Sanitary infant environment suspected for high allergy incidence

Some 86 percent of people born in the 1970s have allergies against things such as mites and cedar pollen, researchers at the National Center for Child Health and Development in Tokyo estimated Monday.

The figure is extremely high, even compared with other countries such as New Zealand, where there are high incidences of allergies, as the percentages in reports from those countries stand at below 70 percent, the researchers said.

“We have recently been paying attention to the assumption that babies who were raised in sanitary environments are more prone to having allergies,” said Hirohisa Saito, head of the center’s Department of Allergy and Immunology.

“In Japan, the sanitary conditions involving raising babies improved dramatically in the 1970s, and this may have to do with the results we have seen in our studies,” said Saito, who led the research on allergies among people mainly in their 20s.

The project involved taking blood samples from 258 Jikei University students who were born between January 1971 and March 1980 and testing whether the samples produce an antibody called IgE when exposed to 14 types of allergens. If large amounts of the antibody are detected, researchers can determine that the person is allergic to the specific allergens that triggered the production of IgE, according to the researchers.

Of the subjects, 222 people, or 86 percent, were allergic to one or more of the allergens. Among those who were born and raised in cities with populations of more than 1 million, the percentage was 92 percent, while the rate was 80 percent among people from small and midsize cities.

In a similar study conducted among about 50 people working at medical-related companies, 88 percent of subjects born in the 1970s had allergies, while the rate was only 44 percent for those born in the 1950s and 1960s, the researchers said.