This post is briefly explains why I’m tossing out my worn plastic cutting boards and mats, and rehabbing a few wooden cutting boards to take their place.
This, based on two absolutely ridiculous research findings regarding the amount of microplastic in the diet, as measured in credit cards per year.
This will all make sense by the time I’m done.
A ratio of credit cards.
A few weeks back, you may have read that the average American eats a credit-card’s-worth of micro-plastic a week, on average. The obvious click-bait potential for such a bizarre and gross assertion meant that it got lots of attention on the internet. (The research has been around for a while, but for some reason, there was a recent resurgence of reporting on it.)
I’m not giving a reference for that, because, as discussed below, that’s total 💩.
But, because normal isn’t newsworthy, you’d be hard-pressed to find any internet mentions of the the debunking of that credit-card-a-week. Other scientists have taken the same (~) underlying data and calculated a weight of microplastic in the diet of around one-millionth of a credit-card a week. Just under five millionths-of-a-gram per week, not five grams per week.
(How? To be as charitable as I can, it turns out to be difficult to take counts of a few dozens of microscopic plastic fragments, in a few samples of food, and extrapolate those data to come up with the total weight of microplastic in the diet. As I read the scientific debate, the authors of the various “credit-card” studies simply made an exceptionally poor choice of extrapolation method.)
Now, you personally may have thought that that “credit-card-per-week” figure was implausible. And yet, because “microplastic in the diet” is such a squishy entity (starting with, invisible), you really had no way to prove that your instincts were correct.
Now, thankfully, somebody has jumped the shark. There’s a new study claiming that, in addition to plastic in the food chain, the use of plastic cutting boards adds a further ten credit-cards a year of plastic to the diet.(?)(!).
FWIW, this is the cutting board analysis refernce The piece that points out the problems with the 52-credit-cards-a-year analysis is this reference.
The cutting-board estimate estimate is also total 💩. But it’s useful 💩
💩 ? Yep. Same reason as the credit-card-a-week study. See above.
But its useful in the following ways.
First, this most recent “credit-card-consumption” study is self-debunking for the average user. Because, while I’m not exactly sure what “microplastic in the diet” looks like, I for sure know what a plastic cutting board is.
Do the math, and at 5 grams per credit card, ten is just shy of two ounces a year. This research is claiming that the average person’s plastic cutting boards erode from knife cuts at the rate of (~) two ounces/year/household member.
Really? For your consideration, I offer Orange Cutting Mat (below), weighing in at a svelte 1.1 ounces:
If the erosion rate really were two ounces a year, the mat above would have been worn to shreds a decade or two ago. It’s old. Origins are lost in the mists of history. It’s used more-or-less daily. It’s obviously scratched from use.
And yet this venerable cutting mat continues to serve.
Worse — and for shame — the authors of this 10-credit-cards-a-year study could have convincingly debunked their own finding with a day of work and a kitchen scale. Weigh a cutting mat (per above, 32 grams). Chop vegetables on that mat for five hours (300 minutes) to simulate 30 days of typical household chopping. If the estimated two-ounces-per-year is correct, you’ll have lost about one credit-card’s-worth of plastic, or about 5 grams. At the end of the day, if the erosion rate was as-stated, that plastic mat ought to weigh just 28 grams. That amount of plastic weight loss should be easily detectable on a gram kitchen scale.
In other words, you can literally check their work by subtraction. With a kitchen scale. And a month’s worth of vegetable. And some manual labor. Just weigh the cutting mat pre- and post- a marathon cutting session.
But as importantly, this study makes you realize that, yep, some of the plastic from those scratches is exiting as tiny fragments. And you’re eating those tiny plastic fragments. Some of them, anyway. There’s no reason to think that the authors did their lab work incorrectly.
And, if you follow the thread here, because 10/52 =~ 20% based on the well-known Universal Law of Credit Card Accounting, using plastic cutting boards ups your dietary consumption of microplastic by 20%. Or so. Under the assumption that both studies embody the same degree of (gross) overstatement of the actual weight of plastic.
I don’t know whether the actual amount of microplastic in the diet causes significant harm or not.
On the one hand, humans have been using copious amounts of plastic for decades. If there is some health hazard from microlastic in the diet, chances are good that it has already occurred. I suspect we’re hearing a lot about microplastic due to some change in technology that makes it easier and cheaper to detect.
(Take that cynicism with a grain of salt, as my entire house is carpeted in cut-pile polyester wall-to-wall (Post #1943, carpet fiber burn test). And, accordingly, I must surely live in veritable airborne-microplastic-polyester-fiber-fragment miasma.)
On the other hand, you at least have to recall the mechanism of action of asbestos for lung cancer. My recollection is that it was a micro-fiber disruption argument, The fiber in question, thought to spur generation of lung cancer, was an eensy asbestos fiber fragment that got inside the lung cell. And proceeded to screw up the works just enough, when that cell next divided. That’s how I recall the theory of it.
So, durable microscopic fibers (or other plastic bits) can’t be readily dismissed. Plausibly, it only takes a tiny amount of that stuff to cause whatever havoc it’s going to cause.
Conclusion: Putting the ick in clickbait.
The upshot is that while the jury’s out on the dangers of microplastic in the diet, there’s no sense in force-feeding yourself with it.
Not when you can easily cut your food up on something else.
As final insult to injury, I note two things.
First, as I read it, based on the underlying data used, that 10-credit-cards-a-year from use of plastic cutting boards would be in addition to the estimated 52 credit-cards’-worth already supposedly in the diet. So the purported total now stands at 62 credit-cards a year, for those who both eat food and use plastic cutting boards.
Second, I infer from this glimpse of the literature that there’s a whole slew of scientific papers in the pipeline that use minor variants on this same (bad) extrapolation methodology. So, changes are, there’s now going to be a string of articles showing the mind-boggling amounts of microplastic you eat due to fill-in-the-blank. These will, of course, be rapidly popularized on the internet, because they put the “ick” in clickbait. Literal accuracy is not required, only some plausible (i.e., science journal) source.
