Malodor counteractants

THE SCIENCE OF COSMETICS Edward M. Jackson, PhD

Malodor Counteractants IR FRESHENER PRODUCTS have traditionally been malodor-masking products. However, new malodor counteractant technology is changing the air freshener product formulas as well as expanding into product types that are not air fresheners. Consumer exposure to malodor counteractants is something that the practicing dermatologist should be aware of because of the potential for exposure to the skin and eyes from products containing malodor counteractants. This column will explore malodors and the malodor counteractant technologies currently in use in both air freshener products and cosmetic products. THE PHYSIOLOGY OF MALODOR DETECTION

Malodors are chemicals that both humans and animals detect with the olfactory sense. When a malodor touches an appropriate olfactory nerve, that nerve sends a signal to the brain, which correlates it to stored signals in the brain. When that signal is matched to a stored signal, the malodor is identified. This results in some form of action such as moving away from the source of the malodor, using an air freshener, or increasing the ventilation in the area. This is basic in understanding how modern malodor counteractants work. Table 1 lists the various types of malodors: chemical odors, body odors, organic odors, and product odors. Readily recognizable chemical odors are ammonia and hydrogen sulfide. Methylmercaptan and the mercaptans as a class are typically a malodor problem with hair dye products. Short-chain fatty acids are part of the body odor family of chemicals as well as odors from unscented products with oleaginous bases. Trimethyl amines, along with ammonia, hydrogen sulfide, and the mercaptans, are another gaseous malodor that must be controlled under the federal Offensive Odor Control Law. Body odors arise from perspiration and bodily

secretions. Axillary perspiration is principally composed of the malodor chemical known as (E)-3methyl-2-hexanoic acid, whereas foot perspiration is comprised chiefly of isovaleric acid. 1 All of us are familiar with the organic odors from cooking, petroleum, smoke, mildew, mold, and solvents such as gasoline and alcohol. Finally, certain products have malodors, such as iodine antiseptics and disinfectants of various kinds. MALODOR COUNTERACTANTS IN AIR FRESHENERS AND COSMETICS

Table 2 lists the various types of air fresheners currently available. Their forms range from simple liquids to sprays to various types of impregnated materials. Some of the latter are activated by heat, such as impregnated candle wax and nightlight types of products that are plugged into electrical outlets. The malodor counteractants used in these air freshener products are now finding their way into cosmetics and other products. Unscented or unfragranced cosmetics often have an oleaginous base odor that is not attractive to consumers. The addition of a single ingredient or complex formulas of maldor counteractant chemicals can either mask the base odor or actually neutralize it entirely. MALDOR COUNTERACTANT TECHNOLOGIES

There are five types of malodor counteractant technologies currently in use (see Table 3). Masking malodors with either single ingredients, such as vanilliu or menthol, as well as simple

FromJackson ResearchAssociates, Inc, Sumner, WA. Address reprint requests to Edward M. Jackson, PhD, President, Jackson ResearchAssociates, Inc, 20203 121st St Court E, Sumner, WA 98390. Copyright © 1995 by W..B. Saunders Company 1046-199X/95/0603-0012503. 00/0

American Journa/of Contact Dermatitis, Vol 6, N o 3 {Se ptem ber), 1995: p p 185-187

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EDWARD M. JACKSON Table 1. Malodors

Table 3. Malodor Counteractant Technologies

Chemical odors Ammonia (NH3) Hydrogen sulfide (H2S) Short-chain fatty acids Trimethyl amine ([CH3]3N) Methylmercaptan (CH3SH) Body odors Perspiration Bodily secretions Organic odors Cooking odors (fish, cabbage) Mildew Mold Petroleum Smoke (tobacco, wood) Solvents (gasoline, alcohol) Product odors Antiseptics (iodine) Disinfectants Hair dyes Unscented product odors (oleaginous bases)

Masking odors Physical entrapment of odors Chemically complexing odors Quenching odors Physicochemical interaction with odors

mixtures of fragrance ingredients is the oldest and most basic type of malodor counteractant technology. Masking is simply covering up a malodor with a more pleasant odor. The result is either mixing the malodor with the pleasant odor or overpowering the malodor with the pleasant odor. In the United States, deodorants are classified as cosmetics and antiperspirants as over-the-counter drugs based on the fact that deodorants mask or cover up body odor whereas antiperspirants reduce the amount of perspiration containing the malodor. Physical entrapment of the malodor, making it unavailable for sensory perception, is perhaps the second oldest technology. Cyclodextrins, 2,3 abscents powders, 4 and the zeolites are all used in both air fresheners and cosmetic products to entrap various Table 2. Types of Air Fresheners

