Other causes are harder to pin down.

其它原因就很难下定论了。

youdao

But it is harder to pin down more subtle health effects.

但是限制对健康的影响多一点，难度就更大一点。

youdao

But it is harder to pin down more subtle health effects.

但是限制对健康的影响多一点，难度就更大一点。

youdao