Science - October 15, 2010

Mussel tests without using animals

Ten thousand mice and rats are definitely still being used in Europe to detect poisonous substances in mussels and oysters. PhD student Arjen Gerssen has come up with an alternative to animal testing.

The poisonous algae Dinophysis acuminate, the cause of poisonous substances in mussels.
The poisonous algae Dinophysis acuminate, the cause of poisonous substances in mussels.

photo: .

Every Wednesday, samples are taken from various mussel plots in the Eastern Scheldt and the Wadden Sea. These are brought to Wageningen where RIKILT inspects them for the presence of toxic substances, namely marine biotoxins produced by various algae. The institute has to report on its findings by 1:30 pm on Friday, so that the mussels can be released to the market, or otherwise.
Most of the toxins can be detected by chemical equipment at this food safety institute, but one group of poisonous substances is tested elsewhere, using rats. These lipophilic (related to fats) toxins attack the intestine walls of humans and animals and cause diarrhoea. They are not deadly to humans and rats. Mussels are fed to starving rats. If the rats get diarrhoea, then it's no go.
Late summer
Fortunately, this hardly happens. The last time in which a batch of mussels was rejected because of the presence of these poisonous substances was in 2002. Yet in Italy last month, two hundred people fell sick from these, says Gerssen.  Infections occur more often in late summer, he says, because sea water conditions are then often ideal for the growth of these poisonous algae. These minute algae are then taken up by shellfishes which obtain their food by filtering the water.
Mussel extract
Most European countries test for the presence of these marine toxins with mice injected with a mussel extract. If the mussel contains poison, the mouse will die. If the mouse tests negative, the mouse will still be killed off. Every year in the European Union, ten to twenty thousand mice are used as test animals for this purpose, Gerssen estimates. Yet, this mouse test is not infallible. In 2008, Gerssen got hold of a batch of mussels from Belgium which killed the test mice. While this had led to panic in the Belgium and Zeeuwse mussel sectors, Gerssen could not detect any poison; neither could the National Institute for Public Health and the Environment (RIVM). Partly for this reason, the European Union intends to scrap animal tests for marine toxin detection from 2013 onwards.
Right time
Gerssen's new chemical testing method therefore comes at the right time. First, he feeds the mussel extract through a liquid chromatograph, which separates any poisonous substances that are present. Subsequently, these substances go into a mass spectrometer. Every toxin has a unique structure and, as such, a unique weight. The weight in the spectrometer can tell Gerssen if a particular substance is present. In addition, he can accurately determine its quantity. 'The advantage of this method is that it tells us something about individual toxins', says Gerssen. 'The mice and rats test cannot tell us what make the animals sick. Moreover, this test enables us to detect smaller quantities which humans and animals do not fall sick from. By measuring the overall situation, you get to know how these poisons amass themselves in the mussels. An animal test can't tell us this.'
European standard
Meanwhile, it has been made clear that this chemical analysis can trace very minute quantities of marine toxins. A validation study is now being carried out to see if other control labs in Europe can also trace the toxins with the method developed by Gerssen. These are now examining shellfish samples from RIKILT. If the tests are successful, Gerssen's detection method would be put up as the European standard. Not bad for a PhD student. He will graduate on 15 October under Prof. Ivonne Rietjens of Toxicology and Prof. Jacob de Boer of Environmental Chemistry and Toxicology in the VU in Amsterdam.