The brands of CFL tested contained generally from 1 to 3 mg of mercury, other lamps might have greater or smaller levels of mercury;
The tested CFLs were new lamps and likely have greater mercury vapor available for immediate release versus spent lamps;
Stahler et al. (2008) illustrated that variability exists between trials within a scenario and between scenarios. This variability was not so great, however, as to affect the overall results.