Plasticizer contamination could be one of the causes of the decline in the populations of these species, along with climate change and fishing pressure.
A recent CSIC study has detected plasticizer chemical compounds in sardines, anchovies and hake from the Mediterranean Sea, although the levels found do not constitute a risk to human health. The study, led by the Institute of Environmental Assessment and Water Research (IDAEA-CSIC) in collaboration with the Institut de Ciències del Mar (ICM) and the Spanish Institute of Oceanography (IEO-CSIC), has been published in the journal Environmental Pollution.
The plasticizers studied are organophosphate esters, a family of chemical compounds widely used in industry (for plastics, textiles, furniture, etc.). Some of these compounds have been shown to have toxic effects on the nervous and endocrine systems, and may affect the reproductive system or have carcinogenic effects.
The study includes the analysis of 55 samples of sardines, anchovies and hake collected in the western Mediterranean area, specifically in the Cap de Creus, the Ebro Delta, the Gulf of Valencia and the Gulf of Alicante. All but two individuals showed plasticizer levels of up to 73 nanograms per gram of muscle.
"In general, the four areas studied showed similar levels of contamination, with no significant differences between them, indicating a similar use of plasticizers throughout the studied area ", explains the IDAEA-CSIC researcher Ethel Eljarrat, lead author of the study.
However, differences are observed between the three species, with sardines being the species with the highest amount of plasticizers found, followed by anchovies and hake. According to the experts, these differences are related to the different acquisition, bioaccumulation and metabolism capacities of each species. The lower levels found in hake, which is a partial predator of sardines and anchovies, suggest that these contaminants do not biomagnify along the food chain, as contamination levels do not increase from prey to predator.
The risk assessment of these contaminants on human health indicates that consumption of these fish alone does not pose a threat. "However, human exposure to these contaminants occurs through different routes such as ingestion of food (and not only fish), inhalation of indoor and outdoor air, or ingestion of dust, among others.
All these sources of exposure could pose a certain risk to human health. It is therefore advisable to minimise human exposure to these plasticizers by reducing contamination in marine ecosystems and preventing increased levels in fish", states Eljarrat.
The problem of plasticizer contamination is not only a human health problem, but also a problem for fish populations themselves. The ICM-CSIC team is studying the decline of sardine and anchovy populations on the west coast of the Mediterranean Sea.
"There are several hypotheses to explain this trend, such as increased fishing pressure, warmer water temperatures due to climate change, or the presence of pollutants such as those analysed in this study," explains the ICM-CSIC researcher Joan Giménez.
This study helps to better understand the threats faced by these fish, as they are not only important at an economic level, but also play a key role in the functioning of marine ecosystems.
This study has been developed in the context of the PELWEB (CTM2017-88939-R), PELCAT (CAT 152CAT00013, TAIS ARP059/19/00005) and EXPOPLAS (PID2019-110576RB-I00) projects, funded by the Ministry of Science and Innovation and the Government of Catalonia.