[hilbert42]

"I seriously doubt that the microbial load would have been lower before the invention of washing machines. And with older washing machines, using those nasty aggressive washing agents:…"

Nasty aggressive washing agents have a pretty devastating effect on bacteria, molds etc. especially bleaching percarbonates and such used for whiteners/stain removers. Surely then it's just a matter of increasing the amount of washing powder to achieve the desired sanitation level.

A rule I use is that if soap suds aren't still present in reasonable quantity on top of water until the end of the wash cycle then there's not enough soap powder being used.

Perhaps the trend towards minimizing the amount of cleaning agents used in washing has gone too far.

Similarly, perhaps also we've gone too far by removing phosphorus (in the form of trisodium phosphate—aka TSP, etc.) from washing powders, which has been a trend in recent years through environmental concerns. TSP, Na₃PO₄, is remarkably good at removing heavily ingrained dirt. It's also highly alkaline and hostile to living organisms.

That said, surprisingly TSP is not very toxic to humans—at least in small amounts. It's used as an acidity regulator/preservative in food, it's E339.

[ghssds]

TSP can be bought at an hardware store and then added as needed in your cloth washing machine and your dishwasher.

[hilbert42]

Yeah, I know. My hardware shop sells packs of 2kg of TSP for less than $10 and I use it for many things—cleaning paint surfaces, removing mold (small concentrations left on surfaces even prevent mold from forming), softening surfactants including washing powders, etc.

Those of us with some chemistry knowledge do such things but those people referred to in the story are unlikely to even know about TSP let alone add it or anything else to washing except perhaps fabric softener.

I found the story lacking detail so I went to the source paper† and whilst detailed in parts I also found it quite unsatisfactory. For example, during the test only 14g of 'unspecified' detergent was added. That little amount added to my wash certainly wouldn't remove dirt or oily stains let alone blood stains (which you'd expect to find on dirty medical workers clothes).

Moreover, whilst the paper mentions there are differences between liquid and powder detergents (including rhise with enzyme) little else is said about them. (Surely one should know the exact nature of one's bactericide before one commences.)

Quote extract from paper's conclusion:

"It is however difficult to determine the antimicrobial efficacy of the detergent itself from this study investigations.…"

Why? Again, you'd reckon that would be prerequisite and part of the controls (i.e.: take a fresh concentration of 14g detergent in the equivalent of a washing machine load of clean water and test it then increase the concentration in steps until 99.99% of the bugs died (that level of kill is required of an effective bactericide).

"Several studies have showed that the HAI organisms MRSA and A. baumanii and other Gram-negative bacteria can survive washes performed under 60°C without detergent…."

"without detergent" — for heaven's sake, that's hardly relevant. Who would wash clothing without detergent? None I'd suggest let alone medical workers.

When one actually reads some of these papers one can only conclude that some conclusions are questionable. Perhaps we've a case of bullshit baffling brains (here I mean those funding the research). Had I been on the funding committee I'd have not been happy with this paper.

BTW, those conducting the research are all from a school of pharmacy, you'd reckon they'd know enough chemistry and quantitative analysis to conduct a more exhaustive test.

*†https://journals.plos.org/plosone/article?id=10.1371/journal....