Environmental and cosmetic factors in hair loss and destruction.

Acquired hair loss may be a manifestation of various internal diseases, hormonal and nutritional conditions, systemic intoxications and genetic traits. However, exogenous exposures may be major contributors to hair thinning and decline of texture, color, luster, elasticity and manageability. In this review, we describe the effects of various exogenous agents on hair, including hair cosmetics, traction, heat, water, solar radiation and X-irradiation.