Article by: Perry Romanowski

This recent article about scientists discovering bacteria living in hairspray provides a good example of why cosmetic products need to be preserved. Microbes can grow almost anywhere! And these tiny organisms bring with them some distasteful product changes or even disease. As a cosmetic chemist it’s up to you to formulate properly and keep these invaders at bay. You typically do that by adding preservatives to your formulas. Unfortunately, you’ll have to know more than just the science as preservatives are some of the most highly regulated and restricted ingredients you will use.

Why you need cosmetic preservatives

There are two primary reasons you need preservatives.

1. To stop microbes from spoiling your products.
2. To stop microbes from causing disease.

The microbes that can infect your formulas primarily include bacteria, mold, and yeast. In small quantities they don’t represent much of a problem but when they multiply, look out. Bacteria like Pseudomonas can cause all kinds of health problems including skin and eye infections, toxic shock, strep throat, and even food poisoning. Yeast like Candida albicans can cause thrush. And many other bacteria can cause your products to smell awful, change color or otherwise break down. (This is what stability testing is for).

The following is a list of common preservatives used in cosmetic and personal care products. As a future (or current) formulator, you will undoubtedly be using many of them.


Parabens are the most commonly used preservatives. They are derivatives of p-hydroxybenzoic acid and go by names like Methylparaben, Propylparaben, and Butylparaben. They are typically supplied as powders and can sometimes be difficult to incorporate into a system due to the water solubility limitations. They are effective against a broad spectrum of bacteria and fungi. They do have pH limitations and are not effective against all microbes so you usually will need an additional preservative.

Formaldehyde donors

Formaldehyde derivatives are the next most common preservative. These compounds interfere with membrane proteins which kills microbes. They are effective against bacteria, fungi, and mold. Bad press and real safety concerns have led cosmetic chemists to stop using formaldehyde. Instead ingredients that dissociate into formaldehyde when put in a water solution are used. These are compounds like DMDM Hydantoin, Imidazolidinyl Urea, and Gluteraldehyde. They are most often used in surfactant systems.

Phenol derivatives

Phenol derivatives have been used in cosmetics for many years and can be effective against a range of microbes. Unfortunately, they are not as effective as the previous ingredients so their use is limited. The most common examples is Phenoxyethanol.


Compounds that contain nitrogen and have a positive charge when placed in solution are called quaternary compounds (or quats). Many of them demonstrate an ability to kill microbes. This include ingredients like Benzalkonium Chlroide, Methylbenzethonium chloride, and Benzethonium chloride. Their cationic nature makes them less compatible with anionic surfactants which limits their application & use.


Ethanol is a great preservative but you need to use it in high levels and it faces significant environmental restrictions. Other compounds like benzyl alcohol, dichlorobenzyl alcohol, and even propylene glycol all have some anti-microbial effect. In lower levels, these compounds are less effective at preserving products.


Synthetic compounds like Methylchloro- Isothiazolinone and Methyl-Isothiazolinone are effective at incredibly low levels. They have been shown to work at a wide range of pHs and in many different formulas. There use has been stymied however, by at least one study that suggested it could cause skin sensitization.

Organic Acids & Others

Various other compounds are used as preservatives but all face some limitations not experienced to the same extent as the previous ingredients discussed. Some of the most important include Sodium Benzoate, Chloracetamide, Triclosan, and Iodopropynyl Butylcarbamate. Pyridine derivatives like Sodium pyrithione and zinc pyrithione are used to kill the bacteria that causes dandruff.

Why cosmetic preservatives are vilified

More than any other ingredient, preservatives are most often called out as the worst ingredients you can use in a formula. Even people who know nothing about chemistry have likely heard about the “evil” parabens and formaldehyde.

Preservatives are designed to kill cells. That’s why they are effective. Unfortunately, that’s also why they are potentially hazardous. They don’t easily discriminate between good human cells and bad microbial cells. But ultimately, the risk from using preservatives is significantly lower than that of using unpreserved cosmetics. There are safe levels of “toxic” chemicals. All chemicals can be deadly if you’re exposed to a high enough level. How many people die from water exposure (e.g. drowning)?

