For those who love eating clams and just like myself wonder how safe it is to eat clams, while they filter huge amount of water -- yes, it would be like eating a used filter, that's why clams that you get in restaurants must be grown in very clean water [1].
People have been eating used filters for millions of years. In particular, just 60 years ago you could find small clams almost in any beach and we believe homo erectus ate those.
But just less than 80 years ago, rivers started carrying all kind of new chemical compounds, like mines' waste, from coal cleaning particles to mercury and cadmium compounds.
Then we added other chemicals like detergents, or machine oils, or silver halides from photography, plastifiers and plastic or resins synthesis residues, Hormones like "the pill", fertilizers, heavy metals like Pb, industrial acids, pharmaceutical residues and I could go on and on.
In some places like in the Mediterranean sea clams just have been dissolved by acid waters or pollution just killed most of them.
This is specially true in the river mouth of big industrial rivers.
It is not lack of rationality, quite the contrary, people with information,like those that do quality analysis of waters will never eat things like fish coming out of some of them.
I don't know if it's rational or not, especially since I'm sure there are plenty of microplastics and pollutants in everything else, but I've completely removed filters & anything whole like shrimp from my diet.
I enjoy shrimp and scallops, but honestly I feel like given my current knowledge it's not worth it. Maybe we'll find out that all the microplastics in the ocean are totally fine, but better safe than sorry in my opinion.
Generally foreign contaminants introduce chronic immune responses. A rise in autoimmune disorders could potentially be a result. Or perhaps a single particle has a small chance of inducing cancer in a cell that endocytically engulfs it. In a situation like these the effects of low numbers will be small and hard to attribute to the source but that doesn’t mean it won’t continue to make it much worse for us.
That’s why I mentioned I’m sure they are everywhere, so maybe I’m overcautious.
At the same time though I’m certain any marine life is subjected to way more micro plastics than those on land. So consuming anything that functions as a filter is gonna have high concentrations of it. At least that is my logic.
That is to let them spit their sand out, and it only takes about 20 minutes.
If you want to let them spit overnight, you should put them into salt water, fresh water will kill them.
Most shellfish for consumption are farmed, and it's really important that they're grown in clean water to taste good, especially if the intent is to eat them raw.
[1] https://www.thurstoncountywa.gov/planning/planningdocuments/...