Skin disease after occupational dermal exposure to coal tar: a review of the scientific literature.

For about a century, coal tar has been used in industry and has been applied in the therapeutic management of several skin diseases. However, in the last decades the benefits of coal tar exploitation for humans could not outweigh its harmful effects on health. The aim of this study is to present the main adverse effects of coal tar on skin, with the emphasis on occupational exposure. The scientific literature indicates that dermal exposure to coal tar and coal tar pitches can be the cause of phototoxic reactions, irritation and burn, allergic dermatitis, folliculitis, occupational acne, atrophy of the epidermis, and hyperpigmentation. Moreover coal tar has been implicated in tumorigenesis, a relationship shown in numerous studies but not confirmed yet as the mechanism has not been fully clarified. A common finding in most studies is that exposure over a long period is the main risk factor for malignancy development, even in low exposure levels. Additional prospective, well-designed studies need to be performed to confirm the validity of the carcinogenic, mutagenic, and cytotoxic potential of coal tar on skin.