Microbiological Challenges with Cosmetic Products
Ben Elmadi
Head of Stability and Preservative efficacy testing
Microbiological Solutions Limited
Challenges
• Maintaining Quality
• Complying with regulations
• Knowing when to test
• Knowing what test to use
• Correctly Preserving
Risks
UK
US
Maintaining Quality
Maintaining Quality - GMP
Maintaining Quality – Factory Isolate
Preservative Efficacy
Cosmetic Regulation and Preservative Efficacy Testing
• Testing not performed on all products
• No specified test
• Plenty to choose from – ISO 11930, USP 51, E.P 5.1.3.
• Creating the argument
Risk Assessing • BS EN ISO 29621:2017
• Definition of a low risk product
• Low risk characteristics
• BACKED BY LITERATURE!
Risk Assessment Workshop Product 1 1. Oil based 2. Lip Balm 3. No Preservative
Product 2 1. 2 in 1 Shower Gel and Conditioner 2. Aqueous
Product 3 1. Nail Polish 2. Alcohol Based
Product 4 1. Pressed powder compat
Product Characteristic Workflow
Reference
Summary of approach
All Powder A1* Risk assessed – no Challenge test req’d
Low water activity ≤0.75 (Confirmed) N/A Risk assessed – no Challenge test req’d
Suspect low water activity ≤0.75** A2 Reduced Challenge
Wipes A3 Full Challenge test req’d
Extreme pH (≤3/≥10) N/A Risk assessed – no Challenge test req’d
≥20% Alcohol content N/A Risk assessed – no Challenge test req’d
Organic Solvent Based (Ethyl acetate, Butyl acetate) N/A Risk assessed – no Challenge test req’d
Alkaline compounds (Ammonia, Monoethanolamine) N/A Risk assessed – no Challenge test req’d
Hydrogen peroxide N/A Risk assessed – no Challenge test req’d
≥20% Aluminium chlorohydrate and related salts N/A Risk assessed – no Challenge test req’d
≤0.75 Water activity AND was filled at ≥65oC N/A Risk assessed – no Challenge test req’d
Pressurised, single dose (e.g. sachet/canister) N/A Risk assessed – no Challenge test req’d
Flow Chart A1- Robust Powder test
7 day reduced test/Surface mould
test shows formulation to be low
risk.
PRODUCT NOT SUITABLE FOR
MARKET.
Historic data shows formulation to
be low risk.
PRODUCT SUITABLE FOR
MARKET.
NO
NO
Yes
Yes
Product Characteristic Workflow
Reference
Summary of approach
All Powder A1* Risk assessed – no Challenge test req’d
Low water activity ≤0.75 (Confirmed) N/A Risk assessed – no Challenge test req’d
Suspect low water activity ≤0.75** A2 Reduced Challenge
Wipes A3 Full Challenge test req’d
Extreme pH (≤3/≥10) N/A Risk assessed – no Challenge test req’d
≥20% Alcohol content N/A Risk assessed – no Challenge test req’d
Organic Solvent Based (Ethyl acetate, Butyl acetate) N/A Risk assessed – no Challenge test req’d
Alkaline compounds (Ammonia, Monoethanolamine) N/A Risk assessed – no Challenge test req’d
Hydrogen peroxide N/A Risk assessed – no Challenge test req’d
≥20% Aluminium chlorohydrate and related salts N/A Risk assessed – no Challenge test req’d
≤0.75 Water activity AND was filled at ≥65oC N/A Risk assessed – no Challenge test req’d
Pressurised, single dose (e.g. sachet/canister) N/A Risk assessed – no Challenge test req’d
Flowchart A2 – Suspect low Water activity
7 day reduced test shows
formulation to be low risk.
PRODUCT NOT SUITABLE FOR
MARKET.
PRODUCT SUITABLE FOR
MARKET.
