Related Experiment Videos
Evaluation of seven sunscreens on hairless mouse skin
Abstract:
The ability of seven sunscreens to protect against ultraviolet (UV)--induced inhibition of epidermal DNA synthesis was evaluated in vivo using a hairless mouse model. There were statistically significant differences among sunscreens in their ability to prevent UV-B (290 to 320 nm) inhibition of DNA synthesis. The protective factor (PF) of a sunscreen was arbitrarily defined as the ratio of the dose required to inhibit DNA synthesis by 50% with and without a sunscreen. The following PF values were determined: Coppertone 4, 4.4; Sundown Extra Protection, 8.4; Supershade 15, 21.0; Eclipse 15, 22.2; Blockout 15, 22.4; and Bain de Soleil 15, 27.6. Zinc oxide ointment protected against any significant suppression of DNA synthesis at all UV-B doses used. There was a relatively good correlation between the PF and the sun protection factor (SPF) claimed for each sunscreen by the manufacturer. However, the PF values determined in mouse skin were generally higher than the SPF values measured in human skin. Further studies are needed to determine if sunscreen substantivity (resistance to removal by water) can be evaluated by this technique.
Insights
This study evaluated sunscreen efficacy in protecting mouse skin from UV-B damage. Zinc oxide offered the best protection, and a new Protective Factor (PF) correlated with Sun Protection Factor (SPF) but showed higher values in mice.
Area of Science:
- Dermatology
- Photobiology
- Toxicology
Background:
- Ultraviolet (UV) radiation exposure can damage skin by inhibiting epidermal DNA synthesis.
- Sunscreens are crucial for mitigating UV-induced skin damage.
- Evaluating sunscreen efficacy requires reliable in vivo methods.
Purpose of the Study:
- To assess the effectiveness of seven sunscreens in preventing UV-induced inhibition of epidermal DNA synthesis in a hairless mouse model.
- To define and determine a Protective Factor (PF) for sunscreens.
- To compare the determined PF values with manufacturer-claimed Sun Protection Factor (SPF) values.
Main Methods:
- An in vivo hairless mouse model was used to evaluate seven sunscreens.
- UV-B radiation was applied to assess inhibition of epidermal DNA synthesis.
- Protective Factor (PF) was calculated as the ratio of UV dose required to inhibit DNA synthesis by 50% with and without sunscreen.
Main Results:
- Significant differences were observed in the sunscreens' ability to prevent UV-B-induced DNA synthesis inhibition.
- Protective Factor (PF) values ranged from 4.4 to 27.6, with zinc oxide ointment showing complete protection.
- A good correlation was found between PF and claimed SPF, though PF values in mice were generally higher than human SPF.
Conclusions:
- The hairless mouse model provides a viable method for evaluating sunscreen efficacy against UV-B-induced DNA synthesis inhibition.
- The defined Protective Factor (PF) shows promise as a metric for sunscreen effectiveness.
- Further research is needed to validate this method and explore its potential for assessing sunscreen substantivity.