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Bleach Found To Neutralize Mold Allergens

September 25, 2005
National Jewish Medical and Research Center
Researchers at National Jewish Medical and Research Center (NJMRC) have demonstrated that dilute bleach not only kills common household mold, but may also neutralize the mold allergens that cause most mold-related health complaints.
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"It has long been known that bleach cankill mold. However, dead mold may remain allergenic," said lead authorJohn Martyny , Ph.D., associate professor of medicine at NationalJewish. "We found that, under laboratory conditions, treating mold withbleach lowered allergic reactions to the mold in allergic patients."

Theneed for denaturing or neutralizing mold allergens is a critical stepin mold treatment that has not been fully understood. Currently, mostrecommendations for mold remediation call for removal since dead moldretains its ability to trigger allergic reactions, according to Dr.Martyny.

The researchers grew the common fungus Aspergillusfumigatus on building materials for two weeks, and then sprayed somewith a dilute household bleach solution (1:16 bleach to water), somewith Tilex® Mold & Mildew Remover, a cleaning product containingboth bleach and detergent, and others only with distilled water as acontrol. They then compared the viability and the allergenicity of thetreated and untreated mold.

The researchers found that the use ofthe dilute bleach solution killed the A. fumigatus spores. When viewedusing an electron microscope, the treated fungal spores appearedsmaller, and lacked the surface structures present on healthy spores.In addition, surface allergens were no longer detected by ELISAantibody-binding assays, suggesting that the spores were no longerallergenic.

The National Jewish researchers then allergy-testedeight Aspergillus -allergic individuals with solutions from the bleachand Tilex®-treated building materials. Seven of the eight allergicindividuals did not react to the bleach-treated building materials, andsix did not react to the Tilex®-treated building materials. Thisevidence suggests that, under laboratory conditions,fungal-contaminated building materials treated with dilute bleach orTilex® may have significantly reduced allergic health effects.

"Thisstudy was conducted under controlled laboratory conditions. In order toassure that the bleach solutions will function similarly under actualfield conditions, additional experiments will need to be conducted,"said Dr. Martyny. "We do believe, however, that there is good evidencethat bleach does have the ability to significantly reduce theallergenic properties of common household mold under some conditions."

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

NationalJewish is the only medical and research center in the United Stateddevoted entirely to respiratory, allergic, and immune-system diseases,including asthma, allergies, and chronic obstructive pulmonary disease.It is a non-profit, non-sectarian institution dedicated to enhancingprevention, treatment, and cures through research, and to developingand providing innovative clinical programs for patients regardless ofage, religion, race, or ability to pay.

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The above story is based on materials provided by National Jewish Medical and Research Center. Note: Materials may be edited for content and length.

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National Jewish Medical and Research Center. "Bleach Found To Neutralize Mold Allergens." ScienceDaily. ScienceDaily, 25 September 2005. <>.
National Jewish Medical and Research Center. (2005, September 25). Bleach Found To Neutralize Mold Allergens. ScienceDaily. Retrieved April 25, 2015 from
National Jewish Medical and Research Center. "Bleach Found To Neutralize Mold Allergens." ScienceDaily. (accessed April 25, 2015).

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