1. The precautionary principle in the EU waste and chemicals legislation and case law

The precautionary principle is codified in Article 191 of the Treaty on the Functioning of the European Union (TFEU) as one of the guiding principles of the environmental policy of the EU. The precautionary principle is also explicitly mentioned as an underpinning principle of the regulatory regimes or specific obligations in many sector-specific regulations and directives. Among others, the Waste Framework Directive (2008/98/EC; WFD)Footnote ²⁴ and the REACH Regulation ((EC) No 1907/2006; REACH),Footnote ²⁵ which are the two focal pieces of legislation in the regulation of material circulation and hazardous chemicals, are based on the precautionary principle.

Article 1(3) of REACH provides that:

Moreover, according to recital 9 of REACH, the reason underlying the commencement of the regulatory reform of the European chemicals regulation that eventually led to the adoption of REACH was “the need to do more to protect public health and the environment in accordance with the precautionary principle”. The preamble of REACH also emphasises the importance of the precautionary principle in the regulation of Substances of Very High Concern (SVHCs).Footnote ²⁶ According to recital 69 of REACH, SVHCs should, “having regard to relevant human population groups and possibly to certain vulnerable sub-populations, and the environment”, and be subject to careful attention “in accordance with the precautionary principle”.

In WFD, the precautionary principle is particularly mentioned in the context of the waste hierarchy set out in Article 4. The principal aim is to reduce the amount of waste generated by fostering resource efficiency. If waste, however, is generated, it should be prepared for reuse, recycled or otherwise recovered. Waste should be disposed of (ie landfilled or incinerated without energy recovery) only if none of the abovementioned options can be applied. Article 4(2) of WFD requires Member States to apply the waste hierarchy by taking into account “the general environmental protection principles of precaution and sustainability”.

Furthermore, the preamble of WFD describes the more generic role of the precautionary principle as the underlying guideline in the implementation of waste policies. Pursuant to recital 30 of WFD, it is necessary to set general environmental objectives for the management of the waste in the EU “[i]n order to implement the precautionary principle and the principle of preventive action enshrined in Article [191] (2) [TFEU]”, and that “[b]y virtue of those principles” the EU and its Member States are required to eliminate the recognised risks that such waste brings about. Thus, the recovery objectives of WFD and the prevention of the harms caused by the hazardous substances that the recovered materials contain are both based on the precautionary principle.

REACH is independent of the legislation on waste, and wastes are excluded from the scope of REACH.Footnote ²⁷ However, REACH sets out specific rules for materials that are defined under WFD as by-products and for former wastes that have ceased to be wastes (end-of-waste; EoW). The provisions of REACH may guide the application of the respective provisions of WFD. The ECJ has, for example, stated that the compliance of the material with the REACH provisions may be relevant for determining whether EoW has occurred.Footnote ²⁸ However, in the big picture, the tensions between the recovery objectives of WFD and the safety objectives of the chemicals regulation are much more complicated. Whilst WFD aims at achieving environmental benefits by fostering the reuse and recycling of materials, the restriction mechanisms of the chemicals regulation protect human health and the environment from the harmful chemical substances that the recovered materials may contain. The transition to a circular economy requires a radically new kind of reconciliation of these objectives.Footnote ²⁹

In accordance with the precautionary principle, the authorities should restrict the use of any secondary raw material that contains a hazardous substance that may pose a real harm to human health or the environment. However, as held several times by both the ECJ and the General Court (GC), such restrictive measures cannot be applied to “purely hypothetical risks”.Footnote ³⁰ As is well illustrated by the Solvay case, this does not prevent the application of restrictive measures in cases where the existence of a potential risk is not yet confirmed but the application of the precautionary principle also cannot lead to the requirement to prove the lack of any such risk.Footnote ³¹

On the other hand, the authorities are required to ensure that any preventative measures are based on as thorough a scientific risk assessment as possible, as the lack of such assessment could lead to the adoption of “arbitrary measures which cannot be rendered legitimate by the precautionary principle”.Footnote ³² In the regulation of (hazardous) chemical substances, which are subject to comprehensive risk assessment, this forms a direct link between the precautionary principle and the procedural requirements. The authority must ensure that it complies with the relevant procedural requirements and that its conclusion is based on careful and impartial examination of all of the relevant facts of the individual case in question.Footnote ³³

Ultimately, it is for the competent public authority to examine on a case-by-case basis what is the level of unacceptable risk that triggers the precautionary measures. In a veterinary drug case, such as Pfizer, the authority performing such an examination may take account of, for example, the severity, extent, persistence, reversibility and possibility of delayed effects of the any potential adverse effects that the actualisation of the respective risk would entail.Footnote ³⁴ Therefore, the more severe the potential harmful effects in question, the less evidence is needed regarding the probability of the actualisation of the suspected risk to apply the precautious restrictive measures.

