<prompt> Translate the following text to EnglishTofauti ya utafiti inahusu ukweli kwamba masomo tofauti yaliyochapishwa ya uhusiano huo wa uchafuzi na athari za afya kwa kawaida hayaripoti matokeo sawa  <response>: Across-study variation refers to the fact that different published studies of the same pollutanthealth effect relationship typically do not report identical findings 