Most pressure-treated lumber is made from Southern Yellow Pine, somewhat brittle softwood. Pine has a reputation for severe splintering and checking (cracking) under all weather conditions and is highly susceptible to insect infestation and decay. To reduce the risk of decay and insect damage, chemicals, such as arsenic and chromium or ammonia and copper, are injected into the wood. There is considerable debate as to the safety and durability of pressure-treated lumber. Studies show extreme leaching of the chemicals out of the wood, and the treating process can alter the molecular make-up of the wood, weakening its structural integrity. While the chemicals render the wood resistant to decay and insects, they do not prevent or reduce splintering and cracking. Redwood and cedar's natural resistance to rot and insects makes it a logical choice when faced with the possibility of chemical-related hazards.