Trying to understand what's in the Harman selenium toner safety data sheet, here:
https://www.ilfordphoto.com/wp/wp-content/uploads/2017/04/HARMAN-Toner-Selenium-EN-E17-44-10477.pdf
The paper states there is 1-5% od sodium selenite in the bottle. Oral acute toxicity for rat is 7 mg / Kg if taken orally. Any help on how to interpolate these data to a darkroom worker would be much appreciated.
Well thats quite easy to explain.
You should multiplicate the weight of a rat - let us name a very heavy rat as : "Oskar" So Oskar should be heavy with its real 500g !
A heavy beast of a rat.
If your weight is let us say 95kg (sorry for this ) - we can also calculate 100kg.
At last we multiplicate Oscars lethal (oral ) dosis with factor 200 - this is for you finally!
To Oscar (look above ) 3,5 mg of your chemisty is its end.
Your letal dosis should be in the near of
700mg thats absolute exactly 0,7 g of pure sodiumum selenite.
The fact is you are no rat at least. May be Oskar is a tough guy ?
But if you may have 1 Liter of original Ilford Selen Toner the concentration of 1 - 5 % of the relevant tocic compound should be between 1 - 5 g.
For you in your darkroom that means : you could obviously murder your wife (estmated 50kg) up to 3 - 15 times with just one bottle of Ilfords Toner.
Because she couldn't be in the near of Oskars toughness !!!

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Or in other words : NEVER DRINK YOUR SELEN TONER FROM ILFORD HARRMAN
because the given advice from the PDF
indicates : It is real TOXIC !!!!!!!!
Beware of you skin like advices given in addition.
with regards