Remember, it’s the dose the matters!

To be sure, cosmetic science research is ongoing in the field of preservatives since many things previously deemed safe have been reclassified as hazardous. Suppliers who can come up with even safer preservatives will likely make a lot of money. Hopefully, they’ll do it soon but there do not appear to be any promising materials on the horizon.


About the Author

Perry Romanowski

Perry has been formulating cosmetic products and inventing solutions to solve consumer problems since the early 1990’s. Additionally, he has written and edited numerous articles and books, taught continuing education classes for industry scientists, and developed successful websites. His latest book is Beginning Cosmetic Chemistry 3rd Edition published by Allured.


  1. Avatar


    I am want to make a Tumeric face scrub with rice powder at around 6o% of the formula. Do you have an suggestions for safe preservatives that I could use against bacteria,mold and yeast.

  2. Avatar
    Laura Pham

    I would like to apply Sodium Benzoate for shampoo to preserve about 2 years. Can I use this ingredient alone or I have to blend with other? How percent can I use in shampoo formula?

    1. Avatar
      Perry Romanowski

      Sodium Benzoate probably won’t be an adequate enough preservative to last 2 years. You should use something like DMDM Hydantoin.

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  4. Avatar
    Aaron Jin

    Hello Perry!Good article ! I have a problem reading paragraph “Quats” line 3 about the substance”Methene aommonium chloride”.I can’t find it in chemical books. And in the word “aommonium” I wonder if there is an extra “o” after the first “a”? Thanks for sharing your professional konwledge again!

    1. Avatar
      Perry Romanowski

      Thanks for the question. This was written long ago and that looks like a typo. I’ve corrected the post.

  5. Avatar
    Adesina Ayodele

    Hi, want to use this medium to ask this question again, I need advice/recommendation for a very effective preservative for starch/Polyvinyl Alcohol blend that can preserved
    for about 2 years. I’m into the manufacturing of laundry starch and the raw materials consist of gelatinized starch, Polyvinyl Alcohol and Vinyl acetate.

    1. Avatar
      Perry Romanowski

      Try something like DMDM Hydantoin.

  6. Avatar
    Marina Georgiou

    hi there,
    thank you for the wonderful community.
    i am about to take a face cream for testing and I am still hesitant as still unsure if there was a more effective way to formulate rather than stand alone preservative..
    I currently use Geogard ECT, as I wanted something that is ECOcert and considered more natural.

    My question is, i had some few concerns. Some people pass the stability tests and some do not, ofcourse depending on their formulations etc.

    My question is, is there something that Geogard ECT can be paired with to make it more effective in the long run that i should consider before taking it for testing? I mean usually from what i read, it can last from 6months to a year.

    I wanted to know my options before i take it for testing as i am in the early stages.

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  9. Avatar

    I am DIY HA with rose water. How long is the shelf life with out preservative? Thanks

    1. Avatar
      Perry Romanowski

      Less than a week.

  10. Avatar
    Deana Sanderson

    Hi Perry, thank you for creating this website. It has a wealth of information in it that I am finding very useful! With respect to preservatives – I use Geogard ECT at 1% in the cool down phase of my hand lotion and cleanser formulations. I noticed the other day that one of my hand lotions turned watery after 2 months. The hand lotion didn’t have a bad odor nor did it separate. Does this sound to you like a preservative issue?

    1. Avatar

      This sounds like too much water content, or not enough emulsifier to begin with. If you reheat the product again to add additional emulsifier, you might then need to compensate for any preservatives that have lost their originl efficacy

  11. Avatar
    Mira Farhanah

    Hye. Im Mira. If vapor rub contain preservative, do we need to performthe antimicrobial preservative test?

    And, as vapor rub in oleaginous ointment, how to dilute or dissolve this type of sample?

    Thanks 🙂

    1. Avatar
      Perry Romanowski

      Yes, you need to perform a preservative test on it.

