Podcast
Questions and Answers
What percentage of males report never using sunscreen?
What percentage of males report never using sunscreen?
Which skin cancer types are primarily linked to ultraviolet radiation exposure?
Which skin cancer types are primarily linked to ultraviolet radiation exposure?
Which pollutant is primarily responsible for ozone depletion?
Which pollutant is primarily responsible for ozone depletion?
What was the aim of the Surgeon General’s Call to Action in 2014?
What was the aim of the Surgeon General’s Call to Action in 2014?
Signup and view all the answers
At what time of day is UV radiation exposure typically highest?
At what time of day is UV radiation exposure typically highest?
Signup and view all the answers
What effect does cloud cover have on UV radiation levels?
What effect does cloud cover have on UV radiation levels?
Signup and view all the answers
What is the expected trend for melanoma treatment costs by 2030 without intervention?
What is the expected trend for melanoma treatment costs by 2030 without intervention?
Signup and view all the answers
Which of the following mediators is released in response to UV radiation exposure causing erythema?
Which of the following mediators is released in response to UV radiation exposure causing erythema?
Signup and view all the answers
What proportion of adverse drug reactions is accounted for by phototoxicity and photoallergy?
What proportion of adverse drug reactions is accounted for by phototoxicity and photoallergy?
Signup and view all the answers
What is the maximum value on the UV Index scale indicating extremely high exposure?
What is the maximum value on the UV Index scale indicating extremely high exposure?
Signup and view all the answers
Which type of ultraviolet radiation is primarily responsible for causing long-term skin damage and increased risk of skin cancer due to its deep dermal penetration?
Which type of ultraviolet radiation is primarily responsible for causing long-term skin damage and increased risk of skin cancer due to its deep dermal penetration?
Signup and view all the answers
What percentage of UVB radiation is typically blocked by the Earth's ozone layer?
What percentage of UVB radiation is typically blocked by the Earth's ozone layer?
Signup and view all the answers
Which of the following statements correctly describes UVC radiation?
Which of the following statements correctly describes UVC radiation?
Signup and view all the answers
What is the primary beneficial effect of UVB radiation in humans?
What is the primary beneficial effect of UVB radiation in humans?
Signup and view all the answers
Which statement about UVA radiation is accurate?
Which statement about UVA radiation is accurate?
Signup and view all the answers
What causes the formation of oxygen free radicals in the skin during UV radiation exposure?
What causes the formation of oxygen free radicals in the skin during UV radiation exposure?
Signup and view all the answers
Which factor does NOT influence immediate pigment darkening in the skin?
Which factor does NOT influence immediate pigment darkening in the skin?
Signup and view all the answers
Which of the following statements regarding Squamous Cell Carcinoma (SCC) and Basal Cell Carcinoma (BCC) is accurate?
Which of the following statements regarding Squamous Cell Carcinoma (SCC) and Basal Cell Carcinoma (BCC) is accurate?
Signup and view all the answers
What characteristic distinguishes Cutaneous Malignant Melanoma (CMM) from non-melanoma skin cancers?
What characteristic distinguishes Cutaneous Malignant Melanoma (CMM) from non-melanoma skin cancers?
Signup and view all the answers
Which condition is incorrectly linked to the risk factors for skin cancers?
Which condition is incorrectly linked to the risk factors for skin cancers?
Signup and view all the answers
Signup and view all the answers
Study Notes
Photosensitivity
- Photosensitivity is a reaction caused by ultraviolet radiation (UVR).
- UVR is the primary cause of photosensitivity reactions in humans.
- UVR is categorized into four wavelengths: UVA1 (340-400 nm), UVA2 (320-340 nm), UVB (290-320 nm), and UVC (200-290 nm).
Incidence, Prevalence, and Epidemiology of Ultraviolet Radiation Exposure
- Epidemiologic evidence links UVR exposure to various skin diseases.
- Public attitudes toward tanning and sun exposure are changing.
- Skin cancer is a common yet preventable cancer.
Changing Lifestyles and Increased UV Exposure
- Increasing outdoor activities and recreational tanning are contributing factors.
- Longer lifespans and seasonal shifts to sun-rich areas (Sunbelt) increase exposure.
- Emphasis on Vitamin D deficiency and sun exposure increases time in sun.
- Increased human exposure to sunlight as a result.