Absorptive materials in decorative containers Blotter paper Corn cob shavings Candle wax (impregnated with malodor counteractant) Cardboard Cedar shavings Electrically activated (night-light types for electrical outlets) Liquids Sachets (impregnated organic material) Potpourri Pumps Aerosol pumps Spray pumps

types of malodors. These same materials can be used to entrap and time release various ingredients as well. These chemicals are a kind of crystalline forerunner to the microencapsulation technologies. 5 Another form of malodor counteractant technology is the actual chemical complexing of the malodor with another chemical, which results in the effective sensory neutralization of the malodor. Metazene (Pestco Inc, Pittsburgh, PA), 6 Epoleon (Epoleon Corp of America, Torrance, CA), 7 and Veilex (Bush Boaks Allen Inc, Montvale, NJ) 8 are all effective chemical complexing mixtures. Sodium chlorite and D-limonene are singleingredient chemical complexing agents and, as such, their mechanisms of action are a little better understood. Sodium chlorite is acted on by low pH malodors that work like inorganic or organic acids on it. The chemical reaction between the low pH malodor and sodium chlorite results in chlorous acid that is unstable, readily giving off oxygen. When the activating agent on sodium chlorite is an inorganic or organic acid, the process is a bleaching process. 9

D-limonene has traditionally been thought to be a masking ingredient much like vanillin or menthol. However, commercial launderers discovered that their use of D-limonene for its degreasing properties on petroleum-soiled clothes from refinery workers and auto mechanics also resulted in the elimination of the residual petroleum smell from these commercially laundered work clothes. ~0,11 Quenching is a phenomenon in fragrance formulation that is known and taken advantage of but little understood. It may be chemical complexing or physicochemical or something quite different. Until its chemistry is understood, it should be considered a separate malodor counteractant technology. Quenching fragrance ingredient sensitizers by carvone, cinnamic aldehyde, citral, farnesol, and other fragrance ingredients has been reported.52 The final malodor counteractant technology takes advantage of a chemical or mixture altering the physicochemical characteristics of the malodor.

MALODOR COUNTERACTANTS

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As an e x a m p l e of this type o f technology, E x o d o r

CONCLUSION

(Walex Products Co, W i l m i n g t o n , N C ) has b e e n

A n awareness of the various types of m a l o d o r c o u n t e r a c t a n t technologies will increase the practicing dermatologist's insight into the increasing n u m ber of chemicals that the c o n s u m e r m a y be exposed to in air fresheners and in their use of cosmetic products.

d o c u m e n t e d as c o m p l e x i n g with isovaleic acid due to its strong affinity for f o r m i n g a polar covalent bond with isovaleric acid. This actually prevents the isovaleric acid f r o m vaporizing, which m e a n s it cannot escape to be d e t e c t e d as a malodor. 13

REFERENCES 1. Kanda F, Yagi E, Fukuda M, et al: Quenching short chain fatty acids (SCFA) responsible for body odors. Cosmetics &Toiletries 108:67-93, I993 2. Amann M, Dressnandt G: Solving problems with cyclodextrins in cosmetics. Cosmetics & Toiletries I08:90-95, 1993 3. Vaution C, Hutin M, Glomot F, eta]: The use of cyclodextrins in various industries, in Duchene D (ed): Cyclodextrins and Their Industrial Uses. Paris, France, Editions d'Sante, 1987, chap 8 4. Abscents Deodorizing Powders, product brochure, UOP, Tarrytown, NY 5. Jackson EM: Encapsulation and its toxicologicalimplications. Cosmetics & Toiletries 108:47-48, 1993 6. Metazene: An odor counteractant for the retail, institutional & industrial markets. Soap, Cosmetics and Chemical Specialties, April 1993, pp 48-61 7. Epoleon Corporation of America: Epoleon Neutraliz-

ing Agents, product brochure. Torrance, CA, Epoleon Corporation of America 8. Schleppnik AA: Method, compositions and compounds, useful in room fresheners employing cyclohexyl alcohol and ester derivatives. United States patent 4,622,221, November 11, 1986 9. Degussa AG: Sodium chlorite, product brochure. Frankfurt, Germany, Degussa AG 10. McBride J: Arizona Chemical Company presentation to the 1lth International Naval Stores Meeting in New Orleans, LA, October 24, 1984 11. Eisenberg MM: Citrus terpenes. Industrial Launderer January" 1990, p 19020 12. Larsen WG: Perfume dermatitis.J Am Acad Dermatol 12:I-9, I985 13. Kintish L: Odor fighting with Exodor. Soap, Cosmetics and Chemical Specialties August 1992, p 20