Exogenous Factors in Hair Disorders

The 2004 document reviews how exogenous factors such as grooming practices, chemical treatments, and environmental exposures can damage hair, leading to disorders like alopecia and changes in hair appearance. It details the hair structure and growth cycle, explaining that damage, or 'weathering', can occur from everyday activities and that hair can be affected by substances like copper or by trauma and dermatological treatments. Cosmetic products can either protect or damage hair, with conditioners reducing friction and damage, while styling products may build up or cause allergic reactions. Chemical processes, if overused, can cause hair breakage and loss, and physical styling can lead to traction alopecia. Thermal tools and solar radiation can degrade hair proteins and pigments, while X-irradiation can cause alopecia. The document emphasizes the importance of proper hair care to prevent damage, as hair does not repair itself, and suggests new sunscreen classes for hair protection. It does not provide specific study participant numbers, indicating it is a general review rather than a new study.