Before I start, I'd like to educate you on the Turtleverse.
First, there is not one single timeline for TMNT. There are, as of now, three separate dimensions in which the turtles came into being.
1) Splinter was the pet of Hamato Yoshi, who is later killed by the Shredder (1984/2003)
2) Master Splinter is mutated into a rat who then later mutates the turtles (1987/2012)
3) Master Slinter is Hamato Yoshi reincarnated, who's sons are all killed at the hands of the Shredder; later to become the TMNT, since they too are reincarnated (1999)
Now, I could say that these show are on the same network - that's pretty obvious - but that's not all to it.
Originally the ooze never made anyone to monsters, but made them larger, stronger, and sometimes gave the super powers. This "toxic waste" that Tritannus absorbs is oddly similar to that. Tritannus also can utilize the toxin's power to mutate other creatures, as well, which was seen numerous times in the most recent show.
Now if I was stupid, which I am, I'm hope we'll get some confirmation on this.
Again, this is a theory, not something I'm 100% sure of. Still is fun to think about, though.
I thought the TMNT were subject to radioactive toxic waste rather than oil and general polution