Household cleaning products could be linked to childhood asthma, research published today suggests.
A study of 2,000 newborns found those whose parents most frequently used items such as dishwashing detergent, laundry products and surface cleaner were 37 per cent more likely to be diagnosed with asthma by the age of three.
It is thought cleaning chemicals may damage the lining of the airways in babies if they are very frequently exposed to the products.
This could lead to an overactive inflammatory response in the respiratory tract.
More than five million people in Britain have asthma, including 1.1million children.
After years of warning about outdoor air pollution, caused by traffic and factory emissions, experts are increasingly concerned about the dangers of indoor pollution.
The problem of airborne chemicals - many from cleaning products - is exacerbated by modern energy-efficient, air-tight homes.
The latest research, led by Canadian scientists at Simon Fraser University in Vancouver, involved 2,022 families.
Each family, whose babies were younger than four months, were asked how often they used a list of 26 products, such as bleach, detergents and polish.
Washing up liquid was the most commonly used - with 90 per cent of families using it each day.
Dishwasher detergent, surface cleaner, laundry detergent and toilet cleaner were used at least once a week by most families.
The researchers, whose findings are published in the Canadian Medical Association Journal, then tracked the babies for three years, carrying out annual tests.
The team found that the quarter of children whose families had the highest frequent cleaning product use were the most likely to develop asthma.
By three, these children were 37 per cent more likely to have a diagnosis of asthma and 35 per cent more likely to have a recurrent wheeze when compared with the quarter of families with the lowest cleaning product use.
The team said scented and sprayed cleaning products were associated with the highest risk.
Study leader Professor Tim Takaro said: ‘Our study looked at infants, who typically spend 80 to 90 per cent of their time indoors and are especially vulnerable to chemical exposures through the lungs and skin due to their higher respiration rates and regular contact with household surfaces.’
Researcher Jaclyn Parks said parents should read labels on products and choose those that do not contain volatile organic compounds.
Using products that are not sprayed can also help.
An article in the same journal said the study had exposed a ‘potentially important public health concern’.
And it warned: ‘Even products labelled “environmentally friendly” or “green” may contain harmful substances, as such claims are largely unregulated.’