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Yes To Grapefruit Brightening Vitamin C Glow-boosting Mud Mask

Grapefruit Brightening Vitamin C Glow-boosting Mud Mask

Brightening vitamin c glow-boosting mud mask.
Uploaded by: malloryraquelleann on

Skim through

Ingredient name what-it-does irr., com. ID-Rating
Water (Aqua) solvent
Aloe Barbadensis Leaf Juice soothing, moisturizer/​humectant goodie
Kaolin colorant, abrasive/​scrub 0, 0 goodie
Bentonite viscosity controlling 0, 0 goodie
Propanediol solvent, moisturizer/​humectant
Hamamelis Virginiana (Witch Hazel) Water soothing goodie
Citrus Grandis (Grapefruit) Fruit Water perfuming
Cetearyl Alcohol emollient, viscosity controlling, emulsifying, surfactant/​cleansing 1, 2
Magnesium Aluminum Silicate viscosity controlling 0, 0
Titanium Dioxide (Ci 77891) colorant 0, 0
Glyceryl Stearate emollient, emulsifying 0, 1
Hydrogenated Vegetable Glycerides emollient, viscosity controlling
Polyglyceryl-10 Oleate
Citrus Paradisi (Grapefruit) Seed Oil perfuming
Citrus Grandis (Grapefruit) Fruit Extract perfuming
Vaccinium Myrtillus Fruit Extract
Saccharum Officinarum (Sugar Cane) Extract moisturizer/​humectant goodie
Butyrospermum Parkii (Shea) Butter emollient goodie
Prunus Armeniaca (Apricot) Kernel Oil emollient 0, 1-2 goodie
Citrus Aurantium Dulcis (Orange) Fruit Extract
Citrus Limon (Lemon) Fruit Extract
Glycyrrhiza Glabra (Licorice) Root Extract soothing, skin brightening superstar
Acer Saccharum (Sugar Maple) Extract
Hydrolyzed Jojoba Esters
Illite abrasive/​scrub
Montmorillonite viscosity controlling goodie
Ascorbyl Glucoside antioxidant, skin brightening goodie
Glycerin skin-identical ingredient, moisturizer/​humectant 0, 0 superstar
Dipotassium Glycyrrhizate soothing, moisturizer/​humectant goodie
Xanthan Gum viscosity controlling
Glyceryl Caprylate preservative
Tetrasodium Glutamate Diacetate chelating
Ethylhexylglycerin preservative
Citric Acid buffering
Phenoxyethanol preservative
Fragrance (Parfum) perfuming icky
Iron Oxides (Ci 77491) colorant 0, 0
Limonene perfuming, solvent icky

Yes To Grapefruit Brightening Vitamin C Glow-boosting Mud Mask
Ingredients explained

Also-called: Aqua | What-it-does: solvent

Good old water, aka H2O. The most common skincare ingredient of all. You can usually find it right in the very first spot of the ingredient list, meaning it’s the biggest thing out of all the stuff that makes up the product. 

It’s mainly a solvent for ingredients that do not like to dissolve in oils but rather in water. 

Also-called: Aloe Vera | What-it-does: soothing, moisturizer/humectant

Aloe Vera is one of today’s magic plants. It does have some very nice properties indeed, though famous dermatologist Leslie Baumann warns us in her book that most of the evidence is anecdotal and the plant might be a bit overhyped.

What research does confirm about Aloe is that it’s a great moisturizer and has several anti-inflammatory (among others contains salicylates, polysaccharides, magnesium lactate and C-glucosyl chromone) as well as some antibacterial components. It also helps wound healing and skin regeneration in general. All in all definitely a goodie. 

Kaolin - goodie
Also-called: Type of clay, China clay | What-it-does: colorant, absorbent/mattifier, abrasive/scrub | Irritancy: 0 | Comedogenicity: 0

Kaolin is a type of clay or to be precise, a naturally occurring hydrous aluminum silicate. When you hear clay, you probably think of a muddy greenish-black mess, but that one is bentonite, and this one is a fine, white powder. It is so white that it's also often used, in small amounts, as a helper ingredient to give opacity and whiteness to the cosmetic formulas.

As a clay, it's absorbent and can suck up excess sebum and gunk from your skin, but less so than the more aggressive bentonite. As it's less absorbent, it's also less drying and gentler on the skin, so it's ideal for dry and sensitive skin types.  

