Possible radiator pipe oxidisation

Hoping for some advice about something I just noticed on a few of our radiators. Some of the pipes have what appears to be oxidisation (I'm guessing based on the turquoise colour) although there are no obvious leaks. The turquoise residue flakes off when touched but can't be totally cleaned easily by the looks of it.

I've attached pictures of the worst 3 radiators, all are situated on the left of the radiator, the opposite side to the temperature control.

Is this something I should be concerned about and need to get fixed? We have 2 young kids who might try to touch it which is an obvious concern if it poses any risk to their health.

Any advice much appreciated.

Get it looked at before it gets colder would be my advice.

what you have is called verdigris , usually because flux has been used during soldering and not cleaned off after but yours are all compression joints so no flux should have been anywhere near the joints, just get some wire wool and scrub them clean.

https://en.wikipedia.org/wiki/Verdigris

I had a plumber check this out when he was doing some other work and he reassured me that it was nothing to worry about and easy enough to clean off.

Thanks for people's replies.