What Is Propylparaben?
Propylparaben is a preservative used in skincare and cosmetic formulations.
Propylparaben is classed as a paraben, a group of preservatives with slightly different functions and anti-microbial activity based on their size. Other common parabens include methylparaben, butylparaben, isobutylparaben, and ethylparaben.
Propylparaben is used to extend the shelf-life of a product life by preventing microbial contamination. Microbial contamination can occur from exposure to bacteria and molds in the air and general use of the product from your hands. Preservatives like parabens are designed to reduce the likelihood that bacteria and molds can grow in your product. This is important for ensuring the safety of a product.
Propylparaben naturally occurs in some fruit and vegetable products, such as barley, flaxseed, and grapes. Parabens are found in plants in the form of p-hydroxybenzoic acid (PHBA), a chemical that breaks down to become parabens to protect the plant. The parabens used in cosmetics are identical to those found in nature. If parabens are absorbed through the skin, the human body can quickly metabolize them to PHBA and eliminate them.
Parabens have up until recently been the most widely used group of preservatives in skincare and cosmetic products. Parabens were so popular because of their gentle, non-sensitizing, and highly effective in comparison to other preservatives. However, the use of parabens is now controversial due to their alleged relation to health concerns.
the good: Protect products against the growth of bacteria and mold and improve the shelf life of a formulation.
the not so good: May be linked to several health concerns, including hormone disruption, cancer, and allergy.
Who is it for?All skin types except those that have an identified allergy to it.
Synergetic ingredients: Works well with most ingredients.
Keep an eye on: Propylparaben has many different names when used in formulations such as potassium salt propylparaben, 4-hydroxy-propyl ester benzoic acid, and propyl ester.
Why Is Propylparaben Used?
Propylparaben functions as a preservative in cosmetics and personal care products. In most formulations, parabens are used at very low levels ranging from 0.01 to 0.3%. The use of preservatives is necessary to prevent microbial contamination, as well as to prevent degradation by environmental factors such as heat, light, and air.
Skincare are highly susceptible to microbial contamination and growth. The most susceptible products are creams and lotions that are packaged in jars, opened frequently, and applied to the skin with the fingers.
Further, by limiting the growth of bacteria and fungi, preservatives like isobutylparaben help keep us safe from infection and other diseases. It’s true that skin already acts as a barrier, but if contaminated creams are applied to the skin, an inflammatory response can be elicited, and lead to skin damage in the long term.
In addition, bacteria can easily invade our bodies if contaminated product is applied to broken skin, or if small amounts of contaminated lipstick or lip balm are accidentally ingested through the mouth.
Parabens help to stabilize the formulation of a product, increasing its shelf-life. Without preservatives, most skincare or cosmetic products would only last 2-4 weeks before going rancid.
In many ways, the inclusion of such preservatives is indispensable in our day and age. We often take for granted how cheaply some skin care products can be purchased, and the fact that we don’t have to waste money throwing away too many expired products in the trash. In many ways, this is achieved through the use of parabens and other preservatives.
Why Are Preservatives Needed?
In most formulations, parabens are used at very low levels ranging from 0.01 to 0.3%. The use of preservatives is necessary to prevent microbial contamination, as well as to prevent degradation by environmental factors such as heat, light, and air.
Cosmetics have a high potential for microbial contamination and growth. The most susceptible products are creams and lotions that are packaged in jars, opened frequently, and applied to the skin with the fingers.
Inadvertent contamination may also occur after the use of makeup brushes around the eyes or other parts of the face that touch the skin and the cosmetic repeatedly. Each use increases the chance of contamination. Furthermore, contamination may occur if the consumer leaves a product container open for an extended period.
Another major cause of product contamination is storage conditions. Since the majority of products are stored at room temperature, the warm temperature can stimulate the growth of microorganisms. Plus, the ingredients used in cosmetic formulations, such as water, oils, peptides, and carbohydrates, create the perfect environment for microorganism growth.
Microbial contamination can lead to significant health problems, from skin irritation to infections. To avoid these problems, a strong yet non-irritating preservative must be added to the formulation.
What Are The Controversies Surrounding Parabens? Are Parabens Safe?
Over the past 10 years, parabens have become criticized for use in cosmetics due to research that has revealed their potential in relation to health concerns. However, the research on parabens is conflicting and polarizing.
The concern around parabens started when a 1998 study found that parabens had a weakly estrogenic effect in rats. This means that the study suggested that parabens were able to bind to estrogen receptors, potentially disrupting hormone production.
This was of potential concern as, if parabens had the ability to mimic the hormone estrogen, they could interfere with the hormone balance in the body. This is of particular concern when we think of hormone related cancers such as some specific types of breast cancers.
It is important to note that despite estrogen usually being classified as a female hormone, both sexes produce estrogens and could potentially be affected by hormone disruption. Hormone disruption can affect reproductive activities in the body, such as pregnancy and menstruation.
