ASTM E640 Standard Test Method for Preservatives in Water-Containing Cosmetics

Get Certified ASTM E640 Testing for Reliable Preservative Performance Evaluation 

ASTM E640 testing determines the efficacy of a preservative or preservative system for providing adequate antimicrobial activity in water-miscible cosmetic products. Skilled personnel test model cosmetic formulations with proper microbiological methods and microorganisms. Surviving microorganisms are monitored, and the antimicrobial effectiveness of the preservative system is assessed. The results are useful for cosmetic formulation development, quality control, and documented preservative-performance assessment.

The scope of ASTM E640 includes:

• Material: Water-containing and water-miscible cosmetic formulations containing a preservative or preservative system under evaluation. 
• Objective: Determine the suitability of a preservative or preservative system for protecting cosmetic formulations against microbial contamination. 
• Property measurement: Antimicrobial/preservative performance by recovering and assessing the recovery of microorganisms in challenged formulations. 
• Method: A microbiological challenge test involves challenging selected microorganisms to model formulations and then microbiological recovery and enumeration using appropriate procedures. 
• Result: Results represent the preservative activity of the formulation tested by determining the survival or reduction of microorganisms under the conditions provided.
• Test limitations: The method requires model formulations and does not cover all possible formulations, microorganisms, regulatory demands, and safety issues. 
• Environmental conditions: controlled microbiological laboratory conditions; handling, maintenance, recovery, and enumeration procedures for the selected microorganisms. 
• Applications: Useful for formulation development of cosmetics, evaluation of preservative systems, quality control, and comparative assessment of preservative performance.

What are the uses of ASTM E640 testing? 

ASTM E640 offers a standard microbiological challenge process to determine the ability of preservatives or preservative systems to protect water-miscible cosmetic products. The method also contains both test formulations and non-preserved controls to allow the analysts to compare the preservative activity to the formulation without preservative. This standard-

• Assesses preservatives in cosmetic products that contain water. 
• Supports selection and evaluation of preservative systems. 
• Designates minimum requirements for preservative performance in model formulations. 
• Uses selected bacterial and fungal microorganisms as challenge organisms. 
• Supports recovery and enumeration of surviving microorganisms. 
• Provides a common basis for comparing different preservative systems.
• Supports formulation development and quality-control investigations.

Which Materials Can Be Tested Under ASTM E640? 

ASTM E640 is applicable to cosmetic products for which the submitter believes preservative activity is appropriate for demonstration. The standard calls for test formulations with the preservative or preservative system being tested and non-preserved control formulations. It is designed specifically for miscible cosmetic products and not for an individual cosmetic product type.

Why is ASTM E640 important?

ASTM E640 is important because water-containing cosmetic formulations can support microbial growth when preservation is inadequate. A standardized challenge test can be used to assess preservative performance in a controlled microbiologic environment as opposed to formulation composition or preservative concentration.

ASTM E640 Testing Process and Data Collection 

In ASTM E640 testing, analysts expose preserved cosmetic formulations and appropriate non-preserved controls to specific microorganisms. Technicians can determine the antimicrobial response of the preservative system by recovering the microorganisms using proper neutralization and recovery techniques. Data records should include formulation, preservative system, control sample, microorganisms, challenge configuration, recovery procedure, microbial counts, and related observations. The standard specifies recommended culture media and allows the use of suitable standardized cultures or microorganisms or cosmetic spoilage isolates when appropriate.

Common Challenges and Troubleshooting 

ASTM E640 testing requires careful control of formulation compatibility, microorganism selection, culture maintenance, challenge preparation, preservative neutralization, and microbial recovery. Residual preservative activity can interfere with recovery if the neutralization system does not adequately address the preservative, while unsuitable recovery media can reduce recovery of surviving microorganisms. Analysts should maintain appropriate controls, verify microbiological procedures, document formulation incompatibilities, and ensure that recovery methods provide suitable growth support for the selected microorganisms. The standard also emphasizes the need for appropriate safety, health, environmental, and regulatory practices.

• Laboratories report microbial recovery or reduction results using the applicable microbiological counting units and document the corresponding test and control results. 
• Technicians document the basic preservative performance result, along with the cosmetic formulation, preservative system, microorganisms, and test condition. 
• Analysts document the challenge configuration, culture and recovery procedures, neutralization approach, microbial counts, and observations that may affect interpretation. 
• Engineers, formulators, and analysts compare the observed preservative performance with applicable formulation, product development, quality control, or regulatory requirements.

Link to ASTM E640