NO Yes
Product Characteristic Workflow
Reference
Summary of approach
All Powder A1* Risk assessed – no Challenge test req’d
Low water activity ≤0.75 (Confirmed) N/A Risk assessed – no Challenge test req’d
Suspect low water activity ≤0.75** A2 Reduced Challenge
Wipes A3 Full Challenge test req’d
Extreme pH (≤3/≥10) N/A Risk assessed – no Challenge test req’d
≥20% Alcohol content N/A Risk assessed – no Challenge test req’d
Organic Solvent Based (Ethyl acetate, Butyl acetate) N/A Risk assessed – no Challenge test req’d
Alkaline compounds (Ammonia, Monoethanolamine) N/A Risk assessed – no Challenge test req’d
Hydrogen peroxide N/A Risk assessed – no Challenge test req’d
≥20% Aluminium chlorohydrate and related salts N/A Risk assessed – no Challenge test req’d
≤0.75 Water activity AND was filled at ≥65oC N/A Risk assessed – no Challenge test req’d
Pressurised, single dose (e.g. sachet/canister) N/A Risk assessed – no Challenge test req’d
Flowchart A3 – Wipes Undertake ISO 11930 test method
Does product pass criteria A of ISO
11930?
Does product pass criteria B of ISO
11930?
Does the product have a
short PAO assigned?
Does product have positive batch
release results for microbial limits
testing?
PRODUCT SUITABLE FOR MARKET. PRODUCT NOT SUITABLE FOR MARKET.
YES
YES
YES
YES
NO
NO
NO
NO
Product Characteristic Workflow
Reference
Summary of approach
All Powder A1* Risk assessed – no Challenge test req’d
Low water activity ≤0.75 (Confirmed) N/A Risk assessed – no Challenge test req’d
Suspect low water activity ≤0.75** A2 Reduced Challenge
Wipes A3 Full Challenge test req’d
Extreme pH (≤3/≥10) N/A Risk assessed – no Challenge test req’d
≥20% Alcohol content N/A Risk assessed – no Challenge test req’d
Organic Solvent Based (Ethyl acetate, Butyl acetate) N/A Risk assessed – no Challenge test req’d
Alkaline compounds (Ammonia, Monoethanolamine) N/A Risk assessed – no Challenge test req’d
Hydrogen peroxide N/A Risk assessed – no Challenge test req’d
≥20% Aluminium chlorohydrate and related salts N/A Risk assessed – no Challenge test req’d
≤0.75 Water activity AND was filled at ≥65oC N/A Risk assessed – no Challenge test req’d
Pressurised, single dose (e.g. sachet/canister) N/A Risk assessed – no Challenge test req’d
Aqueous • BS EN ISO 11930:2019 – Preservative efficacy test made for cosmetics
• Works in conjunction with BS EN ISO 29621:2017 – Risk assessment standard
• Criteria A & Criteria B
Undertake ISO 11930
test method
Does product pass criteria A of ISO 11930?
Does product pass criteria B of ISO 11930?
Does the product have
additional packaging
controls to reduce
microbial risk? E.g. Pump,
pipette applicator, low
volume container, no
direct contact with
consumer?
Does product have positive
batch release results for
microbial limits testing?
PRODUCT SUITABLE
FOR MARKET.
PRODUCT NOT
SUITABLE FOR MARKET.
YES
YES
YES
YES
NO NO
NO
NO
In use testing • Doesn’t simulate real life, it is real life.
• Not enough control over parameters
• Suitable for products that have low risk characteristics
• Good for additional data
Dealing with failure Common mistakes -
Some products require extra care to ensure homogenous.
• Powders – tendency to clump with wet inoculum
• Wipes – pooling of organisms
• Oils – pooling of organisms
• Contaminated at point of manufacture
Dealing with failure • Product Design
• Preservative choice
1. Compatibility
2. Activity requirements during manufacture (temperature/pH)
3. Final specification
The Future
• Vegan – VeganSure® Testing