You’re eating a credit card’s worth of plastic every week | Hacker News Reader

You’re eating a credit card’s worth of plastic every week

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10 pointselectic7 comments

Where does the 5g come from? And, whats the distribution by economy and class, and by other dietary habits..

I mean sure: if there is some plastic leaching from tins, I get that. If the PET bottle my milk comes in leaches, I get that. But I eat a lot of fresh fruit and we bake our own bread. If the model assumes tinned fruit and package bread, without more information how can I assess my personal exposure?

How does tap water reduce 90k from bottled water to only 40k particle exposure? Whats the path of microplastics in the water supply? Did this assume everyone keeps tap water in plastic filter jugs? or that the water supply is plastic pipes and not copper or iron or ..

Again.. How much is this specific to a regime of water treatment in one economy?

I can believe this, if I get better evidence for this.

Quoting from the study: «The consumption of plastic particles, commonly termed microplastics (MPs; 0.1–5000 µm in size) and nanoplastics (NPs; < 0.1 µm in size) can occur either directly through the food chain or indirectly via the ingestion of inhaled and regurgitated particles (Wright and Kelly 2017). According to a study by the Marine Biology and Ecology Research Centre (MBERC) in England, the plastic load released from clothes made of synthetic fibers (polyester, polyester-cotton and acrylic) amounts to over 700,000 large MP fibers per machine wash (per 6 kg load) (Napper and Thompson 2016) that end up in waste water. Tons of plastic particles reach their final destination in the sea to enter the food chain through ingestion by marine life (Cho et al. 2019; Van Cauwenberghe and Janssen 2014), through sea salt (Karami et al. 2017; Kosuth et al. 2018; Yang et al. 2015) and/or drinking water (Mason et al. 2018; Schymanski et al. 2018) to further reincarnate on our dining tables. Recent studies have also indicated the presence of MPs in some terrestrial food items, such as edible fruit and vegetables and store-bought rice, but further research is needed to replicate these findings (Dessì et al. 2021; Oliveri Conti et al. 2020). Translated into more imaginable numbers, on average we ingest five grams of MPs per week per person (roughly corresponding to the mass of a credit card) depending on the region in which we live, our lifestyle, and diet (Senathirajah and Palanisami 2021).»

It goes on, quoting a study of this and a study of that, adding up what we eat, drink and breathe and converting to weight: 5g/week.

It's not invariant though. The title of one of the studies quoted is «Low levels of microplastics (MP) in wild mussels indicate that MP ingestion by humans is minimal compared to exposure via household fibres fallout during a meal». Good news for those of us who don't wear hoodies made with 50% plastic.

The plastic bottle 40k/90k thing will also be because of fallout. Pour water into a plastic bottle, squeeze and shake it a bit, let it stand, do it again, a few particles will be released into the water.

> Senathirajah and Palanisami

here's a quote from their abstract:

As such, there is confidence that based on the literature reviewed and subsequent analysis performed that up to 5 g/week of microplastic particles is potentially ingested by humans. Having said that, it should be stressed that the amount of the microplastics ingested by an individual will depend on a combination of parameters that is highly variable not only pertaining to the characteristics of the microplastics but also to each’s age, size, geographic location, demographics of the location, nature of development and life-style options.

This study is being reviewed for publication; the full methodology and supplementary data will be available upon acceptance.

Do you see those weasel words "UP TO" in there?

There abstract also says:

A critical research of the available literature and subsequent unit normalized calculation of the amounts of microplastics ingested by humans through various exposure pathways suggest that on average, humans may be ingesting as much as 5 g/week of microplastics.

So they are being a bit contradictory.

I am wondering if somebody has conflated the maximum potential, as the average?

Every paragraph I read suggested wide variance in each contributing factor, "up to" isn't unusual. Also wide variance in the contributing factors.

Note two things, however: ① 5g/week isn't the sum of the very worst cases observed in the studies they added up. ② It's a sum of varying nonnegative terms, which means that the only way to get a really low sum (say 0.1g/week) is for every term to be in the smaller end of its range. If even one term is in the larger end of its range, then the sum is large, too.

Up to 5g means it's on the right quartile. 0.1g would be in the left quartile. The peak of the curve would be less than 5g. And by less I mean 2-3g or less not 4.9g. Sorry, but even under your model it's not possible to be "on average" 5g and also "up to" 5g. If the risk of multiple independent varying non-zero contributors is high enough I can score a big hitter then "up to" would be higher.

I am sure I injest microplastics but I want good science behind how I assess the risk.

One of their cites appears to be a paper on a catastrophic fire in a plastics feedstock factory in a rural location in south Asia. I am sure they got a lot of contamination. But Australia isn't importing those foods. The authors are in Australia. I'd really like them to indicate how much of this burden is in the supply chain in Australia.

The main reference paper (austria not australia this time) talks about plastics aggregation in shellfish. And a lot about BPA contamination of breastfeeding bottles. There's been a push to remove BPA from plastics in the food chain, so I would hope there would be some detail on how this is changing. A lot of the citations are on the cytotoxic qualities of plastics, but not on the indicative amounts in the food chain.

So my primary problem is that I want to believe we have a significant issue here. I truly do, I think petrochemicals and plastics contamination have to be take seriously. But I am concerned this paper is promulgating a magic scare number which is going to be challenged and wind up undermining the case.

Btw most of that 5g would be excreted. What isn't is hugely worrying. Do not use plastic bottled water, and try to limit your use of plastics in microwave cooking especially of oily and sugary foods (which maximise absorption of plastics and pthylates)

How does that compare to, for instance, the amount of silica-based sand and grit eaten every week?

More or less in quantity? More or less in effects? I haven't really seen any clear description of what microplastics _do_ to people. I could certainly believe it's harmful, but I could also believe it's a bit of a panic.

Some plastics like bisphenol-A absolutely not a panic: its a real problem. it's been removed from food plastics in my economy because of significant concern of its effect on young kids, and so the citation of evidence of BPA contamination in breastfeeding bottles is a concern.

Most of the soluble contamination is excreted. Some isn't. Some is fat soluble and so use of plastics in microwaves, with fat and sugary (hotspot) contents is a concern. Use of recycled plastics in PET bottles and the rise of bottled water is a concern because the leaching from this kind of plastic is higher.

Some of this is at-source contamination. Use of plastic contaminated treated sewage water in farming is common. The water goes on the plants and can be directly absorbed (fresh leafy greens) or goes into the soil and is taken up by the root system and then enters seeds and roots.

Some of this is post-farming contamination. Packaging, processing.

Some of this is in-home contamination. Clothes washing liberates a huge amount of highly mobile plastic microwaste dust. We're shedding and breathing this all the time. It gets into our food because our food is in the same environment.

But at root, I share your questions: better graphs on the primary high volume risk sources, how the distribute worldwide, would help enormously.

We did this for lead contamination. We know how that works, we know how to test for, and sample for, and account for widescale lead contamination.

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