We often buy fresh fish thinking that by putting it in the refrigerator inside its packaging We are doing the right thing to protect it. However, recent research led by the Institute of Environmental Assessment and Water Research (IDAEA-CSIC) has focused on a process that often goes unnoticed by the consumer: the migration of chemical substances from plastics into the food itself while it rests in the cold of our homes.
This study, which involved collaboration with the University of Florence, reveals that it is not necessary Heat the container in the microwave so that the additives can move; the low temperatures of refrigeration and freezing also allow that potentially harmful compounds They end up in the salmon, tuna, or hake that we later serve at the table. This is an everyday reality that affects food safety in the home.
The phenomenon of chemical transfer under cold conditions
The research focused on analyzing how substances like phthalates, bisphenols, and other plasticizers behave when in prolonged contact with fish. Unlike other studies that only examined the product as it left the supermarket, this one recreated what happens in a typical home: leaving the fish out. 48 hours in the fridge at around 4 degrees Celsius or keep it in the freezer for a whole month at -18 degrees Celsius. The data is clear: the longer it sits, the more these chemicals fill the animal's tissues.
The most striking finding is that some additives designed to give plastics flexibility and strength showed a migration rate of up to 100% in certain scenarios. This is no joke, as we are talking about components that the human body should not process in large quantities. The scientific team analyzed a total of 49 different contaminants, finding that all of them types of plastics The tested methods allowed this transfer to a greater or lesser extent.
Differences depending on the type of fish and the packaging used
Not all fish absorb chemicals in the same way. The study found that the fat and water content of each species plays a key role. For example, compounds that bind well to fats (lipophilic compounds) migrate with astonishing ease towards fatty species like salmonIn the case of alternative plasticizers such as DEHA, transfers exceeding 95% were recorded in this type of fish.
On the other hand, hake, which is a fish with a higher water content, seems to attract certain bisphenols more. But if there is one thing that has surprised researchers, it is the role of the trays called compostableAlthough they may sound better for the environment, in this particular study they showed higher levels of plasticizers than other packaging, suggesting that the bioplastic decomposition It still presents significant technical challenges.
- Polystyrene trays: Common in fishmongers for daily dispatch.
- Films and freezer bags: Used massively to organize shopping.
- Compostable trays: A modern alternative that requires greater toxicological monitoring.
Public health and the new regulations in Europe
The concern isn't just theoretical. Many of these additives are known to act as endocrine disruptors, meaning they can disrupt our hormonal system. The European Food Safety Authority (EFSA) has taken a firm stance and recently cracked down on them. daily exposure limit of bisphenol A, drastically reducing it after discovering that the health risks are greater than previously thought.
In Spain, although the 2022 Waste Law already mentioned restrictions on these components, the reality is that they are still detected in commercial packaging. At the European level, regulations were approved for limit the use of bisphenols in contact with food, which came into force in January 2025. However, a three-year grace period has been given for the industry to fully adapt, so we will still be living with these materials on the shelves for a while.
The current situation highlights the need to be much more attentive to how we store food at home, as the levels of total chemical exposure They don't just come from fish, but from everything we eat, breathe, or touch. It is vital that authorities continue to push for new materials that replace traditional plastic to be truly safe and undergo thorough toxicity studies before reaching our kitchens, to prevent us from creating a health problem in the process of trying to solve an environmental one.
