I think is has to do with "toluene". The newer vulcanizing cement often does not even smell the same as it used to. Ha... Ask any Huffer. Other solvents and adhesives that use aromatic solvents for their bond are suffering too. Note that Testors styrene model cement and even plumbing PVC Cement is nothing like it was 8 years ago.

Sure, allot of these solvents and aromatics are dangerous or even now deemed carcinogenics. So what do we do? We hoard those old unopened containers of vulcanizing cement in the frig in hopes they do not evaporate in their unopened tubes... Ha