In addition, the authorisation of chemical substances for specific uses, such as plant production products, is based on the precautionary principle. Therefore, when authorising a plant production product, the absence of harmful effects cannot be presumed, and the burden of proof on the conformity with the applicable criteria lies with the applicant for the authorisation.Footnote ³⁵

On those premises, the precautionary principle has been applied by the ECJ and the GC in a variety of cases concerning restrictive measures for hazardous chemical substances. The application of the precautionary principle has led to:

• Strict application of the exemptions of the restrictions set out for the hazardous substances in electrical and electronic equipment;Footnote ³⁶

• The requirement for the Commission to reject an application of an active substance of plant protection products in a case where a risk to human health could not be excludedFootnote ³⁷ and an application for an active substance that could have endocrine-disrupting properties even in the absence of guidelines for assessing such properties;Footnote ³⁸

• Accepting strict national restrictions for a fuel additive even in the absence of comprehensive risk assessment;Footnote ³⁹ and

• Allowing the identification of substances such as an SVHC under REACH even with the existence of uncertainties as regards the determination of the safe level of exposure to that substance.Footnote ⁴⁰

In the application of the waste regulation, the precautionary principle has resulted in a non-restrictive interpretation of the concept of waste.Footnote ⁴¹ The ECJ has pointed out several times that in recovering production residues, special precaution must be taken as regards the potentially hazardous nature of their composition.Footnote ⁴² The precautionary principle has been relied on in recent case law concerning waste management. In particular, the precautionary principle played an important role in the ECJ’s reasoning in Verlezza, which concerned the conditions under which a waste must be classified as hazardous, and Prato Nevoso, which concerned the conditions for EoW.

The classification of waste as hazardous in accordance with Annex III of WFD is a crucial dimension of waste management under WFD, as wastes classified as hazardous must be treated in specialised facilities that are subject to a specific permit procedure. In Verlezza, the ECJ considered that in accordance with the precautionary principle the starting point is that the classification of waste as hazardous is required only where, following as complete an assessment of the risks as possible, there is objective evidence that such classification is required.Footnote ⁴³ However, the starting point for such assessment depends to a large extent on what is known about the composition of the waste batch in question. When applying the provisions on hazardous waste classification, the Member State must strike a balance between the precautionary principle on the one hand and technical feasibility and economic viability on the other. Therefore, the waste holders may confine themselves to ascertaining the substances that may reasonably be found in the waste in question and assess the hazardous properties of the waste based on that information. If it is impossible to determine the presence of hazardous substances but doubt regarding the hazardous properties of the waste remains, the waste must be classified as hazardous.Footnote ⁴⁴

In Prato Nevoso,Footnote ⁴⁵ the ECJ applied the precautionary principle in the context of EoW; that is, as regards the conditions under which a waste may cease to be waste. The dispute concerned the use of residual vegetable oils in a power plant to replace methane. One of the conditions for EoW set out in Article 6(1) of WFD is the absence of adverse environmental or human health impacts of the substance or object in question. The role of the precautionary principle and the need to balance different environmental impacts were explicitly considered in the ruling. The ECJ held that the Member State could, taking into account the precautionary principle, decide not to authorise the combustion of vegetable oil, as the risks of that use to human health and the environment “are potentially higher than those associated with the use of such oils to produce biodiesel”.Footnote ⁴⁶ Moreover, in accordance with the precautionary principle, the Member State was required to refrain from confirming the EoW status of the vegetable oil if it had not been demonstrated that the combustion of vegetable oil was devoid of adverse impacts on the environment and human health.Footnote ⁴⁷

Verlezza, Prato Nevoso and other recent judgments related to the precautionary principle can be seen as new, more restrictive readings of the precautionary principle that have led to a stricter application of environmental provisions.Footnote ⁴⁸ The application of the precautionary principle also depends on the subject matter of the case in question.Footnote ⁴⁹ Therefore, the strict approach of the precautionary principle may not be applied in all subject matters. The precautionary principle should be applied differently, for example, in such water and nature conservation cases where the effects of the planned activity are very difficult to predict and in the regulation of the well-known health risks of certain hazardous substances.Footnote ⁵⁰

In addition, as Sobotta points out, many decisions actually involve a choice where there are scientific doubts about the harmfulness of all options, including the do-nothing option. In such cases, the strict application of the precautionary principle is impossible, as some of the uncertain options must inevitably be chosen.Footnote ⁵¹

This is where the trade-offs of the circular economy are inevitably brought into the decision-making. In fact, most of the decision-making in the circular economy with complex, uncertain and ambiguous risk problems – including situations like those of Verlezza and Prato Nevoso – is subject to such competing uncertainties. Recovering materials that may contain hazardous substances may pose uncertain risks to human health or the environment, but harm to the environment may also result from treating the magnitude of wastes through hazardous waste treatment procedures for safety’s sake or from obtaining other fuels when the waste-based fuel cannot be used as intended. In cases such as the latter, attention must also be paid to the environmental benefits of the different uses: it may be better for the environment to use recovered vegetable oils as raw materials of biofuels instead of combusting them as such. The requirement for a “high level of protection” set out in Article 191(2) TFEU in combination with the precautionary regulatory frameworks force risk managers to seek “transformable” standards that respect the chosen level of protection in order to make the necessary normative conclusions concerning the adverse effects of the issues at stake, and they also force them to evaluate whether future developments would not allow us to design policies that retrospectively define current practices as insufficient.Footnote ⁵²

