So what is this really telling us?

The peer-reviewed study, published on Thursday in the Environmental Science and Technology journal, found PFAS at levels in milk ranging from 50 parts per trillion (ppt) to more than 1,850ppt.

There are no standards for PFAS in breast milk, but the public health advocacy organization Environmental Working Group puts its advisory target for drinking water at 1ppt, and the federal Agency for Toxic Substances and Disease Registry, within the Department of Health and Human Services, recommends as little as 14ppt in children’s drinking water.

Actually, it’s telling us that analysis of trace elements has become better in recent years. When I first started in metals in the 1990s analysing to parts per million was still a fairly hazy idea. Could be done, certainly, but you’d not get the same results from different labs. Parts per billion, ppb, was something even the environmentalists only started worrying about more recently. Now we’re on to parts per trillion, ppt.

It’s possible that there is a real problem here, possible. But the real lesson to take first is how much better we’re getting at analysis.

As to personal opinion I’d worry much more about the contamination of the sampling equipment than anything else. The claim is that these chemicals are in packaging. OK, so, what’s the packaging of the testing equipment?

17 thoughts on “So what is this really telling us?”

  1. Speaking as a trained analytical chemist with 40+ years experience, I would treat all determinations at the ppt and ppq level as suspect unless the scientists concerned can demonstrate adequate inter and intra laboratory calibration at that concentration and demonstrate the absence of cross contamination. In my experience most environmental scientists don’t bother with such elementary quality control procedures which is why the scientific literature has been full of crap (that’s a scientific term) data for decades.

    Note we still have difficulty achieving satisfactory inter laboratory agreement for transition metals at the ppb level even after 50 years of trying.

  2. This is like those periodic scare stories in the media about nuts and snacks on bars being ‘contaminated with fecal matter’, isn’t it?

  3. It’s the ‘No linear threshold’ bollocks.
    eg: If I drop a fourteen pound bowling bowl on your your head from 6 feet it will do some damage. Ergo, If I drop a ping pong ball on your head from six feet it will do some damage.

  4. 0.050 to 1.850 parts per billion? BWAHAHAHAHAHAHA. Yet more proof that people as a rule don’t understand very small or very large numbers at all… And the points about contamination, reproducibility etc. at such ridiculously small concentrations are very on point. Those figures are so small as to be essentially zero. The 50 ppt means that in 80kg of milk there’s 4 micrograms!!!

    On the homeopathy scale, and rounded to the nearest whole figure, those figures are D10-D9.

  5. PTFE was ubiquitous in the lab I worked in, featuring in items such as equipment seals, solvent tubing, syringes, specialist greases, filters and liquid chromatography fittings. I would be very interested to know how they managed to exclude every possible source of nanogram level contamination.

  6. It’s getting to the point that they are scaremongering about the presence of individual atoms in a gallon of sample. Wanders off to look up Avogadro’s Number.

  7. Or at 50 ppt: less than 9 tablespoons dispersed in an olympic-sized swimming pool. At a litre each per day, that would take 100,000 woman 25 days to fill.

  8. @jgh: 6.022×10^23 to 4sf. I had a few more sig fig memorised when I were a lad, but it seems the accepted value has been revised up somewhat; indeed it had been by the time I learnt it, but that hadn’t yet made it to the textbooks…

  9. jgh: well, of course if we apply the EU’s extreme version of the Precautionary Principle, that single atom of U238 in my morning milk may emit an alpha particle into a cell in my stomach wall, eventually leading to it turning nasty & growing into a cancer. So even parts in 10^-22 need to be measured!!!! Obvious, innit!

  10. @TomJ: it was 6.023 in my day. But I found that, as the years rolled by, the bastards kept changing that sort of thing without consulting me.

    But they never do anything sensible such as redefine the metre so that g = pi^2.

  11. As with everything (Covid, Climate Change…) there is the ability to detect and measure but not a corresponding sense of proportion and significance

  12. dearieme: I want the metre and second redefined so that c=3.00000000×10^k. I mean, who designs a universe where one of the constants is 2.99792458.

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