Bio-deterioration of Cosmetics and Personal Care Products

By: Kassapa Ellepola

Bio-deterioration can be defined as an undesirable change occurring in a natural or processed material of economic importance, which is brought about by the activity of living organisms especially the microorganisms.

In the case of Cosmetics and Personal Care Products, bio-deterioration can cause them to be objectionable for use and also could be therapeutically inactive. These products contain a number of chemicals which support microbial growth. Mainly chemicals such as sugars as sweetening agents, polymers such as starch and cellulose used as thickening agents and for use in suspensions, and oils and fats used in the preparation of creams and emulsions can be considered. Also the growth of microorganisms on many of these products causes the formation of foul smelling odors, and the separation of emulsions into their component parts.

Bio-deterioration of Cosmetics and Personal Care Products can be caused by bacteria, yeasts and fungi which are extremely metabolically diverse as they are with the capacity of genetically modifying themselves to adapt to a broad range of environmental conditions.

Microorganisms can be introduced in to the product via the raw materials, the processing plant, packaging materials and from operatives or by elsewhere in the environment. But the growth and multiplication of these organisms can be supported by the formulation of the product, ambient temperatures as well as by the humidity factor.

The application of cosmetics can occasionally cause irritation and this may be a result of high levels of microbial contamination. The contaminants may produce foreign proteins which can evoke allergic reactions. Particularly the ‘eye’ is susceptible to infection from contaminated cosmetics and other personal care products.

Cellulose polymers which are commonly found in cosmetics can act as potential targets for microbial attack and sometimes support extensive growth under suitable conditions. As a result, cellulosic substances can be converted from a stiff gel into a running liquid, thereby rendering the cosmetic unfit for use. Three different types of enzymes (exo-beta-1, 4-glucanase, endo-beta-1,4-glucanase and beta-glucosidase) are involved in the degradation of crystalline cellulose. Enzyme production is basically done by three fungi belonging to the genera Aspergillus, Fusarium and Penicillium.

Microorganisms also possess a significant ability to inactivate biologically active molecules. Antibiotics in cosmetics may be destroyed by microbial action, for example penicillin will be destroyed by any β-lactamase producing organism. Microbial enzymes which inactivate chloramphenicol is also known. Many preservatives, disinfectants and surface active agents are metabolized by bacteria, although usually at concentrations below the normal ‘in use’ concentration. There have, however, been a number of reports of the degradation of simple preservatives such as benzoic acid at ‘in use’ concentrations.

Visible growth of microorganisms can be observed in liquid formulations such as sediments, turbidity or pellicles. These are good indicators of bio-deterioration. Color changes due to alterations in the components of the product may result from the pH, redox or other changes caused by the metabolic activities of an organism. The color changes may also be due to pigment production, as an example the Pseudomonas genus has the ability to metabolize a broad range of products and produce soluble pigments ranging in color from blue to green to brown. These organisms can render conditions that favor the growth of anaerobic organisms. Some oxidative yeasts can cause a rise in pH by utilizing organic acids, encouraging the bacterial growth.

Gas production is also a visible indicator of bio-deterioration of the products especially when glycerol, a common ingredient in many cosmetics is fermented by some common waterborne organisms.

Apart from those changes, the physicochemical condition of emulsions can be changed. The oil phase can be hydrolyzed and also an increase in the viscosity and aggregation of particles may be observed.

Olfactory effects can also change due to bio-deterioration. Off odors can be formed due to the production of gases such as Ammonia, amines and also hydrogen sulphide. These odors can be disastrous to cosmetics and toiletry preparations which depend on specific perfumes. The smell of mould is one of the common olfactory warnings. Actinomycetes growing on products cause an earthy odor due to ‘geosmin’. Spoilage by yeast gives a typical alcoholic odor.

The texture may also feel different where creams can get a lumpy or ‘gritty’ texture and there might be changes in the viscosity which can be felt when applied to the skin.

Oil/ water emulsions are very much susceptible to spoilage as the water allows the microorganisms to spread. The spread occurs throughout the continuous phase of water and also at the boundaries. The concentration of microorganisms depends on the relative solubility of the oil in water.

The degradation of creams depend on the presence of water. As water is one of the major products of metabolism, the degradation process becomes autocatalytic. Many preservatives, disinfectants and surface active agents are metabolized by bacteria.

Recently there is a tendency to use natural ingredients such as animal proteins and vitamins. These ingredients are highly nutritious to microorganisms. Glycerol which is abundant in creams can be metabolized by microorganisms such as Klebsiella producing gases in poorly preserved products. Mould growth can occur in products such as antifungal, calamine, baby and hair creams and other cosmetic formulations including moisture and cleansing creams.

When ointments and oils are considered, normally they will not support the growth of microorganisms as they are anhydrous material. But the containers they are filled into may contain air spaces which could allow the growth of moulds which utilize atmospheric moisture. Maize and olive oil can be spoiled by bacteria and fungi.

Shampoos are contaminated by a range of Gram-negative waterborne bacteria. They can cause slimy sediments, pellicles, discoloration and odor. The loss of lathering properties can also take place. Shampoos also have a potential to be spoiled by bacteria such as the Pseudomonads.

Powder products can be spoiled by visible growth of moulds in damp conditions and it is very important that topical preparations do not contain Clostridia spores. Precautions should be made on powders and other solid cosmetics that are applied in the region of the eyes.

Solid cosmetics such as lipsticks can be subjected to mould ‘blooms’ where moulds can grow on the lipstick while it is inside the lipstick case. This may be a result of it been moistened by breath when used or when moistened from perhaps saliva.

Soap gives off moisture and if wrapped with an impermeable plastic over paper or card, may become discolored due to mould growth on damp paper.

Therefore bio-deterioration of cosmetics and personal care products must be prevented as it is significantly important with relation to health and economy. The disease causing microorganisms must be removed from the product. The presence of many thousands of organisms however indicates that spoilage will occur. Regular monitoring during development and manufacturing, establishing the type and minimum number of organisms which are achievable for each specific product should be well defined.

Reference:

• Dart, R. K., Microbiology for the analytical chemist, Royal Society of Chemistry (Great Britain), Information Services, pg: 16, 17 (14.01.2010)
• Harrison, L.A. 1987, Microbial degradation of cellulose polymers used in cosmetics and toiletries, Int J Cosmet Sci. Apr;9(2):73-84.
• Smart, R., Spooner, D.F., 1972, Microbiological spoilage in pharmaceutical and cosmetics, J. Soc. Cosmet. Chem. 23:721-737