New research suggests that passive exposure to bleach in the home is linked to higher rates of childhood respiratory and other infections.

The findings from this study are of public health concern in light of the widespread use of bleach in the home, say the researchers, who call for further more detailed studies in this area.

For the study, researchers looked at the potential impact of exposure to bleach in the home among more than 9000 children between the ages of 6 and 12 attending 19 schools in Utrecht, The Netherlands; 17 schools in Eastern and Central Finland; and 18 schools in Barcelona, Spain.

Their parents were asked to complete a questionnaire on the number and frequency of flu; tonsillitis; sinusitis; bronchitis; otitis; and pneumonia infections their children had had in the preceding 12 months. And they were asked if they used bleach to clean their homes at least once a week.

Use of bleach was common in Spain (72 percent of respondents) and rare (7 percent) in Finland. And all Spanish schools were cleaned with bleach, while Finnish schools were not.

Researchers found that the number and frequency of infections were higher among children whose parents regularly used bleach to clean the home in all three countries.

These differences were statistically significant for flu, tonsillitis, and any infection.

The risk of one episode of flu in the previous year was 20% higher, and recurrent tonsillitis 35% higher, among children whose parents used bleach to clean the home.

Similarly, the risk of any recurrent infection was 18% percent higher among children whose parents regularly used cleaning bleach.

Researchers warned that this is an observational study, so no definitive conclusions can be drawn about cause and effect.

The findings are detailed in the journal Occupational & Environmental Medicine.