique gastric physiology. While the physical damage of plastic ingestion is well documented, there is limited knowledge about the toxicological risks from plastic-associated chemicals. This thesis addresses this gap by studying the digestive fate and endocrine-disrupting potential of ingested plastics in Procellariiformes.

An in vitro Procellariiform gastric model was developed to simulate digestion and examine the leaching dynamics of chemicals (i.e., additives and sorbed POPs) from plastic. The model revealed that both lipid and aqueous components enhance chemical leaching, with dynamics influenced by the chemical properties of plastic-associated molecules, diet, and polymer type. Results indicate that plastic additives likely pose a higher risk than sorbed POPs due to their prolonged leaching (i.e., for weeks to months) at high concentrations.

The potential hormonal disruption caused by the leaching of chemicals from ingested plastic was studied in vitro by using northern fulmar (Fulmarus glacialis) estrogen receptors (ERs). Fulmar and human ER response were compared in the presence of known chemicals and showed species-specific sensitivity differences. Plastics recovered from fulmar stomachs were also incubated for 14 days in solvents mimicking stomach fluids. Over half of the fulmars exhibited ER activation and/or inhibition after one day of leaching, with more than a third showing a subsequent ER response after 5 and/or 14 days. These findings suggest that plastic ingestion may contribute to hormonal disruption in Procellariiformes. This work provides valuable insight into the toxicological risks of plastic ingestion in Procellariiformes.

Jury members :

• Prof. Cathy Debier (UCLouvain) (Supervisor)
• Prof. Myra Finkelstein (METX-UCSC, U.S.A.) (Co-supervisor)
• Prof. Michel Ghislain (UCLouvain) (Chairperson)
• Prof. Isabelle Donnay (UCLouvain)
• Prof. Jean-François Rees (UCLouvain)
• Prof. Krishna Das (ULiège, Belg.)
• Dr. Christopher Tubbs (SDSWA, U.S.A.)

Pay attention : the public defense of Liesbeth VAN HASSEL will also take place in the form of a videoconference

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