PARENTS should strip their houses of fitted carpets and other soft furnishings
if they wish to reduce the risk of their children developing asthma later
in life, a researcher in the US warned this month. Thomas Platts-Mills of
the University of Virginia sounded the alarm after publishing a study in
the New England Journal of Medicine (vol 324, p 502) showing that a one-year-old
is more likely to develop asthma later in life if exposed to high levels
of an allergen generated by mites in carpets.
House-dust mites are about one third of a millimetre long and transparent.
Living in beds, curtains and other soft furnishings, they deposit an allergen
called Der p 1 in faecal pellets that small children may inhale. According
to Platts-Mills, mites favour 鈥榗omfortable鈥� homes, so improvements in living
standards have raised Der p 1 levels sharply in Britain and the US.
鈥榃e have put in fitted carpets and central heating, so we are living
in optimal areas for mite growth,鈥� said Platts-Mills. 鈥極ur estimates of
faecal particles were up at 500 000 per gram of house dust.鈥�
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Platts-Mills and an Anglo-American team analysed dust samples taken
in 1979 from the homes of 59 one-year-olds born in Dorset, southwest England.
In 1989 they checked the children, now 11 years old, for asthma. They found
that one-year-olds living in homes with house dust containing more than
10 micrograms of Der p 1 per gram were 4.8 times more likely to have developed
asthma at the age of 11 than those not exposed.
Some of the children developed an allergy to Der p 1 but failed to progress
to asthma. However, those with the allergy were 14.6 times more likely to
develop asthma than those without.
In its conclusion, the team said: 鈥楾here seems to be sufficient evidence
to suggest a causal relationship between house-dust mites and asthma. Exposing
young children to high levels of foreign proteins in their homes should
be regarded as an important health risk.鈥�
Death rates from asthma are rising even though drug treatments for the
disease have improved. 鈥楾his is a worldwide problem,鈥� said Platts-Mills.
鈥業t is a risk factor in Dorset, Sydney, New Zealand, the US and Sao Paulo
in Brazil.鈥�
Platts-Mills said the mites thrive in warm, humid environments. He was
sceptical about the ability of either vacuum cleaners, special carpets or
chemical mite killers to combat the problem. Instead, he favours changing
housing design. 鈥楨ither you dry the house or cool the house or you remove
the carpet,鈥� he said.
