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In 2009 the International Agency for Research on Cancer (IARC) reassessed the carcinogenic evidence of the UV radiation, allocating both the whole UV range and the single UV bands in the Group 1. This means that UVA radiation by alone has an impact in terms of health risk greater than that assessed by existing protection guides (e.g. ICNIRP and ACGIH) and translated into current occupational exposure limits (especially for skin), taking also into account the growing biological data on UVA effects.
Methods
Current evidence of UVA biological effects are critically reviewed, together with occupational sources and situations where UVA exposure is significant. Exposure levels are discussed in relation to biological and epidemiological data.
Results
A number of biological effects are observed in animal cells and tissues exposed to UV radiation, including DNA damage, synthesis of reactive oxygen species, modulation of gene expression, interaction with chemical toxicants and carcinogens. So the carcinogenic risk of UVA radiation is more difficult and complex to evaluate with respect to what formerly believed. Also, a lot of artificial sources displays significant emission in the UVA range, including metal halide lamps, fluorescent lamps, arc devices, which may give a prolonged exposure. The sun itself may represent an important source of UVA not only outdoor but even indoor, when sunlight passes glass surface.
Discussion
Compliance with exposure limits for UVA radiation (alone or spectrally weighted with other UV bands) does not fully protect from carcinogenic or other long term effects. In authors’ opinion the reassessment of UVA radiation from group 2A to group 1 by IARC suggests, together with biological considerations and exposure levels typical of several occupational sources, that the risk assessment and protective measures for UVA exposure have to be performed increasing the level of protection of the exposed workers, with particular reference to skin protection.