They are reporting about feeding mice with 400 mg/kg/day during 6 to 8 weeks. For humans, this is equivalent to 33mg/kg/day. So for a 80kg body: 2.6g, half a sugar cube every day.
If you feed an animal (including us) with unreasonable levels of most anything you will observe weird stuff.
For example feeding mice with high fat diets gives them a kind of Alzheimer disease.
But humans have much more time to ingest it. Parkinson develops during decades, not weeks.
It reminds me a bit of the datasheet for sodium chloride - common table salt - that describes the skin contact LD50 (the amount that is a lethal dose for 50% of a population of test rabbits) as ">25kg".
So what do we read from that? If you drop a sack of salt weighing as much as an eight-year-old child on a series of rabbits, roughly half of them will die? I can't say I'm *very* surprised...
No, you should read exactly what it says. If you put a series of rabbits in skin contact with 25kg of salt each, less than half of them will die. That's how we know the LD50 is greater than 25 kilograms.
I assume 25 kilograms was the limit of testing, and that's why the result is reported the way it is.
I'm also willing to go out on a limb and assume the number of test rabbits that died from being put in skin contact with 25kg of salt was zero, which is less than half of the test pool as long as it contained a positive number of rabbits.
That seems a pretty safe assumption.
Depending on what height it was applied from
> less than half of the test pool as long as it contained a positive number of rabbits.
Positive integer number of rabbits, with any luck, although I suspect in this instance imaginary rabbits may have been used. Definitely not complex ones though.
But for e.g. a contact poison absorbed through the skin, sticking your finger into a large pool of the stuff might get you a bigger dose than sticking your finger into a tiny puddle, even with little to no difference in surface area of skin making contact.
Going back to salt, it is known and used for its ability to draw water out of other materials. If you stay in contact with a large quantity of salt, it will kill you through dehydration, because even though it can't flow, the water that you contain can. Your skin should have a good amount of resistance to this; the inside of your nostrils, or an open wound, not so much.
I'm speculating here; if you really want a definitive answer, you'll need to find someone who creates data for MSDS sheets.
I found this: "However, some of these diets contain levels of dietary fat that are much higher than the levels that humans routinely consume. The question has been raised as to whether experimental use of these diets with very high levels of fat adequately models the situation of human obesity." https://www.nature.com/articles/s41366-019-0363-7
How does one convert that? It makes sense that this isn't necessarily linear, but I have no idea how to turn one of those numbers into the other
Generally, from mice, it's ([mouse dose in mg/kg] * (3/37)) = human equivalent dose in mg/kg.