Study Indicates Bleach Neutralizes Mold Allergens

Researchers at the National Jewish Medical and Research Center (NJMRC) have demonstrated that bleach not only kills common household mold, but may also neutralize the mold allergens that cause most mold-related health complaints. The study, published in the September issue of The Journal of Allergy and Clinical Immunology, is the first to test the effect on allergic individuals of mold spores treated with common household bleach.

We have known that bleach can kill mold, however dead mold may often remain allergenic," said lead author Dr. John Martyny, PhD, associate professor of medicine at NJMRC. "With these new findings, it appears that mold treated with bleach lowers allergic reactions, under laboratory conditions, in patients allergic to mold.

The need for denaturing or neutralizing mold allergens is a critical step in mold treatment that has not been fully understood, Martyny said. Currently most recommendations for mold remediation stop at simple removal or killing of mold when dead mold retains its ability to trigger allergic reactions, according to Martyny.

NJMRC researchers began by growing the common fungus Aspergillus fumigatus on building materials for two weeks, and then sprayed some with a household bleach solution (1:16 bleach to water), some with Tilex® Mold & Mildew Remover, a cleaning product containing both bleach and detergent, and others only with distilled water as a control. 

The researchers then took the mold and conducted standard skin-prick tests on allergy-sensitive patients. Seven of the eight allergic individuals did not react to the bleach-treated building materials, and six did not react to the Tilex-treated building materials.  The results suggest that, under laboratory conditions, fungal-contaminated building materials treated with dilute bleach or a bleach-based product, may have significantly reduced allergic health effects.

In order to assure that the bleach solutions will function similarly under actual field conditions, additional experiments will need to be conducted, said Martyny. We do believe that there is strong evidence that bleach can significantly reduce the allergenic properties of common household mold under some conditions.

This study was partially funded by a grant from the Clorox Company.