The dispersion of hazardous substancesFootnote 1 in a circular economy has previously been highlighted as an anomaly, as a consequence of inferior, uncontrolled, and immoral recycling. For example, when electrical waste is exported from the global north to the south where plastic and rubber are burned to quickly access the precious metals, with risk to human health and the environment (Man et al. 2013).

However, it is less noticed that also formal, or to be more precise, industrial recycling and reuse can increase the distribution, dilution and accumulation of hazardous substances (Johansson et al. 2020). Researchers and NGOs have uncovered the unintentional recycling of hazardous substances into new articles. Elevated levels of hazardous substances from recycling have been identified in, for example, consumer articles such as toys (Chen et al. 2009; DiGangi and Strakova 2015; Guzzonato et al. 2017), kitchen utensils (Samsonek and Puype 2013; Turner and Filella 2017; Kuang et al. 2018), food packaging (Jurek and Leitner 2017; Abdallah et al. 2018; Geueke et al. 2018), and industrial products such as fertilizers (Johansson and Krook 2021).

But while the dispersion of hazardous substances through recycling has been documented, at least for some specific products and substances, it is still unclear how the problem of hazardous substances is, and should be, handled in a circular economy (cf. Johansson 2021). Previous studies on the governance of hazardous substances in a circular economy have primarily focused on isolated issues such as food contact materials (De Tandt et al. 2021), risk assessments (Bodar et al. 2018; Wang and Hellweg 2021), the sectoral separation of policies (Alaranta and Turunen 2021), threshold limits (Johansson and Krook 2021), and communication (Friege et al. 2021). This short paper aims to highlight specific complexities of a circular economy from the aspects of its application to regulation of hazardous substances. The paper concludes by proposing an alternative approach to regulating hazardous substances in a circular economy based on Ulrich Beck's (1992) advocacy of reflexivity.

Hazardous substances in a circular economy

The effort to keep materials in the economy as long as possible may keep hazardous substances that should really be phased out in the material loops, as legacy substances (Bodar et al. 2018). For example, antiques such as mirrors and vases may contain mercury, while plastics may contain “forever chemicals” such as polychlorinated biphenyl (PCBs).

In addition, different types of materials and substances are usually mixed during waste collection. For example, even in the separate collection of plastic waste, different types of polymers from different products and time-periods are typically mixed. Modern recycling plants can separate some polymers from each other. However, depending on the use, different additives are added to the plastic such as plasticizers and flame retardants that make even products made of the same polymers substantially different. As a result, secondary plastics tend to be significantly more contaminated than their virgin counterpart (Groh et al. 2019).

When the waste-based resources shall be included in new products, new additives may also be added, adapted for the specific product. In sum, the presence of hazardous substances are higher and more unpredictable in products based on recycled materials, compared to products made of conventional resources from nature. Formal and industrialized circulation may thus dilute, disperse and accumulate hazardous substances.

The regulation of hazardous substances

Hazardous substances are partly regulated prospectively, upstream, through control mechanisms and prohibition. For example, some chemicals such as persistent organic pollutants (POPs) and elements such as mercury are completely or partially banned in products through multilateral agreements such as the Stockholm Convention (2001) and the Minamata Convention (2013), respectively. By limiting the introduction of hazardous substances in products upstream, the potential occurrence of hazards when the material becomes waste downstream is potentially affected.

In the EU, the use of hazardous substances in products is controlled by various regulations that require registration, labelling, evaluations and safe handling (EU 2006, 2008). Industry must demonstrate safety for the European Chemical Agency (ECHA) before the product can be placed on the market, according to EU chemicals regulation, Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) (EU 2006). The rules differ for substances that are included in mixtures, such as washing powder and substances that are included in products. All substances, manufactured or imported into the EU (2006:article 6 (paragraph 1)), more than one tonne per year need to be registered. For products, only substances of very high concern (SVHC) imported or used in products more than 1 tonne per year, which exceeds 0.1% by weight of a product, are regulated (EU 2006:7(2)).

Substances with hazardous propertiesFootnote 2 may be listed as substances of very high concern on the candidate list (ECHA 2022a) for possible inclusion in the authorization list (EU 2006:XIV). If a substance is listed on the candidate list, a notification to ECHA, information to actors downstream, and labelling is required. If listed on the authorization list, permission by ECHA (2022b) is needed before the substances can be released on the market.

SVHC can also be listed in Annex XVII to REACH (EU 2006) and will thereby become restricted by a total ban or threshold limits (ECHA 2022c), according to what concentrations are considered as acceptable risks. The limitations usually vary depending on how the substance is used. For example, for cadmium, plastic articles may contain a maximum of 0.01% cd, painted layers on products 0.1% cd, while the use of cadmium is prohibited in metallic layers.