Prevent Sun Damage
- Avoid sun from 10 AM to 4 PM.
- Wear wide-brimmed hats and sunglasses.
- Use sunscreen.
- Wear long-sleeved shirts.
- Drink plenty of water.
Sunlight as a Causative Factor in Skin Diseases
- Epidemiologic evidence links UVR exposure to various skin diseases.
- Public attitudes toward tanning and sun exposure are gradually changing.
- Skin cancer is the most common yet preventable cancer.
Skin Cancer: The Role of UVR
- Skin Cancer Types: Squamous Cell Carcinoma (SCC) and Basal Cell Carcinoma (BCC).
- These account for over 50% of skin malignancies in the U.S.
- SCC and BCC are closely linked to UVR exposure.
Melanoma: Rising Incidence Rates
- Melanoma incidence increased annually from 2003 to 2016.
- An average of 78,000 new melanoma diagnoses occur each year.
- Without intervention, melanoma treatment costs are expected to triple by 2030.
Skin Cancer Prevention Initiatives
- CDC estimates that a national skin cancer prevention program could prevent 230,000 melanoma cases.
- The Surgeon General's Call to Action (2014) focused on skin cancer as a major public health issue.
- Aimed to raise awareness and reduce sun exposure risks.
Melanoma Mortality Rates and Treatment Advances
- Melanoma diagnosis continues to increase, but mortality rates have decreased by approximately 5% annually.
- New treatments for advanced melanoma have contributed to this decline.
Other Reactions to UVR Exposure
- Common Photosensitivity Reactions: Sunburn, photo-aging, immunologic changes in the skin, cataracts, photodermatoses, phototoxicity, and photoallergy.
- Drug- or chemical-induced: Phototoxicity & photoallergy account for up to 8% of adverse drug reactions.
Sunscreen Use and Its Effectiveness
- Sunscreen and photoprotective behaviors help reduce UVR-related health issues.
- Despite this, sunscreen use remains low.
- Less than 15% of males and 30% of females use sunscreen as recommended.
- 42% of males report never using sunscreen.
Etiology of Ultraviolet Radiation Exposure
- Understanding the UV radiation spectrum and its effects.
Ultraviolet Radiation (UVR) and Photosensitivity
- UVR is the primary cause of photosensitivity reactions in humans.
- UVR is categorized based on four primary wavelengths: UVA1: 340-400 nm, UVA2: 320-340 nm, UVB: 290-320 nm, and UVC: 200-290 nm.
UVA Radiation (320-400 nm)
- Closest to visible light in wavelength.
- Less erythemogenic than UVB but can cause deep dermal damage.
- Penetrates into the dermis and causes long-term skin damage, aging, and increased risk of skin cancer.
- 10 to 100 times more UVA reaches Earth's surface than UVB.
- Contributes up to 15% of the erythemal response at midday.
UVB Radiation (290-320 nm)
- The most erythemogenic (causes redness) and melanogenic (promotes tanning) of the UV bands.
- Primarily absorbed by the epidermis and can cause DNA damage, leading to skin cancer.
- Up to 90% of UVB is blocked by the Earth's ozone layer.
- UVB alters immune function, increasing the risk of skin cancers.
UVC Radiation (200-290 nm)
- Absorbed by the Earth's atmosphere and does not reach the surface.
- Highly harmful if directly encountered, but not a natural environmental concern.
Environmental Effects on Ultraviolet Radiation (UVR)
- The amount of UVR reaching the Earth's surface is influenced by various environmental factors.
- Ozone Layer and Pollution: The ozone layer plays a critical role in blocking UV radiation, particularly UVB. Ozone depletion is caused by pollutants like chlorofluorocarbons (CFCs), nitrous oxide, and other greenhouse gases (GHGs).
Factors Influencing UV Radiation Exposure
- Time of Day: 75% of daily UVR occurs between 9 AM and 3 PM. Short shadows indicate higher UV intensity and a greater risk of sunburn.
- Cloud Cover: Clouds reduce UV and infrared radiation. Reduced heat warning can increase the risk of UV overexposure.
- Surface Reflection: UV reflection from surfaces. Sand and water reflect significant UV rays. Snow also reflects harmful rays.
- Other Factors: Seasonal variations. Geographic latitude and altitude impact UV levels.