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    hello everyone, im making a face cream. is it alright for me to add preservatives to my formulation which contains fermented yeast. do fermented yeast contains yeast which is microbial. i dont know what inside the fermented yeast at the first place. thank you for any reply.. sincerely piji.

    1. Avatar
      Perry Romanowski

      No, fermented yeast is not a proper preservative.

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    What is the best preservative and what quantity should I use in a lipstick made with a combination of waxes, oils, dyes, pigments and micas, and a drop of flavourings?

    1. Avatar
      Perry Romanowski

      It depends on many factors but you could try Benzyl Alcohol. Of course, you should never sell any product that hasn’t been tested for safety.

  14. Avatar
    Andrea Demarco

    I’m making my own homemade body butter with all oil based products. Shea butter, coconut oil, olive oil, rose hip oil, almond oil, and vitamin E. Do I need preservatives? I’ve read so much online and am very confused

    1. Avatar
      Perry Romanowski

      I would say yes you should use a preservative. There is no downside to including a preservative even if you may not need one based on the amount of water in the formula. Think of a preservative as a fire insurance policy. You probably won’t need it but it’s good to have.

      1. Avatar
        Andrea Demarco

        What is a good preservative to use in a mostly oil blend?

        1. Avatar
          Andrea Demarco

          And also, what are the chances of being able to talk over the phone?

  15. Avatar

    I too would like some more insight into whether or not hyaluronic acid (HLA) is good to keep on the surface of skin long-term. I have only read positives (probably marketing) about it so far, as well as a journal article about how even larger molecules of HLA effectively penetrate skin cells, and don’t just sit on the surface or between cells.
    Does this lead to worse wrinkles and skin health & appearance long-term as Jonathan asked above?

    1. Avatar
      Perry Romanowski

      In general Hyaluronic acid is thought to be beneficial to skin. It works as a humectant so will provide some moisturzation effects. Don’t expect it to get rid of wrinkles however.

      1. Avatar

        Dear Perry,
        If the H.A. moisturizes and plumps up the skin then it will fill wrinkles right?

        1. Avatar
          Perry Romanowski

          Well, theoretically. But that doesn’t mean it will in reality.

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    Hi perry I would first like to say that I love this site. It is very helpful as well as informative. I am a recent cosmetology grad and I would love to create my own products. I would like to keep them as natural as possible but I know that’s not very realistic. I would like to know what preservatives would you recommend for lipsticks and or lipgloss. Thank you

    1. Avatar
      Perry Romanowski

      That really depends on what else is in your formula.

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  18. Avatar
    ashwin meshram

    i want a formulation of vanishing cream ,cold cream, night massages cream all purposes cream

  19. Avatar

    I’m considering creating an anhydrous skin-protectant “jelly” and a baby diaper balm using a variety of oils, butters and beeswax. I don’t plan on using any botanicals or any fragrance oils or essential oils. Would Optiphen be a good preservative to use? My concern is where these products will be applied, mainly face and baby bottom.

    Most people tend to dip bare, dirty fingers into creams and double-dipping could prove to be even more hazardous. Would a preservative like Optiphen be sufficiently effective? I think about the potential dangers and it scares me to death!

    1. Avatar
      Perry Romanowski

      I don’t think that would be a good choice as it is not a particularly strong preservative. Better would be something with a formaldehyde donor technology.

  20. Avatar

    Hi, I want to ask if the formula of the following in cream preparation have enough preservatives? Thank you
    Part A (Oily Phase)
    Stearic acid 1.25%
    White beeswax 0.75%
    Stearyl alcohol 2.5%
    Cetyl alcohol 3.25%
    Mineral oil 2.5
    Solanum lycopersicum extract 1.0%

    Part B (Aqueous Phase)
    Propylene glycol 2.5%
    Triethanolamine 1.0%
    Methylparaben 0.005%
    Propylparaben 0.02
    Water Up to 50%

    1. Avatar
      Perry Romanowski

      I don’t know, you would have to test it. However, 0.005% methylparaben is pretty low. I would suggest 0.1% or 0.2% of parabens.

