Key Learning Points:
Post signs to remind personnel to wear personal protective equipment when working with or near UV sources.
You might take it for granted that everyone in the lab knows to protect their eyes and skin from laboratory UV sources, but accidents do occur.
A post-doc had been working in a univeristy laboratory for about 6 months. During that time he had used the lab’s transilluminator many times. On one occasion he forgot to use a UV face shield and received an exposure for a few seconds before he realized his mistake. Later that evening his eyes were hurting severely and were extremely red. He was sent to an ophthalmologist. Luckily, because his exposure was so brief there was no long-term damage to his eyes. There was also an incident where a student worked with a uv source wearing goggles rather than a face shield and ended up with a sunburn on all of the areas of the face that were unprotected.
Exposure to light from transilluminators, uv germicidal lamps and crosslinkers can cause severe eye damage and skin burns from very short exposures. Painful irritation of the cornea and the conjunctiva (the membrane connecting the eyeball with the inner eyelid) cause a feeling of "sand in the eye" and sensitivity to light. UV-B is most effective in causing this "sunburn of the eye". The eye is more sensitive than the skin to UV radiation. Symptoms appear from six to 24 hours after exposure and usually disappear within the following 48 hours. No permanent damage to the eye is expected unless a severe exposure has occurred. However, for persons who have had the lens of the eye removed (e.g. because of cataracts), the same exposure can cause permanent retinal damage, resulting in blindness.
UV exposure to the skin causes sunburn, with blistering and peeling in severe cases. Chronic or a severe skin exposure has been linked to premature skin aging, wrinkles and skin cancer.
What to do?
Protective Equipment: If there is any potential for the eyes and face to be exposed to UV radiation, a polycarbonate face shield stamped with the ANSI Z87.1-1989 UV certification must be worn to protect the eyes and face. Double glove using nitrile or latex gloves wear long-sleeved, closely-woven clothing or labcoat to protect hands and the body.
Signs and Labels: Areas where exposure to UV radiation is possible should have appropriate warning signs. Also, to help prevent eye and skin injuries, any equipment that emits UV radiation must be conspicuously labeled with a caution label with wording such as the following:
UV RADIATION HAZARD
USE ONLY WITH SHIELDING IN PLACE
PROTECT EYES AND SKIN FROM
EXPOSURE TO UV LIGHT
Use equipment safely: UV radiation should be contained or confined to a restricted area when practicable. The UV lamp in a Biological Safety Cabinet (BSC) should only be utilized when the room is not occupied. Some biological safety cabinets are equipped with an interlocking switch which deactivates the UV lamp when the fluorescent lamp is activated. Personnel should remember to ensure that the UV light is off prior to working at the cabinet. Placing labels that fluoresce when exposed to UV inside the biosafety cabinet should be considered if the UV lamp is not interlocked with the fluorescent lamp. Transilluminators and hand-held UV units are never to be used without the protective shield in place. Crosslinkers must not be used if the door safety interlocking mechanism is not working properly.
Key Learning Points:
Wear appropriate personal protective equipment.
- While attempting to visualize the results of a DNA digestion on a UV transiluminator, a new technician removed his face shield to get a closer look (the bands were indistinct), exposing his unproteced eyes for about a minute.
- A reseracher turns on a light box he has repaired to ascertain that it works properly. His eyes were exposed to UV light for about 30 seconds.
- A student works for fifteen miutes at a clean air bench while the UV is on. She was not wearing any eye protection.
Several hours after each of these incidents, these people experienced extreme discomfort as the result of "sunburned" corneas; the delay in the appearance of symptoms is common to this type of injury. Fortunately there were no long term effects in any of these incidents. Even the briefest exposure to UV light requires eye protection; a face shield is preferable to goggles for avoiding a sunburned face.
Not all shields protect against UV; when ordering, be sure that the item is specified by the manufacturer as providing protection at the wave length(s) used.