Bentonite - goodie
Also-called: Type of clay | What-it-does: viscosity controlling, absorbent/mattifier, emulsion stabilising | Irritancy: 0 | Comedogenicity: 0

When it comes to oil-absorbing clay masks, bentonite will probably be one of the first ingredients on the INCI list. Technically bentonite clay is mostly montmorillonite + something else, and thanks to the something else bit, bentonite comes in different types and colors

The color depends on the mineral content of the clay: white bentonite is rich in boron and fluoride, yellow is rich in manganese and zinc, green is rich in copper, zinc, and manganese and the pink clay is rich in boron.

Also-called: Zemea | What-it-does: solvent, moisturizer/humectant

Propanediol is a natural alternative for the often used and often bad-mouthed propylene glycol. It's produced sustainably from corn sugar and it's Ecocert approved. 

It's quite a multi-tasker: can be used to improve skin moisturization, as a solvent, to boost preservative efficacy or to influence the sensory properties of the end formula. 

What-it-does: soothing, astringent

The distillate created from different parts of the hazelnut-bush-like magic tree, commonly called Witch Hazel. Hamamelis Virginiana Water is a bit of a sloppy ingredient name as the leaves, the twigs and the bark can be used to create extracts or distillates and the different parts contain different amounts of biologically active components. But what you are getting is probably a nice water with astringent, soothing, antioxidant and antibacterial magic properties.  

We went into great detail about Witch Hazel in cosmetics here, detailing the main biologically active components and how they are different in different parts of the plant. Click here and read more >>

What-it-does: perfuming

We don't have description for this ingredient yet.

What-it-does: emollient, viscosity controlling, emulsifying, emulsion stabilising, surfactant/cleansing | Irritancy: 1 | Comedogenicity: 2

An extremely common multitasker ingredient that gives your skin a nice soft feel (emollient) and gives body to creams and lotions. It also helps to stabilize oil-water mixes (emulsions), though it does not function as an emulsifier in itself. Its typical use level in most cream type formulas is 2-3%.  

It’s a so-called fatty alcohol, a mix of cetyl and stearyl alcohol, other two emollient fatty alcohols.  Though chemically speaking, it is alcohol (as in, it has an -OH group in its molecule), its properties are totally different from the properties of low molecular weight or drying alcohols such as denat. alcohol. Fatty alcohols have a long oil-soluble (and thus emollient) tail part that makes them absolutely non-drying and non-irritating and are totally ok for the skin.

What-it-does: viscosity controlling, absorbent/mattifier | Irritancy: 0 | Comedogenicity: 0

A type of clay mineral that works as a nice helper ingredient to thicken and stabilize formulas. As a clay, it consists of platelets that have a negative charge on the surface (face) and a positive on the edge. So the face of one platelet attracts the edge of the other and this builds a so-called "house of card" structure meaning that Magnesium Aluminum Silicate (MAS) thickens up products and helps to suspend non-soluble particles such as color pigments or inorganic sunscreens (zinc oxide and titanium dioxide).

As the "house of card" structure takes some time to form but collapses quickly if the formula is stirred, products thickened with MAS can be thick in the jar but become easily spreadable upon application (called thixotropy). MAS also gives nice sensory properties, it is not tacky or sticky and gives a rich, creamy skin feel. Also a good team player and works in synergy with other thickeners such as Cellulose Gum or Xanthan Gum

Also-called: Titanium Dioxide/Ci 77891;Ci 77891 | What-it-does: colorant | Irritancy: 0 | Comedogenicity: 0

Ci 77891 is the color code of titanium dioxide. It's a white pigment with great color consistency and dispersibility.

What-it-does: emollient, emulsifying | Irritancy: 0 | Comedogenicity: 1

A super common, waxy, white, solid stuff that helps water and oil to mix together, gives body to creams and leaves the skin feeling soft and smooth.

Chemically speaking, it is the attachment of a glycerin molecule to the fatty acid called stearic acid. It can be produced from most vegetable oils (in oils three fatty acid molecules are attached to glycerin instead of just one like here) in a pretty simple, "green" process that is similar to soap making. It's readily biodegradable.

