The tiny amount of lead involved is very unlikely to be harmful. You could probably safely eat the amount of solder used to assemble that board. I do think thi

The tiny amount of lead involved is very unlikely to be harmful. You could probably safely eat the amount of solder used to assemble that board. I do think think a case is necessary though, as those SOIC packages will not last long in pocket with keys before they are ripped off the PCB.