Which Fish Contain the Most Microplastics — and Why You Should Avoid Eating Them

An Australian study revealed that 100 grams of sardines contain up to 30 micrograms of plastic. Other seafood such as squid, oysters, and the now-famous blue crabs also contain microplastic levels that may be harmful to health if consumed regularly. Let’s take a closer look at which fish are best avoided — and why.

🧬 Microplastics: A Growing Threat to Our Health

We’ve often discussed how microplastics — tiny fragments of plastic less than 5 mm in size — enter our bodies through the food we eat, the water we drink, and even the air we breathe, causing damage that is still not fully understood.

According to a WWF analysis, the average person ingests around 5 grams of plastic every week — roughly the weight of a credit card. Alarmingly, shellfish account for around 10% of that intake.

A recent study by the Quex Institute (a collaboration between the Universities of Exeter and Queensland) confirmed the presence of microplastics in nearly every type of seafood tested.

🔬 The Study: How It Was Conducted

Researchers purchased a selection of seafood from Australian fish markets, including:

• 10 farmed oysters

• 10 farmed tiger prawns

• 5 wild blue crabs

• 10 wild squid

• 10 wild sardines

They were prepared and analyzed just as a consumer would consume them. The edible parts were tested using pyrolysis-gas chromatography-mass spectrometry, a high-precision method that detects even the smallest plastic particles in complex organic material. This process identified particles such as polystyrene, polyethylene, PVC, polypropylene, and methyl methacrylate.

🐟 Which Fish Contain the Most Microplastics?

While microplastics are found in almost all seafood, some species accumulate more due to their feeding habits and biological structure.

Here are the results, ranked by microplastic content:

These levels are concerning, especially in sardines, which are commonly eaten whole — bones, organs, and all — increasing exposure to plastic particles.

⚠️ What Happens If We Eat Microplastics?

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