It seems that every part of the industrialized world is going “green,” including the cosmetic industry.1-3 As such, consumers are becoming more environmentally savvy and want to make a conscious effort to do their part for sustainability. The cosmetic chemist wants to satisfy this new breed of consumers but the task of creating natural cosmetic products that are safe and perform as well as their conventional counterparts is challenging. In addition to the formula, product development must also consider packaging. Packaging components may potentially pose another risk by unwanted synthetic chemicals. One example is bisphenol-A, a major component in plastic containers, which was shown to be a xenoestrogen, a breast cancer-causing agent.4

Formulating natural products is no easy task. Natural ingredients or extracts are complicated chemical mixtures. This presents an issue to formulators because they must understand the chemical behavior and properties of these complex mixtures so that risk is minimized and performance, odor, color, safety, cost, and most importantly, stability and preservation are not compromised. The challenge also includes efficacy and consumer benefits as well as using renewable resources.
In this article, we will focus on the key information needed to formulate natural products using the Natural Product Association’s guidelines.

No Definition

Since no government authority, such as the FDA, defines natural, cosmetic products cosmetic brands use their own definition and some may follow the definitions set by Ecocert, BDIH, Cosmos, NaTrue, Natural Product Association (NPA) or others.

According to the NPA, to be certified natural, personal care product ingredients must come from a renewable/plentiful resource found in nature, with absolutely no petroleum compounds. This includes ingredients found in fauna, flora and minerals. Furthermore, synthetic ingredients may be used only if they have no negative impact on the consumer or the environment. A list of allowable natural ingredients can be found on the NPA website. There are also certain ingredients such as parabens, phthalates, glycol, sodium lauryl sulfate (SLS) and petrolatum that should always be avoided because of their questionable safety profiles.

If a product is labeled or branded “natural” as per NPA, it must adhere to the following:
• Made with at least 95% natural ingredients;
• Contain synthetic ingredients only if they are environmentally friendly and pose no harm to the earth;
• Ingredients must be listed as Generally Recognized as Safe (GRAS) by the FDA and must meet the heavy metals purity criteria;
• Companies must fully disclose their ingredients accurately and truthfully;
• No animal testing of ingredients or products.

Dos and Don’ts

Allowable synthetic ingredients cannot exceed 5% of the formula and must consist of the following:
• Synthetic preservatives must be paraben-free and non-formaldehyde-donating;
• Fragrances be phthalate-free and non-irritating;
• Hair conditioners must be quaternary anti-static;
• Coco betaine

Prohibited Ingredients

From color cosmetics to body wash, more consumers are opting for products with natural ingredients.

Prohibited ingredients vary for BDIH, Cosmos, NaTrue and NPA. The chemist must research the restrictions that pertain to the markets for which they are formulating.

Many of the methods used in producing ingredients may affect the natural status. BDIH, Cosmos, NPA and NaTrue all have their own defined allowable list. The NPA lists the following allowable ecological process:
• Saponification of oils to make soap. This is acceptable only if KOH and NaOH are used as the reagents.
• Hydrolysis of complex proteins into simple amino acids. This process is acceptable if KOH and/or NaOH are used as catalysts.

Splitting of oils into glycerin and fatty acids. Acceptable when using high pressure steam and only the following reagents are used: zinc oxide, nickel, palladium and platinium.

A complete list of allowable process can be found on the NPA website.

The Preservation Of Natural Formulae

Nothing can match the preservative efficacy of synthetic ingredients, but there has been a lot of bad publicity regarding them and therefore one may wish to formulate with natural preservatives. All natural preservatives must meet the following criteria:
• Low level of toxicity;
• High antimicrobial activity; and
• Have no impact in the aesthetic/performance of the finished product.

Some common natural preservatives include:
• Olive (Olea europaea leaf extract);
• Rosemary (Rosemarinus officinalis) leaf extract;
• Lavenda (Lavandula angustifolia) flower extract;
• Oregano (Origanum vulgare) leaf extract; and
• Lemon (Citrus medica limonum) peel extract.

Safety and Efficacy Of Natural Formulae

The human population may become sensitive to many natural ingredients and therefore adequate testing must be done to ensure tolerability. The easiest method is to collect all the toxicity data on every single ingredient used. Also the finished product must be tested for irritation and sensitization. A Human Repeat Insult Patch Test on at least 100 panelists will suffice to ensure the product is neither an irritant nor an allergen to most of the population. Safety in-use and phototoxicity tests are also recommended. For efficacy, instrumentation and clinical testing are recommended.

This article has detailed what natural ingredients to use and what ingredients to avoid, as well as how to preserve natural products and how to validate safety and efficacy of the formulation. Now we will give some examples of how to formulate different types of natural products.

Formulating a Natural Fragrance

Some brands define natural fragrance as being prepared exclusively from the intact flower or plant. The extraction process involves using only organic certified materials.

