In Focus

Efficient substitution

Restricting hazardous substances in electrical and electronic equipment

Electrical and electronic equipment contain substances which pose a risk to human health and the environment but which, from a technical perspective, have long been regarded as essential components in the manufacture of products such as printed circuit boards (PCBs), compact fluorescent lamps and fluorescent tubes. Since 2006, the EU's Restriction of Hazardous Substances (RoHS) Directive has limited the use of six of these substances: lead, mercury, cadmium, hexavalent chromium and flame retardants polybrominated biphenyls (PBB) and polybrominated diphenyl ethers (PBDE). In July 2019, four phthalates, which are used as softening agents in plastics, will be added to the list of restricted substances. However, the RoHS Directive permits time-limited exemptions for these substances in certain applications. Since 2006, the Oeko-Institut has conducted studies on behalf of the European Commission, reviewing more than 100 exemption requests in order to determine whether they were justified and complied with the relevant criteria. Recommendations were then submitted to the European Commission.

Exemptions permitting the use of substances listed in the RoHS Directive may only be granted if certain criteria are met. “The general criteria which must be met for an exemption to be granted are that substitution is not possible from a scientific and technical point of view, or if there is no permitted alternative, or if the negative environmental or health impacts caused by substitution are likely to outweigh the human and environmental benefits of the substitution,” says Yifaat Baron, Senior Researcher at the Oeko-Institut. “However, the exemptions are time-limited and must be renewed at regular intervals.” In contrast to the four heavy metals, no exemptions were requested by industry for the brominated flame retardants (BFRs) mentioned above. “In these instances, substitution was the easier option, but that’s not to say that it is sustainable,” says Yifaat Baron. “In some groups – as is the case here – the substances differ only slightly, in terms of their structure, from the banned equivalents, so they may be equally hazardous to human health and the environment.”

Over the past decade and more, researchers at the Oeko-Institut have been continuously reviewing and assessing exemption requests, evaluating the available data and analysing information provided by stakeholders or applicants. “With its criteria, the Directive certainly offers scope to assess whether or not substitution is already possible for certain substances from a scientific and technical point of view,” says Yifaat Baron. “However, we do rely heavily on applicants submitting adequate data and stakeholders taking an active role in the process.” One often-heard argument is that possible substitutes do not possess all the technical properties of the original substance, such as reliability. To ensure that this aspect is adequately assessed, generally applicable rules on testing are required in order to measure performance. “The example of cadmium in flatscreens shows how important it is to have these rules in place.”


One of the new flatscreen technologies is based on quantum dots, used to achieve high-quality colour performance in televisions and monitors but containing cadmium, a highly toxic and carcinogenic substance. As part of its assessment of the relevant exemption request, the Oeko-Institut looked at the information provided by the applicants and competitors engaged in the development of similar technologies which do not contain cadmium. “One particular challenge was that different measurement standards exist for the assessment of cadmium quantum dot technology and the alternatives,” says Yifaat Baron. “Energy consumption is determined not only by the technology itself but also by the degree of energy efficiency in the electronics required for the operation of the screens.” So while some models available on the market may in theory offer a technological advantage, this is not always achieved in practice; indeed, the screens may consume more energy than other comparable devices. “The information from the applicants and from competitors did not allow any firm conclusions to be drawn about total energy consumption,” Yifaat Baron explains. The study was therefore based on a comparison of the technologies and current standards for the assessment of image quality. On that basis, the researchers recommended an exemption allowing the use of cadmium quantum dots for a period of three years. “From a toxicological perspective, the alternative substances currently offer no significant benefits or disadvantages,” says Yifaat Baron. “The key factor, however, was the much higher energy consumption of cadmium-free screens – by around 20 per cent – found in the comparison of the technologies.” The short exemption period recommended by the researchers has one clear goal: it is specifically intended to support environmentally-oriented innovations in display technology which avoid the use of hazardous substances while achieving high-quality colour performance.


The Oeko-Institut’s researcher regards the RoHS Directive as a valuable and effective tool. “In the years after the Directive’s entry into force in the EU, mercury content in lamps, for example, was reduced by around 75 per cent to 2.86 tonnes in 2013.” However, the number of exemptions listed in the relevant Annex to the Directive increased at the same time. “But that is positive, as the current exemptions – unlike the initial phase after the Directive entered into force – are much more specific and the use of the restricted substances is now permitted only in certain very clearly defined applications,” says Yifaat Baron. “A larger number of exemptions means that the problematical substances are being used in diminishing quantities and in fewer applications.” These are mainly applications in which substitution is more complicated or no alternatives are available. As these applications tend not to involve mass-produced items, there is less motivation to find a substitute. “It may be beneficial, in such cases, to provide targeted support for the search for substitutes through research funding,” notes Baron.

In her view, it would also be useful to compare the effectiveness and efficiency of various mechanisms such as the RoHS, the European chemicals regulation REACH and the EU Ecolabel. “We should look at how these various frameworks are being applied in practice,” says Yifaat Baron. “It may not be necessary to harmonise the directives, but I think we can learn how to improve the work on restricting and finding substitutes for hazardous substances and see how certain aspects can be better addressed together.“