An´alisis de los resultados con acoplamiento esp´ın-

Contents

Introduction ...163 Scope and microbiological targets of preservation ...166 Preservation of finished products ...167 Formula parameters ...168 Commercial preservatives ...169 Preservative adjuncts...172 Perfumes and natural preservatives ...172 Process considerations ...172 Role of packaging ...173 Preservation during manufacturing ...173 Raw materials preservation...174 System preservation ...174 Conclusions...175 References...175

Introduction

In order to explain the pathways to cosmetic microbiological quality includ-ing the strategies for preservation, it is necessary to identify the unique nature of cosmetic products. The most appropriate starting place is the definition established in the U.S. Food, Drug, and Cosmetic Act.¹ The term cosmetic covers:

(1) articles intended to be rubbed, poured, sprinkled, or sprayed on, introduced into, or otherwise applied to the human body or any part thereof for cleansing, beautifying, promoting attractive-ness, or altering the appearance, and (2) articles intended for use

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164 Cosmetic Microbiology: A Practical Approach as a component of any such articles; except that such term shall not include soap.

The great diversity of intended uses identified by the act requires that successful preservation can only be established if one considers all aspects of development from concept and design through manufacturing to the last consumer use before disposal. Complexity is immediately encountered with the wide range of cosmetic ingredients that includes components as refined as reagent quality chemicals and as unknown as obscure plant extracts. The microbiological quality of each component must be main-tained under control.

This is no easy task — a reading of a typical product label reveals tens of ingredients, including a “perfume” that itself is composed of a score or more compounds. Ingredients are combined in unique ways including con-trolled chemical reactions, partial precipitation and crystallization processes, precise blending, uniquely applied temperature gradients, and particle siz-ing and emulsification to form solutions, suspensions, emulsions and mix-tures. Products are dispensed as fluids, pastes, creams, sticks, loose and pressed powders, and solids at rates of hundreds of units or more per minute and in quantities ranging from a fraction of an ounce to more than a pound.

Packaged units such as bottles, tubes, sachets, pens, pans, paper-wrapped bars, and aerosols may be combined with implements such as brushes, wands, pads, sponges, and other microbiologically sensitive articles, each necessitating its own microbiological quality controls.

Once packaged in final product form, these cosmetic units are expected to remain stable through the vagaries of temperature and humidity during distribution and ultimate consumer acquisition, use, and storage. Finally, once they arrive in the hands of consumers, the microbiological quality of cosmetics is subjected to special risks because consumers intentionally add water, spit on mascara wands, share cosmetics, and store them under con-ditions potentially hostile to preservative stability — in hot cars, damp bathrooms, and wet showers.

Each of the steps and events involved in taking raw materials through product formulation and consumer use is unique to the cosmetics industry, both in complexity and risk for microbiological compromise. When such compromise occurs, it is not trivial and affects consumer health and product integrity and carries regulatory compliance consequences.^2–4

Of these, clearly the consumer health risk is the most important. Infec-tion, illness, and even death have been attributed to microbes in a contam-inated cosmetic. Hopfer et al.⁵ reported infections and one death attributable to contaminated shampoo used by neutropenic patients about to undergo chemotherapy. They visited a hospital salon where their hair was washed with a shampoo product diluted with tap water and their heads were shaved to address anticipated alopecia. The diluted shampoo used was heavily contaminated with Pseudomonas aeruginosa that infected small nicks caused

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chapter seven: Preservation strategies 165 by shaving. These infections fulminated in these immunosuppressed patients and proved fatal to one.

In other exposures to microbially compromised products, exposure to contaminated mouthwash in an intensive care unit resulted in 74 nosocomial infections.⁶ Infections secondary to indirect exposure to contaminated cos-metics have also been reported after a number of hospital infections were traced to a nurse’s use of a contaminated hand cream.⁷

Cosmetic-related infections can also occur in consumers’ homes. Signif-icant eye infections and even blindness have resulted from ocular infections following the use of contaminated mascara products; mascara brushes facil-itated infection by abrading eye surfaces.^8,9 In each of the above cases, a form of physical or immune compromise-facilitated infection occurred and such conditions are not unusual. About 20% of the U.S. population is immuno-compromised.¹⁰

While consumer health is the primary concern of the cosmetic microbi-ologist, product functionality and esthetics are subject to direct risk of micro-biological contamination. The phenomenal degradative capabilities of typi-cal cosmetic contaminants place almost every cosmetic ingredient at risk, from surfactants to antimicrobial solutions that may be incorporated into products.^11–13 The clouding of clear fluids represents visible degradation, but also at risk are opaque products such as emulsions. These products are subject to microbe-mediated phase separation, a phenomenon that can result from the mere presence of dead bacteria.^14–16

Ironically, some isolates of the common Pseudomonas aeruginosa cosmetic contaminant have been found to form emulsions from otherwise distinct lipid–water combinations.¹⁷ Microbial contamination can also compromise product appearance via the pigmentation effects characteristic of contami-nants such as the red prodigiosin of Serratia marcescens¹⁸ and the greenish pigments of Pseudomonas aeruginosa.¹⁹ Finally, product perfume aroma is a uniquely important quality parameter of cosmetics and frequently serves as an effective trademark for a product. While product aroma entails great formulation effort, it is readily compromised by microbially synthesized volatile organic compounds that have thresholds of detection at parts-per-million if not parts-per-trillion levels.²⁰ These compounds include skatole, indole, hydrogen sulfide, and diverse fungal volatiles.^21,22

Sharing manufacturers’ concerns for consumer health, regulatory bodies are alert to contaminated cosmetics. A review of FDA records finds about 150 recalls of cosmetic and related over-the-counter (OTC) drug products in the United States for microbial contamination reasons since 1990.^23,24 The majority of these recalls were based on the presence or possible presence of Gram-negative P. aeruginosa and Burkholderia cepacia bacteria and involved products of all types from shampoos to mascaras to eye drops. The literature extends these observations to include a greater diversity of products from aerosol saline eye washes²⁵ to antiseptics and antibiotics^26,27 and validating the issue that microbiological contamination of cosmetics is of global con-cern.^28–30

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166 Cosmetic Microbiology: A Practical Approach