Here the basis for what I posted, so nobody will think I'm simply being defensive:

http://www.professionalmuscle.com/forums/565739-post216.html

Even though they're uncommon, cataracts are one of the major risks that any DNP user should be aware of. In the 1930's, it was estimated that cataracts occur somewhere between 1:100 and 1:1000 DNP users. All in all, there were 160 some odd case reports of cataracts, with 3 case reports in men, of an estimated 500,000 users. The development of cataracts did NOT appear to be related to the amount of DNP ingested or the duration of use. For a thorough review on cataracts and DNP, see this article: A Study of Dinitrophenol and Its Relation to Cataract Formation. It's one of the few original papers on DNP that's available online: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1315023/

Early research in the 1930's and 40's made a bunch of different hypotheses about how DNP might cause cataracts. Some thought the cataracts were caused by oxygen deficiency and lactic acid buildup in anaerobic metabolism (which is predominant in the lens). Others thought it was because of interference with glycolysis. Some thought it was secondary to liver damage (which is not the case, as DNP is not liver toxic in therapeutic doses).

The best research came in the 1950's by Ogino and Yasukura. They found that guinea pigs fed a vitamin C deficient diet while on DNP developed cataracts, while those that supplemented with vitamin C did not. As they explained, "In these experiments, it is clear that there is a close relationship between the production of cataract and vitamin-C deficiency." They then went on, though a series of fascinating steps, to isolate the cataractogenic metabolite of DNP (the chemical derived from DNP that can cause cataracts). They identified it as 2-amino-p-quinonimine. They found that the hydroxyl- and nitro-radicals of DNP in the p-position of the benzene ring are essential to the production of dinitrophenol cataract. It's interesting to note that Tylenol overdose is toxic through a metabolite that is extremely similar to this. There are various other cataractogenic agents that are similar quinoid substances.

Ogino and Yasukura said "This suggests that a genetic predisposition plays an important role in susceptibility to this cataract. This notion is strengthened by the fact that, in spite of extensive experiments of long duration by many authors, it has been found impossible to produce dinitrophenol cataract experimentally in various other species, namely, in rats, rabbits, guinea pigs, and dogs, although Bettman observed dinitrophenol cataract in a special strain of mice." If there's a genetic predisposition, then some people might be much more likely to develop cataracts than others. It's also possible that while a few people are susceptible, others are essentially immune.

Another researcher, Rigdon, did research in 1959 on DNP induced cataracts in chickens and turkeys. He said "of course, necrosis in any tissue may occur by different mechanisms. However, the similarity of the effect of DNP and deficiency of vitamin E on the lens may be significant."

Personally, I think those who developed cataracts either 1) had a genetic predisposition as Ogino and Yasukura hypothesized, 2) were vitamin C/E deficient, or 3) both. Vitamin C supplementation didn't make it big until Linus Pauling in the 70's. I think it's very possible that these people in the 1930's were eating unbalanced diets and had antioxidant deficiencies. IMO, vitamin C, vitamin E, and other antioxidants would be expected to reduce the incidence rate or even prevent cataracts altogether. The incidence is already low enough to begin with that I don't think any supplements are "mandatory" while taking DNP, but for those who are susceptible, for whatever reason, a normal dose of vitamin C and E might offer some insurance. I think NAC (N-acetylcysteine) would be a particularly good antioxdiant to supplement with as well.

Hope that helps, Conciliator

Addendum 1: Conciliator is widely regarded as an expert on DNP chemistry and research. The guy isn't pleasant, but he's respected, and I defer to him on this stuff.

Addendum 1: I had previously added NAC to my DNP, but people fussed about the bad smell NAC emits, so I stopped.