“Preservative known to have compounds that cause cancer.”

CCA isn’t the only toxic wood preservative to be the focus of safety concerns.

Edward Polaski, the former state employee who compiled a critical report on CCA, also wrote a report for the state Department of Conservation and Natural Resources that reviewed research on an older preservative, called creosote, which is used in Pennsylvania in the Timber Bridge Program administered by the U.S. Forest Service.

The Forest Bureau has built one such bridge in Centre County, and has plans for 22 more in state forests. Creosote-treated wood bridges also have been built by the state Department of Transportation and local municipalities.

The Baileyville Bridge, a timber bridge just outside State College, was built in 1991 out of glued, laminated red oak timber. Creosote drips and seepage are visible on many of the wood beams, and creosote stains are visible on the rocks, in and along the stream it crosses.

Similar creosote stains can be seen on the rocks and in the stream below the red maple timber bridge in East Pennsboro, Cumberland County.

While Pennsylvania is just beginning to build such bridges, a 1995 report on 51 creosote-treated timber bridges in West Virginia found that 15 - 29.4 percent - showed creosote problems, including stream and stream bank contamination. Under the Fieldcrest Bridge in Morgantown, W.Va., for example, Polaski said he saw “football-sized gobs of creosote” in the stream.

Terri Shistar, assistant professor of environmental studies at the University of Kansas and a board member of the National Coalition Against Misuse of Pesticides, said creosote’s toxicity varied from batch to batch, but that all batches contained known cancer-causing compounds.

“Whether from pressure-treated wood or brushed on, if creosote is oozing out of bridges and released into the environment or into streams, it’s not a good thing,” said Shistar.