I have found some articles (published) related to the "Public Health", providing references from some local newspapers of certain countries in their "Introduction" part. I am not sure whether it is scientific or not? What are your suggestions?
Shakil - it depends what you mean by scientific? No - they are not peer reviewed etc - but they may be reporting important local events or even studies being conducted in the area. As long as the newspaper source is reported in context in the article, and such sources are limited by their use, then it is appropriate to use such sources in manuscripts.
Where there is no scholarly literature to provide the information you need, it may be appropriate to cite journalistic or other accounts. I think that generally theoretical ideas should come from peer-reviewed sources, but factual information and trends may be appropriate from other sources if the sources are judged to be legitimate. Avoid Wikipedia and other encyclopedia-type sources.
It would appear meaningful to cite non-scientific publications such as newspapers in the case of reports on events, activities, an interview or news that would otherwise not be reflected in peer-reviewed journals. Especially in community-based public health, I would assume that that is often the case.
Should you need to cite a newspaper article due to lack of peer-reviewed information on the given topic, I would say that it should only be done so truly if there is no other reliable source AND in combination with the respective critical appraisal of the cited source/information.