As science and testing improves, people often find out that many of the practices they simply accepted are actually quite harmful to the human body. This is probably best seen in the decline in use and eventual banning of asbestos in construction. For decades, asbestos was seen as an incredible innovation that was very useful as insulation while also being fire- and spark-resistant. The realisation that it was extremely harmful to humans was coupled with a feeling of collective dread as asbestos was present in practically every building at the time.
