GLEED -- When the flames started, no one expected them to spread so fast nor burn so hot.

"These things are solid gasoline. They really rip," said Jim Fuehrer, who was among a group of firefighters, farmers and fruit packers who recently gathered for a test burn of plastic apple bins in Gleed.

They stacked nine plastic bins and nine wood bins in towers and ignited both. The plastic bins burned roughly three times faster and much hotter than the wood.

The plastic tower went up so fast that Dave Sylvanus barely had time to replace the dead batteries on his camera.

"I walked like 20 feet to get batteries, and by the time I returned they were totally engulfed," said Sylvanus, a Perry Technical School instructor. He supervised instrumentation students who built thermacouples that started the fire and birddogged the instrumentation data.

Only a fraction of the Yakima Valley's apple bins are plastic. But that fraction represents some 300,000, and that number is expected to grow.

Nobody is suggesting packing houses stop using plastic bins. But the results of the test burn could lead to changes in rules about how far apart apple bins should be stacked. Insurance companies may rethink their regulations, too.

Fuehrer, a Yakima police detective and an assistant fire marshal, said the demonstration was not about learning how to fight bin fires.

"Once it's going, you're going to have to take a defensive stance. In slang terms, we call it surround and drown," he said.

He described the burning plastic bins as "ignitable liquid fire" that melted and traveled 25 feet, giving off toxic fumes.

Meanwhile, burning plastic puts out a smoke that carries different toxins than wood, said Gary Pruitt, director of Yakima Clean Air Authority. They include chlorine and phosgene gasses, both chemicals used as nerve agents during World War I.

However, someone would have to breathe huge quantities inside a poorly ventilated building to be harmed instantly, he said.

The fumes also could cause lung cancer and other respiratory problems with repeated small exposures, but that's true for wood smoke, too, he said.

"We're not out to say the plastic bins are bad," said Derald Gaidos, Yakima County deputy fire marshal. "It's just as fire professionals we needed to know a lot more about them than we did."

Such information is becoming more important as the state's $1.2 billion apple industry gradually shifts to plastic bins, favored for their lack of nooks and crannies that can harbor diseases and pests, such as the codling moth.

The codling moth -- the industry's nemesis -- sometimes bores into wooden apple bins and hides out until growers fill the those bins with apples. The bugs can't do that in plastic bins.

Plastic bins began showing up in warehouses in the early 1990s, and companies have gradually been buying more of them to replace wooden bins, which began their use in the late 1940s, said Keith Mathews, executive director of the Yakima Valley Growers-Shippers Association.

Today, Yakima Valley warehouses use about 4.5 million apple bins. Currently, about 300,000 of those are plastic, said Mathews. That's less than 7 percent.

But expect more of them.

"I think, over time, people will continue to move toward plastic," Mathews said.

Of course, both wood and plastic burn.

Thousands of bins -- both wood and plastic -- burned last fall outside a Matson Fruit Co. cold storage facility in Selah.

Investigators suspect the fire may have started in a stack of plastic bins, but that hasn't cooled the company's opinion of them, said Dan Stephens, operations manager for the company. Matson still uses mostly wood but adds plastic bins to its inventory every year as finances allow.

They also have begun spacing all their bins -- again, plastic and wood -- farther apart than codes require, Stephens said.

"If somebody wants them to burn, then it's going to happen," he said.