Could the microplastic ingested by seafood in the ocean be transmitted to humans who taste a starter of scallops, for example? This is the question that researchers tried to answer during an unusual experiment conducted in the Magdalen Islands.
The subject is making more and more headlines in the media and scientific magazines. Microplastic is everywhere. They are found on land, in the oceans and even in the air. Entire ecosystems are now polluted by plastic and the study of this new source of pollution is in its infancy.
However, if microplastic is everywhere, could we find it in our favorite recipe for giant scallop with garlic and lemon butter? The question seems very pointed, but the sea scallop (Placopecten magellanicus) was indeed the subject of an unusual experiment conducted by a team from the Merinov research center in the fall of 2020 in the Magdalen Islands.
The findings of this study were presented as part of the 89and Congress of the Francophone Association for Knowledge (Acfas), which ended Friday.
Merinov is a research center specializing in fisheries, aquaculture and marine bioresources technology with its head office in Gaspé. He specializes in industrial research. Its mandate is therefore to support the fishing industry in the face of various problems.
“We have little data on microplastic contamination in Quebec and Canada. We therefore asked ourselves how to support the industry with an issue that will become a problem”, explains Nicolas Toupoint, project manager at Merinov.
Effects on mice
The choice of the giant scallop was quickly imposed. On the one hand, this mollusc has a certain commercial interest in Quebec. On the other hand, it is a species that can be quite sensitive to contamination by microplastics since its shell does not close completely, unlike that of the oyster or the mussel, for example.
The experiment was carried out in September and October 2020 in the Magdalen Islands with the collaboration of students from the Cégep de la Gaspésie et des Îles. The team first exposed 30 sea scallops to various concentrations of microplastic for a month in tanks designed for this purpose.
The scallops were then analyzed according to different criteria and the flesh was freeze-dried for the rest of the experiment. Over the next 28 days, around 30 mice were fed the freeze-dried scallop meat following a rigorous protocol. The scallop made up about 4% of the mice’s diet during this period.
The results of this experiment turned out to be rather worrying for the mice, but much less so for the scallops.
“In the case of scallops, we did not observe any mortality, regardless of the concentration of microplastic used,” says Nicolas Toupoint. The various measurements and analyzes did not reveal any marked problems in the molluscs tested either.
One would have thought that the results would have been similar for mice. But these contain surprising data.
Mice that ingested scallop meat containing the highest concentration of microplastics ended up with hearts that weighed 10% less than mice in the test group. That is, those who ate scallops that had not been exposed to microplastic.
The analyzes also revealed effects on the blood balance of mice exposed to the highest concentrations of microplastic. Effects on the liver have also been observed.
“We can speak of significant indirect impacts,” notes Nicolas Toupoint.
The expert is careful, however, not to draw broader conclusions, in particular on the possible effect on humans. He specifies that it is all the meat of the scallop which was served to the mice, whereas it is the muscle which is consumed by the man.
“In theory, microplastics will generally end up in the mollusk’s digestive system rather than in its muscle. Care must therefore be taken before making analogies for humans. It’s going to take us more research to measure that. »
Nicolas Toupoint specifies that it will be important to do further research with a larger number of individuals to validate these results. Experiments could also be carried out with other species. “It shows the importance of continuing research efforts on the impact of microplastics on marine products, in particular to support the industries that depend on them. »
Microplastic and carbon 14
Researchers from the Université du Québec à Rimouski, in collaboration with Nicolas Toupoint, from Merinov, are developing a project that would make it possible to more precisely assess the effects of microplastics on sea scallops. Microplastic samples will be marked with carbon 14, which will make it possible to find their trace more precisely in the mollusc, thus allowing more detailed analyzes of contamination.
- In 60 years, the plastics industry has seen its annual production increase from 1 to 360 million tonnes worldwide.