Madonna, Juliet Stevenson and Lady McCartney have all been singled out for not checking their facts before they speak by a campaign that aims to stamp out bad science.

Sense About Science, a charity that promotes the importance of scientific evidence, warns that celebrities are prone to backing theories and therapies that make no scientific sense and offers them the chance to check their facts first.

It has published a leaflet explaining why some theories promoted by celebrities are wrong and giving a telephone number they can call to be put in contact with experts before getting involved in a campaign.

The leaflet is being sent to luxury hotels, nightclubs and bars, airport lounges and football clubs.

In it, the charity points out that Madonna has spoken of the need to develop a means of “neutralising radiation” which is impossible, while Ms Stevenson used the opportunity of her role in a drama about the MMR vaccine to advance the discredited claim that it is not safe.

Lady McCartney and the pressure group People for the Ethical Treatment of Animals have wrongly claimed that drinking milk is linked to childhood obesity.

David Baddiel, the comedian, Melinda Messenger, the model, and Sharron Davies, the swimmer, were all involved in a campaign by the environmental group WWF about dangerous chemicals in the human body which has been derided by scientists as scaremongering. Toxicologists said that the levels of such chemicals in the body were too insignificant to worry about.

The leaflet also exposes scientific mistakes made by the actors Joanna Lumley and Jenny Seagrove, the lifestyle adviser Carole Caplin and the television presenter Gillian McKeith.

Leading scientists explain why claims are wrong, and encourages celebrities to ring a number to be put in touch with experts who can verify facts.

Tracey Brown, director of Sense About Science, said that nobody expected celebrities to be scientific experts.

She said: “We know some people aren’t interested in good science or evidence. We are equally sure some will be glad to talk through claims they are asked to front, because they take their impact seriously. But it’s not been obvious where to go for that. We are producing this leaflet to show those in the public eye how easy it is now to get help from scientists.”

She said that the charity was frequently sent examples of celebrities promoting theories that made no sense.

“We have been working out ways for science to be more available,” she said. “I think this leaflet is a friendly hand.” Some public figures have welcomed the initiative.

Derren Brown, the TV illusionist, said: “We’re more than aware that the media prefer a shocking story over delicate fact. In areas like food, environment and medicine, this can have serious results: such as a now dangerously low level of British kids inoculated against MMR following an unfounded media scare.

“Scientists, traditionally a quiet bunch, are now trying to redress the balance and find ways of promoting fact over misinformation.”

Simon Singh, the science writer and former presenter of Tomorrow’s World who is a trustee of Sense About Science, said: “There are numerous examples of actors or musicians scaremongering over vaccines or pesticides when they have little or no knowledge of the subject.

“Celebrities can have a huge influence on the public, but they need to make sure they are doing more good than harm by checking their facts before making any proclamations.”

Professor John Toy, of Cancer Research UK, said: “Celebrities often have a real effect on how members of the public view particular issues, especially health and lifestyle. They have a major responsibility, therefore, to be well-informed before they make statements endorsing particular treatments or products.”