Hydrogenated Vegetable Glycerides is a blend of fatty acid mono and diesters (kind of like an oil molecule but not with three but only one or two fatty acid chains on the glycerin) that exists in lots of versions. It can be a consistency-giving wax (think something like glyceryl stearate), or it can be a rich jelly emollient that acts as a petrolatum alternative. 

We don't have description for this ingredient yet.

What-it-does: perfuming

We don't have description for this ingredient yet.

What-it-does: perfuming, astringent

We don't have description for this ingredient yet.

Also-called: Bilberry Fruit Extract

We don't have description for this ingredient yet.

Also-called: Sugar Cane Extract | What-it-does: moisturizer/humectant

Also known as Sugarcane, Saccharum Officinarum is a handy moisturizing ingredient mostly used as a humectant. This means that it can help the skin to attract water and then to hold onto it. 
 
It bears a close relationship to AHA superstar, Glycolic Acid that can be derived from it, so it's often claimed that Sugarcane Extract itself also exfoliates and brightens the skin. We could not find any research studies to back this up, but Saccharum Officinarum very often comes to the formula combined with other acid containing plant extracts trade named ACB Fruit Mix. According to manufacturer data, 5% of the fruit mix increases cellular renewal by 24%, while 4% pure Glycolic did the same by 33%. So maybe, a tiny bit of exfoliation, but if you want proven efficacy, stick to pure acids. 

Also-called: Shea Butter | What-it-does: emollient

Unless you live under a rock you must have heard about shea butter. It's probably the most hyped up natural butter in skincare today. It comes from the seeds of African Shea or Karite Trees and used as a magic moisturizer and emollient.

But it's not only a simple emollient, it regenerates and soothes the skin, protects it from external factors (such as UV rays or wind) and is also rich in antioxidants (among others vitamin A, E, F, quercetin and epigallocatechin gallate). If you are looking for rich emollient benefits + more, shea is hard to beat. 

Also-called: Apricot Kernel Oil | What-it-does: emollient | Irritancy: 0 | Comedogenicity: 1-2

The emollient plant oil coming from the kernel (the seed of the seed) of the delicious apricot fruit. Like other plant oils, it contains antioxidant vitamin E and nourishing fatty acids (mostly oleic acid 54-74%, linoleic acid 12-35%).

It's a nice general purpose emollient, has nourishing and moisturizing properties (as a high oleic oil it's ideal for dry skin types) and is quite easily absorbed into the skin.

Also-called: Orange Fruit Extract

We have to start by writing that there are about 900 citrus species in the world, and plenty of them are used to make different kinds of extracts used in cosmetics. This particular one, Citrus Aurantium Dulcis Fruit Extract is a very common ingredient, however, the species "Citrus Aurantium Dulcis" seem to exist only on ingredient lists and the real world calls this guy Citrus Sinensis or, you know, orange. 

To complicate matters further, there are lots of varieties and lots of extraction methods, so it is a bit hard to know what you are getting with this one, but we will try our best to summarize the possibilities. 

Also-called: Lemon Fruit Extract

If life gives the cosmetic industry lemon, it makes lemon fruit extract.  As to why, we can write here extremely similar things to our shiny description of orange fruit extract.  Being both of them citruses, they contain very similar active compounds with very similar (potential) effects on the skin. 

Just like orange fruit, lemon fruit also contains citric acid so it is commonly used as a natural, mild exfoliating agent. If this is the case, it is usually combined with other AHA containing fruit extracts such as bilberrysugar cane, orange, and sugar maple in a super popular ingredient mix trade named ACB Fruit Mix.

Also-called: Licorice Root;Glycyrrhiza Glabra Root Extract | What-it-does: soothing, skin brightening

You might know licorice as a sweet treat from your childhood, but it's actually a legume that grows around the Mediterranean Sea, the Middle East, central and southern Russia. It's sweet and yellow and not only used for licorice all sorts but it's also a skincare superstar thanks to two magic properties:

Nr. 1 magic property is that it has skin-lightening or to say it another way depigmenting properties. The most active part is called glabridin. The topical application (meaning when you put it on your face) of 0.5% glabridin was shown to inhibit UVB caused pigmentation of guinea pigs. Another study even suggested that licorice is more effective than the gold standard skin-lightening agent hydroquinone. All in all, licorice is considered to be one of the safest skin lightening agents with the fewest side effects.

