Likely not what you’re describing, but this hypothetical is what came to mind.

Consider if organism A consumes organism B in a symbiotic way. E.g., organism B makes berries.

Then, we engineer A to seek out and consume DDT, perhaps by making DDT delicious or fragrant to A.

Unexpected consequence: organism B evolves to produce berries that are absolutely redolent with DDT.

This might happen centuries later, due to the DDT-phillic genes outlasting the presence of artificial DDT in the environment, or it could happen much sooner, or it might never happen. Hard to know. “Life finds a way.”