Two big labor unions that champion ironworkers and meat cutters are now fighting for workers in the artificial flavoring industry. The Teamsters and the United Food and Commercial Workers claim workers have lost substantial amounts of their breathing capacity to a disease called bronchiolitis obliterans, which the unions claim was caused by exposure to diacetyl, a widely used buttering flavor. Over the weekend, 40 job health experts joined the unions in urging the Bush administration to issue an emergency order restricting workers’ exposure to the chemical.

“Although the precise number of workers already suffering respiratory effects from exposure to diacetyl is unknown, the potential magnitude of the problem is sizable,” the experts said in a letter to U.S. Labor Secretary Elaine Chao.

OSHA currently sets no limits for worker exposure to diacetyl. Industry representatives noted that artificial flavoring companies deals with many hazardous chemicals, and the industry has a strong history of protecting workers from exposure. According to the Sacramento Bee, the level of worker protection in the flavoring business varies from company to company as job safety is largely self-policed.