There is no inherent health risk, assuming you don't spend you time chewing on the
And no particular need to worry. Selenium rectifiers are still made and used
in a range of specialist applications where silicon recitifers can't do the same job, and
selenium is also used in various photo-electric devices.
However, if you were
planning to have the unit refurbished or repaired at some point, then it would make sense
to replace the selenium rectifier with modern silicon diode(s) at that time. With things
like vintage radios and TV, restorers often disconnect the selenium rectifier but leave it
in situ to maintain the vintage look of the hardware (if it is visible).
selenium rectifier starts to fail in use, it normally overheats and produces a really
nasty garlic/onion sulphurous kind of smell that can't be ignored. The fumes are really
noxious but not life-threateningly toxic or carcinogenic in likely concentrations in a
room -- but you won't want to stay anywhere near the faulty gear anyway! Just switch it
off and take it outside (while holding your breath!). Come back in a week after the smell
has gone to collect it for repair.
It is usually fairly simple to replace selenium rectifiers with modern silicon diodes
given some electronics aptitude and a voltmeter, and you can find information on how to
work out what specification the selenium rectifier has on various websites.
Technical Editor, Sound On Sound