The numbers cited are not my conclusion, but published data. To save you the time and since I had already looked up all the data,
1 ppm FDA limit on mercury in tuna (or 1 ug/g)
355 g in a 12 ounce can ==> 355 ug in a 12 ounce can, which is 0.355 mg, which I quantized to 0.5 mg
As I said, it depends on what numbers you like or accept, but the mercury in a CFL reportedly ranges from 0.5 mg (about the same as a can of tuna) to 4 mg or so.
Other common mercury exposures:
Watch battery -- up to 25 milligrams Thermometer -- up to 2 grams
Tilt thermostat -- up to 3 grams
Comparison in mercury between CFLs and incandescents