Also-called: Sugar Maple Extract

The extract coming from the Sugar Maple tree, the one whose leaf is on the Canadian flag and gives us maple syrup.

The main reason it is used in skin care is that it contains natural AHA acids, namely Malic and Tartaric, and hence why it supposedly helps slough off dead skin cells in combination with other acid-containing fruit extracts as part of the trade name ACB Fruit Mix. The manufacturer claims that both malic and tartaric increase elasticity in the skin, but from our research, the only confirmed uses of these acids are as pH adjusters, especially in the tiny amounts they can be found in the Fruit Mix (less than 1%).  

We don't have description for this ingredient yet.

We don't have description for this ingredient yet.

Also-called: Type of clay | What-it-does: viscosity controlling, absorbent/mattifier, emulsion stabilising

A type of clay that was originally found next to the French village, Montmorillon. Nowadays, Montmorillonite is used almost like a synonym for the most common type of clay, bentonite. Technically bentonite is montmorillonite and additional crystalline structures, or to put it another way, montmorillonite is 100% clean bentonite. 

As for montmorillonite in skincare products, it's used for its magic absorbent properties. It's excellent at instantly sucking up sebum and gunk from the skin and it might even be helpful in treating some rashes or skin irritations (contact dermatitis). But be careful, it can also be drying

Also-called: Form of Vitamin C | What-it-does: antioxidant, skin brightening

A form of skincare superstar, vitamin C. If you do not know why vitamin C is such a big deal in skincare, we have a really detailed, geeky description that's good to read. :) 

So now you know that because pure vitamin C is such a diva (very unstable and hard to formulate) the cosmetic industry is trying to come up with some derivatives that have the badass anti-aging properties of vitamin C (antioxidant protection + collagen boosting + fading hyperpigmentation) but without the disadvantages. This is a hard task, and there is not yet a derivative that is really proven to be better in every aspect, but Ascorbyl Glucoside is one of the best options when it comes to vitamin C derivatives. Let's see why:

Glycerin - superstar
Also-called: Glycerol | What-it-does: skin-identical ingredient, moisturizer/humectant | Irritancy: 0 | Comedogenicity: 0
  • A natural moisturizer that’s also in our skin
  • A super common, safe, effective and cheap molecule used for more than 50 years
  • Not only a simple moisturizer but knows much more: keeps the skin lipids between our skin cells in a healthy (liquid crystal) state, protects against irritation, helps to restore barrier
  • Effective from as low as 3% with even more benefits for dry skin at higher concentrations up to 20-40%
  • High-glycerin moisturizers are awesome for treating severely dry skin
Read all the geeky details about Glycerin here >>

Also-called: Licorice | What-it-does: soothing, moisturizer/humectant

The salt form of one of the main anti-inflammatory ingredients in the licorice plant, monoammonium glycyrrhizinate. It’s a yellowish powder with a nice sweet smell. 

It’s used mainly for its soothing and anti-inflammatory properties, but according to manufacturer info, it’s also sebum regulating so it's a perfect ingredient for problem skin products. 

It's one of the most commonly used thickeners and emulsion stabilizers. If the product is too runny, a little xanthan gum will make it more gel-like. Used alone, it can make the formula sticky and it is a good team player so it is usually combined with other thickeners and so-called rheology modifiers (helper ingredients that adjust the flow and thus the feel of the formula). The typical use level of Xantha Gum is below 1%, it is usually in the 0.1-0.5% range. 

Btw, Xanthan gum is all natural, a chain of sugar molecules (polysaccharide) produced from individual sugar molecules (glucose and sucrose) via fermentation. It’s approved by Ecocert and also used in the food industry (E415). 

What-it-does: preservative

A 100% plant derived, natural (Ecocert approved) multi-functional ingredient that has emollient and moisturizing properties, can work as a co-emulsifier (meaning that next to other emulsifiers it can help water and oil to mix)  and even more importantly has a strong antimicrobial activity

Thanks to this last thing, it allows a lower percentage of traditional preservative or it might even be able to completely replace them. 

What-it-does: chelating

We don't have description for this ingredient yet.

What-it-does: preservative, deodorant

If you have spotted ethylhexylglycerin on the ingredient list, most probably you will see there also the current IT-preservative, phenoxyethanol. They are good friends because ethylhexylglycerin can boost the effectiveness of phenoxyethanol (and other preservatives) and as an added bonus it feels nice on the skin too.

