Home Cosmetic Science Talk Formulating Advanced Questions Amount of microbes in a cosmetic product

  • Amount of microbes in a cosmetic product

    Posted by Abdullah on December 3, 2021 at 12:40 pm

    In PET test they add 10^6 cfu/g of bacteria and fungi to a product and see how much of that will be killed by preservative and in how much time.

    My questions are
    1. Why 10^6 cfu/g?

    2. If i product doesn’t have preservative, how much microbes can grow in it at maximum in cfu/g?

    3. Up to How much microbes are safe in a product and above that are not safe for human use or product stability in cfu/g?

    4. How much microb is 10^6 cfu/g approximately? For example can we see 10^6 cfu/g mold or yeast by eye or at how much microbes a visible change in color or smell of a not fragranced and colored lotion can be seen? 

    PhilGeis replied 2 years, 6 months ago 4 Members · 12 Replies
  • 12 Replies
  • Cosmetic_Chemist

    Member
    December 3, 2021 at 2:42 pm

    When a lab carries out your test, they count the number of colony-forming units on the petri dish. They give you the results of the number of colony-forming units, for the number of grams or millilitres of test material that they put on the petri dish.

    so 10^6 cfu/g means 10^6 colony forming units per gram of your sample. You would be able to see the colonies but might not be able to manually count each individual one because there are so many. 

    As for safety, it depends on what the product is but for cosmetics generally <500 cfu/ml or the equivalent in cfu/g is considered acceptable. 

    It is difficult to assess the maximum microbe growth in a formulation without a preservative because there are so many variables like the formulation itself (does it contain water or probiotics etc), the environments its in and any contamination that could have occurred.

    My advice would be to NEVER skip the preservative!! There are thousands of preservatives out there that you can pick and choose from to suit your formulation and any claims you make. 

    Preservatives ensure consumer safety and increase the products shelf-life by helping inhibit the growth of microorganisms inadvertently introduced into the product during the manufacturing process or during consumer use.  Without preservation, cosmetics containing water, would only last two weeks and microorganism contamination of yeast, mold, bacteria and fungus could cause skin irritation, allergic reactions, infections and more.
     

  • PhilGeis

    Member
    December 3, 2021 at 6:53 pm

    titer can be 10E6+ cfu/g with or without a preservative and can offer no product change  - or discolor, stink and slime up, break emulsions, swell packages, grow as colonies on and in, etc.

    not aware of minimal infective dose - depends on the microbe and application.  

  • Pharma

    Member
    December 3, 2021 at 8:50 pm
    Because single living microbes can’t be counted in a product, one takes a small amount of known volume or weight and puts it on a plat at different dilutions. What then happens is that every living microbe will grow and form a visible colony, hence Colony Forming Unit. Take a plate where you can count the colonies easily; the dilution rate and the initial amount used for incubation tells you how many CFUs aka living microbes are in the product.
    In pharmaceuticals, tolerable CFU depend on the product (what type and which usage) and the microbe (environmental germs, facultative pathogens, or pathogens such as faecal bacteria like E. coli and toxin producing microbes such as Aspergillus sp.). The tolerated CFU/g or /ml in pharmaceuticals are listed in pharmacopoeias.
  • PhilGeis

    Member
    December 4, 2021 at 11:52 am

    To the point - for the great majoriy of product types, production with proper controls should deliver products with no detectable microorganisms.

  • Abdullah

    Member
    December 5, 2021 at 6:30 am

    Thank you all 

    The product is shampoo and skin lotion.

    Does one colony in test means one microb? ;)

  • Pharma

    Member
    December 5, 2021 at 8:12 am

    Abdullah said:


    Does one colony in test means one microb? ;)

    Simply said, yes.

  • Abdullah

    Member
    December 5, 2021 at 9:43 am

    Pharma said:

    Abdullah said:


    Does one colony in test means one microb? ;)

    Simply said, yes.

    I saw a paper that they had collected some cosmetic products from store and tested them for microbes, many of them had microbes in range of 10^5-10^6 cfu/g. 
    does consumer know anything from looks or smell of a product that is contaminated with that amount of bacteria or fungi so he can stop using it?

  • Pharma

    Member
    December 5, 2021 at 11:24 am

    Maybe, maybe not. Some microbes aren’t visible at way higher amounts, don’t produce neither smell nor gas… just think about yoghurt. You wouldn’t know it’s spoiled milk if you didn’t know what yoghurt actually is.

  • Abdullah

    Member
    December 5, 2021 at 11:34 am

    Pharma said:

    Maybe, maybe not. Some microbes aren’t visible at way higher amounts, don’t produce neither smell nor gas… just think about yoghurt. You wouldn’t know it’s spoiled milk if you didn’t know what yoghurt actually is.

    What about mold? At what amount of contamination it can be visible by eyes? 

    Or the other way, if we can see the mold by eyes, what would be the minimum cfu/g of mold in that product? 

  • PhilGeis

    Member
    December 5, 2021 at 12:01 pm

    Abdullah said:

    Pharma said:

    Maybe, maybe not. Some microbes aren’t visible at way higher amounts, don’t produce neither smell nor gas… just think about yoghurt. You wouldn’t know it’s spoiled milk if you didn’t know what yoghurt actually is.

    What about mold? At what amount of contamination it can be visible by eyes? 

    Or the other way, if we can see the mold by eyes, what would be the minimum cfu/g of mold in that product? 

    You can  seemold if it grows sufficiently on the surface.    Not sure what you mean by minimum - it’s addressed by the same numerical quality limit.

    The concept of cfu is not a good one for mold - mycelial fungi.  The cells do not separate so one cfu could represent 19’s-100’s of cells.

  • Abdullah

    Member
    December 5, 2021 at 1:42 pm

    PhilGeis said:

    Abdullah said:

    Pharma said:

    Maybe, maybe not. Some microbes aren’t visible at way higher amounts, don’t produce neither smell nor gas… just think about yoghurt. You wouldn’t know it’s spoiled milk if you didn’t know what yoghurt actually is.

    What about mold? At what amount of contamination it can be visible by eyes? 

    Or the other way, if we can see the mold by eyes, what would be the minimum cfu/g of mold in that product? 

    You can  seemold if it grows sufficiently on the surface.    Not sure what you mean by minimum - it’s addressed by the same numerical quality limit.

    The concept of cfu is not a good one for mold - mycelial fungi.  The cells do not separate so one cfu could represent 19’s-100’s of cells.

    What i was saying is can we see for example 10^3 cfu/g of mold by eyes? If no then how much minimum mold should it be there so that we be able to see it by eyes?
    If yes then what about 10^2 cfu/g or lower? 

  • PhilGeis

    Member
    December 5, 2021 at 4:14 pm

    To be countable, prob spores - and no.  If you can’t see 1000/g, you’ll not see 100 or fewer.

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