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United States Department of Agriculture

Agricultural Research Service

Mildews Don’t Cotton to These Swabs / May 26, 1997 / News from the USDA Agricultural Research Service

Mildews Don’t Cotton to These Swabs

By Jill Lee
May 26, 1997

Keeping cotton swabs mildew-free is critical to physicians and consumers. A new sterilization treatment, using the anti-bacterial agent methocel, can ensure green and black mildew never gain a toehold.

The key is applying methocel properly. A scientist with USDA’s Agricultural Research Service developed effective methods for treating the swabs with this environmentally-safe mildew killer, based on research begun at a private company and completed at ARS.

Heat-based bleaching treatments that give cotton swabs their clean white look usually kill microorganisms. But heat, humidity in darkness and the cotton’s inner moisture can undo the bleach’s protective barrier over time. Tests with methocel show a longer-lasting protection.

The ARS scientist worked in collaboration with engineers at a Connecticut-based cotton swab company to solve the methocel application problem. The Connecticut company was concerned because their swabs were stored under hot, humid conditions in a Florida warehouse. The company engineers said the state’s steamy environment was giving the microbes an unfair advantage.

The engineers estimate that preventing a mildew outbreak in the stored swabs will save the company as much as $100,000 annually. This treatment is good news for the entire cotton swab industry, which represents $100 million in U.S. sales, the scientists said. Ensuring quality swabs helps protect this value-added commodity market for cotton.

Extensive clinical tests show swabs treated with methocel are perfectly safe for human skin. The new application method is also designed to protect plant workers. And, at just 25 cents per pound, methocel is relatively inexpensive. The cost is even more reasonable since less than 0.01 percent active ingredient is needed to sterilize swabs.

Scientific contact: D. V. Parikh, ARS Southern Regional Research Center, New Orleans, La. , phone (504) 286-4331, fax (504) 286-4234,

Last Modified: 5/9/2014
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