Almost every other popcorn maker followed suit.
But now, government health investigators are reporting that the "new, safer, butter substitutes" used in popcorn and others foods are, in some cases, at least as toxic as what they replaced.
Even the top lawyer for the flavoring industry said his organization has told anyone who would listen that diacetyl substitutes are actually just another form of diacetyl.
So what is the Obama administration going to do about it? Nothing meaningful, at least for a year, it said this week, stunning unions, members of Congress, public health activists and physicians who have pleaded for government action to protect workers and consumers from the butter flavoring.
"We've been very clear to flavor manufacturers, food companies and regulators that these so-called substitutes are diacetyl," said John Hallagan, general counsel for the Flavor and Extract Manufacturers Association.
When diacetyl trimmer is in the presence of heat and water, it will release diacetyl. And butter starter distillate is not a substitute for diacetyl because it contains high concentrations of diacetyl. However, it is considered a natural material, which is a boon to companies that wish market their food items with the "natural" label, Hallagan said in an interview from Colorado.
Hallagan said that his trade association discouraged using these materials and calling their products "diacetyl-free."
But he added that his group "is not a regulator and has no legal authority to prohibit their use. That's up to the food manufacturers."
Those companies, citing competition, repeatedly refuse to discuss what they're using today to add the butter flavor to what they sell.
But, at their professional conferences, food scientists and flavorists openly discuss that they are using blends called starter distillates and trimmers as substitutes for the rich butter flavors that consumers love so much.
Government health investigators already have concluded that these butter surrogates may be unsafe.
"The inclusion of these alternative substances neither eliminate diacetyl nor (ensure) safety for workers,'' physicians from the National Institute for Occupational Safety and Health -- Drs. Kathleen Kreiss and Nancy Sahakian -- wrote this year.
Monday, Dr. Daniel Morgan, with the Respiratory Toxicology Group at the National Institute of Environmental Health Sciences, said he found the same danger in one of the principle components of the butter substitute, a concoction called 2,3-pentanedione.
"It caused the same injuries in test animals as diacetyl, and our preliminary data indicates the toxicity is close to identical," Morgan said in a phone interview from his laboratory in Research Triangle Park, N.C.
"We don't really know what industry is using as a substitute in these 'diacetyl-free' items. But if 2,3-pentanedione was being used, it's being done without toxicity data."
The disease from exposure to diacetyl -- bronchiolitis obliterans -- is debilitating and potentially fatal. It irreversibly destroys the small airways in the lung. The only hope for many is a hard-to-get single or double lung transplant.
It has been almost a decade since Dr. Allen Parmet, an occupational medicine specialist, figured out that workers at a Missouri microwave popcorn factory were being sickened by something in the process. NIOSH quickly pointed to diacetyl as the likely villain at similar plants throughout the Midwest.
Over the years, unions, congress, scores of physicians and scientists, and occupational health experts called on OSHA to take action.
In June 2006, Rep. Hilda Solis, a Democrat who represented the Los Angeles district where two stricken flavoring plant workers lived, reacted to media reports on their illness and demanded that OSHA do more to protect workers.
"These illnesses and deaths are preventable," Solis said at the time. "Further inaction is inexcusable."
Last month, another Democrat, Sen. Sherrod Brown of Ohio, wrote to the Labor Secretary, citing the popcorn lung disease of a constituent.
"I am concerned that OSHA has not acted fast enough to compel employers to reduce workplace exposures to this deadly additive," Brown wrote.
Public health advocates told themselves that when Democrats took over the health and safety agencies, the Bush regulations-are-bad era would vaporize. One measure was going to be how quickly the Obama team addressed something as well-researched as diacetyl.
Well, this week the new Labor Secretary, who happens to be Hilda Solis, did something.
Solis released her plans for worker health and safety, mentioning several specific hazards, including diacetyl.
Yet instead of expediting carefully crafted rules for diacetyl and worker safety, she ordered another peer review of diacetyl's health effects.
Still, there is a chance that something may happen in Labor.
The Senate over the weekend finally confirmed David Michaels as the head of OSHA. Michael, who directed the Project on Scientific Knowledge and Public Policy, and his colleague Celeste Monforton, have been strong advocates for government action on diacetyl.
They not only went after OSHA but also told the FDA it had a responsibility to protect consumers, consumers like Elaine Khoury.
Khoury worked for Blockbuster Video for five years in Florida and Missouri. As the store manager, every Friday and Saturday, she would pop 30 bags of microwave popcorn in a small back room, then empty them into a popcorn machine to give the appearance that they had been freshly popped.
Last year, a lung biopsy at the Mayo Clinic confirmed that she had full-blown bronchiolitis obliterans. She is now waiting for a lung transplant.
But the doctors treating Khoury and advocates for other popcorn lung victims are worried that an unknown number of popcorn lovers may be going undiagnosed because doctors think the problem has been solved.
She is the third case of non-factory workers contracting popcorn lung. Lawsuits involving two more alleged victims -- in New York and California -- are expected to be filed shortly, lawyers say.
"No one knows how many cases of consumers injured by the flavoring vapor for the microwaved popcorn because no one has really looked," said Dr. David Egilman, a specialist in internal and occupational medicine who has examined scores of popcorn plant and other workers and testified on their behalf in litigation against flavoring companies.
"Allegedly all of the companies have taken diacetyl out of their popcorn, but that doesn't seem to be the case."
In response to continued worker complaints about diacetyl in flavoring, NIOSH conducted a health hazard evaluation at the General Mills bakery mix facility in Los Angeles.
In a report made public last week, NIOSH said that investigators found concentrations of butter flavoring agent 2,3-pentanedione in liquid buttermilk flavoring and during production of a bakery mixes.
A "safe" level of diacetyl has not been established, and even low levels of diacetyl are potentially hazardous, the report said. It concluded that "the toxicology of other flavoring ingredients, including diacetyl substitutes, can result in deeper lung penetration and perhaps greater toxicity.'"
"Until more is known, these (diacetyl substitutes) should not be assumed to be safe," said NIOSH, which is the worker health and safety research arm of the Centers for Disease Control.
General Mills was advised to limit exposures to flavorings through a combination of engineering controls, work practices and respiratory protection. Workers should report symptoms to their personal physician and the company, NIOSH suggested.
More study on flavors is needed, said Kreiss, chief of NIOSH's Field Studies Branch in Morgantown, W.Va.
"Toxicology is a very slow process, and I doubt that in my lifetime we'll see testing on all the flavors that we believe should be examined," she said. "It's a challenge to figure out how to regulate these flavorings, and we certainly want to do more than just diacetyl."