Hazardous substances are also regulated in the actual use of the waste, downstream, i.e. when the waste-based material is given a new opportunity as a resource, and shall be circulated. Mainly by stating threshold limits for hazardous substances. The Stockholm Convention (2001) contains limits for POPs that determine when waste is allowed to be recycled. For example, the limit for PCBs is at 50 mg/kg mass. If the concentration of hazardous substances is below the limits, it may be circulated, otherwise it should be discarded.

The non-regulation of hazardous substances

The European Union has arguably the strictest legislation of hazardous substances in the world (EU 2020b). Approximately 26,000 substances have been registered in the region (ECHA 2022d). However, given that more than 200,000 substances are estimated to be present in the European economy (ECHA 2022e), only about 15% of all substances are registered. Many substances remain unregistered since EU’s chemical legislation, REACH, requires registration only when more than 1 tonne per year of a specific substance is manufactured or imported (EU 2006:6(1)). Thereby, direct imports for personal use are generally exempted from REACH. Besides, if a new substance is used in a product, registration is not needed. This means that many substances end up uncontrolled in the waste stream.

For substances to be regulated in products, it needs to be classified as a SVHC. However, only a few substances of the 26,000 registered are classified as SVHC and thus regulated in products. Eurostat (2021) estimates that about 75% of the substances in the economy by volume are hazardous. About 220 substances are listed in the candidate list (ECHA 2022a), but with no quantitative restrictions. Of these 220 substances, about 60 are listed in the authorisation list and require permission (ECHA 2022b). About 70 different substances are listed in Annex XVII and thus banned or restricted (ECHA 2022c). In total,Footnote 3 only a small percentage of all substances are thus restricted or banned upstream.

EU’s chemical legislation and the obligation to provide information ceases when products become waste (EU 2006:2(2); EU 2018). This means, for example, that producers do not have to inform recyclers about the presence of SVHC in their discarded products. Wasted products containing both unregulated and regulated hazardous substances thus reach recycling actors blindly. When the waste is recycled into a new product, the chemicals legislation becomes applicable again (EU 2006:1(2)). But since the recyclers who receive the waste lack information about the hazardous content, information cannot be passed on to the manufacturers that shall produce the waste-based products. Hence, elevated levels of hazardous substances have repeatedly been identified in waste-based plastic products with a risk of exposure such as toys and food contact articles (Abdallah et al. 2018; Geueke et al. 2018; Chen et al. 2009), with the consequence of increased risk of leaching (Greassimidou et al. 2022).

Elevated levels of SVHC are, therefore, partially permitted in circulated products. For example, according to annex XVII in REACH (EU 2006), the threshold limit for cadmium in new plastics is 0.01% cd, while the limit for recycled plastic is 0.1%, and thus 10 times higher. In the Stockholm Convention (2001:4(3)) there are also stated possibilities for countries to exempt products from the regulation of POPs based on recycled material.

The legislation of chemicals in the EU (2006:1(1)) covers, indeed, the reuse and sharing of old products on the market. But in practice, second-hand shops as well as households that share or resell old products typically lack information about the products' content of hazardous substances. This means that old products are generally distributed unrestrained to new owners. In addition, the legislation contains exemptions for reuse and repairs. For example, old mercury thermometers placed on the market before 1957 are allowed to be resold (EU 2006:XVII). In addition, new spare parts for repairing electrical products, placed on the market before 2006, are allowed to contain substances that are restricted or prohibited (EU 2011:4(4)).

How the European Union addresses the gaps

To reduce the dilution, dispersion and accumulation of hazardous substances in a circular economy, the preferred strategy is to avoid introducing such substances to the economy in the first place, expressed as “toxic free material cycles” (EU 2020b:5) and “non-toxic from the start” (KEMI 2020:1).

However, limiting the introduction of hazardous substances upstream is difficult, as substances typically fulfil an important economic and technical function. For example, POPs such as flame retardants reduce the risk of fire, while additives in plastics improve the flexibility and durability. Chemical substances are also considered essential for triggering innovation and thus economic growth (Goldenman et al. 2017). Consequently, in the discussions on a forthcoming ban on persistent Per- and polyfluoroalkyl substances (PFAS) substances in the EU (2020b:14) used, for example, extensively in plastics, only the substances “rarely used” and “not necessary for the society” are to be considered (KEMI 2021).

This means that the responsibility of controlling hazardous substances is in practice directed to the downstream regulation and actors, i.e. a focus post consumption. The EU intends, for example, to improve the flow of information through the whole value chain by introducing a database (EU 2020b:6), investing in decontamination techniques such as chemical recycling (EU 2020b:6), and developing threshold limits (EU 2020a:14) that determine what may and may not be circulated.

