Balance between Health Risks and Benefits for Outdoor Workers Exposed to Solar Radiation: An Overview on the Role of Near Infrared Radiation Alone and in Combination with Other Solar Spectral Bands.
Level 5 - mechanism / opinion, no new human data
Narrative review synthesizing in vitro mechanistic data without new human clinical or epidemiological data.
PubMed 32093162 · doi:10.3390/ijerph17041357
What was done
This narrative review synthesized evidence on the biological effects of solar near-infrared radiation (infrared A or IRA, comprising over 40% of the solar spectrum), alone and combined with ultraviolet (UVA, UVB) and visible light, to evaluate health implications for occupationally exposed outdoor workers.
What was found
The abstract reports no numerical data or effect sizes. It notes that IRA penetrates to subcutaneous tissue and the retina, induces cellular reactive oxygen species (ROS) production, alters the mitochondrial respiratory chain, and modulates gene expression and metabolic pathways through thermal and photochemical mechanisms. Cellular pathways overlap partly with UV-mediated pathways. The review notes few in vivo studies and zero epidemiological datasets addressing full solar spectrum occupational exposures.
Why it matters
Occupational safety standards currently focus almost exclusively on ultraviolet radiation. Accounting for near-infrared radiation may refine occupational risk assessment, protective equipment recommendations, and individual exposome characterization.
Limits
The paper relies almost exclusively on in vitro mechanistic studies. The abstract explicitly highlights an absence of epidemiological data and a paucity of in vivo studies, precluding quantitative clinical risk-benefit determinations in human populations.
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- context Plant foliage reflects near-infrared light that penetrates the human body surface and stimulates mitochondrial function.