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DoorlessCarp🐭's avatar

Another must see is this science memo from New Zealand (2022).

The regulators put Bovaer as GHS Category 2 for reproductive toxicity.

(It's worse still for rats).

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... The EPA considers that the mechanism of toxicity is not sufficiently characterised to enable a firm

conclusion that the toxicity to the testis and epididymis is a rat specific finding but does suggest that

other species may be less sensitive to the compound. Therefore, the EPA does not consider that it

can be concluded that this finding has no human relevance. Consequently, the clear evidence of an

adverse effect on reproduction in a combined toxicity screening study in the absence of other toxic

effects, supported by evidence from repeat dose studies showing the male reproductive organs to be

the target organs for toxicity justifies classification for reproductive toxicity. The EPA concludes that

the appropriate classification is GHS Category 2 for reproductive toxicity.

https://www.google.co.uk/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.epa.govt.nz/assets/FileAPI/hsno-ar/APP204100/APP204100-Science-Memo-Final.pdf&ved=2ahUKEwi13dyMhLeKAxWYQUEAHVixJw4QFnoECBcQAQ&usg=AOvVaw3vrxcW6687mcstvafc9aHm

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DoorlessCarp🐭's avatar

The "N" in 3-nitrooxypropanol got me thinking about metabolites, such as N-nitrosamines, which have loooong been associated with cancer. It's why we were told not to eat too much bacon, etc.

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Induction of liver tumors in Wistar rats by sodium nitrite given in pellet diet

M Aoyagi et al. J Natl Cancer Inst. 1980 Aug.

https://pubmed.ncbi.nlm.nih.gov/6931259/

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Which is why nitrite formation as a breakdown metabolite of Bovaer presents "a bit of a problem".

The fix is simple. Redefine nitrites as safe, and no longer linked to cancer 🤞👌🤫

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Nitrites are now safe again

... An oxidant called 3-nitrooxypropanol (3-NOP, aka Bovaer) binds to the active site of MCR and oxidizes an essential SH group, inhibiting production of methane in bacteria. The effect only lasts for 5 hours at a concentration of 1 μM,[7] after which the bacteria reactivate the enzyme. 3-NOP is rapidly absorbed by the intestine and makes its way through the animal's bloodstream, and is then denitrated in the liver. This probably explains why 100× more 3-NOP is needed to produce the effect in the animal than in cultured bacteria. 3-NOP is metab­ol­ized to nitrate, nitrite, and 1,3-propanediol.

https://randombio.com/nitrite.html

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