The Safety of UltraViolet (UV) Light Sources

1. The Safety ofUltraViolet (UV)Light Sources Professor Pete Cole Radiation & Laser Protection Adviser

2. UV Basics • UVC: 100 – 280nm • UVB: 280 – 315nm • UVA: 315 – 400nm

3. Arc Welding • Mercury Discharge Lamps • Germicidal Lamps • UV Curing Lamps • Fluorescent Lamps • Medical phototherapy (UVA & UVB) • Social exposures (sunbeds) • UV LEDs & lasers UV Sources • Artificial Sources

4. UV Sources Reactors Transilluminators Fume hoods Hand-held lamps UV Spectrometers

5. Further Potential Sources of UV • UV-producing systems can also be found in • Banking and commerce • Law enforcement • Entertainment facilities e.g. nightclubs • Materials inspection • Ultraviolet photography • Printing & electronics • Insect traps • Floodlighting in studios and on stage • General lighting

6. Germicidal Lamp Arc Welding Fluorescent Lamps Artificial UV Spectra

7. UV Sources - 2 • Natural Source – the Sun: • Occupational exposure (outdoor workers) • Social exposures (sunbathing)

8. Solar UV Spectrum

9. UVR & the SED • Solar skin exposure is often measured in ‘SEDs’ • SED = Standard Erythemal Dose • Usually taken as 100 J/m2 • Erythemally effective radiant exposure

10. SED & MED • MED = Minimum Erythemal Dose • Type 1 / 2 skin, MED = 1-3 SED • Type 3 / 4 skin, MED = 3-7 SED • Type 5 / 6 skin, MED = 7-12+ SED • Type 1 skin • 3 SED = erythema • 5-8 SED = moderate sunburn • 10+ SED = painful, blistering sunburn

11. Effects of UVR • Classified into two main types of effect: • Acute • Chronic • Two main organs affected by UVR • Eyes • Skin

12. UVR andthe Eye - 1 • Acute effects: • Photokeratitis / Photoconjunctivitis • Maximum sensitivity at 270nm • Threshold occurs at ~50J.m-2 • UVC germicidal lamps & arc welding sources need only a few seconds to induce the effect • Many unpleasant hours before it resolves

13. UVR and the Eye - 2 • Chronic Effects – Cataract? • UV radiation may well cause cataracts, but there are other known contributory factors • Age, diet, childhood dehydration • Genetic pre-disposition

14. UVR Skin Effects • Acute: • Erythema – reddening (sunburn) • Photodermatoses – rare conditions • Chronic: • Photoageing (wrinkling) • Freckles, Naevi & Keratoses – skin lesions • Cancer

15. UVB UVA Erythemal Action Spectrum • UV effects depend on wavelength • Known for erythema • ‘erythema action spectrum’ • The same for cancer?

16. UVR and Skin Cancer • Incidence of skin cancer rising • 90% increase in incidence over last 30 yrs • 60% increase in mortality in same period • Mortality rising 3-7% per year • Big problem in some countries • 2/3 of Australians will develop skin cancer

17. Squamous cell carcinoma Often this cancer appears as a firm red bump. Sometimes the tumour may feel scaly or bleed or develop a crust. This type may spread to nearby lymph nodes. Basal cell carcinoma Most common type, it appears as a small raised bump that has a smooth, pearly appearance. Basal cell carcinoma may spread to tissues around the cancer, but it usually does not spread to other parts of the body. Types of Skin Cancer Melanoma Most dangerous type. Normally dark and irregular shaped edges. Metastases are very often fatal.

18. UVR and Skin Cancer – 2 • Very complex relationship: • DNA • Absorbs UVB radiation • Sunburn, immune system, skin cancer • Hardly absorbs UVA • Other Chromophores • Absorb UVA to produce singlet oxygen and free radicals

19. UVR and Skin Cancer – 3 • Depends on Exposure Pattern • Chronic, cumulative exposure to UVA and/or UVB thought to be linked to squamous cell carcinoma • Acute intermittent exposure may be linked to malignant melanoma & basal cell carcinoma

20. UVR and Skin Cancer – 4 • Limited experimental data suggests that: • UV-induced immunosuppression increases skin cancer rates in exposed sites • Threshold for immunosuppression is lower than for erythema • There will be some DNA damage even if erythema is not present • Acute protection  long-term protection

