For 47 years, untreated creosote was being dumped into the harbor by The Baxter McCormick Creosoting Company. Creosote is the name used for a variety of products: wood creosote, coal tar creosote, coal tar, coal tar pitch, and coal tar pitch volatiles. These products are mixtures of many chemicals created by high-temperature treatment of beech and other woods, coal, or from the resin of the creosote bush.

Breathing vapors of the creosotes, coal tar, coal tar pitch, or coal tar pitch volatiles can cause irritation of the respiratory tract. Eating large amounts of creosote (any form) may cause a burning in the mouth and throat and stomach pains. Eating large amounts of herbal remedies containing creosote bush leaves may cause liver damage, while large amounts of coal tar creosote may result in severe skin irritation, eye burns, convulsions, unconsciousness, and even death.