Long-Term Effects of UV Radiation on the Skin - An Overview

Introduction

UV radiation is the most recognized risk factor for skin cancer and other environment-influenced skin diseases. Excessive UV exposure harms health, causing atrophy, wrinkles, pigment changes, and cancer. Thus, UV radiation (UV), also known as a potent carcinogen, can generate gene mutation (mutagenesis), act as a non-specific harmful agent, and as a tumor initiator and promoter. However, UV improves human health by mediating natural vitamin D and endorphin synthesis in the skin. Consequently, UV has complex and mixed effects on human health.

What Is Ultraviolet (UV) Radiation?

Ultraviolet (UV) radiation is electromagnetic radiation emitted by the sun and artificial sources like welding torches and tanning beds. There are three types of radiation:

1. Extremely High-Energy (High-Frequency) Radiation - X-rays and gamma rays.

2. Extremely Low-Energy (Low-Frequency) Radiation - Radio waves.

3. UV Rays - The middle of this spectrum.

Ionizing radiation is a type of higher-energy UV radiation, depending on its intensity level. This indicates they possess sufficient energy to ionize or take an electron from an atom or molecule. Ionizing radiation can potentially harm cells' DNA (deoxyribonucleic acid) genes, which could eventually result in cancer. However, even the most intense UV rays lack the energy to penetrate deeply into the body; as a result, their principal impact is on the skin. Three categories of UV radiation are differentiated:

• Ultraviolet A (UVA) Radiation: UVA photons are the least energetic photons. These rays can age skin cells and inadvertently harm DNA in some cells. Although UVA rays are primarily associated with long-term skin damage like wrinkles, they may also be responsible for some types of skin cancer.

• Ultraviolet B (UVB) Radiation: Compared to UVA rays, UVB rays have more energy. They are the primary rays responsible for sunburn because they can directly harm the DNA in skin cells. Most skin cancers are also believed to be caused by them.

• Ultraviolet C (UVC) Radiation: The energy of UVC rays is higher than that of other UV rays subtypes. Due to this, they interact with ozone high in the atmosphere before reaching the earth and are rarely a cause of skin cancer. However, artificial sources, such as mercury lamps, arc welding torches, and UV sanitizing bulbs intended to eradicate bacteria and other pathogens, can also produce UVC rays.

What Are the Common Sources of UV Radiation?

• Sunlight: Sunlight is the primary source of UV radiation. UV rays of various types reach the earth in varying amounts. The sun's UVA rays account for around 95 % of the UV rays that reach the earth, with the remaining five percent being UVB rays.

• UV Rays Emitted by Artificial Sources: People might also be exposed to UV radiation from artificial sources. These are some examples:

• Phototherapy (UV therapy): Treatment with UV light can help some skin conditions, such as psoriasis. A medication called Psoralen is first administered as part of the PUVA treatment. However, the medication accumulates in the skin, making it more vulnerable to UV rays.

• Sunlamps and Tanning Beds: The amount and kind of UV radiation emitted by a tanning bed (or booth) depends on the person who remains in the bed and how frequently the person uses it. Most current UV tanning beds release UVA photons primarily, with the remainder being UVB.

Is Ultraviolet (UV) Radiation Carcinogenic?

The two most prevalent kinds of skin cancer, basal, and squamous cell cancers, are caused by UV radiation in sunlight and are most commonly found in sun-exposed body areas. Their prevalence is typically linked to lifetime sun exposure. Sun exposure is also linked to the risk of melanoma, a more deadly but less common type of skin cancer. Exposure to various artificial UV radiation sources has also been associated with skin cancer. Basal and squamous cell skin malignancies are connected to various sun-exposure behaviors such as:

• Sun damage to the neck's skin, such as liver spots, actinic keratoses (rough skin), and solar elastosis (thickened, dry skin).

• Living in a place with lots of sunlight.

• Having suffered from severe sunburns in the past.

• Recreational time spent in the sun, including going to the beach and spending a lot of time in a swimwear in the sun.

What Are the Long-Term Effects of Ultraviolet (UV) Radiation on the Skin?

UV radiation produces the following long-term effect on the skin depending on the amount and form of radiation and the skin type of the individual exposed:

• Photodamage (photoaging).

• Chemical sensitivities.

• Dry, leathery skin.

• Actinic keratosis (rough skin patches that might be precancerous).

• Premature skin aging.

• Solar elastosis (thickened, dry, wrinkled skin produced by sun exposure).

• Sun-damaged skin.

• Wrinkles.

• Liver spots.

• Inflammation of the eye's cornea (the eye's clear front surface).

Sunburn is caused by short-term overexposure, but premature aging and skin cancer are caused by long-term UV exposure. In addition, UV exposure raises the risk of potentially blinding eye conditions if no eye protection is worn. UV radiation overexposure can cause major health problems, including cancer and basal and squamous cell carcinoma.

Does Skin Pigmentation Play a Role in Ultraviolet (UV) Radiation on the Skin?

The risk of developing skin cancer is increased by both UV exposure and skin pigmentation. Since, UV rays can easily penetrate the epidermis and injure keratinocytes and melanocytes (skin cells) in the deeper layers, people with light skin pigmentation are more susceptible to UV damage. Conversely, people with fair skin receive higher UV radiation doses through their skin. Melanoma and skin cancer are caused directly by the accumulation of UV-induced mutations.

Conclusion

UV radiation can cause premature skin aging and sun damage symptoms such as actinic keratosis, wrinkles, brittle skin, liver spots, and solar elastosis. In addition, certain cataracts are more likely to develop due to UV exposure. Despite being treatable with eye surgery, cataracts impair vision. Excessive exposure to sunlight can also cause various skin cancers, such as basal cell carcinoma and squamous cell carcinoma. A majority of melanoma cases, a type of fatal skin cancer, are caused by UV radiation exposure. Therefore, it is advisable to protect oneself from the sun all year long, using a hat, a shirt, or sunscreen to shield oneself from the sun.