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ANSES - French Agency for Food, Environmental and Occupational Health & Safety

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Updated on 21/09/2016

LED – light-emitting diodes

Health effects of lighting systems using light-emitting diodes (LEDs)

Keywords : Light, Lighting, LED (Light-emitting diode)

Light-emitting diodes (LEDs) are undergoing rapid technological and economic development as a new source of lighting. For many years, they were only used in electronics but are now found as integral parts of lighting systems. Currently, the most economic method of manufacturing LEDs is to combine a diode emitting at a short wavelength (in the blue region) with a yellow phosphor, thus generating white light. The intense wavelengths in the blue part of the spectrum of light emitted by LEDs, and the associated radiation intensity, raise the question of new health risks related to these sources of lighting. In this context, ANSES published a report on the health effects of LED-based lighting systems in October 2010, along with recommendations intended in particular to improve controls on marketing of these products.

In application of the European EuP Directive, which aims at improving the energy performance of certain everyday consumer goods, the European Commission Decision dated 18 March 2009 provides for gradual phasing out of the sale of high energy consumption lamps, over the period between 2009 and 2017. Over time, these products are to be replaced by compact fluorescent lamps (so-called energy-saving lamps), or other sources of lighting such as light-emitting diodes (LEDs) that are more energy efficient.

 

Light-emitting diodes (LEDs)

Light-emitting diodes used in lighting are undergoing rapid technological and economic development. For many years, they were used in electronics as a source of low-intensity monochromatic light for indicator lamps, but are now found as integral parts of lighting systems. 

The first LED for visible spectrum light was developed in 1962 and emitted light of extremely low intensity. The blue LED was invented in 1990, followed by the white diode, paving the way for important new applications, particularly in the areas of lighting, television screens and computer monitors. The first white LEDs then gradually reached the market and are now increasingly powerful, at levels of a few Watts to several dozen Watts. To produce white light, the most common method is to couple blue LEDs with yellow phosphors.

Lighting accounts for 10% of total electricity consumption in France, i.e. 350 kWh per household annually . LED systems consume considerably less energy than other types of lighting and have much longer lifespans.

LED technology, which has certain advantages compared to other types of lighting (energy efficiency, lifespan), is changing rapidly. It has a wide range of applications including public, domestic and commercial lighting, sport facilities, indicator lamps (toys, signposting, etc.), vehicle lighting, and therapeutic products (light therapy). However, the quality of the light emitted by these lamps (colour temperature , colour rendering index ) does not always provide the same level of performance as other sources of lighting.

The intense wavelengths in the blue part of the spectrum of light emitted by some LEDs, and the associated radiation intensity, raise the question of new health risks related to these sources of light.

In view of this situation, the Agency issued a formal internal request to assess the health effects of LED-based lighting systems.

 

The Agency’s activities

The expert appraisal carried out by ANSES showed that the risks of greatest concern, both in terms of the associated hazards and the probability of occurrence in a context of generalised use of LEDs, are related to the photochemical effects of blue light and glare. They are caused by: 

  • spectral imbalance (significant proportion of blue light in white LEDs);
  • high levels of radiance5 (high brightness density per surface unit emitted by these very small sources).

The photochemical risk is associated with blue light and the level of risk depends on the cumulative dose of blue light to which an individual is exposed. It is generally the result of low-intensity, repeated exposure over long periods of time. There is significant evidence of this risk. 

Populations that are particularly sensitive to this risk or that are highly exposed to blue light have been identified and include children, people with certain eye diseases and certain professional groups exposed to high-intensity light. 

There is currently little data on exposure to lighting, irrespective of whether the systems are based on LED or other light sources. As a result, ANSES was able to present risk assessments with supportive numerical data only for cases of exposure to blue light, in accordance with the principles described in Standard NF EN 62471. This standard on the photobiological safety of lamps proposes a classification in risk groups based on the maximum acceptable duration of exposure of the eye to light. 

Measurements of radiance6 indicate that certain commercially available LEDs that may potentially be used for domestic lighting, signposting and guide lights, belong to higher level risk groups than conventional lighting. 

Moreover, it was found that Standard NF EN 62 471 is not entirely suitable for LED-based lighting because exposure limits are not appropriate, measurement protocols are ambiguous, and certain sensitive populations are not taken into account. 

 

Risk of glare

In interior lighting, it is accepted that radiance above 10,000 cd/m2 7 is visually uncomfortable, regardless of the position of the lamps in the visual field. Particularly because of their small-scale light emission areas, LEDs may generate radiance 1000 times higher than these levels. The degree of direct radiation emanating from this type of source can therefore easily exceed the level of visual discomfort, far more so than so-called “conventional” sources of light such as halogens, and energy-saving lamps.

Concerning the risk of glare, there are a number of standards8 that provide guidelines on visual ergonomics and safety. In commercially available LED lighting systems, the LED lamps are often directly visible in order to avoid reducing the level of light generated. This may lead to non-compliance with standard requirements. 

 

Recommendations

On the basis of these findings, ANSES considered it necessary to restrict sales of LED light systems to the general public to those systems that do not involve higher risks associated with blue light than conventional lighting. Furthermore, ANSES recommends revision of Standard NF EN 62 471 on the photobiological safety of lamps to adapt it to the specific characteristics of LEDs, to take into account sensitive populations and high exposure groups including certain professions such as lighting installers, entertainment industry workers, etc. 

ANSES also recommends compliance with standards concerning visual comfort and ergonomics in the workplace and in the home. In this respect, ANSES recommends reduction of the radiance of LEDs, particularly via optical devices or suitable light fixtures in order to limit the risk of glare. 

With the aim of improving information to consumers, ANSES also recommends that labelling for lighting systems should clearly indicate information on light quality and the level of photobiological safety, in accordance with Standard NF EN 62 471. 

 

 

[1]Source: ADEME 2010.

[1]The colour temperature of white light is used to define its hue from more or less warm or cool; warm hue light "tends" toward yellow-orange and has a colour temperature below 3000 K. The higher the colour temperature, the cooler the hue.

[1] The colour rendering index (CRI) is an index ranging from 0 to 100 and defines the ability of a light source to reproduce the colours of the objects it illuminates, with respect to a reference source. Sunlight has a CRI of 100, while some low pressure sodium lamps (used in road tunnels for instance) have a CRI of 20. In shops, schools and offices, the CRI should always be higher than 80. 

2 CSTB: French Scientific and Technical Centre for Building. 

3 INRS: National Research and Safety Institute for the prevention of occupational accidents and diseases.

4 LNE: National Metrology Institute and Reference Laboratory for French Industry. 

5 Radiance (in cd/m2) quantifies the intensity of light per surface unit. It defines the impression of light perceived by an observer looking at the source. It is therefore a measure of glare.

6 - The measurements taken corresponded to energy radiance (depending on wavelength) adjusted to the level of phototoxicity of blue light. 

7 – This is a commonly cited value above which uncomfortable glare is experienced in indoor lighting. Standard NF X 35 103 concerning visual ergonomic principles applicable to workplace lighting indicates an acceptable radiance level of 2000 cd/m² for a small source present in the work surface.

8 – The standards referred to are: Standard NF X 35-103 "Ergonomics: Visual ergonomic principles applicable to workplace lighting"; NF EN 12464-1 "Workplace lighting – Part 1: Indoor workplaces"; NF EN 12464-2 "Workplace lighting – Part 2: Outdoor workplaces”; series of standards NF EN 13201 “Public lighting”; and NF EN 12193 “Lighting for sport facilities”.