  21. Avatar
    Arlene Phillips

    I purchased Liquid Germall Plus. Your thoughts. My lotion molded in less then 2 days.
    Thank you

    1. Avatar
      Perry Romanowski

      There are a few things.
      1. You may not have used enough.
      2. You may have added it too hot and deactivated the preservative
      3. Your starting materials were too contaminated when you started.
      4. Your manufacturing conditions were not clean enough.
      5. You have microbes that are resistant to the preservative you’re using.

  22. Avatar

    Hi Perry,
    I was going to make a anti aging facial serum that i got from a formulation company,and use Leucidal liquid SF for my natural preservative. This is fine right to make safe? The chemist put the formula together for me, i mean the recipe i actually have to put it together, anyway i thought i would get another opinion before actually making this . Also i will be using a testing kit. What is your opinion on Leucidal liquid SF Thank you for your help.

    1. Avatar
      Perry Romanowski

      I don’t really know. I would personally not trust the safety of the product as I don’t think Leucidal is an adequate enough preservative, but it really depends on a number of factors. People claim to have made products with it that are microbially safe but I’m skeptical. I don’t think there are any good reasons for people who put together formulas to stray from ingredients that have been proven to work and are safe.

  23. Avatar
    Ann Green

    Hi, I used a lip balm with the ingredients :-
    Organic – Apricot Kernel Oil, Cocoa Butter, Beeswax, Avodado Oil, Caster Oil,
    Pepperment essential Oil and Natural Vit E.
    Is it possible that this lip balm gave me Thrush in my mouth?

    1. Avatar
      Perry Romanowski

      I suppose it’s possible. Yeast spores could exist on the surface of your lip balm which is why preservatives are often included in even anhydrous products.

  24. Avatar

    The perservative I use in a cooling process is phenoxyethanol. Could you please advise the toxicity involved. I have not found anything negative on a professional chemist site only on WordPress etc. What is the precautions used when working with this product in the cooling phase.

    1. Avatar
      Perry Romanowski

      Phenoxyethanol is perfectly fine for use in most cosmetics. The only caution is in something like nipple cream where a baby might ingest some of the product. Otherwise it is safe.

      1. Avatar

        HI PERRY, Can phenoxyethanol be used alone as a preservative in anti-aging eye cream w/ peptides? Or Do I need other ingredients w/ phenoxyethanol as a preservatives? I have read nothing good about this preservatives yet I see all these expensive cosmetics brands have this as their ingredients. Is it only in the cooling phase to add this preservative or needs to be heated up to be active?

        1. Avatar
          Perry Romanowski

          It can be used if it is effective. Every system is different and may require a different type of preservative. Typically, having multiple preservatives is better than only having a single one. This preservative is not heat sensitive so you can add it at most any point in the procedure.

  25. Avatar
    Robert Lucas

    Hello, I’m planning on selling a coffee based product and would like help with the preservatives. Could you send me an email by any chance? Not sure what to use and how much of it to use. It’s a body scrub, and I’m afriad the preservatives could be skin-damaging.

    1. Avatar
      Perry Romanowski

      Use preservatives like methylparaben or DMDM hydantoin. They will not damage skin.

  26. Avatar


    I would love to get your opinion on the best preservative for a face and body mist. I would like to create a face and body mist using water and a mix of essential oils. I would love to be “natural” or “preservative free” but it is my understanding that mixing any oil with water requires a preservative. What would you suggest the safest preservative would be for this type of “natural” product?

    1. Avatar
      Perry Romanowski

      It really depends on what is in your formula. If you are going to have essential oils mixed with water you’ll need an emulsifier. You could try something like Sodium Benzoate if you keep the pH under 5.0. Phenoxyethanol can work. See our post on alternative cosmetic preservatives.

  27. Avatar

    Hi Perry
    is vitamin e or vitamin c a good cosmetic preservative?

