Which are the safety recommendations for soldering?

The dangers of breathing soldering vapor has nothing to do with lead content of the solder. The vapor pressure of lead is so low at soldering temperatures that there just aren't that many lead molecules in the air.

The hazards of breathing soldering vapors is due to the flux getting vaporized, and sometimes parts of components emitting gasses when they get too hot. Lead solder is actually a little safer in that regard since soldering temperatures are lower. However, the biggest variable is the composition of the flux.

If you are worried about this, get something called a fume extractor. This is a little box with a fan and a filter. You place it right next to where you are soldering. It pulls the vapor from soldering away from you and thru its filter. By the time the vaporized stuff gets to the filter, it's no longer vaporized but a bunch of small particles. The filter removes these particles from the stream before exhausting it out the back.

If you want to sell your products in any civilised country you will be using lead free solder.

Creating lead vapour that you can breathe in with a soldering iron is impossible. It has a boiling point of 1749°C, and the melting point is only just below what you are soldering at. If you compare that to water, your solder is a block of ice, and when you are soldering you're melting the ice to tap water (or colder) temperature. You have to put the water in a kettle and heat it up to about 50% of its boiling point (50°C) to get it to start steaming. For lead that'd be around 850°C.

The fumes you see rising off the solder are not metal vapours, they are the fumes from the flux. Most common flux is contained in Rosin, a natural plant product, and it is the vaporisation of that which you see while soldering.

If you really must use leaded solder the main possibility of lead poisoning is through physical contact with the solder (getting lead on your hands) and then eating without washing your hands, thus transferring the lead to your food and then to your stomach.

Incidentally, countries that have banned the use of lead in solder have done so not because of safety or health reasons, but purely because of reclamation and recycling reasons.