Understanding the UV Index
- The UV Index (http://www.epa.gov/sunwise/uvindex.html) is a public health tool developed by the EPA, National Weather Service, and CDC.
- Forecasts UVR intensity for each ZIP code worldwide, for the noon hour.
- Scale: 1 (low exposure) to 11+ (extremely high exposure)
Factors Influencing UVR Exposure
- Sun elevation: Higher sun, stronger UVR.
- Ozone levels: More ozone, less UVR.
- Cloud cover: Clear skies: 100% UVR. Scattered clouds: 89%. Broken clouds: 73%. Overcast: 32%.
- Skin Sensitivity: Darker skin requires more UVR exposure to cause erythema.
Pathophysiology
- The effects of UV radiation on the skin, including erythema and oxygen free radicals.
Introduction to Erythema
- Excessive exposure to UVR (Ultraviolet Radiation) leads to an erythematous reaction in the skin.
- Affects both epidermal and dermal layers.
- Types of UVR: UVA and UVB radiation.
Mechanism of Erythema
- UVA and UVB cause the release of vasodilatory mediators like Histamine, Prostaglandins, and Cytokines.
- These mediators increase blood flow (erythema, skin redness).
- Tissue exudates cause swelling, warmth sensation, and characteristic sunburn.
Effects of Severe UVR Exposure
- Severe UVR exposure, especially UVB, can cause blister formation, desquamation (skin peeling), fever, chills, weakness, and shock.
UVA-Induced Changes in the Dermis
- UVA causes significant damage to vasculature (blood vessels) and dense cellular infiltrates that penetrate deeper into the skin.
Role of Oxygen Free Radicals
- UVR causes skin to absorb energy, which interacts with oxygen, leading to the formation of oxygen-free radicals.
- These free radicals cause tissue damage in the dermis.
Immediate Pigment Darkening vs. Delayed Tanning
- Tanning is an adaptive response of the skin to UVR. Melanocytes produce melanin to absorb radiation.
- Immediate Pigment Darkening (Meirowsky Phenomenon) occurs during UVA exposure.
- Caused by oxidation of existing melanin.
- Results in transient grayish-brown skin discoloration.
Influencing Factors for Immediate Darkening
- Duration and intensity of exposure
- Pre-existing melanin or prior tanning.
- Individual's skin type.
Limitations of Immediate Pigment Darkening
- Immediate pigment darkening does not protect against UVB-induced erythema.
Photocarcinogenesis: Squamous Cell and Basal Cell Carcinoma
- UVR exposure is a major factor in the development of non-melanoma skin cancers (SCC and BCC).
- These cancers most often occur on sun-exposed areas (Face, neck, arms, hands, and back of forearms).
Risk Factors
- Geographic proximity to the equator (Higher risk closer to the equator).
- Lower melanin content in the skin increases susceptibility.
- Outdoor occupations increase risk.
- Family history of SCC/BCC increases risk up to twofold
SCC vs. BCC
- SCC has a stronger link to UVR exposure than BCC.
- Individuals with sensitive skin types are more prone to non-melanoma skin cancers.
Cutaneous Malignant Melanoma (CMM)
- Link to UVR Exposure: Primarily associated with UVR-induced sunburns. Five or more severe sunburns during adolescence doubles the risk.
- Risk Factors: Geographic proximity to the equator and lower melanin content increase susceptibility. Family history is significant (8-12% of cases show a familial link).
- Characteristics: Unlike non-melanoma skin cancers, CMM is not clearly linked to cumulative UVR exposure. Commonly occurs on intermittently sun-exposed areas (e.g., males: back, females: lower legs). Predominantly affects middle-aged individuals and indoor workers
Photoeffects on the Eye
- Ocular Adverse Effects of UVR Exposure: Cataracts (Age-related opacification of the lens. Incidence increases after 50 years, affecting 30% of people over 74, caused by protein oxidation and precipitation in the lens).
- Symptoms include blurred vision, halos around lights, color changes, and blindness.
- Advanced treatment is Surgical removal.
- Conjunctival degeneration and proliferation. Squamous Cell Carcinoma (SCC) (of the cornea and conjunctiva).
UVB and UVA Impact on the Eye
- UVB is absorbed by the cornea and lens, causing slow oxidative damage. UVA penetrates deeper structures, leading to cumulative damage.
