Deterioration light-promoted

Photochemistry involves the interaction of visible and ultraviolet light with cellulose whereas radiation chemistry involves its interaction with high-energy radiations, such as from y-radiation. Light promotes the deterioration of cellulosic products, particularly cotton fabrics, and certain dyes or other additives greatly accelerate this process known as phototendering. Ionizing radiation is used to sterilize medical and bioproducts many of which are cellulosic. Several authoritative reviews are available [511-514]. 

The detection and quantification of one or more of the above lipid peroxidation produas (primary and/or secondary) in appropriate biofluids and tissue samples serves to provide indices of lipid peroxidation both in ntro and in vivo. However, it must be stressed that it is absolutely essential to ensure that the products monitored do not arise artifactually, a very difiScult task since parameters such as the availability of catalytic trace metal ions and O2, temperature and exposure to light are all capable of promoting the oxidative deterioration of PUFAs. Indeed, one sensible precaution involves the treatment of samples for analysis with sufficient levels of a chainbreaking antioxidant [for example, butylated hydroxy-toluene (BHT)] immediately after collection to retard or prevent peroxidation occurring during periods of storage or preparation. 

Deterioration of paint films is promoted by photolysis, photooxidation or photo thermal reaction as a result of exposure to natural light. Specifically, UV light (wavelength 40-400 nm) decomposes some polymer structures. Polymer Aims, such as vinyl chloride resins, are gradually decomposed by absorbing the energy of UV light. 

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