    1. Avatar
      Perry Romanowski

      Neither of them are preservatives. Both are antioxidants and can help inhibit rancidity but they do not protect your product from microbial contamination which is why people use preservatives.

  28. Avatar
    Patricia Swayze

    I have been reading that Japan has the highest standards when it comes to making cosmetic products. I wonder what preservatives they use for their skin care lotions etc.? I would be interested in buying Japanese products here in the states but I am not sure if the ones that they export would have the same ingredients as what they sell in their country because the US is not as strict. In other words they might export less quality items to the US than what they sell in their own country. So far I only make facial serums with oils because I am afraid of making products with water since, I am not a chemist. I think that anyone that makes and sells their own hydrous products should have them made in a lab. Thanks for any information that you can provide. Patricia

    1. Avatar
      Perry Romanowski

      In the US, it is illegal to sell unsafe cosmetic products. That is the law. How do you make something safer than safe? You can’t. There is no evidence that cosmetics in Japan are more safe than the ones in the US or the EU.

      I agree that until you learn about proper preservation you should not be selling products made with water.

  29. Avatar

    If I want to make natural organic cosmetics product for sell them ,what is the most safe preservative should I use to have safe product and how I know it’s expiry date?

    1. Avatar
      Perry Romanowski

      That really depends on the type of product you are making and the raw materials you are using.

  30. Avatar
    amy myers

    I haven’t seen any comments regarding aspen bark as a preservative. Any thoughts?

    1. Avatar
      Perry Romanowski

      It’s not effective enough to use as your primary preservative.

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    Hi, perry.. please explain why my product ( sunblock & toner) in few months become moldy?

    1. Avatar
      Perry Romanowski

      Most likely because whoever put the formula together didn’t use an effective preservative.

  32. Avatar

    If your raw ingredients for cosmetics have bacteria (whether growing or stable), is there a way to kill the bacteria or stop the bacteria from growing? If you heat the ingredients up for an extended period of time, will that do the trick?

    1. Avatar
      Perry Romanowski

      Heating the ingredient for an extended time can work but it can also damage the ingredient. If you know that something has bacterial growth I wouldn’t use it.

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    I’m not a chemist, so this might be a totally stupid question. But if you use preservatives that convert into formaldehyde, how is that different from using formaldehyde in the first place?

    1. Avatar
      Perry Romanowski

      You use a lot less formaldehyde.

      1. Avatar

        Well then what is the recommended dosage of formaldehyde in a home made shampoo that lasts an year?

        BTW the discussion is very helpful. Best Regards

        1. Avatar
          Perry Romanowski

          It’s not recommended to put formaldehyde in a formula as the preservative. Better are things like DMDM Hydantoin, or Imidazylidinyl Urea. These are typically used at 0.2% but it depends on your formula.

  34. Avatar

    Can you show me the interaction between chemical agents in cosmetics
    Many thanks

    1. Avatar
      Perry Romanowski

      I don’t know what you mean. What specific interaction do you want to know about?

  35. Avatar

    What are your thoughts on Leucidal Liquid? It’s tough out here in the natural world. I would much rather send out a product that is safe, but with so much information out there, many consumers seem to ignore the whole “preservatives are needed”. I would love to be able to tell them the real scoop on the “natural” preservatives so that my products don’t get frowned upon when they are safely made.

    1. Avatar
      Perry Romanowski

      Hello Erica – That preservative can work in some systems but it does not have a broad spectrum of activity so I’d be skeptical that if you just use it that your formulas will be effectively preserved.

      1. Avatar

        They weren’t! In my lighter lotions, mold formed rather quickly, even though I used the recommended amounts. Thank goodness for testing. What a mess that would have been. As always, thanks for the great blog!

  36. Avatar

    Hi Perry! Thanks for the great article, as always! I hope you don’t mind commenting on a preservative mystery. One of my friends was looking at a product (I believe a face moisturizer) that contained seven different parabens, and she asked me why it might need so many different kinds. I’m used to seeing perhaps two to four parabens in a formula. Unfortunately I don’t know the product or the specific ingredients. Would you mind sharing your thoughts on why so many different parabens might have been required for the preservative system?

