On Sept 4, management of the San Francisco Opera announced that it has agreed not to use a glycol-based theatrical fog, after at least seven chorus members withdrew from forthcoming productions out of concern for the possible health risks involved.

In a memo delivered to the San Francisco Opera Chorus Joint Committee, general director Pamela Rosenberg said that the stage fog, produced by Rosco Laboratories Inc. of Stamford, Conn., would not be used in the company’s productions of Arshak II by Tigran Chukhadjian and Saint-Saens’ Samson et Dalila.

Despite repeated studies commissioned by both the Opera and Actors’ Equity that have shown the fog effects to be safe, members of the opera have continued to complain about its effects. According to an article in the San Francisco Chronicle, Rosenberg called off the use of Rosco “to allow us time to have further discussions . . . and as a gesture of good will.”

Whether her decision will placate worried and angry choristers remains to be seen. Both productions will continue to use a less controversial type of effect called DF 50, which uses mineral oil in solution to produce a fine mist. But some singers believe that DF 50 is no less problematic than Rosco.

“Both of them are no good,” chorus member Joy Graham-Korst told the Chronicle. “Some people are highly sensitive to these products. I have had to take myself out of current productions that use them.” A company spokesperson said seven members of the chorus had been excused from the Arshak production.

Local 802 President Bill Moriarity told Allegro, “We also continue to receive complaints from orchestra members about these smoke and fog effects. Neither our members nor members of the San Francisco Opera should be exposed to any of these materials until they are absolutely proven safe. And they have not been.”

Moriarity stressed that “the burden of proof should not be on us. Management should have to prove that these materials are harmless before they are used – not after our members and other get sick.”