Not at all. That's not how science works. A huge percentage of rigorous scientific studies are specifically showing correlations between things.
"Correlation doesn't equal causation!" cried the internerds.
It doesn't need to. If you've got a set (P) of N people who consume substance X, and N people (Q) who did not consume substance X, and 100% of set P died within half an hour of that act, and 100% of Q are still happy little dandelions, that is an entirely valid scientific finding, and an entirely sufficient reason to stop the supply of substance X.