There's some new research that might not sit well with fastidious new mothers and clean-freak new fathers.
Exposure to pet dander, roach droppings and other household bacteria in the first year of life appears to reduce the chances a person will suffer from allergies or asthma, according to a new study.
Researchers at Johns Hopkins Children’s Center found that exposure to allergens in the first year of life was important in order for exposure to be beneficial.
Previous studies had shown that children who grew up on farms are less likely to develop allergies or asthma because of their exposure to allergens,
"Our study shows that the timing of initial exposure may be critical," says study author Robert Wood, M.D., chief of the division of allergy and immunology at the Johns Hopkins Children's Center in a statement released today
. "What this tells us is that not only are many of our immune responses shaped in the first year of life, but also that certain bacteria and allergens play an important role in stimulating and training the immune system to behave a certain way."
Researchers hope the findings will lead to ways to prevent allergies and wheezing, which are both precursors to asthma.
Asthma is one of the most common pediatric illnesses, affecting some 7 million children in the United States, according to the U.S. Centers for Disease Control and Prevention.
For the study, Wood and his colleagues tracked 467 inner-city newborns from Baltimore, Boston, New York and St. Louis. Over three years, they visited them to measure levels and types of common allergens in their homes.
They also tested the children for allergies and wheezing using blood tests, skin-prick tests, physical exams and parental surveys.
They also took bacterial counts on samples of dust collected from some of the homes.
What they found was that children exposed to mouse and cat dander as well as cockroach droppings in their first year of life “had lower rates of wheezing at age three, compared with children not exposed to these allergens soon after birth.”
Researchers also found that exposure to all three was better than one, two or none.
Wheezing was three times more common for children not exposed to allergens compared to those who were exposed to all three.
A greater variety of bacteria proved better at stemming allergies and wheezing, researchers said.
The amount of allergens was also critical, as researchers said children free of wheezing and allergies at age three had gorwn up surrounded by the highest levels of household allergens. Forty-one percent of those without wheezing and allergies grew up in bacteria-rich homes. Only 8 percent of those who had wheezing and allergies had been exposed to allergens in their first year of life.
According to Wood, the children tracked in the study are now turning seven and are being checked again to see if exposure to allergens early in life was still reducing the prevalence of allergies and wheezing.
A report on the study was published today in the Journal of Allergy and Clinical Immunology