The Science: Hormone disruption
However there are a few issues with those who use this study to support the claim that parabens are linked with hormone disruption.
Firstly, the results of this study, while they showed some estrogenic effect on the rats, the effect was extremely low. The estrogenic effect of parabens on the rats was about 10,000-2,500,00 times weaker than the natural hormone, estrogen. This suggests that paraben’s potentially harmful effects on the body is negligible.
One of the other issues with this using this study to support the claim that parabens cause hormone disruption is that it was conducted in rats. Rat and mice studies can be useful in determining safety or to get an idea of how ingredients or drugs may affect the body; it doesn’t always translate to effects in humans. This is why human studies are used to determine the efficacy and final safety of drugs and ingredients.
Another issue with using this study as evidence to this claim is that the mice were injected with parabens. This makes this study impossible to compare to topical use or use in skincare products.
A 2004 study also looked at the concentrations of parabens in breast tumours. The study found parabens present in breast tumours. With that finding the study was picked up by the media and claims that parabens cause breast cancer, ran rampant.
The Science: Breast cancer
The first thing to point out here is that the study found that breast tumours contain parabens. They did not suggest that there was a direct link between paraben use and the development of breast cancers.
There are a number of issues with the study that are important to note. The first is that the study did not have a control group using non-cancerous tissue. If you remember back to highschool science, in order to compare your results you needed a sample that had not received any treatment.
This study didn’t use a control for non-cancerous tissue, instead all of their samples were cancerous tissue. This made it hard to identify if parabens, which are naturally occurring in plants, are normally found in breast tissue or whether it was linked to cancerous tissue. If they had used a control like this their results would have been more meaningful. This means that it had no causal link.
Think of a causal link through this scenario. If you studied the diets of those who had stomach cancer you may see a commonality that they all drink water. If you didn’t have a control group who would also consume water, as we all need to do to survive, then you might think that water causes stomach cancer. This is why control groups are so important.
The study used compared cancerous tissue that had been exposed to parabens to cancerous tissue that had not been exposed to parabens. Interestingly, some of the blank or paraben-free samples that they used showed higher levels of parabens than the paraben-containing samples.
The authors of the study actually released a statement 6 months following its publication to clarify that no claim was made that parabens cause breast cancer. The American Cancer Society has concluded that there is insufficient scientific evidence of parabens increasing breast cancer risk.
Regardless of the flaws in the experimental design of the breast cancer and parabens study, the presence of parabens in the cancerous tissue doesn’t indicate a causal link.
Given how weak parabens are in relation to hormone disruption, as the 1998 study has told us, the presence of parabens in the breast tissue is unlikley to have any impact on the health of the individual. Even some much stronger estrogenic compounds haven’t been linked with breast cancer or hormone disruption. An example of this is estradiol.
Research that strongly dispells these claims
A 2005 study published in the journal Critical Reviews of Toxicology concluded that “it is biologically implausible that parabens could increase the risk of any estrogen-mediated endpoint, including effects on the male reproductive tract or breast cancer.”
Other research indicates that parabens are safe as used in cosmetics and preferred since they are gentle, non-sensitizing, and highly effective. In fact, parabens were found to be beneficial due to their ability to deter the growth of mold, fungi, and other harmful pathogens.
Furthermore, these studies have demonstrated that parabens did not have any effect when compared to natural hormones in the body.
Overall, the cosmetics industry has determined that the low levels of parabens used in cosmetic products are safe. The US Food And Drug Administration finds that while parabens may mimic estrogen, the actual effects of this low level of activity on the body do not cause cancer in a higher incidence than naturally occurring estrogen.
The controversial nature of these ingredients has meant that there has been a respectable amount of research into the safety of parabens. Given the controversy most jurisdictions have limited the use of parabens to low concentrations, for example in the EU, the use of butylparaben is limited to 0.4%.
It is generally considered that longer chain parabens such as propylparaben or isobutylparaben are more likely to be disruptive in the body. The main parabens that are used in skincare and cosmetic formulations are usually of the smaller variety. Research into parabens as a class of ingredients is being continued and updated regularly.
Do Parabens Cause Irritation Or Allergic Reactions?
Parabens have previously been linked to some irritation, allergy and sensitivity, particularly in sensitive or irritated skin.
Parabens are used because they are gentle and non-irritating. However, like any ingredient some people may be more likley to experience irritation than others. For instance Healthline suggests that some people have reported allergies to methylparaben specifically.
It is generally recommended that hyper-sensitive skin types such as those prone to eczema or dermatitis or those with broken skin avoid the use of parabens if they find them to be irritating.
Parabens are also more likely to irritate the skin when it is broken such as if you have a wound or cut on the skin. If your skin is broken, it is best to avoid the use of parabens in that area.
Another concern with parabens and other parabens is the possibility of an allergic reaction. However, the actual incidence of allergy and true allergic contact dermatitis to parabens is very low, less than 2 percent.
