LOTION MAKING 101 | SNOWDRIFT FARM

Lotionmaking 101
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Stopping Bacteria & Fungi

Gum Benzoin

Both benzoic acid and sodium benzoate are well accepted food grade preservatives. FDA allows up to 0.1% benzoic acid and sodium benzoate as a direct additive to foods.

Gum benzoin is a natural source of benzoic acid and benzoic acid esters. Various sources cite free benzoic acid contents up to about 40 %. These natural source compounds are as effective as the synthetic compounds. Gum benzoin is the source used to prepare natural benzoic acid.

Gum benzoin is obtained from Styrax benzoin trees indigenous to Sumatra and Thailand. The resinoid is prepared by alcoholic extraction of the crude benzoin which is scraped directly from the trees. The resinoid is a brown, highly viscous mass. It has a faint, pleasant odor reminiscent of vanilla, due to the presence of small amounts of vanillin. At normal use levels, it should not impart an odor to your finished product. Benzoin resinoid is often sold dissolved in ethylene glycol to improve room temperature pourability. It is better to use pure gum benzoin in your formulations as an anti-fungal. Warm the bottle in a basin of warm water to improve pourability. Wear gloves-- it is sticky. Clean up using alcohol as the solvent since gum benzoin does not even approach water solublity.

Potassium Sorbate

Sorbic acid and its salts are present in Sorbus species. (Mountain ash) Dried berries have been used as a traditional food preservative. Modern day sorbic acid is prepared synthetically.

Sorbic acid is a short chain fatty acid with demonstrated antimicrobial and antifungal properties. It is compatible with mammalian systems. Sorbic acid is more effective over a wide range of pH conditions. There are claims that it is more effective against bacteria and fungi than sodium benzoate or methyl paraben.

Sorbic acid is GRAS under the food additive regulations. Preservative function has several aspects which need to be discussed. They fall into two broad categories, bioavailability of the active compound, and activity spectrum. This could get long so -- executive summary --potassium sorbate is the clear winner.

In these common systems, methyl paraben, sodium benzoate, formaldehyde and potassium sorbate, only a portion of the compound is active as a preservative. Several factors play a role in determining how much of your preservative is actually active. This is also where pH plays a role since the acid rather than the salt is active compound.

In a rinse off product at pH 5 (typical pH for lotions), over 35% of potassium sorbate (sorbic acid) is in the active form whereas the value for sodium benzoate (benzoic acid) is 13% and formaldehyde (formic acid) is 5%. At pH 6 potassium sorbate drops to 6 % active while the other two drop to nil. Potassium sorbate retains some activity to pH 6.5 although this is playing at the edge of the cliff. In an aqueous product you know that all of the preservative must be in the water phase or at the bottom of the reaction kettle, but lotions contain both oil and water. Thus the next important issue is partition between oil and water in an emulsion. This is important if you want to preserve lotions. Bad bugs can only grow in water, not in the oil phase. The active form of the preservative must be the water phase for it to be effective. So if the majority of the preservative that you add ends up in the oil phase you have wasted your money on an ineffective preservation system. The active compounds in these systems prefer to be in oil not water.

The concentration of active in the oil phase for methyl paraben is 5.8 times that in the water phase; benzoic acid 6.1; but sorbic acid only 3.0. A higher proportion of active in the water affords greater protection and sorbic acid delivers.

A simplistic concrete example using a lotion which is 50% oil, and 50% water not counting the other ingredients. The emulsifying agent and other ingredients play some role in determining the partition, but will be ignored for the moment. This is not a real emulsion, but only an illustration because the calculations are easier for this mixture. Start with the standard statutory 0.1 % (1000 ppm) concentration that both methyl paraben and benzoic acid are limited to and partition it between the phases. If all of the compounds were in the active form the concentrations in the water phase would be methyl paraben 150 ppm; benzoic acid 140 ppm, and sorbic acid 250 ppm. BUT remember only a portion of the preservative is present in the active form to be partitioned between the phases. I'll use pH 5 to give everyone a fair chance but your chances drop to nil at pH 6. Now the effective benzoic acid concentration is about 20 ppm but sorbic acid is 90 ppm. Now we must look at the MIC to determine if we have an effective preservative. The MICs for Candida albicans are as follows sorbic acid 100 ppm; benzoic acid 500 ppm and methyl paraben 750 ppm. While both methyl paraben and benzoic acid would be ineffective in this formulation; sorbic acid is merely marginal. Since FDA limits methyl paraben and benzoic acid to 0.1% there are few practical measures which can be taken to make them effective against Candida albicans in this formulation. But because the naturally occurring sorbic acid is considered GRAS its concentration can be doubled to ensure effectiveness. Common use rates for potassium sorbate are 0.2 to 0.5 % (2000 to 5000 ppm). EU allows contents above 0.6 %, but requires a warning label at concentrations above 0.6%.

