[grammaton]

"What I like to see, is when many countries do studies and they all come up with similar results."

Leaving aside the fact that different countries are basically irrelevant here, what you are describing is a scientific consensus. These are always founded not on a single or even a handful of studies, but rather on many, many studies and mountains of evidence, meta-studies analyzing the studies, independent verification of results, and so forth. Science doesn't move forward by individual studies - that's a common misconception - it moves forward when enough of those studies accrue that a clear consensus emerges and shifts the prevailing paradigm. This is also why the lone brilliant genius who overturns everything with their piercing insight is such a stupid meme - even Einstein had to verify his results and wait for the rest of the community to double check his work.

And that's why it's a fallacy to place too much weight on a single study, and an even bigger fallacy to disregard places where there is, in fact, a clear consensus - e.g. cellphones don't cause cancer, global warming and evolution are real, etc...