Small sewage spills can poison mussels

Steaning Mussels algaeSteaming mussels. Photo: Norway Today Media

Small sewage spills can poison mussels

It’s not just poisonous algae that can poison mussels. Sewage from land or vessels can also contaminate the delicasy.


Every Friday, the Norwegian Food Safety Authority publishes its mussel warning from a wide range of test sites along Norway’s coastline.

– There are no geographical distinctions as to where algae growth can occur that can poison mussels. It can occur anywhere and at any time, says inspector in the Food Safety Authority (Mattilsynet), Anne Kari Hansen. She works at the FSA in Trondheim and surrounding areas and is responsible for registering and publishing the results of all the tests made for a few weeks this summer.

In recent times there has been no poisoning of the public who has followed the advice from the Norwegian Food Safety Authority and its mussel warning service.

Algae poison

It is often mussel farmers and the Norwegian Food Safety Authority who take samples of water and shells, that subsequently are sent in for analysis at Algae Laboratory and the University at Ås.

The two most common algae poisons lead to diarrhea and abdominal pain (DSP) or a tingling sensation and short-term paralysis (PSP). This is caused by the algae species Dinophysis, which usually is present at the end of summer and during the autumn, and Alexandrium that flourish earlier in the summer.

E. coli

Mussels and water are also tested for the E. coli intestinal bacteria. The mussel warning adheres to the limits that apply to commercial sales.

– The reason for finding E. coli can be sewage spills nearby, a local contamination originating either from land or from sea going vessels. One of our advices is to harvest mussels in areas with flowing water to prevent sewage contamination among other things, the inspector states.


Anne Kari Hansen informs that she as a matter of course consults the mussel warning before she harvest the delicacy.

– It is important to follow the general advice, such as picking tem as close to possible to outlets. With regards to algae poison, extra care should be taken as the advice is different from one place to the next along the same stretch of coast, she says.

It is stated on the mussel warning website where the mussel samples are taken, but for exact details one can ask a local resident or call the nearest Food Safety Authority.


© NTB scanpix / #Norway Today