Maine policy-makers need to take another look at the state’s approach to the use of creosote- treated timbers in coastal waters. Rules developed to implement the Natural Resources Protection Act in effect prevent the use of timber treated with creosote for marine piers and other structures. Last summer, we began to pay the price. In a single year, shipworms destroyed pilings in Belfast, Rockland and Searsport, and an aquaculture company in the Damariscotta River had damage to its oyster growing facilities.

Roberto Lopez-Anido and colleagues at the University of Maine have assessed the extent and nature of the damage caused by shipworms in those communities. Similar problems elsewhere in Maine may very likely have gone unreported.

Shipworms, also called the termites of the sea, are not actually worms. They are highly modified clams that have evolved into efficient wood eating machines. In their search for a home, the larvae bore tiny holes on the surface of woody materials. The adults use their shells as a rasp and create larger tunnels inside the wood, in effect turning solid timber into a brittle honeycomb. Damage is often discovered too late to do anything except replace the infected structures.

Shipworms have long been a global scourge of maritime activities. In 1502, Christopher Columbus scuttled two of his four ships because of extensive shipworm damage. Pier owners in San Francisco Bay saw an estimated $1.3 billion (today’s dollars) in shipworm damage in the early 1920s. In the last decade, the City of New York has spent well over $100 million to protect and replace worm-damaged structures.

No one knows why shipworms chewed through so much more wood last summer in Maine than in previous years. Kevin Eckelbarger, director of the UMaine Darling Marine Center, and Dan Distel, professor biochemistry at UMaine, have studied the biology of shipworms and suggest that relatively warm water temperatures could have played a role. Eckelberger is advising marine businesses and will begin new research efforts this spring.

Meanwhile, wood remains the most economical material for harbor structures and marine industries, and methods to protect it are critical to the well being of our coastal communities. The most common preservative in the U.S. for all purposes is CCA which is responsible for the green hue of pressure treated lumber. CCA treated wood is legal in Maine waters, but it tends to be brittle and not suitable for pilings.

The purpose of Maine’s creosote ban was apparently to prevent contamination of coastal waters by toxic PCBs. Two decades ago, some creosotes indeed contained PCBs as a contaminant. Maine’s ban was a precautionary move. No cases of PCB contamination in Maine coastal waters had been traced to the use of creosote.

To be sure, creosote is a toxic chemical. 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. Creosote-treated timbers have a long record of effective use in marine waters, and those who use Maine’s harbors and other marine facilities should not be put at a disadvantage.

This commentary was submitted by the following UMaine faculty: Douglas Gardner and Barry Goodell, of the Department of Forest Management; Roberto Lopez-Anido, of the Department of Civil and Environmental Engineering; and Kevin Eckelbarger, of the Darling Marine Center.