Is a nurse allowed to wear earrings while she is on the job?

My wife is going to college to become a nurse. She has been told by friends that nurses aren't allowed to wear earrings while working. Is this true?

She currently has ten earrings in each ear.

I must admit that I've never noticed any of the nurses at my doctor's offices wearing earrings. In fact, the most I've seen on them is a watch.

It's a safety issue, that's all. Things happen beyond our foresight and jewelry creates a risk.

Depends what the employee hand book says where she will be working.
Most places probably don't allow excessive jewelry because it looks unprofessional.
Typically they are not allowed to wear earrings when dealing with patients, and very few places are going to let her wear 10 in each ear.
one stud may be ok, but not ten. if it is not in the way it is fine
it depends on where she works. maybe one or two in each ear, but probably not 10
Although piercing and tats are becoming more exceptable in the work place, every work place can effect their own rules around things like earrings and make them a condition of employment as long as they are universally applied.

There are three issues for Nurses:

1. Looking professional
2. Safety - Earrings can puncture the wearer or potentially a patient
3. Infection - although a low risk - having holes in your body does increase your risk of infection or giving a patient an infection.
Most nursing schools and hospitals have dress codes that limit attire, including jewelry. Earrings are usually OK, but many places will limit how many can be in each ear. Also, it is not a good idea to wear long dangly earrings as they can catch on things or be pulled by patients.