Now, before anyone accuses me of using an unrealistic system, let me suggest that the picture gets much better for low oil content lotions making all three potentially effective preservatives. But sorbic acid is still the winner in being able to deliver higher effective concentrations in the aqueous phase. However since the methyl paraben and benzoic acid systems are still at the edge, challenge testing is required during the development of the preservation system. Since it is reasonable to assume that potassium sorbate is readily capable of delivering well above the MIC, challenge testing really only provides verification that your system is working, but is not required as a development tool.

if you can make salad dressing, you can make lotion

Now for activity. I hesitate to try to create a table which would be garbled by the server. These are the results subjectively, but I can provide exact numbers if anyone is interested. Against Fusarium sp., Aspergiius sp., Penicilum sp. Trichoderma viride and Candida albicans sorbic acid had MIC values of less than 500 ppm some around 100 ppm. In all cases sorbic acid had a lower MIC than either benzoic acid or methyl paraben in that order. Sorbic acid's activity was also superior to that of Methyldibromo glutaronitrile.

A variety of challenge tests were run using Staphylococcus aureus (gram positive bacteria), E. coli, Psudomonas aeruginosa (gram negative bacteria), Aspergillus niger (mold), and Candida albicans (yeast). The systems used 0.4% potassium sorbate as the preservative at around pH 5.4 with citric acid present in two examples and not in the third. In all cases the concentration of test organisms wet from 1,000,000 per gram of product to non detect (< 10) in less than 7 days and stayed down until the end of the test cycle at 28 days. No adaptation of the test organisms occurred and no loss of preservative activity occurred. Formaldehyde releasing systems just can not meet this gradual loss of activity test.

Both potassium sorbate and sorbic are approved world wide including the EU, USA and Japan. The same can not be said for many other preservative systems. The clear winner is sorbic acid and potassium sorbate with broader range of acceptable pH, better partition between oil and water, broad strong activity against organisms, GRAS status and broad regulatory approval, no added carrier solvent to a pure product, gentle on skin with no photo effects and readily biodegradable. The water soluble potassium sorbate is also formulator friendly allowing concentrates of up to 50 % in water to aid dispersion. For more information, please visit our preservatives chart.

Methyl paraben

Methylparaben is naturally occurring compound which is effectve as a preservative.. Isolation from vaginal secretions of dogs during estrus. M.Goodwin et al. Science 203, 559 (1979) This one is not used from its natural source for obvious reasons. Advocates of Premarin might say it's possible though. For more information, please visit our preservatives chart.

Compound Preservatives

Compound preservatives are made up of several different preservatives whose combined activity is greater than each individual component. Phenonip® by Nipa Labs is a good example of a compound preservative. It provides solid broad spectrum protection against gram negative and gram positive bacteria, yeasts and moulds. It is a blend of paraben esters in phenoxyethanol.

INCI Name - phenoxyethanol, methylparaben, ethylparaben, butylparaben, propylparaben, isobutylparaben.

All the components are included in the EC Cosmetics Directive Annex VI list of permitted preservatives. Phenonip is also permitted for use as a preservative in the USA and Japan. Methylparaben and propylparaben have GRAS (Generally Recognized As Safe) status in the USA.

Phenonip retains its effectiveness over a range from pH 3.0 - 8.0 and is compatible in almost all cosmetic applications. It is non-volatile and there is no loss of preservative due to volatility, even in prolonged storage. Typical use rate is less than .5%. In the presence of polysorbates and other surfactants, increase the use rate to .5 -1.0%

Phenonip is a low irritant preservative. For more information, please visit our preservatives chart.