    1. Avatar
      Perry Romanowski

      That many is probably not required but the cosmetic chemist who originally put the formula together probably just used a blend containing all of those. In theory, more paraben types will kill more types of microbes. The other thing is that the manufacturing facilities might not have been clean enough and they needed additional preservative to prevent contamination.

      1. Avatar

        Thank you for the interesting and unexpected answer! I never considered that the environment in which products are made might affect the chemist’s decisions. I really appreciate you taking the time to share your thoughts!

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    Dr. Vineet Sharma

    Can anyone suggest me ZPTO compatible preservatives, preferably other than DMDM and Isothiazolinones.

    1. Avatar
      Perry Romanowski

      What do you mean by ZPTO? I’m unfamiliar with the abbreviation. It also depends on what else is in the formula.

  38. Avatar

    Hi there.
    I was told that potassium sorbate and sorbic acid are excellent preservatives for the use in skin care products. Is that correct or are there some better working alternatives? Can I use Vitamin C for instance to have a better position for my adverts?

    1. Avatar

      I would not say that they are excellent preservatives. Those would be the parabens. But potassium sorbate and sorbic acid can be good enough. It does limit your formulation ability however. You can add vitamin C to your formula but it is not a preservative.

      1. Avatar

        Sorbic and benzoic acids are, by themselves, pretty poor cosmetic preservatives.

        1. Avatar
          Perry Romanowski


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  42. Avatar

    Hi Perry. Concerning preservatives, can you give a list of the popular types of preservatives that the ‘all natural’ community do use? I am trying to appeal to that market, and I am aware that they have to turn to some synthetics etc but unsure of which ones. Thanks in advance

  43. Avatar

    Can anyone recommend a vegetarian microbial test kit that can be used to test for contamination? Thanks.

      1. Avatar

        vegetarian? what do you mean?

  44. Avatar

    Thank you for the exciting topic and useful information!
    More than anyone I’m interested in understanding how do you, chemists, decide which preservative system fits your needs and how much of it you need to use. Our company has long experience with natural preservatives in the food industry (we have a patent on rosemary preservative for foodstuffs). Based on this know-how, we developped cosmetic preservatives from rosemary, olive leaves, pomegranate and even onion extract. All challenge tests (US Pharmacopoeia) show excellent anti-microbial activity. The main problem is price. Phenoxyethanol for example costs <4$/kg (which is around 8$/pound) and the prices of our products are higher. How much should a 100% natural preservative cost? The dosage we recommend is 0,25 – 0,5%. Also, some of these preservatives have a color (for ex. pomegranate is reddish), is this a nogo?

    Thank you very much for your help 🙂

    1. Avatar

      Hello Liliana – Very good questions.

      The primary considerations in picking a preservative are (in no particular order)…
      1. Effectiveness
      2. Formula compatibility
      3. Price
      4. Marketing story

      Of these, price is probably the smallest factor as the preservative usually doesn’t add much to the overall cost of the formula. It would matter if the price got too high however. It sounds like your preservatives would have some niche application because color and odor effects are a problem. In my opinion, the current preservatives work and have no real problems associated with them. Indeed there is a push from some areas of the market to have “all natural” preservatives but for cost and compatibility reasons I doubt the market for alternative preservatives will ever get too large.

    2. Avatar

      Liliana, does your company sell the preservatives you described?
      Please share if that’s ok. Thanks, Laura

  45. Avatar
    LaNita Darden

    Yes, I would like recommendations on this also.

  46. Avatar

    what are the process to avoid the contamination during manufacturing of cosmetic products!!!!?

  47. Avatar
    LaNita Darden

    Naturagard Ultraâ„¢ which is Gluconolactone (and) Sodium Benzoate. What can you tell me of this? It is considered an ECOCERT certified preservative. Will this do the job for amore natural preservative?

