MONDAY, Nov. 29 (HealthDay News) -- Children and teens who are overexposed to antibacterial soaps that contain the chemical triclosan may be at increased risk for hay fever and other allergies, a finding that suggests that being too clean can actually make people sick, researchers say.

The study also found that exposure to higher levels of the chemical bisphenol A (BPA) may weaken an adult's immune system.

Triclosan is an antimicrobial agent widely used in products such as antibacterial soaps, toothpaste, medical devices and diaper bags. BPA, which is used to make many types of plastics and other consumer products, is believed to affect human hormones.

In this study, researchers at the University of Michigan School of Public Health analyzed data from the 2003-2006 National Health and Nutrition Examination Survey. They compared levels of triclosan and BPA in the urine with cytomegalovirus (CMV) antibody levels and diagnosis of allergies or hay fever in adults and children over age 6.

"We found that people over age 18 with higher levels of BPA exposure had higher CMV antibody levels, which suggests their cell-mediated immune system may not be functioning properly," study first author Erin Rees Clayton said in a university news release.

The investigators also found that children and teens with higher levels of triclosan were more likely to have been diagnosed with hay fever and other allergies.

The study findings are published in the Nov. 30 online edition of the journal Environmental Health Perspectives.

"The triclosan findings in the younger age groups may support the 'hygiene hypothesis,' which maintains living in very clean and hygienic environments may impact our exposure to microorganisms that are beneficial for development of the immune system," principal investigator Allison Aiello, an associate professor at the University of Michigan School of Public Health, said in the news release.

Aiello noted that triclosan may change the microorganisms to which people are normally exposed in such a way that children's immune system development is affected.

"It is possible that a person can be too clean for their own good," Aiello suggested.

More information

The Alliance for the Prudent Use of Antibiotics has more about antibacterial agents.