RIPH SYMPOSIUM: ARE WE TOO CLEAN?

A symposium entitled ‘Are we too clean? A question of immunity balance’ was held on September 9th 2002 in London at the Royal Institute of Public Health. The keynote speaker, Professor David Strachan from St George’s Hospital Medical School, London, UK, gave a frank talk about the conflicting evidence that still surrounds his ideas on the Hygiene Hypothesis, which he first proposed 10 years ago. While not abandoning his notions he recognised that the hypothesis was still far from proven. He outlined how the link between hygiene and asthma was very weak and that the hypothesis now seemed to be more aligned to hay fever and atopic eczema.

As the symposium progressed, Professor John Warner from the Department of Child Health, University of Southampton, UK, was invited to the speakers’ podium to review alternative explanations for the increase in atopy. Among the factors discussed were those such as diet, obesity and maternal age. He mentioned how, until very recently, he had always been a supporter of the Hygiene Hypothesis. However, he now felt that the more he reviewed the evidence the more convinced he was that it was not the answer.

John Pickup, a Consultant in Scientific Issues, reviewed trends in the consumption of hygiene products. He described how soap and detergent use had increased worldwide during the last 30 years, but estimated that the increase in Europe was only around 50-75%. Current patterns of soap and detergent use were also shown not to correlate with trends in atopy. Interestingly, within Europe, atopy was detailed as being greatest in the UK, Ireland and in some parts of Finland – the very same countries that were recorded as having only moderate soap and detergent use. On the other hand, atopy in southern Europe, where soap and detergent use is highest, is low by comparison. The presentation also illustrated how microbes continue to be found in the home in substantial numbers and how hygiene standards remain poor. Whilst not dismissing the Hygiene Hypothesis, Mr Pickup’s studies did not show any conclusive evidence that home hygiene or soap and detergent use was a factor in atopy.

Presentations from Dr Martin Schweiger, Consultant for Communicable Disease Control, Leeds, UK and Professor Hugh Pennington of Aberdeen University, reviewed trends in community hygiene and in infectious diseases. Both talks reiterated and futher developed the theme that we are far from being too clean or free from disease, and that the major improvements in hygiene and health were those that occurred 100 years ago, not in the last three decades.

Dr Ros Stanwell-Smith (Public Health and Epidemiology Consultant) briefly reviewed how probiotics and dirt vaccines could be used as ways of possibly reversing the increase in atopy where lack of microbial exposure is the cause. Later, Dr Martin Jones of Unilever Research Port Sunlight, Merseyside, UK, showed how the targeted hygiene approach developed by the IFH provided the most effective way of preventing the spread of harmful microbes, whilst still allowing incidental exposure to environmental microbes if this proved to be an important factor in the regulation of the immune system. The major challenge is how to persuade the general public to carry out hygiene measures more effectively.

In the concluding discussion, the panel remained unconvinced or undecided about the validity of the Hygiene Hypothesis but recognised the dangers of neglecting hygiene.

The Royal Institute of Public Health is intending to publish a more detailed synopsis of this symposium in the not too distant future in their journal ‘Health and Hygiene’.