In lotions, Phenonip should be added to water or glycerin in the water phase.

Formaldehyde Releasers (Germaben Products)

Several preservative systems which contain or release formaldehyde are available. These tend to be commercial compounded systems. Because it is a transient system which suffers high losses to volatility and degradation, direct addition should not be considered alone as a preservative. Formaldehyde releasing systems are often used, but there are some legitimate toxicological concerns with their use. Another important point about formaldehyde releasing systems is that as the system is used up effectiveness decreases. This is part of the trade-off in designing a safe system and specifying maximum shelf life.

Formaldehyde is part of a detoxification pathway in mammalian systems. In this pathway it is almost immediately destroyed. Although mammalian systems do have effective methods of destroying formaldehyde, some modes and levels of exposure have been implicated in both carcinogenisis and sensitization. It should be noted that the significant daily exposure occurs from many sources. A study of Danish workers in a particle board factory failed to find significant effects of formaldehyde exposure by inhalation once exposure to wood dust, and other materials were factored in. Other studies show that there are limits to the body's capacity to destroy formaldehyde at high concentrations. It is part of the pathway that MTBE follows and is part of the reason for concern about MTBE.

Grapefruit Seed Extract

For argument's sake, let's assume that the quaternary ammonium compounds in GSE have similar activity to benzalkonium chloride, a well known hard surface cleaner and disinfectant. Efficacy in a hard surface cleaner does not translate directly to efficacy as an antimicrobial agent in cosmetic formulations nor does it translate to in vivo efficacy against the wide variety of organisms claimed by the purveyors of such products. I could be convinced by properly managed studies published in reputable refereed journals, but to date none have been delivered to me.

The cited studies do not include cosmetic challenge tests which are done on formulated products. Basically you inoculate the product with a variety of bacteria and fungi and see how they grow. The desired result is that they all go away or are their growth is inhibited. Since each type of product has a different distribution of components, a wide variety of products must be tested to ensure efficacy. An oil in water lotion has different chemical characteristics than a water in oil lotion and a preservation system that works in one may not work in the other. The function of some preservative systems is pH dependent. This effect also has not been investigated adequately. Other naturally occurring preservative systems such as the sorbic acid and benzoic acid based systems have been well studied in a wide variety of applications and meet the criteria for a preservation system. Their restrictions are well known.

The studies for in vivo effects which have been cited appear to be in alternative health journals which may be captives of the nutritional supplement industry. Since these studies probably would not pass the NIH criteria for clinical studies, the only claims which the FDA allows is as a nutritional supplement. No therapeutic effects may be claimed since the studies do not meet the criteria for drug applications.

But there is a far more serious issue with grapefruit seed extract. That is its potential endocrine disrupting activity. The compounds which the sellers claim are in GSE are known to have estrogenic activity. GSE has never been evaluated for its estrogenic activity using the OECD protocols.

Phytoestrogens are wide spread in the foods which we consume and mammalian systems have adequate means to cope with low level exposure. GSE will probably not pose a problem for your customers at the recommended usage levels, but your own safety is another matter. Over exposure to endocrine disrupting substances (including phytoestrogens) can have serous impacts on reproductive biology in both males and females.

Genistien and Diadzien are the phytoestrogens which occur in soy products. These phytoestrogens occur at levels of 500-3000 milligrams per Kg in soy beans, and in lower levels in soy products such as miso, soy milk, and tofu. Asian cultures understand the dangers associated with regular exposure to phytoestrogens which is why soy beans are heavily processed prior to consumption. This is at about the normal usage level for GSE in cosmetic products. This is why I stated that GSE would probably not be a problem for consumers. The risk is in use of the concentrate during production work.

From Nutriteam, a GSE vendor "This liquid is loaded with polyphenolic compounds, including quercitin, helperidin, campherol glycoside, neohelperidin, naringin, apigenin, rutinoside, poncirin, etc. The polyphenols themselves are unstable but are chemically converted into more stable substances that belong to a diverse class of products called quaternary ammonium compounds."