Formula 1 is a water-based, alcohol-free fragrance. It contains a combination of the natural aroma with trideceth 9, PEG 40 hydrogenated castor oil and polysorbate 20 which will solubilize the natural aroma into the water. The preservatives of choice can be a combination of rosemary, lemon and lavender oils.

Formula 1
INGREDIENTS%WT.
Waterq.s.
Natural aroma8.0
Trideceth-97.0
PEG-40 hydrogenated castor oil4.6
Polysorbate 200.4
Olea Europaea leaf extract0.5
Preservativesq.s.

Formulating a Natural Body Wash

Formula 2 is a body wash utilizing the natural oils such as goji, buriti, magnolia and acai. It is also made by cold process and 90% natural according to NPA guidelines.

Formula 2
INGREDIENTS%WT.
Waterq.s.
Sodium lauroyl sarcosinate8.0
Cocamidopropyl betaine5.0
Cocoamidopropylamine oxide4.0
Sucrose cocoate and alcohol3.0
Glycerin3.0
Citrus reticulata oil2.0
Xanthan gum1.0
Punica granatum extract0.5
Euterpe oleracea fruit oil0.5
Magnolia sieboldii flower oil0.5
Helianthus annus seed oil0.5
Potassium sorbate0.15
Sodium benzoate0.15
Lycium barbaru extract0.12
Lactic acidto pH 6.0-6.5

Formulating a Mousse

The mousse formula below has a unique feel. It is natural based on the NPA’s guideline of the natural content being greater than 95%. The emollients are of natural origin. The natural-based emulsifier, emulium kappa (candelilla/jojoba/rice bran polyglyceryl-3 ester, cetearyl alcohol, glyceryl stearate and sodium stearoyl lactylate), is used to impart superior cushioning.

Green ingredients are finding their way into a wide range of finished products.

Formula 3
INGREDIENTS%WT.
Waterq.s.
Caprylic capric triglyceride5.0
Cetearyl alcohol5.0
Vitis vinifera seed oil4.0
Stearyl alcohol2.0
Glycerin3.0
Candelilla/jojoba/3.0
rice bran polyglyceryl-3 esters
Cetearyl alcohol1.0
Glyceryl stearate1.0
Sodium stearoyl lactylate0.5
Sucrose0.05
Mannan0.05
Xanthan gum0.02
Parfumq.s.
Formulating a Natural Polymer
Formula 4 is made of natural polymer that delivers good film forming. Formula 4 is greater than 95% natural. Amaranthus caudatus extract is used to provide hair gloss.

Formula 4
INGREDIENTS%WT.
Waterq.s.
Hydroxypropyltrimonium 1.5
hydrolyzed corn starch
Glycerin3.0
Vitis vinifera seed oil2.0
Amaranthus caudatus extract 2.0
Hydrolyzed wheat protein/1.0
PVP crosspolymer
Hydrolyzed wheat protein1.0
Parfumq.s.
Hydroxylethyl cellulose2.5
Potassium sorbate0.15
Sodium benzoate0.15

Formulating a NaturalLip Balm

Stick lip products are more challenging than the synthetic counterparts; the conventional stick uses a lot of petroleum by-products that are not considered natural by the NPA and the criterion of most brands. Formula 5 contains tribehenin, which is naturally derived from glycerin. Sucrose polybehenate is naturally derived from plants, and it provides superior emmoliency. Also C10-30 cholesterol/lano-sterol esters provide cushion to the lips. Formula 5 is a natural lip balm stick.

Formula 5
INGREDIENTS%WT.
Cetearyl alcohol20.00
Pentaerythrityl stearate/10.00
caprate/caprylate/adipate
Tribehenin10.00
C 10-30 cholesterol/lanesterol esters5.00
Diisostearyl dimer dilinoleate2.50
Acetylated lanolin2.00
Oleyl alcohol2.00
Sucrose polybehenate1.00
Orbignya oleifera1.00
Helianthus annus 1.00
seed oil
Capric/caprylic triglycerideq.s.

Conclusion
Natural products are challenging to formulate. Choosing the right emulsifiers, preservatives, emollients, solvents and surfactants requires a lot of research to ensure the process is allowable by the NPA’s guidelines. Formulators also have to deal with physical challenges such as color instability, formulation instability and preservation robustness. Commercially we have to ensure that the product is affordable and that the ingredients are from a renewable resources and plentiful. We are also challenged to formulate products that are safe and effective; these naturals must have a value or benefit to the consumers.

References
1. Kromidas, L. 2004. Making natural claims for personal care products. Happi, 41(12):55-59.
2. Kromidas, L. 2008. On the Road Toward Green, Part I. Happi, 45(3):54-61.
3. Kromidas, L. 2008. On the Road Toward Green, Part II. Happi, 45(4):55-59.
4. NTP (2008) National Toxicology Program’s Report on Bis Phenol A Peer Review (http://cerhr.niehs.nih.gov/chemicals/bisphenol/BPADraftBriefVF_04_14_08.pdf, retrieved February, 2010). 5. http://www.npainfo.org/clientuploads/naturalSeal/NaturalSeal_NPAStandard.pdf.