However, the database covers only the substances classified as SVHC. Besides, the 6000 different chemicals (Aurisano et al. 2021) that may be present in plastics will be a major challenge for plastic recyclers, regardless of whether the composition of individual products can be identified (Friege et al. 2021). In addition, decontamination processes are both ecologically and economically costly. For example, chemical recycling that can handle heterogeneous material flows by separating molecules requires so much energy, resources and chemicals that conventional production based on natural materials may be preferable (Davidson et al. 2021).

Threshold limits indicate the amount of hazardous substances that can be dispersed without adverse effects on health and nature. As threshold limits are developed through modelling, they can appear to be accurate, safe and scientifically sound. However, to keep the cost of sampling down, only a few substances are typically regulated, while others are excluded (Johansson and Krook 2021). In addition, the threshold limits for the same type of waste and substance differ between countries (Johansson and Krook 2021). This indicates that there are different types of choices and starting points in the modelling process that affect its outcome, i.e. the threshold limits.

Towards a reflexive circular economy

The European regulatory regime fails to control hazardous substances in a circular economy. Few substances are regulated. The actors downstream have been given an idealistic responsibility to both neutralize the myriad of hazards that are too important to be banned and at the same time increase circulation. Products based on recycled materials, therefore, end up with elevated levels of hazardous substances, partly in accordance with the regulation. Thereby, the regulatory regime may create an illusion of control, which helps to maintain the perception of recycled products as sustainable.

To increase the institutional capacity to limit hazardous substances in a circular economy, the focus needs first and foremost to shift from the current win–win paradigm of the circular economy (e.g. EU 2020a), to become more reflexive (Beck 1992:234). A reflexive circular economy is open to self-criticism, and thus also considers side effects, problems, tensions, and losers that arise due to a circular economy.

Hazardous substances are a good example of why reflexivity is important in a circular economy. The regulation of hazardous substances in a circular economy can create a policy conflict, where both goals cannot be met in tandem. Strict regulation of hazardous substances can decrease circulation with its positive effects such as reducing litter, climate emissions and dependence on fossil fuels and minerals. A liberal or unrestricted circulation, on the other hand, may increase its negative side effects such as the dispersion of hazardous substances.

If both goals shall be met simultaneously, other policy conflicts may arise. Regulating hazardous substances upstream can limit, for example, product innovation and functionality. Decontaminating material flows downstream, which is technically more difficult, but politically more viable (EU 2020a, b), will, for example, increase the energy consumption (Davidson et al. 2021).

The implementation of a circular economy will thus require that difficult political choices are to be made, which will create winners and losers (Kovacic et al. 2020; Corvellec et al. 2022). These choices and tensions need to be made visible and discussed. For example, by whom and how have the benefits of recycling been considered, so that the cadmium content in recycled plastic is allowed to be precisely 10 times higher than newly produced plastic?

Allowing 10 times higher levels of cadmium in recycled plastic than in new, virgin plastic may be correct, given the benefits of recycling. But to determine its correctness, the trade-offs must be made visible, communicated and discussed. As for now, the complex balancing between the positive and negative effects of a circular economy disappears behind the threshold limits.

The complexities of a circular economy need to be better integrated into the regulatory regime. For example, risk assessments should consider that materials and hazardous substances in a circular economy will not necessarily fulfil one purpose, but may flow through different uses, sometimes unexpected, with varying exposures (Bodar et al. 2018; Wang and Hellweg 2021). In other words, for hazardous substances in products to be released on the market, safe circulation through multiple uses should be assured.

Such requirements would not only reverse the information flow, but also completely change the starting point for the management of hazardous substances in a circular economy (cf. EU 2020b). It would change from producers sharing information on some substances through the value chain so that decontamination processes can be developed accordingly. It would shift to a situation where producers instead adapt product development, and the inclusion of substances, according to the circulation and decontamination processes that are practically available and economically viable downstream. Such reflexivity may constrain product development, but would on the other hand encourage system innovation, rather than the conventional focus of innovation on isolated parts of the value chain.

Furthermore, one of the main challenges for a circular economy is the lack of interest from customers to shift to secondary materials and products from the conventional, stable, predictable materials from nature (EU 2020a). For this reason, customers, users, waste pickers and other actors who will have to bear the consequences of a circular economy need to be invited into political processes. Unlike those actors who create waste, users have an interest in the purity of the materials. By inviting this group of actors to the political process, the ambition of reducing the dispersion of hazardous substances can be represented in a circular economy.