People started to doubt the "experts" in a concerted way during the counter-culture days of the 1960s and 1970s. A great deal of science was accomplished by the "military/industrial complex" - that ill-defined but useful grab-bag of a term, which described secretive and massive consumption for the military, but also the drive for year-on-year commercial growth. There was a great deal of cosy, folksy nonsense talked about Gaia and a near-spiritual relationship between Earth and humankind, but there were also cold, hard, logical, irrefutable facts to testify to the harm being done. The rainforests were disappearing. The ozone hole opened up overhead. Industrial pollution was choking our rivers and seas and mechanised farming and the extensive use of agrichemicals were changing the very landscape.
Scientists were seen as the authors of these threats. Wonderful medical advances came, but so too did poisonings such as Love Canal, in which toxic chemicals dumped in a disused upstate New York waterway began to make people ill. People began to doubt the assurances given by the "experts" - and rightly so, in that so many assurances were carelessly given and so many came from vested interests.
Yet even as the trust between the public and the scientists became corroded, it was the continuing research by scientists that defined and described the emerging environmental and health threats. Scientists found and measured the ozone hole and discovered what caused it. Scientists identified sources of chemical pollution and explained the associated health risks.
The battle continues today as the public tries to understand new threats, real or imagined. There are running, physical battles over mobile-phone masts. People who don't know what genetic modification of food means are rejecting the technology without considering whether there are genuine risks.
People remain slow to accept at face value what they are told by the scientific experts and there is immediate mistrust of new technologies that have yet to be proved. Patients second-guess their doctors and surgeons and seek out a second opinion if there is dissatisfaction with a diagnosis.