Ecotoxicological study and environmental risk assessment of Cocaína in marine ecosystems

Author(s)

Mayana Karoline Fontes

• Document type: Doctoral Thesis
• Press: São Vicente. 2022-03-13.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Biociências. São Vicente
• Defense date: 2022-01-31
• Advisor: Camilo Dias Seabra Pereira; Luciane Alves Maranho

Abstract

Urban sewage represents an important source of pollution to marine ecosystems, mainly due to the population growth on coastal metropolitan regions and the inefficiency of the processes of collection, treatment and disposal of domestic effluents. Pharmaceutical, persoanl care products and illicit drugs, such as cocaine, constitute some of the main substances found in domestic effluents representing serious problem to the public health. Submarine sewage outfalls represent the main source of contaminants of emerging concern (such as illicit drugs) into the marine environment. Previous studies have identified the presence of cocaine (COC) in inland and coastal surface water, as well as biological effects at environmentally relevant concentrations. The present work aimed to assess of the environmental risk of cocaine in coastal environments through a tiered approach that included the COC (and by products) quantification in environmental matrices of Santos Bay (surface water, sediment and mussels) and ecotoxicological tests using as models the mussel Perna perna and the fish Anguilla anguilla. Mussels were exposed to two different concentrations of cocaine (200 ng.l-1 and 2000 ng.l-1), a seawater control and a solvent control, for 168h. The mussels (21 specimens) were divided into 2 aquariums per treatment. After the exposure periods (48h, 96h and 168h), 7 mussels were randomly removed from the aquariums and submitted to cytotoxicity evaluation (by the Neutral Red Retention Time assay) and later they were excised for tissue removal (adductor muscle, digestive tract, gills and gonads) for the analysis of biomarkers (dopamine-DOPA; 5- hydroxytryptamine- 5-HT - serotonin; acetylcholinesterase-AChE; monoamine oxidase-MAO; cyclooxygenase-COX; mitochondrial electron transport-MET; total lipids- TLP; 7- ethoxyresorufin O-deethylase – EROD; dibenzylfluorescein dealkylase – DBF; glutathione S- transferase – GST; glutathione peroxidase – GPX; DNA damage to DNA; and lipid peroxidation – LPO). The bioaccumulation of COC in mussels soft tissues was also verified. In addition, fish (Anguilla anguilla) were also exposed to cocaine (20 ng.l−1) to investigate potential histopathological, immunohistochemical (3β-hydroxysteroid dehydrogenase-3β-HSD; 17β-hydroxysteroid dehydrogenase-17β-HSD type 3; and P450 aromatase) and endocrine (follicle stimulating hormone-FHS); luteinizing hormone- LH and cortisol) damages caused by cocaine in marine vertebrates. Cocaine was found in Santos Bay at concentrations ranging from 1.9 – 203.6 ng.l-1, with the highest concentrations detected in spring/summer, a period that coincides with the population increase in Baixada Santista due to the beginning of the warmer high season. In the sediment, the quantified concentrations ranged from 0.94 – 46.85 ng.g−1. Cocaine was also detected in the soft tissue of mussels collected in the Bay at concentrations ranging from 0.914-4.58 μg·kg−1 (wet weight). The calculated bioaccumulation factor ranged from 163 – 1454 l·kg−1. As for the metabolic pathways investigated, changes were observed in the activities of EROD and DBF, in addition to GST and GPx, indicating impairment in metabolism and antioxidant response. Cocaine exposure caused cytotoxicity in mussels, which was observed by the reduced stability of the lysosomal membrane of hemocytes, and the significant increase in lipid peroxidation and DNA damage. Cocaine increased the levels of neurotransmitters (dopamine and serotonin) in mussels at all concentrations tested. After 168h, a reduction in AChE and COX levels was observed. In addition, an increase in MET and TLP levels was observed at both concentrations. Fish exposed to cocaine showed a delay in the development and maturation of ovarian follicles, a fact that can compromise the reproduction of these organisms. This was also demonstrated by lower expression of 3β-HSD, and P450 aromatase, as well as lower levels of FHS and LH. The results indicated that environmentally relevant concentrations of cocaine, even in the order of ng.l-1, are capable of negatively affecting the health of marine animals through disturbances in their reproductive system and cytogenotoxicity. The risk assessment carried out pointed to moderate to high risks in Santos Bay. It is necessary to improve the structure of sewage collection and treatment in coastal regions in order to minimize the disposal of effluents contaminated with illicit drugs in marine environments. Furthermore, it is important that these substances are included in water quality monitoring programs, in order to establish safety parameters that allow the preservation of natural resources and human health. (AU)

• FAPESP's process: 16/24033-3 - Ecotoxicological study and environmental risk assessment of cocaine in marine ecosystems
• Grantee: Mayana Karoline Fontes
• Support Opportunities: Scholarships in Brazil - Doctorate