The named compounds are flavones which are bonded to sugars. The sugar is cleaved and replaced with amine which is converted to the ammonium chloride salt. Effectively the product is a mixture of water soluble flavones in glycerin. This allows these compounds to be readily absorbed when ingested. The claimed content of flavones by Nutriteam is: Citricidal Liquid Grapefruit extractives: 60%, Vegetable glycerin USP: 40% Citricidal Powder Grapefruit extractives: 50%, Silicon Dioxide-USP: 30%, Glycerin-USP: 20%

Four specific compounds from a class of compounds called isoflavones have been studied the most because of their wide spread impact on human and animal health. The other major class of compounds is the lignans.

This NIH document examines both the good and risks associated with phytoestrogens. Pay attention to the section on risks.

A class of compounds has activity because of its basic shape, but each compound in the class has a different level of activity. Flavones differ from the more widely studied isoflavones by a change in the connection of the phenolic group to oxygen containing ring. You just do not know the exact level of activity until you do the evaluation. But to protect yourself, you need to assume that significant activity could be present and act accordingly.

From the NIH report "Neonatal and in utero exposures to sex steroids regulate the development of sexually differentiated behavior, reproductive physiology, and central nervous system anatomy and neurochemistry. In a letter published in the 24 May 1995 issue of the New Zealand Medical Journal, Cliff Irvine, a professor of animal and veterinary science, and colleagues at Lincoln University in New Zealand indicated that soy-based infant formulas in New Zealand contain 3-5 times as much daidzein and genistein as the amount that will disrupt a woman's menstrual cycle. Considering diethylstilbestrol's estrogenic effects on development, Irvine stated that this exposure should be investigated. Setchell says that infants metabolize the phytoestrogens, but how these compounds act in their bodies is unknown. One point of view is that they might negatively affect development, while others believe developmental effects would be negligible, and that exposure might actually help ward off hormone-related ill health in the future."

Several naturally occurring and synthetic flavones were found to inhibit the aromatization of androstenedione and testosterone to estrogens catalyzed by human placental and ovarian microsomes. These flavones include (in order of decreasing potency) 7,8-benzoflavone, chrysin, apigenin, flavone, flavanone, and quercetin; 5,6-benzoflavone was not inhibitory. 7,8-Benzoflavone and chrysin were potent competitive inhibitors and induced spectral changes in the aromatase cytochrome P-450 indicative of substrate displacement. Flavones may thus compete with steroids in their interaction with certain monooxygenases and thereby alter steroid hormone metabolism.

If you choose to use GSE to produce products, I implore you to protect yourself and your family from the potential risks. If it has strong activity, you can not undo the damage that excessive exposure to endocrine disrupters can do. I can only emphasize the need for you to be very careful to limit your exposure when using the concentrate. This means: wear disposable nitrile gloves, use separate utensils from food utensils always, use a separate wash basin to clean equipment wearing rubber gloves. It is preferable to use disposable droppers or measuring cups for GSE to prevent contamination of wash basins and other equipment. Mark a plastic cup using a measured amount of water and use it to measure the GSE concentrate, then throw it away. Wear an apron and wash it every time you use GSE. Wash your hands and arms well immediately after use. Keep food away from your work area until it is cleaned up. Soap & ammonia water is probably an effective cleaning agent.

If you doubt how quickly this stuff can spread on unwashed hands and improperly cleaned equipment, try an experiment. Put a coating of peanut butter and jelly on your two year old's hands. Turn him/her loose in your kitchen without supervision and see how many things magically become sticky. Try another experiment, spread peanut butter on a plate and put in front of your child. See how it spreads to everything quickly. Without rigorous cleanup many compounds can spread the same ways and you and others can be inadvertently exposed.

Since the estrogenic activity of GSE has never been evaluated, consider its use in production of your products carefully, especially if you wish to be pregnant, wish to be a partner in a pregnancy, are pregnant or are nursing. Also take great pains to keep the concentrate away from children since regular high level exposure to endocrine disrupting substances can affect the development of their reproductive systems.

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Lotionmaking 101 (continued from page 2)

Lotionmaking 101
(continued from page 2)