Related Experiment Video
Updated: Feb 17, 2026
12:37
Pharmacologic Induction of Epidermal Melanin and Protection Against Sunburn in a Humanized Mouse Model
Published on: September 7, 2013
18.8K
Photoprotection by sunscreen depends on time spent on application
Ida M Heerfordt1, Linnea R Torsnes1, Peter A Philipsen1
1Department of Dermatology, Bispbjerg Hospital, University of Copenhagen, Copenhagen, Denmark.
Photodermatology, Photoimmunology & Photomedicine
|December 14, 2017
Summary
Applying sunscreen for longer ensures adequate coverage. This study found a consistent amount of sunscreen applied per minute, highlighting the importance of application time for effective photoprotection.
Area of Science:
- Dermatology
- Photoprotection research
Background:
- Effective sunscreen use requires sufficient quantity and reapplication.
- The impact of application time on sunscreen effectiveness was previously unstudied.
Purpose of the Study:
- To investigate the relationship between time spent applying sunscreen and the quantity used.
- To assess this relationship for both initial and subsequent sunscreen applications.
Main Methods:
- Thirty-one volunteers applied sunscreen twice under controlled laboratory conditions.
- Time and quantity of sunscreen applied were measured for each application.
- Body surface area (BSA) was estimated to calculate sunscreen density.
Main Results:
- A linear correlation was found between application time and sunscreen quantity used (P < .0001).
- Participants applied a consistent 2.21 grams of sunscreen per minute.
- Mean application density was 0.71 mg/cm² after the first application and 1.27 mg/cm² after the second.
Conclusions:
- A constant rate of sunscreen application per minute was observed for both first and second applications.
- Measuring application time can inform studies on real-world sunscreen distribution and effectiveness.
Related Concept Videos
01:19Pigmentation
4.5K
The color of the skin is influenced by a number of pigments, including melanin, carotene, and hemoglobin. Recall that melanin is produced by cells called melanocytes, which are found scattered throughout the stratum basale of the epidermis. The melanin is transferred to the keratinocytes via melanosomes.
Melanin occurs in two primary forms: eumelanin that provides black and brown pigment and pheomelanin that provides red color. Dark-skinned individuals produce more melanin than those with pale...
Melanin occurs in two primary forms: eumelanin that provides black and brown pigment and pheomelanin that provides red color. Dark-skinned individuals produce more melanin than those with pale...
4.5K
01:35Mutations
44.7K
Mutations are changes in the sequence of DNA. These changes can occur spontaneously or they can be induced by exposure to environmental factors. Mutations can be characterized in a number of different ways: whether and how they alter the amino acid sequence of the protein, whether they occur over a small or large area of DNA, and whether they occur in somatic cells or germline cells.
Chromosomal Alterations Are Large-Scale Mutations
While point mutations are changes in a single nucleotide in...
Chromosomal Alterations Are Large-Scale Mutations
While point mutations are changes in a single nucleotide in...
44.7K
01:30Skin Cancer
6.1K
Skin cancer is a type of cancer that occurs when there is an abnormal growth of skin cells, usually triggered by damage to the DNA within the skin cells. It is primarily caused by exposure to ultraviolet (UV) radiation from the sun or artificial sources like tanning beds. Skin cancer is the most common type of cancer worldwide, and its incidence continues to rise.
Basal Cell Carcinoma (BCC): BCC is the most common type of skin cancer, accounting for about 80% of cases. It typically develops in...
Basal Cell Carcinoma (BCC): BCC is the most common type of skin cancer, accounting for about 80% of cases. It typically develops in...
6.1K
01:23Role of Skin in Vitamin D Synthesis
8.1K
The skin plays a crucial role in the synthesis of vitamin D, a vital nutrient for various physiological processes in the body. Vitamin D is unique because it can be synthesized in the skin through a series of chemical reactions triggered by exposure to ultraviolet B (UVB) radiation from sunlight.
The solar UV B rays (290-315 nm) are absorbed by the skin, and 7-dehydrocholesterol (provitamin D3) photolyzes it to previtamin D3, which undergoes a rapid transformation to vitamin...
The solar UV B rays (290-315 nm) are absorbed by the skin, and 7-dehydrocholesterol (provitamin D3) photolyzes it to previtamin D3, which undergoes a rapid transformation to vitamin...
8.1K
02:00Photoreceptors and Plant Responses to Light
28.6K
Light plays a significant role in regulating the growth and development of plants. In addition to providing energy for photosynthesis, light provides other important cues to regulate a range of developmental and physiological responses in plants.
28.6K
01:20Chronopharmacokinetics: Time-Dependent Pharmacokinetics
437
Chronopharmacokinetics studies the temporal change in drug absorption and elimination. These changes can be cyclical or non-cyclical. Cyclical changes occur over a regular interval, while non-cyclical changes occur over a longer, irregular period.
Time-dependent pharmacokinetics refers to non-cyclical changes in drug rate processes over a period of time. It can lead to nonlinear pharmacokinetics, where the relationship between drug concentration and time is not proportional. Non-cyclical...
Time-dependent pharmacokinetics refers to non-cyclical changes in drug rate processes over a period of time. It can lead to nonlinear pharmacokinetics, where the relationship between drug concentration and time is not proportional. Non-cyclical...
437