You can always use lead free solder. Just don't expect as good a joint! Although, vintage gear like pin tables will have leaded solder, and you cannot mix the two. (Doing so gives even worse results than the lead-free variety on its own)
I think we need to keep these things in perspective. There is a whole industry centered around hyping 'pollution' risks completely out of proportion. For example, many medical facilities are no longer allowed to use mercury thermometers because if anyone were to drop one on the floor they would literally have to call out a response team in hazmat suits to 'decontaminate' the place. Which, is a crazy overreaction. Mercury is somewhat toxic, but not THAT toxic.
Most 'heavy metals' are moderately toxic if ingested, but some commonsense needs to be applied over this. The main risk is from inhaling vapour or ingesting soluble salts, the metallic form of most being relatively insoluble. Mercury gives off vapour at temperatures not much above room temp, but lead's boiling point of 1749 °C is too high for any significant vapour to be released at soldering temperatures of 300 °C or so.
In the era of top hats, hatters were using mercury vapour (in the open air of the room) to put a sheen on the cloth. When you think about the levels they were exposing themselves to, it's hardly surprising they developed brain damage.
The Romans actually used a lead salt to sweeten wine.
Seemingly they didn't know of lead's toxicity, or that soluble salts are the most poisonous form of the substance. It's fairly obvious that they didn't drop down like flies from drinking it, or else the connection would have been made and the practice stopped. Though, it has been suggested that some of the behaviours shown by Roman emperors was symptomatic of lead poisoning. I think this underlines the fact that it IS toxic, but that minute levels are not going to be an issue.
Victorian houses used lead plumbing, as did the Romans. Seemingly this doesn't present any health risk so long as the water isn't acidic.
As for soldering, these days I'm careful not to lick my fingers or handle food without washing my hands first. I think that's sensible. I also use a fume extractor, but that's mainly because I'm sensitive to the rosin smoke. I use leaded solder unless I'm repairing kit that has lead-free in it.
HTH.