... or better yet, if you want reliable soldered joints (and who doesn't) carry on using 60/40.
I've done the Risk Assessment (many years ago), and can assure anyone interested that the risks due to poor quality joints (dry, whiskered, and what-have-you) far out-weigh any minuscule risks either to yourself or to the planet (whether real or imagined).
Meanwhile, I agree that keeping your iron clean and bright is good practice. Use the right amount of flux where necessary, and keep the iron at the right temperature. When removing components, always use solder braid, and be wary about jumping straight in with "solder suckers" - as they have been known to rip up circuit tracks with apparent ease!
There are lots of nice "how to solder" videos on YouTube, as well as others that offer good advice about not
using lead-free (together with handy tips such as:- "don't lick the circuit board")! And lastly, always remove flux residue after soldering (that is, clean the board); isopropyl alcohol is good (but try to resist drinking it). And surely I don't need to remind a biomed audience to:- "wash your hands" (often).