21. UV Exposure Limits • Limits agreed by two bodies • ACGIH • American Conference of Governmental and Industrial Hygienists • ICNIRP • International Commission on Non-Ionising Radiation Protection

22. UV Exposure Limits - 2 • The ACGIH/ICNIRP limits relate to occupational (8-hour) exposures • They do not allow for long-term effects • They are based on the eye as the critical organ

23. 180 220 260 300 340 380 1 0.1 Rel.Spec.Eff. 0.01 0.001 0.0001 0.00001 Wavelength (nm) UVC UVB UVA UV Exposure Limits - 3 • IRPA/ICNIRP spectral weighting factors • Based on 30J.m-2 (= 3mJ.cm-2) effective to skin or eye at 270nm • Also must keep below 10,000 J.m-2 (= 1J.cm-2) unweighted • Based on exposure to lightly pigmented skin

24. UV Exposure Controls • Hierarchy of control measures • Engineering Controls • Contain and/or protect the source • Shielding – e.g. UV absorbent Perspex screens • Micro-switch interlocks – e.g. to sash or ‘night door’ • Exposure indication lights • Administrative Controls • Access controls – locked doors • Warning signs and/or lights • Local Rules • contingency plans – eye injury, fire, electric shock etc. • Personal Protection • Definitely should be the last resort • Eyes - full face visors, glasses, goggles, opaque shields • Skin – cover it with UV protective clothing – hands, wrist.

25. LOCAL RULES GOVERNING THE USE OF ULTRAVIOLET RADIATION Local Rules • Should be ‘local’ • Contact details of duty holders • Description of potential UV hazards e.g. equipment and/or areas • Safe operating procedures • Use of PPE • Contingency plan in the event of an untoward occurrence Downloadable from: www.liv.ac.uk/radiation/document.htm

26. Example General recommendations for cabinets, workstations, or fume-hoods containing UVC germicidal lamps: • Ensure that the unit is fitted with a Perspex or acrylic ‘viewing window’ that is suitably UVC protective (check in the operator’s manual or on the window’s markings). • If the window is a sash type, ensure that the sash is fully extended before the UVC is switched on. Ideally this should be interlocked to the UVC lamp(s), in which case the micro-switches should be tested periodically to ensure that they function correctly. Records of these tests (with dates) must be maintained. • If the unit incorporates a ‘night-door’ this must be in position before the UVC lamp is switched on. Comments regarding micro-switch interlocks made above are also applicable here.

27. Example (cont.) • If any units are used without the lamp being totally enclosed by appropriate shields, then operators MUST make use of suitable and sufficient PPE. This includes a full face visor and a combination of gloves and lab-coat to cover all areas of bare skin, e.g. hands, wrists and face. • For the full face visor, the filter must be compliant with BS EN 169:2002 (or its US equivalent) and be marked as such. It is suggested that the filter shade should have a scale number of at least ‘2-4’ which provides an Optical Density (OD) of approximately OD5.5 up to 313nm. Special systems of work must be adhered to in these cases which will involve restricting access to the lab for persons not using the appropriate PPE.

28. Warning Signsand Labels

29. UV Exposure Controls - 2 • Personal Protection • Protective Eyewear • Must protect against the source wavelengths • BS Sunglasses may protect against UVA & UVB but not necessarily UVC • Clothing to protect the skin • All surfaces exposed to the source to be covered • Ensure the clothing protects against the radiation being used

30. Personal Protection Equipment • For eye protection Filter should be marked with a scale number e.g. ‘2-4’ which provides an Optical Density (OD) ~ OD5.5 up to 313nm and ~ OD2 up to 365nm

31. Personal Protective Equipment • For skin protection • Notably face, hands, wrist, and lower sections of the arms • Tight woven cotton gloves or supple leather gauntlets may be OK for a limited exposure to UV • For higher exposures (e.g. arc welding) more substantial gloves may be required • The gloves should be designed to cover hand and wrist and overlap the sleeves • Heavy-duty, dark coloured, opaque fabric will block UV, Visible and IR radiation thus protecting the skin • Ultraviolet Protection Factor (UPF) of 40+ • Note: the combined effects of UV and ozone gas can lead to rapid degradation of glove materials. UPF for Typical Lab Gloves Khazova, M. et al, Rad. Prot. Dosimetry (2006), Vol. 121 (3), pp265 – 274.

