The ripple effects might eventually be felt by wood preservers. The use of safe levels of chemicals, Mr. DeVenzio says, must be considered in the context of environmental benefits that accrue from making a renewable resource like wood last longer. In Georgia, where summer heat and humidity can be intense, he adds, an untreated pine board stuck into the ground would probably show signs of decay and termites within a year and be unuseable within three to five years. Pressure-treated wood, on the other hand, may last five to 10 times longer. With the preservatives in pressure-treated wood, termites don't recognize the wood as food.
Retention is a measure of the pounds of preservative per cubic foot of wood.
Liquid preservative is applied in a pressurized cylinder. The degree of chemical absorption varies. Generally speaking, more preservative is found near the wood's surface. Most Western species have to go through an incising machine, which puts all these shallow little knife cuts into the wood to help the preservative get deeper. The EPA has been working with manufacturers and wood retailers to make sure information about pressure-treated lumber is available to consumers.