Of the 55 web pages included in the scoring process, 28 (51%) were pro-fluoridation, 16 (29%) were neutral and 11 (20%) were anti-fluoridation. Analysis of the top 10 results returned by the most-used search term (‘fluoridation of water’) showed that of the top 43 results (seven were excluded from scoring), 20 (46.5%) were pro-fluoridation and 13 (30.2%) were neutral. The remaining 10 (23.2%) were anti-fluoridation, with the majority coming from fluoridealert.org, run by the Fluoride Action Network (a vocal antifluoride group in the USA).
Of the 55 web pages scored, 35 originated from the USA, 14 from Australia, three from the UK and one from Canada. Two were of unclear origin….
Table 4. Comparison of the top 10 Google-ranked water-fluoridation web pages and their quality score determined according to the study criteria
To the best of our knowledge this is the first published assessment of the quality of online information regarding water fluoridation. We found that .com and anti-fluoridation websites scored lower in credibility, quality and health literacy.
It is a long-standing view that anti-fluoridation lobbyists make up a relatively small, yet vocal, component of the fluoridation debate5. In this study, anti-fluoridation web pages were a minority (20%) and yet produce considerable numbers of attention-grabbing claims (albeit unsubstantiated, through failing to reference reputable scientific articles to support their assertions).
There was a reasonable prevalence of neutral web pages (29%) returned by the search, which presented pros and cons of water fluoridation supported in the literature, such as its dental-health benefit and the possibility of fluorosis. Critical consumers of health information frequently seek information they perceive as unbiased, allowing them to come to their own conclusions21. We also found that the majority of pro-fluoridation web pages came from sources such as government websites, which were more likely to present a balanced view of water fluoridation.
A common misconception held by individuals performing health-related searches is that the order in which search engine results appear is an indication of their quality or relevance14. However, the order of web page appearance is, in fact, generated by an algorithm that takes into account the number of times a page is linked to the search term, with pages that have more links to them appearing higher in the search results. While this algorithm is highly effective when performing consumer searches in which the most popular pages are desirable, it produces a false perception of quality in health-related searches.
In terms of quality, while the majority of pro-fluoridation pages presented accurate information, it was often not referenced or credited to a qualified author. Additionally, they did not disclose affiliations that could produce a conflict of interest or sources of funding for the website. All of these factors are key to establishing a sense of transparency and credibility of the health information and are likely to increase levels of trust. We recommend that those developing online information about water fluoridation credit information to appropriate authors, disclose conflict of interests and state sources of funding, as this will improve their overall quality according to international criteria.