Hi Joachim, I have no idea really all the MSDS says that there is 1 to < 3% of it in there. I would be surprised if a technical product would not be a mix, and if not and some isomers were subject to risk, they would probably state that these are not there. From a toxicity point of view the 1-NAPHTHYLAMINE, N-PHENYL- is indicated as the most toxic ingredient. The MSDS gives also the following info:

Technical grade TCP (tricresylphosphate) may contain various aryl ortho-phosphate esters which after ingestion of high doses has been reported to cause cholinesterase inhibition and delayed neurotoxic effects, in both animals and humans, as well as reproductive effects in animals. These effects are predominately attributed to certain isomeric forms (ie. ortho isomers) and current grades of TCP in this ExxonMobil product have very low levels of the ortho-isomers.  Neurotoxicity testing in hens, and reproductive toxicity tests in rodents of products with up to 3% TCP were without effect.  Tricresyl phosphate (TCP).  TCP (

Thanks - very helpful - my analyses have shown a lack of the o,o,o isomer (good news) but at least 4 other  - possibly mixed m and p isomers.

regardless of isomer - my inclination is to treat them all as potential adverse.

 - joach

certainly - in my personal opinion - reasonable to stimulate search for alternatives.