A new warning for shellfish fans: Scientists in France say mussels, clams, oysters and scallops should be screened for fungal toxins before they are eaten.
Shellfish found in areas contaminated by strains of the Penicillium fungus will contain much higher levels of toxins than in the surrounding environment, according to research published on Friday in the journal "Letters in Applied Microbiology."
A team led by Yves Francois Pouchus, a professor at the University of Nantes, France, set out to assess the risk in shell-fish farming areas. The association between fungi and mussels, clams, oysters and scallops has rarely been studied, the researchers said.
They determined that the fungi produce higher levels of toxins when they grow inside mussels or on a medium containing mussel extract.
"A high level of toxins in the shellfish tells us that we have to be careful not to underestimate the impact of certain Penicillium strains in the water where shellfish are harvested for human consumption," Pouchus said in a statement.
The toxins do not cause food poisoning, but they can have a negative impact on cells and DNA, the researchers said. In theory, these fungal toxins, or mycotoxins, could cause cancer or other health problems in the long run, the researchers said.
"At this point, we think it would be pertinent to begin screening edible shellfish for mycotoxins in order to protect consumers," Pouchus said.
The toxin patulin, discovered in some of the extracts that were studied, has mostly been a concern in apple juice, contaminated by mold on the apples. In April, Wegmans Food Markets recalled organic apple juice and an organic cranberry juice blend over worries that they contained unacceptable levels of patulin.
The Food and Drug Administration has set a limit of 50 parts-per-billion for patulin, but said, in a 2001 review of patulin in apple juice products, that studies had not shown convincing evidence that the toxin can cause cancer.