32. UV Exposure • With a few exceptions, most people’s UV exposure (occupational or social) is solar • Solar exposure varies widely between groups and ages • Children receive 50% of lifetime UV by age 16

33. deg Lat UV Exposure Patterns • How much UV is available? • 2000 – 8000 MEDs / year • Dependent on latitude • And weather!

34. Occupational SunExposure • Outdoor workers receive 20-30% of available UV • Amounts to ~500 MEDs / year • Significant UV exposure • Protection needed

35. Solar UV Protection Methods • Behaviour • Shade • Clothing • Sunscreens

36. Non-Solar Exposures • Most other UV exposures derive from the use of sunbeds • Outputs from sunbeds vary • Depends on: • Age and condition of the tubes & bed • Type of tubes used: • UVA only • ‘sun-like’ tubes with UVA & UVB Arguments can be made for either option

37. Sunbeds • Should they be banned? • Everywhere or just from institutional facilities? • Does this put more sunbed use into the private sector? • Is this a good thing? • Surveys from Professor Harry Moseley in Dundee show sunbed outputs have doubled in 10 years

38. Ban on Sunbeds “Sunbed ban on under-18s demanded to halt rising death toll” The Times – 20th June 2009 “Celebs back teen sunbed ban” The Sun – 13th January 2010 “Under-18’s facing sunbed ban ‘in months’ over skin cancer fears” Daily Mail – 13th January 2010 “Bid for sunbed ban passes MP vote” BBC News – 12th March 2010 12th April 2010 – The Bill to protect children and teenagers from the dangers of sunbeds {in England & Wales} was passed by the House of Lords … in the run-up to the general election. Legislation to ban under-18 sunbed use in force in 2011

39. Danger: May Contain Nuts In UK ~ 50 persons/year die from nut allergies

40. Beneficial Effects of UVR • Yes, there are some! • Essential for Vitamin D synthesis • Still some debate about just how much is needed • Psychological effect of well-being • Little scientific evidence, although ß-endorphins in skin are induced by UVB • Treatment of psoriasis & other medical conditions

41. Beneficial Effects of UVR - 2 • Minority opinion believes that we actually need more sunlight exposure • Suggests current consensus in the UK for minimising exposure is wrong • More information at: www.healthresearchforum.org.uk • Look for ‘Sunlight Robbery’

42. EU AOR • The European Union’s Artificial Optical Radiation Directive • Control of AOR at Work Regulations 2010(in force from 27th April 2010) • Note that these only apply only to artificially-generated optical radiations • Specifically designed to exclude solar radiation exposures • Even if they constitute the major optical radiation hazard!

43. EU AOR - 2 • Key phrase in the Directive states • The employer, in the case of workers exposed to artificial sources of optical radiation, shall assess and, if necessary, measure and/or calculate the levels of exposure to optical radiation to which workers are likely to be exposed so that the measures needed to restrict exposure to the applicable limits can be identified and put into effect.

44. Risk Assessments • Must be documented for all non-trivial sources of AOR (including UVR) at work Identify hazards Who could be harmed Evaluate risks Record findings Significant hazard but is it a risk? Review / revise

45. Hand-Held UV Lamps in R&D B A C D

46. Hand-Held UV Lamps in R&D E F G H

47. EU AOR - 3 • You therefore have two choices • Ensure you have all the necessary data on your optical radiation sources to be able to make a competent risk assessment • Make adequate measurements yourself to achieve that objective

48. UV DETECTION • Two main types of detectors • Broadband devices • Usually measuring irradiance in mW.cm-2 • Spectroradiometers • Usually measuring spectral irradiance in µW.cm-2.nm-1 • Little in the way of personal dosimetry

49. Broadband UV Detectors • Use a silicon photodiode for UVA, • Or a vacuum photodiode for UVB/C • Covered by a filter • Covered by an input optic, usually designed to try and produce a ‘cosine response’ • Connected to a reader

50. Handheld devices (e.g. Solatell) Portable devices (e.g. Ocean Optics) Laboratory instruments (e.g. Bentham) Spectroradiometers • Three main types