Development of a new test for mechanical irritation: Behind the knee as a test site

Abstract

Background/aims: Certain consumer products, such as feminine hygiene products, and baby and adult diapers, are worn for prolonged periods of time in close proximity to the skin. A sensitive test method was needed to evaluate these products and their components for the potential to cause mechanical irritation during use. Methods: We investigated several test sites on the body where normal, daily activities provided the opportunity for movement and, therefore, friction. These test sites were: the back of the knee, the axilla, and the wrist. Three exposure regimens were tested: 6-h daily for 4 days, 24-h daily for 3 days, and 24-h daily for 4 days. Controls consisted of satin fabric (a non-irritating material) or burlap (an irritating material). Test materials were secured to the test sites using an Ace® elastic bandage (on the back of the knee), a snug fitting garment (on the axilla), or an athletic band (on the wrist). Test sites were scored for irritation on a visual scale prior to the initial application and 30-60 min after removal each day. Data were evaluated for the ability to reliably detect irritating materials, and for the ability to consistently differentiate between irritating and non-irritating materials. Quantitative measures of these abilities were used to rank the overall effectiveness of various test protocols as a model for mechanical irritation. Results/Conclusion: The results of these studies indicated that a protocol using the back of the knee as a test site with an exposure regimen of 6-h daily for 4 days, best met the success criteria for an effective test system for evaluating mechanical irritation.