This is why thinking about things in terms of "natural" vs "manmade" is only a crutch. It is a reasonably good rule of thumb that if something is sold in the supermarket and was grown and minimally processed, it is good for you, while if it was heavily processed it isn't. But is just a rule of thumb.

For example, while the science is still up in the air on this as far as I know, it may turn out that Vitamin D supplements are healthier than getting Vitamin D from sunshine, because that same sunshine causes skin cancer.

On the other hand, because of selection bias, there is a pretty good chance that something that has been around for several thousand or million years as part of a natural process is well adapted to the ecology of our planet. The natural processes that disrupted things wildly were either incorporated into a new dynamic equilibrium (oxygen producing cyanobacteria) or died off a long time ago. Oil wells that go miles into the planet's crust underneath miles of deep water are neither of these things.