Scientists patent a method to remove organic pollutants from molluscs

Researchers at the Universitat Jaume I (UJI) and the Spanish Research Council (CSIC) have patented an innovative method to remove organic pollutants, such as pesticide residues, from bivalve molluscs. The new technique increases the rate of removal of organic compounds by a factor of two or, depending on the type of pollutant, even four with respect to other methods used to date.

Bivalve molluscs (mussels, oysters, clams and cockles, among others) obtain their food by filtering sea water in order to retain the organic particles it contains. But together with nutrients, molluscs also tend to accumulate other suspended particles such as organic pollutants, which later enter the human organism when the molluscs are eaten.

The cultivation of bivalve molluscs in shallow waters close to urban, industrial and agricultural areas may cause these organisms to accumulate organic pollutants, including pesticides, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, dioxins, furans and endocrine disruptors. High consumption of these polluted animals during periods of intense contamination represents a serious concern for public health.

According to a number of studies, chronic exposure to pesticides and the other pollutants mentioned above is associated to a higher risk of developing cancer and certain neurodegenerative disorders such as Parkinson's disease. Moreover, endocrine disruptors may interact with the metabolic system of animals and humans and deteriorate a variable number of developmental functions. This is why it is necessary to detoxify molluscs before they are eaten.

To date, this decontamination consisted in treating them with filtered, sterilised water or by applying hydrostatic pressure at high temperatures for 48 hours. However, complete removal of pesticides from the tissues of the bivalve molluscs takes several days, so the conventional treatment may not be sufficient.

'The method that we have developed allows us to improve this process and means that pesticides can be removed from the tissues of molluscs twice or even four times as quickly, depending on the type of pollutant. It also increases tolerance to oxidative stress,' says Roque Serrano, a scientist at the University Institute of Pesticides and Waters at UJI and co-author of the study.

The method consists in utilising N-acetylcysteine, a substance that is capable of stimulating the intracellular synthesis of glutathione and triggers glutathione S-transferase and glutathione reductase activity in mussels. Glutathione is essential in most living organisms, since it intervenes in several very important cellular phenomena, such as detoxification of xenobiotics and the elimination of free radicals. The importance of the work carried out by the UJI and CSIC researchers lies in the fact that it proves that administration of N-acetylcysteine enhances glutathione activity in molluscs and, therefore, has remarkable applications as a technique for removing pollutants from mussels.

The researchers responsible for the invention of the method are Samuel Pena Llopis, who currently works at the Simmons Comprehensive Cancer Centre at the UT Southwestern Medical Centre in Dallas, Roque Serrano Gallego, from the University Institute of Pesticides and Waters at UJI, and Juan B. Pena Forner, from the Department of Biology, Culture and Pathology of Marine Species at the CSIC's Torre de la Sal Aquaculture Institute.