Also, it's an effective deodorant and a medium spreading emollient

What-it-does: buffering

Citric acid comes from citrus fruits and is an AHA. If these magic three letters don’t tell you anything, click here and read our detailed description on glycolic acid, the most famous AHA. 

So citric acid is an exfoliant, that can - just like other AHAs - gently lift off the dead skin cells of your skin and make it more smooth and fresh. 

What-it-does: preservative

It’s pretty much the current IT-preservative. It’s safe and gentle, but even more importantly, it’s not a feared-by-everyone-mostly-without-scientific-reason paraben.

It’s not something new: it was introduced around 1950 and today it can be used up to 1% worldwide. It can be found in nature - in green tea - but the version used in cosmetics is synthetic. 

Also-called: Fragrance, Parfum;Parfum/Fragrance | What-it-does: perfuming

Exactly what it sounds: nice smelling stuff put into cosmetic products so that the end product also smells nice. Fragrance in the US and parfum in the EU is a generic term on the ingredient list that is made up of 30 to 50 chemicals on average (but it can have as much as 200 components!). 

If you are someone who likes to know what you put on your face then fragrance is not your best friend - there's no way to know what’s really in it.  

Also-called: Ci 77491/77492/77499 | What-it-does: colorant | Irritancy: 0 | Comedogenicity: 0

A bit of a sloppy ingredient name as it covers not one but three pigments: red, yellow and black iron oxide.

The trio is invaluable for "skin-colored" makeup products  (think your foundation and pressed powder) as blending these three shades carefully can produce almost any shade of natural-looking flesh tones. 

Limonene - icky
What-it-does: perfuming, solvent, deodorant

A super common and cheap fragrance ingredient. It's in many plants, e.g. rosemary, eucalyptus, lavender, lemongrass, peppermint and it's the main component (about 50-90%) of the peel oil of citrus fruits.

It does smell nice but the problem is that it oxidizes on air exposure and the resulting stuff is not good for the skin. Oxidized limonene can cause allergic contact dermatitis and counts as a frequent skin sensitizer

You may also want to take a look at...