- Photokeratitis (Corneal Sunburn): Painful corneal inflammation, conjunctivitis (onset: 30 minutes to 24 hours after exposure).
- Recovery: Typically resolves in 24-48 hours due to corneal epithelium regeneration.
- Treatment: Cool, wet compresses. Mild anti-inflammatory analgesics (ibuprofen, aspirin, or naproxen sodium).
Phototoxicity and Photoallergy
- Phototoxicity: A drug-induced inflammatory reaction caused by UVR exposure.
- Mechanism: The drug or chemical acts as a chromophore, absorbing UVR, transferring energy to surrounding molecules, causing tissue damage.
- Key factors: Reaction depends on chromophore concentration in/on the skin. Wavelength of UVR required is determined by the chromophore's absorption spectrum.
Photoallergy
- Definition: A delayed hypersensitivity reaction mediated by the immune system.
- Mechanism: Caused by polycyclic photosensitizers reacting with UVA to form antigenic macromolecules. The agent becomes an antigen or hapten, triggering an immune response.
- Differences from Phototoxicity: Requires a sensitization period, does not occur on first exposure, involves antigen-antibody processes or immune mediation, and after sensitization, even minimal exposure can cause a reaction.
Photo-protection
- Overview: Methods and Sunscreen Types - Sunscreens, Protective clothing, Sunglasses, Clothing, and avoiding direct sunlight.
- Sunscreen Types: Sunburn Preventive Agents (Absorb >95% of UVB radiation, preventing sunburn), Sun-tanning Agents (Absorb 85-95% of UVB radiation, allowing tanning without significant sunburn).
Types of Sunscreens
- Chemical Sunscreens: Include both sunburn preventive and suntanning agents.
- Physical (Opaque) Sunblocks: Reflect/scatter all UVA, UVB, and visible light; preventing sunburn and suntanning.
- Broad-Spectrum Sunscreens: Developed to recognize UVA's role in adverse effects. Combine UVA and UVB absorbers for enhanced protection. Beneficial for individuals with photosensitivity to a broad range of wavelengths.
Sunscreens and UVR Absorption
Dibenzoylmethanes, Aminobenzoic Acid and Ester Derivatives, Salicylates, and Homosalate.
Clinical Application of Photosensitivity
Importance of Skin Type in Patient History
- Significance: Skin type is a key factor in assessing UVR risk and photo-protection needs.
Classification of Skin Types
- Patients are categorized into six sun-reactive skin types based on response to initial sun exposure, skin color, tendency to sunburn, ability to tan, and personal history of sunburn.
Suggested SPF for Various Skin Types
- Suggested SPF values are provided based on skin complexion and response to sunlight.
Indicators of Skin Reactivity to Sunlight
- Hair and eye color, history of sunburn, and self-reported sunburn/tanning histories can help indicate skin reactivity to sunlight.
Key Considerations Before Recommending Sunscreen
- Patient History Factors include: Medication history (certain drugs increase photosensitivity), sun-reactive dermatoses (conditions triggered by sun exposure), and allergy history (contact hypersensitivities to cosmetics or topical agents). Intended Activities: Evaluate patient's planned outdoor activities to recommend appropriate protection (e.g. water-resistant, sweat-resistant products).
Risk Factors
Long-Term Effects and Risk Factors of UVR Exposure
- Long-Term Effects: Photocarcinogenesis (development of skin cancer), Photoaging (premature aging of the skin).
- Key Risk Factors: Congenital pigmentation (skin type, hair, and eye color influence UVR sensitivity). Exposure factors (Intensity, duration, and frequency). Early childhood exposure increases risk significantly. Children receive 3x more UVB than adults by age 18.
Skin Cancer Risks
- Malignant Melanoma: Linked to frequent sunburns and intermittent high-intensity UVR exposure. Mole-related risk factors include large congenital moles (>1.5 cm) and multiple or abnormal moles.
- Nonmelanoma Skin Cancers: Associated with cumulative UVR exposure over a lifetime.
Family History and Behavior
- First-degree relatives of skin cancer patients have a higher risk.
- Contributing behaviors include frequent sunburns, poor sunscreen use, and tanning bed usage.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Test your knowledge on skin cancer, UV radiation, and its effects! This quiz covers crucial statistics, facts about pollutants, and the importance of sunscreen. Challenge yourself to understand the impact of UV exposure on health and the environment.
