Drugs

The photodegradation of drugs is of scientific and biological interest because they are frequently found in wastewater (after people or animals take them, they are excreted). As long as they do not degrade, they have harmful effects on aquatic organisms, such as toxicity, endocrine disruption or genetic damage.[2]​ Furthermore, if the drug in its state prior to taking (pill, syrup, etc.) is sensitive to light, the packaging must protect it. For this purpose, amber crystals such as Fiolax amber or Corning 51-L are used. Iodine (in the Lugol solution) and colloidal silver are very frequently used in packaging, because they allow very little ultraviolet light to pass through, and thus prevent photodegradation.

Polymers

Common synthetic polymers such as polypropylene or low-density polyethylene can be attacked by sunlight, particularly its ultraviolet part. The tertiary carbon bonds (one C atom bonded to 3 others) in their chain structures are the centers of attack. Ultraviolet rays interact with these bonds to form "Radical (chemistry)") free radicals, which in turn react with oxygen in the atmosphere, producing carbonyl groups in the main chain. The exposed surfaces of the products may then become discolored and cracked. In extreme cases, complete disintegration of the product may occur.

In fiber products, such as rope used in outdoor applications, the life of the product will be short, because the outer fibers will be attacked first, and the entire product will easily suffer abrasion damage. Discoloration of the rope can also occur, which gives early warning of the problem: if a rope that holds something important becomes discolored, this indicates that it has lost structural strength, so it should be replaced before it breaks.

Polymers whose chains contain parts that absorb ultraviolet (UV) light, such as aromatic rings, may also be sensitive to UV degradation. Aramid fibers, like Kevlar, are very sensitive to UV radiation and must be protected from the destructive effects of the sun. For this reason, bulletproof vests do not have Kevlar fibers in the air, but rather encapsulated in dark opaque fabric.[3]​.

Drugs

The photodegradation of drugs is of scientific and biological interest because they are frequently found in wastewater (after people or animals take them, they are excreted). As long as they do not degrade, they have harmful effects on aquatic organisms, such as toxicity, endocrine disruption or genetic damage.[2]​ Furthermore, if the drug in its state prior to taking (pill, syrup, etc.) is sensitive to light, the packaging must protect it. For this purpose, amber crystals such as Fiolax amber or Corning 51-L are used. Iodine (in the Lugol solution) and colloidal silver are very frequently used in packaging, because they allow very little ultraviolet light to pass through, and thus prevent photodegradation.

Polymers

Common synthetic polymers such as polypropylene or low-density polyethylene can be attacked by sunlight, particularly its ultraviolet part. The tertiary carbon bonds (one C atom bonded to 3 others) in their chain structures are the centers of attack. Ultraviolet rays interact with these bonds to form "Radical (chemistry)") free radicals, which in turn react with oxygen in the atmosphere, producing carbonyl groups in the main chain. The exposed surfaces of the products may then become discolored and cracked. In extreme cases, complete disintegration of the product may occur.

In fiber products, such as rope used in outdoor applications, the life of the product will be short, because the outer fibers will be attacked first, and the entire product will easily suffer abrasion damage. Discoloration of the rope can also occur, which gives early warning of the problem: if a rope that holds something important becomes discolored, this indicates that it has lost structural strength, so it should be replaced before it breaks.

Polymers whose chains contain parts that absorb ultraviolet (UV) light, such as aromatic rings, may also be sensitive to UV degradation. Aramid fibers, like Kevlar, are very sensitive to UV radiation and must be protected from the destructive effects of the sun. For this reason, bulletproof vests do not have Kevlar fibers in the air, but rather encapsulated in dark opaque fabric.[3]​.