The coal tar from which it is made causes cancer in humans, and the U.S. Environmental Protection Agency lists creosote as a probable human carcinogen. Nevertheless, coal tar and related products are approved in medicines used to treat skin diseases such as psoriasis. As applied to wooden pilings in coastal waters, creosote poses little if any risk to people. Creosote is largely insoluble in water and thus maintains its protective ability in wood that is constantly wet. Nonbleeding formulations are now available, but some elements are soluble.
Previous research indicates that there is minimal risk to marine organisms.
More study is needed to determine the extent of this risk as well as the best alternatives. Legislators need to weigh the risk against ongoing damage to structures. Research on composite materials and environmentally safe wood preservatives may play important roles here, and Maine is well positioned to lead such an effort. Work at UMaine s wood composites laboratory may produce new techniques for repairing and protecting piers. It makes little sense to put raw, unprotected wood into our coastal waters.