Light Emitting Diodes (LEDs) are an energy efficient and mercury-free source of lighting, they also can provide fabulously stylish lighting for the home and factory. Not only that, but increasingly they are being used in products such as laptop computers to provide better lit screen displays.
Companies and individuals that are keen to improve their sustainability are turning to this technology for its energy gains, but could society be in danger of being too keen to snap up this new technology? Have all the necessary tests and assessments been made to ensure that new problems are created by this invention. After all, there have been plenty of new technologies, seen at the time as ideal, but only later found to be flawed.
For example, when PCBs were used as cooling oil for transformers in the 1950s, nobody thought to find out about the fate of leaked PCBs, and now the whole of the world’s oceans contain, in every cubic metre, some of this dangerous non degradable, and bio-accumulating substance
Like many other electronic goods it has been found that they could have some negative environmental impacts, according to research. The US study (Potential Environmental Impacts of Light-Emitting Diodes (LEDs): Metallic Resources, Toxicity and Hazardous Waste Classification. Environmental Science & Technology) describes how they tested a selection of LEDs and found that they should be classified as hazardous waste owing to levels of lead, copper, nickel and silver present. They also contain some rare earth metals which could further increase pressure on natural resources. Arsenic may also be present in small quantities.
As the use of LEDs increases, so will the tonnages found in waste, and concerns are therefore beginning to be raised about how to manage them at the end-of-their-lives, with worries that they could in the end turn out to have similar negative environmental impacts to other electronic waste types, such as computers and mobile phones.
To find out whether these fears were correct the study applied standard toxicity leaching tests to samples to examine whether 9 different LEDs bought in the US should be classified as hazardous waste according to the definition of hazardous waste applied by US federal, and Californian, regulations.
The conclusion was that the LEDs included high levels of iron, copper and nickel. Gold and silver were also present at lower concentrations.
The result being that under Californian regulations, the LEDs tested would have to be classified as hazardous waste. All LEDs tested, except the dimmer (low intensity) yellow LED, exceeded California’s limits for at least one metal – copper, lead, nickel or silver. For example, levels of copper in the LEDs were found to be up to 3892 mg per kg, whereas the California limit is 2500mg per kg. Lead levels reached 8103 mg per kg, compared to the limit of 1000 mg per kg.
Looking also at federal regulations, the position was that just one limit was exceeded. That was that of lead concentration in landfills from low intensity red LEDs, which was 186 mg per litre (the threshold is 5 mg per litre).
Others have found difficulties with “red light intensity LEDs” which were the only ones that would not be compliant with the EU’s RoHS Directive1, which sets a lead limit of 0.1 per cent per 1000 ppm of homogenous material.
We are talking of very small amounts of silver and gold had the greatest implications for depleting resources.
Copper and nickel are of particular concern because of potential to harm ecosystems, if leached from landfill, suggesting that all LEDs have potential to damage ecosystems as they all contain these metals.
Of all the variants of LEDs investigated, the white LED, used in general lighting, appeared to be the least harmful because it contained less copper and did not contain arsenic or lead.