I used to teach chemistry, so I am familiar with some toxic chemicals.
Goes like this: Anything the comes from petroleum, if not properly refined (in a very careful and expensive way) will carry along bizarre hydrocarbons that can cause cancer.
Anything sourced from ancient carbon deposits, such as coal or petroleum, can concentrate similar toxic hydrocarbons.
Also, any inhaled particulate (dust) can be bad for you, be it wood smoke, wood dust (sawdust), cigarette smoke or coal dust. Coal dust (unprocessed graphite) can cause a disease called "black lung", so yes, graphite in dust format is bad for you. Graphite in solid form (such as the black stuff in your pencil, which never contains lead anymore) isn't particulate so isn't too bad for you - but pencil shavings are (contain both graphite dust and wood dust!)
So the propellant in the can may cause cancer (methane/ethane/propane propellant), as may the actual silicone lubricant itself.
If you want a low-evaporative, non-toxic, low-viscosity, water repelling lubricant (one that you can actually clean with, get on your skin, drink and even breath the aerosol your lungs) try pure orange oil.
It looks like very thin oil like non-aerosol WD-40, or a sub-SAE 0 motor oil, and feels kind of like naptha, xylene or tolulene. It cleans as well as tolulene, which is incredible, as that stuff cleans most anything. Only acetone and MEK seem to clean better. You can also clean plastics with orange oil, which is impossible with acetone/mek/tolulene/xylene.
Don't let anyone tell you orange oil is "citric acid". Citric acid is water soluble, not organic soluble, and can't dissolve effectively in orange oil. Citric acid may dissolve into orange juice, maybe, but not orange oil.
To clean chemistry glass ware is a 2 step process.
#1 rinse with soap and water.
#2 rinse with acetone (nail polish remover)
if still dirty, repeat.
You can't replace step 2 with orange oil, because the orange oil won't evaporate off.
When All Else Fails!!!!
