They've carried your food, they've carried your clothes, your medicine, and probably part of your house.
But unless you work with those industrial, stackable platforms, it's unlikely that you've heard about pallets, or the ongoing pallet wars.
An estimated 1.2 billion pallets are in use in the United States alone -- in warehouses, in trucks, on the bottom of forklifts -- and for 60 years since the pallet's formal debut, safety issues for this ubiquitous piece of equipment have been minimal.
But in the last few months, pallet industry leaders have been caught up in brewing war over consumer safety that could easily rival the plastic versus wood cutting board battle of the 1990s.
On one side is the new competitor that distributes plastic pallets. On the other are larger, older companies and associations that deal with wooden pallets, such as the National Wooden Pallet & Container Association.
Both are pointing to studies, or potential hazards caused by either plastic or wood. Given the Tylenol recall this December, which affected 60 million bottles, it's easy to see how a few contaminated pallets could affect many.
Plastic pallet distributer intelligent Global Pooling Systems, or iGPS, threw a recent punch this January when the company released results of a multi-city survey that found E. coli, Listeria and Salmonella growing on wooden pallets.
"In New Orleans Louisiana, 43 percent of the pallets came back positive with E. coli, salmonella and listeria," said Bob Moore, CEO and chairman of iGPS.
The samples from 30 pallets in New Orleans was paid for by iGPS and sent to independent labs. Other cities in the iGPS-sponsored survey included Maine, Washington, D.C., Baltimore and Philadelphia.
Moore is arguing that the same contamination that his company found on wooden pallets in fish markets in New Orleans is less likely to show up on his plastic pallets.
"We have found some [contaminated] pallets, because we test them on our own. But nothing like you find on wood pallets because it's non-organic, non-porous," said Moore, who argued that the upcoming GPS tracking devices on his pallets would let him monitor which pallets are at risk.
"I know what a pallet had on it yesterday. If I know that it had dry grocery on it, then I know there's no risk for cross contamination," Moore said.
But the president of the National Wooden Pallet & Container Association argues the iGPS testing doesn't say much about the wooden pallets versus plastic pallets debate, since the company didn't include samples from plastic pallets in its investigation.
"The question is, are these random pallets or are they specifically targeted pallets?" said Bruce Scholnick, president of the National Wooden Pallet & Container Association.
"I could go out and find a [any] pallet that's been sitting outside for 6 months or a year that has waste on it, animal waste and I could send it to a lab," he said.
Scholnick said the inquiry into food-borne illnesses on wooden pallets was spurred by industry attention to the possibility that there are environmental hazards in a flame retardant used in the plastic pallets.
"It frankly started with their flame retardants," Scholnick said of iGPS.
Decabromine is a flame retardant that's been used in products for decades and, according to Scholnick and Moore, it is used in plastic pallets to adhere to fire safety burn tests. In recent years, environmental groups have calculated an increased amount of decabromine in the environment.
As a result, by December 2009, the Environmental Protection Agency forced large producers to phase out the chemical by 2013.
"Decabromine is the most widely used fire retardant flame retardant in the world. It's in the carpet you're sitting one, it in the handset on your phone," said Moore, who added that "it's been in use for 40 years, safely.
"It is, however, a persistent chemical meaning once you make it, it doesn't go away," Moore said.
And as Scholnick pointed out, the chemical can become hazardous to firefighters if the pallets do end up burning.
However, Moore contends that wooden pallets are made with unsavory chemicals too, including a formaldehyde compound.
"The thing about those people making that claim about decabromine, is that their pallets use composite blocks. Those composite blocks are made out of sawdust held together by formaldehyde," he said.
This December, iGPS also publicized a separate issue with chemicals and pallets -- a Tylenol recall.
More than 60 million bottles of Tylenol pills and other over the counter products were recalled after a number of people reported being sickened after swallowing moldy-smelling pills, which originated from Tylenol manufacturer McNeil Healthcare LLC, in Puerto Rico.
The U.S. Food and Drug Administration's investigations linked the sickness to wooden pallets and trace amounts of a chemical called 2,4,6-tribromoanisole.
"The source of 2,4,6-tribromoanisole is believed to be the breakdown of a chemical used to treat wooden pallets that transport and store packaging materials," the FDA wrote in a statement on its Web site. "The health effects of this compound have not been well studied, and to date all of the observed events reported to McNeil were temporary and non-serious."
Scholnick said 2,4,6-tribromoanisole is not permitted for use in the United States, but suspected the pallets treated with the chemical came from South America.
With the number of goods moved on pallets every moment, there's no doubt that a safety issue with pallets could become a crisis in little time.
However, microbiologists and produce safety experts say the pallet industry makers have a lot more work to do to prove that any type of pallet is a top health concern.
Dr. Charles Gerba, a microbiologist at the University of Arizona in Tucson, said more attention should be paid to how surfaces are maintained and cleaned, not the material they are made of.
"Most of our information comes from the cutting board wars," said Gerba. "It's kind of like, 'take your pick.' Both materials have advantages and disadvantages, and it really comes out to how well they are being cleaned and maintained."
While wood is more porous and may absorb bacteria, Gerba pointed out that it is also more likely to keep the bacteria in one place, "then they [bacteria] can't come out so easily."
Wood has natural antimicrobial chemicals, while plastic is easier to clean, according to Gerba. New plastic is less likely to trap bacteria, but once it has nicks and scratches, Gerba said plastic can becomes a host.
"I read all the literature, and I think it's a toss-up," said Gerba.
Trevor Suslow, a research specialist in food safety at the University of California, Davis, said he's not surprised by the high-stakes back and forth between the plastic and wooden pallet industry.
"It's a big market. No wonder they fight about it," Suslow said.
However, as the worries for contaminating produce go, Suslow said pallets have worked well enough that they do not cause a great deal of worry.
"In the hierarchy of things to worry about, it's not on the top of the list, because the product is not loaded directly on the pallet," Suslow said.
Indeed, according to Moore and Scholnick, the FDA only regulates three aspects of the pallet industry and two of the regulations have to do with permitting food items on pallets -- pallets coming into the country must be either heat treated, or treated with methyl bromide to remove pests, only stainless steel pallets can be used in a produce cooling technique called hydrocooling and no raw materials, especially meats, can directly touch a pallet.
"In just about all cases, pallet is a secondary packaging," Moore said.