what‑it‑does solvent
Normal (well kind of - it's purified and deionized) water. Usually the main solvent in cosmetic products. [more]
what‑it‑does soothing | moisturizer/humectant
The famous aloe vera. A great moisturizer and anti-inflammatory ingredient that also helps wound healing and skin regeneration. [more]
what‑it‑does colorant | abrasive/scrub
irritancy, com. 0, 0
A type of clay that's a fine, white powder and is used for its oil-absorbing and opacifying properties. It's less absorbent and less drying than bentonite clay. [more]
what‑it‑does viscosity controlling
irritancy, com. 0, 0
A highly absorbent clay that comes in different colors depending on its mineral content. It's excellent at absorbing things including sebum and gunk in the pores and it also has some skin soothing and "detoxifying" effect. [more]
what‑it‑does solvent | moisturizer/humectant
A natural corn sugar derived glycol. It can be used to improve skin moisturization, as a solvent, to boost preservative efficacy or to influence the sensory properties of the end formula. [more]
what‑it‑does soothing
The distillate created from the hazelnut-bush-like magic tree, commonly called Witch Hazel. It might have astringent, soothing, antioxidant and antibacterial properties. [more]
what‑it‑does perfuming
what‑it‑does emollient | viscosity controlling | emulsifying | surfactant/cleansing
irritancy, com. 1, 2
A super common multitasker ingredient that gives your skin a nice soft feel (emollient) and gives body to creams. [more]
what‑it‑does viscosity controlling
irritancy, com. 0, 0
A type of clay mineral that works as a nice helper ingredient to thicken and stabilize formulas. As a clay, it consists of platelets that have a negative charge on the surface (face) and a positive on the edge. [more]
what‑it‑does colorant
irritancy, com. 0, 0
Titanium dioxide as a colorant. It's a white pigment with great color consistency and dispersibility.
what‑it‑does emollient | emulsifying
irritancy, com. 0, 1
Waxy, white, solid stuff that helps water and oil to mix together and leaves the skin feeling soft and smooth. [more]
what‑it‑does emollient | viscosity controlling
Hydrogenated Vegetable Glycerides is a blend of fatty acid mono and diesters (kind of like an oil molecule but not with three but only one or two fatty acid chains on the glycerin) that exists in lots of versions. It can be a consistency-giving wax (think something like glyceryl stearate), or it can be a rich jelly emollient that acts as a petrolatum alternative. [more]
what‑it‑does perfuming
what‑it‑does perfuming
what‑it‑does moisturizer/humectant
Also known as Sugarcane, Saccharum Officinarum is a handy moisturizing ingredient mostly used as a humectant. This means that it can help the skin to attract water and then to hold onto it.  It bears a close relationship to AHA superstar, Glycolic Acid that can be derived from it, so it's often claimed that Sugarcane  [more]
what‑it‑does emollient
Shea butter that's considered to be a magic moisturizer and emollient. It is also soothing and rich in antioxidants. [more]
what‑it‑does emollient
irritancy, com. 0, 1-2
Apricot Kernel Oil - a nice general purpose emollient plant oil with vitamin E and fatty acids (mostly oleic acid 54-74%, linoleic acid 12-35%). [more]
We have to start by writing that there are about 900 citrus species in the world, and plenty of them are used to make different kinds of extracts used in cosmetics. This particular one, Citrus Aurantium Dulcis Fruit Extract is a very common ingredient, however, the species "Citrus Aurantium Dulcis" [more]
If life gives the cosmetic industry lemon, it makes lemon fruit extract.  As to why, we can write here extremely similar things to our shiny description of orange fruit extract.  Being both of them citruses, they contain very similar active compounds with very similar (potential) effects on the skin.  [more]
what‑it‑does soothing | skin brightening
You might know licorice as a sweet treat from your childhood, but it's actually a legume that grows around the Mediterranean Sea, the Middle East, central and southern Russia. [more]
The extract coming from the Sugar Maple tree, the one whose leaf is on the Canadian flag and gives us maple syrup.The main reason it is used in skin care is that it contains natural AHA acids, namely Malic and Tartaric, and hence why it supposedly helps slough off dead skin cells in combination with other acid-containing fruit extracts as part of the trade name ACB Fruit Mix. [more]
what‑it‑does abrasive/scrub
what‑it‑does viscosity controlling
A type of clay with magic absorbent properties. It's excellent at instantly sucking up sebum and gunk from the skin but can also be drying. [more]
what‑it‑does antioxidant | skin brightening
A stable and easy to formulate form of skincare superstar, vitamin C. In-vitro studies show that it shows all the three anti-aging benefits (antioxidant protection + collagen boosting + fading hyperpigmentation) that pure vitamin C does. [more]
what‑it‑does skin-identical ingredient | moisturizer/humectant
irritancy, com. 0, 0
A real oldie but a goodie. Great natural moisturizer and skin-identical ingredient that plays an important role in skin hydration and general skin health. [more]
what‑it‑does soothing | moisturizer/humectant
The salt form of one of the main anti-inflammatory ingredients in the licorice plant, monoammonium glycyrrhizinate. It’s a yellowish powder with a nice sweet smell.  It’s used mainly for its soothing and anti-inflammatory properties, but according to manufacturer info, it’s also sebum regulating so it' [more]
what‑it‑does viscosity controlling
A super commonly used thickener and emulsion stabilizer. [more]
what‑it‑does preservative
A natural multi-functional ingredient that has emollient and moisturizing properties, can work as a co-emulsifier and has a strong antimicrobial activity. [more]
what‑it‑does chelating
what‑it‑does preservative
It can boost the effectiveness of phenoxyethanol (and other preservatives) and as an added bonus it feels nice on the skin too. [more]
what‑it‑does buffering
An AHA that comes from citrus fruits. It is usually used as a helper ingredient to adjust the pH of the formula. [more]
what‑it‑does preservative
Pretty much the current IT-preservative. It’s safe and gentle, and can be used up to 1% worldwide. [more]
what‑it‑does perfuming
The generic term for nice smelling stuff put into cosmetic products so that the end product also smells nice. It is made up of 30 to 50 chemicals on average. [more]
what‑it‑does colorant
irritancy, com. 0, 0
A mix of red, yellow and black iron oxide. [more]
what‑it‑does perfuming | solvent
A super common fragrance ingredient found naturally in many plants including citrus peel oils, rosemary or lavender. It autoxidizes on air exposure and counts as a common skin sensitizer. [more]