ANCESTRAL EATING: Seafood, pt.3

Some further notes on contamination of seafood with microplastics, a topic people always want to hear more about

Welcome back to ANCESTRAL EATING. Over the past couple of weeks I’ve been talking about seafood as part of an ancestral diet. Two weeks ago I talked about how many of the groups Weston Price studied in Nutrition and Physical Degeneration achieved perfect health through the consumption of large amounts of seafood. Then, last week, I sounded a cautionary note with a detailed discussion of why it might not be best to add too much seafood to your diet, and especially not farmed seafood like salmon.

The majority of salmon consumed in the US are farmed, despite the fact that the US captures more than a third of the world’s wild salmon. Those wild salmon are shipped abroad, mainly to Asia, for cheap processing, and most of them stay there, to cater to the Japanese and burgeoning Chinese markets. What the American people get instead is salmon raised in vast floating farms that rival the worst landbound factory farms for their squalor and the inferiority of the product they produce.

But even wild fish may be better left off the menu, at least if we’re talking about dietary staples. The sad, simple fact is that our rivers, lakes, seas and oceans have become vast repositories of toxic filth. That filth—whether we’re talking about per- and polyfluoroalkyl substances, polychlorinated biphenyls or heavy metals—accumulates in aquatic life, building up to dangerously high levels the further up the food chain you go.

This isn’t to say that the food supply on dry land isn’t contaminated—it is—but our bodies of water represent a special case, because so much of our waste ends up in them, whether inadvertently or by design.

Here, in this week’s edition of ANCESTRAL EATING, I want to add some further points and clarifications to things I said last week.

Note, once again, that I’ll be considering freshwater and saltwater varieties under the rubric of seafood: “seafood” is just a convenient label. If I’m talking about one variety in particular, I’ll make it clear.

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A question I get asked a lot about foods, and especially seafood, is “How many microplastics are there?” Given that the seas and oceans are where the vast majority of plastic pollution ends up, you’d think that seafood would be uniquely contaminated with microplastics. It’s actually more complicated than that, though.

A big difficulty, when we come to try and quantify microplastic contamination of foods, is that there aren’t a lot of data. In a very real sense, we don’t know what it means for a food to have a lot of microplastics in it. Of course, we know that, ideally, food wouldn’t have any at all, and that once upon a time it didn’t. You’ll see stories about new research claiming that humans are ingesting a credit card’s worth of plastic a week now, and obviously it sounds bad and it almost certainly is, but it’s not actually clear a) how these levels correspond to basic concerns like toxicity and endocrine disruption and b) what high levels of relative or absolute consumption of microplastics would look like.

One thing that can be done, is what was done in this interesting study of microplastic contamination of mussels. As filter feeders, you’d expect mussels to end up heavily contaminated with microplastics. All they do is sit there, passing water through their little filters, presumably building up a (relatively) big store of plastic particles in their bodies. But the study shows that, in actual fact, if you sit down at home to eat a bowl of farmed or wild Scottish mussels, the microplastics you ingest from the mussels will be “minimal” compared to the number of microplastic fibres you’ll inhale while you’re eating.

Our predictions of MPs ingestion by humans via consumption of mussels is 123 MP particles/y/capita in the UK and can go up to 4620 particles/y/capita in countries with a higher shellfish consumption. By comparison, the risk of plastic ingestion via mussel consumption is minimal when compared to fibre exposure during a meal via dust fallout in a household (13,731-68,415 particles/Y/capita).

Relatively speaking, then, we can say that, if you’re looking to minimise ingestion of microplastics, you’d be far better off sitting outside to eat your bowl of moules marinières or cleaning your home more thoroughly and getting rid of synthetic fibres, than ditching the shellfish.

If that isn’t food for thought, I don’t know what is.