From Norman Rogers at American Thinker:
As far as I know, there are no Ph.D.s offered in the study of junk science. Maybe there should be. There are numerous instances of credentialed scientists pursuing faulty theories against evidence and common sense. Irving Langmuir’s 1953 talk, “Pathological Science,” is a classic compendium of examples; there is the recent case of cold fusion, with the imaginary tabletop nuclear fusion reactors still being given media credibility.
Often media attention and fawning admirers blind scientists to scientific reality. Junk science also appeals to ideologues if it provides support for their ideology. For example, those who are ideologically opposed to capitalism are welcoming to science that suggests that corporations are poisoning the food supply or polluting the water supply.
The linear, no-threshold method of evaluating risks from small concentrations of things known to be dangerous in high concentrations is an example of sketchy science that is widely used to promote scares and provide work for regulatory bureaucracies. For example, the U.S. Environmental Protection Agency has a large campaign against radon, a naturally occurring radioactive gas, tiny amounts of which sometimes seep into houses.