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ASTM E939
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Quick understanding of the test
ASTM E939 - Standard Test Method of Field Testing Topical Applications of Compounds as Repellents for Medically Important and Pest Arthropods (Including Insects, Ticks, and Mites),Mosquitoes
Application
- Test-repellent solutions are applied to limbs and exposed to natural mosquito populations in the test area, and the time to the first confirmed bite (CPT) is recorded.
- Data is analyzed to evaluate repellent efficacy and compare performance with a standard control.
- This test method ensures the effectiveness and reliability of mosquito repellents during the final phase of development for personal use.
- Simulates real-world conditions to test repellents effectively.
Turnaround Time
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Abstract
This standard test method assesses the efficacy of repellents designed for the protection of people against medically important arthropods, such as mosquitoes and ticks. This test method involves volunteers who meet all the criteria for this test. A measured amount of the repellent is applied to the subject’s skin, and this most often is the forearm or lower leg; then the treated area is exposed to the mosquitoes in the field setting. The primary objective of this test method is to determine how long the repellent gives protection against mosquito bites.
ASTM E939 Test Conditions
The test conditions are:
- Application of the Repellent: A known volume of repellent is applied uniformly to the test subject’s skin, usually 1 mL on the forearms and 1.5 mL on the legs.
- Environmental Factors: Temperature, humidity, and airspeed must be recorded during the tests to ensure that the field conditions are documented. Instruments like hygrothermographs or sling psychrometers are often used to capture these readings.
- Exposure to Mosquitoes: Treated limbs are constantly exposed to mosquitoes in natural conditions. If legs are used instead of arms, then the area of exposition is varied accordingly.
ASTM E939 Test Requirements
The requirements for performing this standard are:-:
- Standardization of Repellent Concentrations: Repellents must be applied at a standardized concentration to allow for direct comparisons between candidate compounds.
- Human Test Subjects: Before performing any test with human test subjects, one needs to obtain written consent for participation, and tests need the concerned authorities’ approval while keeping in mind that these tests meet all ethical standards.
- Paired Testing: In efficacy tests, each candidate repellent is paired with a control; most often, this will be a known standard repellent, such as DEET. By the subject, each treated area is exposed simultaneously to the same mosquito population.
- Round-Robin Testing: It is a controlled method for testing several repellents in a balanced and unbiased manner. In this method, test subjects are randomly assigned to different repellent combinations. Each subject applies a different repellent to each limb, thereby allowing the direct comparison of the repellent in identical environmental conditions. The subjects are rotated among different repellents so that every repellent is tested with every candidate throughout the study.
ASTM E939 Test Methodology
The test methodology for this standard is as follows:
- Preparation: Solutions of the test samples of the repellent are prepared, usually in ethanol solutions. The candidate compound is applied to the forearm or leg of the subject in a specific volume.
- Field Testing: A treated limb is exposed to natural populations of mosquitoes from the test area. The experiment starts when mosquitoes become host-seeking and ends at the time of the first confirmed mosquito bite.
- Complete Protection Time (CPT): The time elapsed between repellent application and the first confirmed bite is considered Complete Protection Time (CPT). A confirmed bite is defined as that of two successive bites given by the same species within a 30-minute time-space.
- Data Collection: The test subjects, along with their supervisors, record all the details regarding environmental conditions, the behavior of mosquitoes, and the effectiveness of the repellents.
- Analysis: The duration for which the repellent is effective is studied from the data. The performance of different compounds is compared to each other, and the candidate repellents’ performance is also compared with the control standard.
Importance of ASTM E939 Test
This test method is crucial in determining the actual effectiveness of the repellent in real life conditions. It has been accepted and established throughout the world as a standard methodology, ensuring that all products developed meet all the regulatory requirements. Such direct comparisons between new products and known standards such as DEET can be made. The test increases consumer safety and confidence and enables the manufacturer to support claims concerning the actual performance and lifespan of their product. Besides, it provides flexibility in species and environments during testing and guides product development.
Compliance with this standard is quite crucial in ensuring that such products comply with international industry standards regarding efficacy and safety. It widely accommodates acceptance by the regulatory world; hence has become a key requirement in the approval of products across several markets. Satisfying this demand would enable companies to show their customers that the repellents they provide have undergone testing under controlled standard real-world conditions, creating the needed confidence upon acceptance and fulfilling all the legal and industrial requirements about the performance of the product.
Strengths of ASTM E939 Test Standard
- Practical Application: The test provides a return result, which shows how the product would function if taken outside the field.
- Flexibility: It can easily be adjusted to be used on several arthropods or when testing repellents under a variety of ecological conditions.
- Reliability: The paired testing method assures that the test is reliable.
Benefits of ASTM E939
Manufacturers benefit from this standard in several ways:
- Regulatory Approval: The test results can be used to meet regulatory requirements in various markets, helping companies gain approval to sell their products.
- Product Development: The information obtained through ASTM E939 may be useful in further product development; hence the manufacturer would be assured to deliver an effective repellent with a better formulation.
- Consumer Confidence: Products that meet the requirements of ASTM E939 could confidently claim to their customers that their repellents had been under strict tests, proving them to be effective.
Conclusion
ASTMe 939 is crucial as it helps manufacturers develop effective mosquito repellents. Such a test method will give a standardized approach to evaluating repellents under real conditions to ensure that the products are effective before they are released into the market.
For those companies seeking to validate their products, MIS (Microbial Investigations Switzerland) offers comprehensive testing and validation services. Contact us today to find out more about how we can help with your repellent testing needs.
Frequently Asked Questions
DR. Martinoz Scholtz
ASTM E939is one of the standardized tests related to testing the efficacy of topical active ingredients in controlling repellency in mosquitoes and other similar arthropods in natural field conditions.
Products that may be tested by the method of ASTM E939 include topical repellents against mosquitoes, ticks, mites, and other medically important arthropods for preventing exposure.
Turnaround time typically ranges from few days to several weeks.
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