Study backs asthma link with excessive washing of toddlers

By LORNA DUCKWORTH

Toddlers who are frequently washed are more likely to develop asthma and eczema, a scientific study says.

The results support the so-called hygiene hypothesis that excessive washing and cleanliness are responsible for a rapid increase in the two diseases.

Researchers investigated how frequently 11,000 small children in Britain were bathed or washed.

Parents then said whether their children suffered the symptoms of asthma or eczema before they were six months old and when they were between two and four.

The survey showed "increased levels of hygiene" were linked to higher asthma and eczema rates when children were 30 to 42 months old, but not in the first six months.

The hygiene hypothesis, raised in a major Herald analysis of asthma in this country, seeks to explain why the disease is spiralling upwards while the health and hygiene of Western people is rapidly improving.

In the Archives of Disease of Childhood, the researchers suggest children who become dirty are exposed to more bacteria and infections that prime their immune system and protect them from disease.

They say parents obsessed with cleanliness may be reluctant to let their children play outdoors or have contact with others, so they have less contact with bugs.

The authors, led by Dr Andrea Sherriff of Bristol University, conclude: "The importance of hygiene in public health should not be dismissed. However, the creation of a sterile environment through excessive cleanliness may potentially be harmful to the immune system."

The study shows that for every increased unit in the hygiene score the likelihood of a child wheezing between the age of 30 and 42 months increased by 4 per cent.

In children under the age of six months, wheezing was partly explained by high levels of chemicals used in household cleaners.

Eczema was associated with high hygiene scores, irrespective of the amount of chemicals used.

The Herald investigation discovered asthma affects one in every six people in New Zealand and costs more than $800 million each year.

It is now the cause of most admissions to hospital for children and the number of sufferers increases 50 per cent every 15 years.

Asthma ranks as New Zealand's third-worst disease (behind depression and anxiety disorders) for its effects on the quality of life.

- INDEPENDENT


nzherald.co.nz/health