The Environmental Protection Authority says regulators are coming up against a growing number of internet sceptics.
Among them, a growing number of fluoridation, 1080, vaccination and climate change doubters.
Auckland University microbiologist Siouxsie Wiles told Mike Hosking they play at people's fears and emotions.
"They use very emotive language, they're very convincing, and they're very vocal because they feel very strongly about it."
"And then the issue is, that they flood the internet with stuff."