Ultraviolet Radiation

Ultraviolet light (UV) is non-ionizing radiation that falls within the 180-400-nanometer wavelength region of the electromagnetic spectrum. Within this region UV rays are commonly broken down into the following three main sections:

Region* / Hazard Potential / Wavelength (nm):

  • UVA / Lowest / 315-400
  • UVB / Mid-High / 280-315
  • UVC / Highest / 100-280

*The International Commission on Illumination

For most people, the main source of UV exposure is the sun. Exposure from the sun is typically limited to the UVA region, since the earth’s atmosphere protects us from the more harmful UVC and 97-99% of the UVB region. As result by limiting our exposure time and/or the use of sunscreen lotions are usually an easy and effective method for controlling overexposure to UV radiation.

However, additional precautions should be taken when working in a laboratory. Common lab equipment can generate concentrated UV radiation in all three regions. Below are examples of common sources found at Tufts University that can generate varying levels of UV radiation.

Common Sources:

UV Light Box/UV Transilluminator*- Commonly used for visualizing nucleic acids, this “box-shape” piece of equipment contains an ultraviolet lamp. The clear, glass face allows the light to illuminate the gel while potentially exposing the user. To reduce risk of injury, most models come equipped with a shield to filter excess light. For older models, there are various types of shields that can be attached that provide equal protection. For specifics contact the manufacturer or the EH&S Department.

UV Crosslinker- Used to attach nucleic acids to a surface or membrane following blotting procedures. Crosslinkers are equipped with door safety interlocks, which similar to a household microwave, prevent operation of the machine when the door is open. If the interlock system is not functioning correctly, please refrain from using and contact the manufacturer.

Germicidal Lamps – Used for disinfecting the interior surfaces of a biosafety cabinet before and after use. Avoid working in or around the safety cabinet while germicidal lamp is on. If possible close sash for extra protection.

*Note: Though most models are stationary, there are hand held devices.

UV Radiation Generating Equipment

  • Bio Safety Cabinet
  • Spectrometer
  • Crosslinker
  • Spectrophotometer
  • Finnigan Surveyor PDA Detector
  • UV Gel Dock
  • Fluorescence Detector
  • UV Microscopes
  • Fluorometer
  • UV Stratalinker
  • HPLC Machines
  • UV Transilluminator
  • Image Station
  • UV-VIS Detector
  • Laminar Flow Hoods
  • Waters 486 Tunable Absorbance Detector
  • Mineralight (Handheld)

Health Risks

Unfortunately, overexposure to UV radiation often times has no immediate warning signs. Symptoms of overexposure, including different stages of erythema (sunburn) or photokeratitis (welder’s flash) typically appear 4-24 hours after an exposure has occurred.

  • Skin- UV radiation can initiate erythema within exposed skin. This “sunburn” consisting of “redness” ulceration varies in severity, and can occur from only a few seconds of exposure. Symptoms can also vary due to one’s genetic makeup. Pale to fair skin individuals are more susceptible to burns. In addition various medications (i.e. birth control) can exaggerate symptoms. Chronic exposure to UV radiation has been linked to premature skin aging, wrinkles and skin cancer. Note: the neck and wrist areas are commonly left unprotected.
  • Eye- UV radiation exposure can damage the cornea, the outer protection coating of the eye. Photokeratitis is a painful inflammation of the eye caused by UV radiation-induced lesions on the cornea. Symptoms include a “sand like” feeling in the eye last can last several days. Chronic exposures to short term UV radiation can lead to the formation of cataracts.

Precautionary Measures

Engineering Controls:

  • Containment/Location- Having equipment located in a separate room, alcove or low traffic area of a lab is ideal. To avoid exposure to other employees, avoid placing equipment in the direct vicinity of desk areas and or other equipment. The use of shields, curtains, UVR absorbing glass, or plastic is recommended.
  • Interlocks- Some equipment comes with interlock devices. Interlock devices prevents the operation of the equipment without use of safety equipment. Interlocks should not be tampered with. They should also be replaced or repaired when defective.
  • Eliminating Reflection- Many surfaces, especially those that are shiny, easily reflect UVR. To reduce the intensity of reflections, painting problematic surfaces with non-UVR-reflective material is effective.

Administrative Controls:

  • Training-As in any activity within a lab setting, personnel should be trained and familiarized with the correct/safe way of using equipment. The manufacturer (user’s guide) of the equipment and/or EH&S can assist employees on safe operating procedures.

At a minimum lab personnel should be familiar with the following items when working with or around UV light:

  • UV Light Producing Equipment
  • Warning Signs
  • Protective Equipment
  • Symptoms

Access- Access should be limited to employees who are directly working with equipment. In addition, limiting the distance and time an employee is working with or around UVR producing equipment significantly minimizes the risk for injury.

Warning Signs and Labels-Many incidents of overexposure to UV radiation are the result of employees not being aware of the hazards associated with UV producing equipment. To avoid employees from being unknowingly overexposed, equipment should contain the following hazard label and/or one similar

Labels are available from EH&S at x6-3615

Personnel Protective Equipment (PPE):

Eyeglasses-Should be ANSI-Z87 rated and provide protection from side exposure via a side lens or “wrap around” lens. Normal eye protection and/or prescription glasses provide little to no protection! To determine if eye protection is rated for UV safety, contact the manufacturer or look for the Z 87.1 label on the lens.

Face Shield-Should be worn in addition to eyeglasses or goggles.

Gloves-At a minimum nitrile gloves are recommended, however glove should protect the employee not only from UV light but from the hazard from the activity being performed.

Lab Coat-Employees should cover exposed skin. Lab coats, along with proper lab attire should be worn.