  48. Avatar


    Oil soluble preservatives inhibit growth of microbes at the interface of the oil and water.

  49. Avatar
    Prajakta Bhuskute

    Please Explain the mode of action of oil soluble preservatives.
    If they are not soluble in aquas phase how do they prevent microbial attack in emulsions.

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  51. Avatar
    David Steinberg

    I am always amazed about the use on non-preservative preservatives. Why? When I ask companies who offer these, why don’t you register them and get approved in the EU and Japan. The responds is usally,the cost of all the safety testing. Duh! Preservatives or any other chemical with cidal properities are bioloigically active. So safety must be done.

    People are so interested in using preservatives which have very limited safety and no peer review, instead of preservatives which have undergone extentisve testing and reviews.

    Why? Usually marketing. “If I don’t know it can’t hurt me”. Nonsense.

  52. Avatar

    Hi Perry,

    Just in relation to article about traditional preservatives and you mentioned there was no promise of any other new materials on the horizon. I would like to mention that we have been doing some very successful production with Dr Straetmans preservative systems of glyceryl caprylate, and p ansinic acid. There are also some other nature identicals like Mackaderm GCP and various systems from Lonza. There is also some other manufacturers based here in Australia who have developed some successful systems as well, though questionable is they are in use in full production scale? Preservation is not something that we tread around lightly either, being a contract manufacturer certainly brings on more challenges than expected. Another point you don’t seem to talk about is water quality. We’ve dabbled in several systems and find our current system to be the best yet, based on ozone. I would enjoy finding out more about reducing water activity as mentioned by David, this is something i have read about in the book he mentioned and think this could be something of benefit in the future with more “natural” options other than glycerine. Another question is, do you know much about the method of milling and product preservation? Aparently it’s and older system that was used in the food industry years ago and has apparently been attempted in the cosmetic industry

  53. Avatar

    We test with 2000ppm MI in aqua. I do not know what the pH is, and the number of positives is a part of the manuscript and therefore confidential at the moment.

  54. Avatar
    David Steinberg

    What level of MI is in your test? What vehicle? What pH?
    What number of positives compared to other allergens?

  55. Avatar

    It is correct when David Steinberg states that the test kit use the mixture with the chloro and non-chloro. However, in the last years methylisothiazolinone alone has also been part of the contact allergy test at the Hospital where I work, and upcoming scientific articles will reveal that methy-isothiazolinone contact allergy is relatively frequent.

    This is not a recommendation to discard isothiazolinones or other allergenic preservatives; they are a necessity but should be used with caution.

  56. Avatar
    David Steinberg

    Isothiazolinone is not a major sensitizer. The chloro derivitive is when left on the skin and used at levels higher than about 15 ppm.

    Michael just lumps everything together is incorrect. Because the chloro is sold with the non-chloro versionat a 3 to 1 ratio, he assumes boith are the cause. As the pure chloro is not a commercial product, the test kist use the mixture. The pure methylisothiazolinone is a commercial product and is recommended for leave on applications. It needs a anti-fungal agent with it to give complete protection.

  57. Avatar

    Concerning isothiazolinones; it is a wellknown fact that isothiazolinone can cause sensitization. methylchloroisthiazolinone/methylisothiazolinone (in a 3:1 combination) has been part of a standard series which tests for contact allergy in more than 20 years, it is one the most frequent sensitizing preservatives. If you search scientific databases you will find numerous studies that describes sensitization and contact allergy to isothiazolinone.

    PS. Drowning is not caused by high level of exposure to water. Drowning is caused by increased CO2 levels in the blood that forces one to inhale water.

    1. Avatar

      Hi Perry, thanks for your informative article. And I’m interested in the article you provide with a link here, but I can’t find it. When I click it, come out with the information that the BME has been closed and insdead of Mendeley. May I ask how to find the article then? Thanks in advance .

    2. Avatar

      Hi,it’s me again. I have found this article. Thanks a lot.

