Parks departments in North Texas are scrambling to address a potential health concern about arsenic in picnic tables, which was uncovered by a News 8 investigation.

Arsenic is a substance known to cause cancer and other health problems. It was widely used for 30 years to keep outdoor wood from rotting.

Because of health concerns, consumers can no longer buy wood with arsenic. However, countless picnic tables are still out there. News 8 found some communities have done very little to correct the problem.

"Children, as they're growing up, put their fingers and hands in their mouth," said Keller Thormahlen, Senior Toxicologist for the Texas Department of Health Services. "They get it on their face and it ends up in their digestive track."

News 8 screened parks in North Texas looking for picnic tables made with lumber infused with arsenic. A scientist wipe-tested tables.

While there is no scientific consensus on what is a safe level of arsenic for a child, News 8 found detectable amounts on the surface of the wood in Cedar Hill State Park and at city parks in Dallas and Duncanville.

After News 8 notified Duncanville it immediately began replacing the wood on about 30 picnic tables.

"We just decided for us to be overly cautious and just change the wood to wood we know is safe," said Tonya Lewis, a spokesperson for the city of Duncanville. "It was a shock to us to even know that we had this problem with our wood."

But it should have been old news. For at least five years, communities have known about the federal government's effort to limit arsenic exposure to children. The government's simplest and cheapest recommendation is to treat the wood with a sealant every other year.

"I don't know anyone who was really aware and made the connections to our picnic tables," Lewis said when asked why no one had treated the wood.

The city of Dallas also took immediate action by removing picnic tables from Tennison Park, which is where News 8 conducted tests. Dallas officials said they are investigating how many tables they have citywide and will then have them all replaced.

The state's toxicologist said a child's risk of exposure at a picnic table is limited, but removing the tables is the right thing to do.

"With hazardous chemicals, you want to reduce or eliminate the exposure," Thormahlen said.

In a News 8 test, a table at Cedar Hill State Park showed the highest level of arsenic.

But instead of hundreds of tables, which is the amount Dallas will replace, the Texas Department of Parks and Wildlife has thousands. Replacing them all at once may not be an option.

"It would be a huge expense," said Robert Crossman, who is charge of maintenance for the statewide park system.

The state said it is working with other state and federal agencies to find the best solution, which may include resealing all of the state's benches and then rapidly phase them out.

"To just react would maybe not make it better," Crossman said. "We want to make sure we do the right thing."

As a contrast, the city of Denton has handled the arsenic issue particularly well. Eureka Playground is made with arsenic-treated wood, which is sealed two times a year and scientifically tested once a year.

A sign warns visitors about health concerns, suggesting children wash their hands after playing. All nearby picnic tables are painted, keeping the arsenic inside.

E-mail dschechter@wfaa.com