Školjkaši su često krivci za otrovanje ljudi hranom. U sat vremena jedan školjkaš može profiltrirati osam litara vode. U njoj se tijekom filtriranja vode zadržavaju hrana, akumuliraju se čestice fitoplanktona i razni mikroorganizmi. Neki od mikroorganizama mogu preživjeti u dagnji tako što prijeđu u vegetativni stadij. Ako takvog školjkaša pojede čovjek, u njegovu organizmu mikroorganizam prelazi iz vegetativnog u aktivni stadij i počinje se umnožavati. To u ljudi često rezultira bolestima kao što su trbušni tifus, hepatitis A, salmoneloze, šigeloze, gastroenteritisi i sl. Nadalje, konzumiranje školjkaša kontaminiranih toksičnim algama (dijatomejama, dinoflagelatima) uzrokuje različita otrovanja, a konzumiranje školjkaša iz područja onečišćenih produktima antropogenoga djelovanja može uzrokovati otrovanje teškim metalima.Shellfishes are often responsible for food poisoning. In one hour, one mussel may filtered eight liters of water. During the filtering, in that shellfish are accumulated all sorts of microorganisms and particles. Some of these microorganisms can survive in mussel by converting to vegetative stage. If such shellfish is eaten by human, in his body the microorganism pass from vegetative to active stage and starts to multiply. That in peoples often results in diseases like typhus abdominalis, hepatitis A, salmonella, shigella, gastroenteritis etc. Furthermore, by consuming shellfish that are polluted by the products of anthropogenic action may cause intoxication with hard metals