  58. Avatar

    Also i’ve been reading about Hyaluronic Acid, dr Loren Pickart wrote something about it ,stating that it isn’t good as an ingredient ?

    1. HA sucks water out of the air and becomes wet. If you put dry HA on a dish, in about 30 minutes you would have a puddle of water. It is a very hygroscopic material, one which attracts moisture from the atmosphere. If not protected from contact with the atmosphere (by being stored under vacuum or under a dry gas) some hygroscopic materials will eventually attract so much water that they will form solutions.

    2. Then this water wets or hydrates the outer skin proteins. This weakens the proteins and loosens the protective skin barrier.

    The weak skin barrier allows bacteria, viruses, and allergens to pass through the skin. Often famous young actors in their late 20s have a very spotted skin (you often see this on a large screen) from skin barrier damage from heavy use of make up and make up removers.

    3. The wet proteins slow keratin production. The signal for the skin to send up new keratinocytes to the surface is a dryness in the proteins in the top of the skin. So skin is replaced slower and damage accumulates.

    4. Many years ago, women used Cold Creams to keep their faces moist when they went to bed. If you have seen “I Love Lucy” or old movies, you have seem women with these white creams all over their face. But they ended up with horrible wrinkles as time went by because their skin had been keep too wet.

    5. There is the idea of a limited cell life but many cell biologists doubt if this is correct. Many cells line that die in about 40 generations will live very long – such a 200 generations – as normal diploid, cancer-free cells if they are given supplemental growth factors such a fibroblast growth factor, GHK, and other hormones. No one knows how long cells can live because very long cell culture experiments are very expensive.

    The body also makes stem cells – even in adults – that can keep setting up new cell lines.”

    So is HA good or not for the skin? 🙁

  59. Avatar

    what about airless packaging? will it be better in preserving a product?

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      Technically, airless can inhibit microbial growth. But that would require near sterile manufacturing conditions and the consumer can’t touch the product in the package. Even in an airless system it would be better to have some type of preservative.

  60. Avatar
    David Steinberg

    Yeast almost never grow in cosmetics as the water activity for yeast is very narrow and is rarely obtained in any cosmetic formulation.

    Parabens also show weak activity against some Gram negative bacteria. They only function when dissolved in water. Exceeding the water solubility is a waste of money.

    Formaldehyde donors rarely dissociate in water. What causes the release is the breaking of the Nitrogen to Carbon bond: -N-CH2-OH.They are weakest aginst molds. Gulteraldehyde does not breakdown to formaldehyde. It is a very strong skin senistizer and is almost never used in cosmetics due to this and is bad odor.

    Quats function best above a pH of 7. Most are very more at any pH against pseudomonas.

    Ther is a debate if propylene glycol is really anti-microbial or is it due to its lowering of water activity. Either way the levels that show inhibition are much higher than those used in cosmetics as above 10% it causes a “burning” feeling to skin.

    Methyliosthaizoline is very weak against mold, the chloro is strongly anti-fungal. The mixture is not recommednded for leave on products.

    Chloroacetamide has been found to be unsafe by the CIR. It causes chloroacne.
    Zinc prithione do not kill bacteria they are strongly anti-fungal and yeast. The gunig cause dandruff- not bacteria.

    As to the hairspray, I have these questions-did the bateria grow in the hair or in the actual spray? How much alcohol was in the hairspray?

  61. Avatar
    David Steinberg

    Some of this information is incorrect. See the book Preservatives for Cosmetics.

    I also do not believe the article of a abacteria growing in hairspray. If the hairspray has over 20% alcohol, nothing will grow in it.

    1. Avatar

      Hello David! Thanks so much for commenting. For those who may not know, David is one of the true experts in this industry.

      The information about preservatives in this article is meant as an introduction. I’m curious which parts you believe are in error.

      I agree that it seems unlikely, but the research about the microbes in hairspray was published in the March 08 issue of the International Journal of Systematic and Evolutionary Microbiology. Perhaps they’re missing some crucial detail.

      Thanks again for your comments.

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