Our First Formula with an Essential Oil

Jennifer Cookson

Formulating a Scented Product

At Mother Dirt, all of our products have been “unscented,” meaning we have not implicitly added any ingredient or raw material with the intention of providing a scent. Up until now: Our Body Oil will be the first.

In addition to our usual, carefully screened for compatibility with our ammonia-oxidizing bacteria collection of ingredients, you’ll also notice the addition of Cymbopogon flexuosus, aka lemongrass oil. So why did we do this?

One of the most common questions we get from users is whether or not certain essential oils are biome-friendly. With time it became clear to us that our users were trying to avoid fragrance in the generic sense, but still wanted to enjoy a mild scent of some sort. This is much more difficult than it seems (hence the long post, but we hope you enjoy the backstory).

The Controversy of Fragrance

Perfume isn’t something new. It’s been around since the ancient Egyptians who used it as part of their religious rituals and applied perfumed oils to the skin for cosmetic and medicinal purposes. Today, however, a considerable amount of the U.S. population has reported adverse health effects or irritation from fragranced products, with many individuals able to identify categories of products that resulted in their symptoms. Sensitization occurs with the highest frequency from perfumes, colognes, and deodorants compared to other cosmetic types. In response to this, the interest in essential oils has been increasing as a potential way to still enjoy a scent but in a way that appears more “natural” and hopefully less irritating.

Essential Oils - Not So Simple

We have all read about the benefits of aromatherapy, the medicinal use of essential oils, the psychology of scent and memory, and maybe less so the pioneering olfactory research and its application and implication in seemingly unrelated diseases but what we are probably most unaware of is the thousands of chemicals that make up your perfume offered at those big box mall stores, or the potential allergens present in that “natural” essential oil.

As essential oils are derived from naturally occurring plants, being labeled as “natural” is both redundant and misleading as “natural” has become a marketing phrase that resonates with customers as “safe.” While we are not saying essential oils aren’t safe, there have been a number of things that have limited their application in our products, namely their potency, and typically their antimicrobial activity. <Read more about essential oils here>

Because we formulate our products for sensitive skin, formulating with essential oils needed to be approached deliberately and thoroughly. Here are the four key factors that drove this product development process.

1. Compatibility with our AOB

Not surprisingly, this is where we start. Our lemongrass oil, as with all of our ingredients, was tested at various levels for compatibility with the AOB, our peacekeeper bacteria. With increased testing capabilities, we have been able to screen many more ingredients than in the past and can do so without operating under broad assumptions that have previously eliminated the use of large categories of materials (eg: essential oils).

2. “Natural” or “Pure” Doesn’t Mean Free of Allergens

There is a misconception that because essential oils are “pure” and from nature, that they will be gentle, or unlikely to cause a reaction. Mother Nature is capable of producing some powerful things. Essential oils are complex and potent. Part of this potency is tied to the presence of allergens that are hard to avoid when formulating with essential oils. Again, because we formulate products for individuals with sensitive skin, we had to give this great care.

While lemongrass oil is also NOT classified as a substance of special concern by the SCCS in their submission of ‘Opinion on Fragrance allergens in cosmetics products’ based on reported cases, there were other guidances we followed as well. Specifically, the Scientific Committee on Cosmetics Products and Non-Food Products (SCCNFP) has further identified 26 fragrance allergens of concern for the elicitation and implication of allergic contact reactions based on a combination of the available literature, reports of adverse reactions, and clinical data. If the composition of an essential oil contains any of these 26 allergens, the responsible party is required to disclose its presence in the product if above the determined safe use threshold.  

We will also add that skin irritation reactions cannot be solely attributed to fragrance ingredients contained in a product, and instead may also be the result of the irritation potential of other ingredients and the levels in which they are present in products. Materials selected for use in the body oil have been carefully reviewed in order to ensure they do not contain any skin irritants or allergens outside of the 26 fragrance allergens determined by the SCCNFP.

3. Allergen Disclosure

The use and disclosure of essential oils and fragrance in personal care and cosmetic products differs between global markets. The Scientific Committee on Consumer Safety (SCCS) and Scientific Committee on Cosmetics Products and Non-Food Products (SCCNFP) has provided guidance to the EU in establishing general thresholds and safe use levels that are targeted towards the safety of most consumer and the majority of sensitized individuals, respectively, from developing contact allergies with fragranced product use. In contrast, the Food and Drug Administration, the governing entity in the US, does not require manufacturers to list fragrance ingredients in personal care products.

The safe use threshold implemented for all leave-on products is 0.001%, however it has been determined that the general threshold, the percentage that limits the development of contact allergies in a majority of the population, is 0.16% for body lotions specifically. The use level of the essential used in our body oil is nearly two times less than this threshold, and more importantly, any identified allergens are even less.

However, because the content of three SCCNFP identified allergens is above the 0.001% general threshold for leave-on products, you will find that they are disclosed on our ingredient label. Those allergens: citral, geraniol, and limonene are present at quantities at or greater than 0.001% but not greater than 0.06%. Transparency has always been a pillar in the development of our products, as we believe consumers should be allowed to make informed decisions.

4. Safety and Impurity Testing

To further ensure we are on the right track, we do a variety of tests on the product to ensure efficacy and safety.

One of the first tests we do is commonly referred to as HRIPT (human repeat insult patch test). In this testing, our final formulation of body oil is applied to the skin of 100 participants through a semi-occlusive patch and maintained on the skin for a period of 48 hours. Thereafter, participants are instructed to remove the patch 24 hours after application, and the procedure repeated until a series of 9 consecutive, 24-hour exposures have been made, 3 times a week, for three consecutive weeks. Phew!

Perhaps these participants are masochists… or maybe more so, this test is specifically designed to evaluate the potential for a test material to elicit irritation or sensitization under simulated, real use conditions. After a 10 – 14 day rest period, a retest/challenge dose is applied to an unexposed test site and evaluated 48 – 96 hours later.

A scoring scale is used for any observed symptoms or reported adverse reactions with 0 (no reaction) being the lowest score, followed by 1 (erythema throughout ¾ of patch area) up to 4 (erythema, induration and bullae). Of the 100 participants tested, “no adverse reactions of any kind were reported” during the course of the study, and further only one individual was assessed with a score of 1 after the second induction. All other participants had a score of 0 throughout the study.

An example of another test we did is to understand the impact on the condition of the skin. Barrier function is vital for skin health. We evaluated our body oil formulation with respect to the skin’s barrier function. Using trans epidermal water loss results (TEWL), it was determined that the use of the body oil did not compromise skin barrier function over a period of 24 hours.

Bringing It All Together

Are you still reading? We know this has been a long one. Thanks for making it to the end! It’s a complex issue, but hopefully some of it was able to connect with you. At a minimum, we hope you see how important this is to us and how much thought we put into it.

Again, we know we know many people with sensitive skin use our products. If you have a known allergy or sensitivity to the allergens or any material listed in our ingredient listing, we do not recommend you use our product(s). If you are unsure, please do a patch test first. If there are other questions we haven’t answered here, please feel free to email us!

For those of you that are looking to try out something different or looking for a little scent, we’ve now included this in our product. We’ve done so at a low amount, using an essential oil whose composition has been fully disclosed to you and taken into account along with many other factors in hopes that a fragranced product, when done right, doesn’t seem so objectionable.

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