Like many skincare ingredients, parabens can cause irritation and sensitization when used on inflamed or damaged skin such as skin types experiencing dermatitis and eczema.
This is why parabens are never used to preserve topical hydrocortisone creams or antibiotic ointments which are used on damaged or inflamed skin. Generally, parabens don’t irritate the skin or cause allergy for normal skin types.
Should You Still Avoid Parabens?
On a daily basis you are exposed to compounds that are far more estrogenic than parabens. Just because something is estrogenic doesn’t necessarily mean that it is dangerous to your health.
As we have seen parabens are extremely weak in terms of their estrogenicity. Many other compounds that we commonly use such as estradiol or birth control or phytoestrogens from foods such as soy are considered to have a stronger estrogenic effect and are still considered to be safe.
Avoiding parabens ‘just in case’ seems unnecessary and expensive.
Are Parabens ‘Natural’?
Parabens can be naturally derived from plants. Parabens are found in plants in the form of p-hydroxybenzoic acid (PHBA), a chemical that breaks down to become parabens in order to protect the plant.
In fact, the parabens used in cosmetics are identical to those found in nature. If parabens are absorbed through the skin, the human body can quickly metabolize them to PHBA and eliminate them.
Are Alternatives To Parabens Safe?
Creating safe and effective products without preservatives isn’t really an option.
The risk of contamination is high when dealing with water-based formulations and not including a preservative can limit how safe and how effective your product will be.
However, given the rumours around the safety of parabens, many brands have replaced parabens with alternatives. There are some issues with this.
Newer preservatives aren’t as well researched as parabens. This means that the health implications are somewhat unknown, particularly their longterm side effects.
In fact, many of these alternatives including the ‘natural’ ones tend to cause more irritation to the skin and don’t work as well in preserving the formulation.
This increases the risk that your product may become contaminated with mold, bacteria and fungi. It also reduces the shelf-life of the product, creating more waste.
Both ‘natural’ and synthetic alternatives to parabens are more likely to irritate the skin and cause sensitivity and allergic reactions. Just because it is paraben-free doesn’t make it safer.
One way that may help to reduce the amount of preservatives needed in a formulation is through packaging design. Packaging design may reduce the amount of exposure to contaminants, such as vacuum sealed products or pumps. However, packaging design does not stop the product from degrading and becoming rancid.
What Are The Differences Between Parabens?
The most commonly used parabens are methylparaben, ethylparaben, propylparaben, isopropylparaben and butylparaben.
The shorter chain parabens methylparaben and ethylparaben are often used in combination with other parabens. The longer chain parabens are often used by themselves.
Some parabens are more likely to cause irritation and sensitivity than others such as methylparaben. And some parabens are considered to be stronger such as the longer chain parabens.
How Do You Use Parabens Safely?
The typical concentration of parabens used in cosmetics is 0.01 to 0.3 percent. Due to the controversy around parabens, they are highly regulated both in Europe and the United States. Their use is limited to low concentrations.
There is little reason to be concerned about their use. However, if you are using a large number of paraben-containing products, then you may be exposing your skin to higher-than-normal levels of the ingredient. This may slightly increase the risk of irritation.
If you have sensitive skin it may be useful to become familiar with common preservatives in order to reduce this risk.
Do Parabens Impact The Environment?
Parabens have been found to be present in the environment due to their use and subsequent release into the environment through the sewage system.
The impact of parabens once they are in the environment is unclear. However, research seems to suggest that they have little to no impact on organisms in the environment.
What Are The Other Uses For Parabens?
In addition to its natural occurrence in some fruits and vegetables, parabens may also be added to food for preservation.
Typical food products that contain parabens for preservation include beer, sauces, desserts, soft drinks, jams, pickles, frozen dairy products, processed vegetables, and flavoring syrups.
CIR, 1995. ‘Final Report on the Safety Assessment of Isobutylparaben and Isopropylparaben’, International Journal of Toxicology.
Cosmetic Ingredient Review, 1984. ‘Final Report on the Safety Assessment of Methylparaben, Ethylparaben, Propylparaben, and Buylparaben’, Journal of the American College of Toxicology, vol. 3, no.5.
Engeli, R, Rohrer, S, Vuorinen, A, Herdlinger, S, Kaserer, T, Leugger, S, Schuster, D, & Odermatt, A, 2017. ‘Interference of Paraben Compounds with Estrogen Metabolism by Inhibition of 17β-Hydroxysteroid Dehydrogenases’, International Journal of Molecular
Hu, P, et al. 2017. ‘Methylparaben and butylparaben alter multipotent mesenchymal stem cell fates towards adipocyte lineage’, Toxicology and Applied Pharmacology, vol. 15, is. 329, pp. 48-57.
Matwiejczuk, N, Galicka, A & Brzóska, M, 2020. ‘Review of the safety of application of cosmetic products containing parabens’, Journal of Applied Toxicology, vol.40, is.1.