Balancing the chemical safety and circular economy objectives may lead, for example, to the need to exempt secondary materials from certain restriction rules of the chemicals legislation.Footnote ⁵³ Setting the same stringent limit value for a hazardous substance in both virgin and recycled materials does not necessarily lead to the most sustainable outcome. This has been recognised in the Chemicals Strategy for Sustainability, which states the following:

Such recovery exemptions are applied, for example, in some of the restrictions provisions under REACH. According to those provisions, polyvinyl chloride (PVC) with up to 0.1% by weight of cadmium can be recovered, whereas the generally applicable concentration limit for cadmium in plastics is 0.01%.Footnote ⁵⁵ Similarly, the applicable REACH restrictions provision allows certain reuses of wood treated with currently otherwise banned copper–chromium–arsenic (CCA) solution.Footnote ⁵⁶ On the other hand, in situations where the chemical risk is specifically related to the contamination of secondary raw materials, safe material circulation may require the application of more stringent hazardous substances concentration limits to secondary raw materials than to virgin raw materials. An example of this is the recently adopted REACH restriction on rubber granules and mulches that are usually manufactured from recycled tyres and used as infill material in synthetic turf pitches or on playgrounds. REACH now limits the concentration of polycyclic aromatic hydrocarbons (PAHs) of those materials to 20 mg/kg, whilst other mixtures can be placed on the market if they contain up 100 mg/kg or even 1,000 mg/kg of the same PAHs.Footnote ⁵⁷

The case of rubber granules and mulches illustrates clearly the need to reconcile the objectives of minimising chemical risks and maximising material circulation. The adoption of the restriction followed the conclusion of the European Chemicals Agency (ECHA) that the generally applicable PAH concentration limits were not sufficient to adequately control the human health risks posed by the rubber granules and mulches used in loose form on playgrounds and synthetic turf pitches.Footnote ⁵⁸ On the other hand, the ECHA considered that the costs of a more stringent option – setting the concentration limit value to 6.5 mg/kg – would exceed its (greater) health benefits (eg because of societal costs and increased greenhouse gas emissions).Footnote ⁵⁹ In some cases, it may also be appropriate to apply different concentration limits to the same secondary raw material in its different uses.Footnote ⁶⁰

The need to reconcile the competing uncertainties and objectives that are in tension is the dilemma facing the precautious circular economy, representing a crucial difference from the context of “classical” risk management issues, under which standards can usually be predefined.Footnote ⁶¹ This can only be solved through careful case-by-case decision-making in which due attention is paid also to the inevitable trade-offs. It should go beyond policymaking focused on legislative action and should involve the communication and collaboration of all relevant actors. Guidance for such decision-making can be sought from the classification of the risk problems, as discussed in Section III.2. Precautionary frameworks facilitate deliberation at the science/policy/society interfaces, moving from a science-centred debate on the probability of risks towards a science-informed debate on uncertainties and plausible adverse effects.Footnote ⁶²

2. Classification of the risk problems of the circular economy

Application of the precautionary principle involves deliberation on a range of normative dimensions.Footnote ⁶³ “Normative” refers here, as described by von Schomberg, to all of the prescriptive statements or value judgments in contrast to factual scientific statements. Deliberation at different levels creates an ideal-type description of all relevant, mutually informing deliberation activities in relation to the precautionary principle.Footnote ⁶⁴

An essential normative political choice is the determination of the chosen level of protection (eg regarding the environment or human health).Footnote ⁶⁵ This is hardly ever defined in quantitative terms, and in cases of significant scientific uncertainty such quantification is not feasible. In addition, the level of protection may need to be redefined in the light of the acquisition of new knowledge. De Sadeleer has argued that the precautionary principle must be seen as part of a dynamic and not a static process, and that decisions taken under the precautionary principle should be understood as open to review in the light of new scientific evidence.Footnote ⁶⁶

Risk problems should be distinguished from risk itself because they also include diverse values regarding how to deal with a specific risk. The distinction between the concepts of risk and the risk problem is well illustrated by the nuclear energy example of the Aven and Renn: the risk that nuclear energy poses is well-known and scarcely contested. However, the related risk problem is characterised by the different views of people on how to deal with this nuclear risk.Footnote ⁶⁷ The classification of risk problems is based on their features (characterisation, perception and/or handling).Footnote ⁶⁸ We base our classification in this paper on the classification of risk problems into “simple”, “complex”, “uncertain” and “ambiguous” presented by Aven and Renn,Footnote ⁶⁹ with the addition of a class of “purely hypothetical risks” (Table 1). It is important to note that the case law excludes from the scope of the principle of proportionality only purely hypothetical risks.Footnote ⁷⁰ All uncertain risks are hypothetical to some extent. Therefore, the concept of “purely hypothetical risk” must be interpreted restrictively, as otherwise it would exclude a considerable amount of genuine risks.

Table 1.

Classification of risk problems and example cases related to material circulation.Footnote ⁷¹

In the case of simple risk problems, the occurrence of events and their consequences can be predicted quite accurately. In the chemicals regulation, the mere intrinsic hazard property of a substance can be a sufficient ground for triggering regulatory actions. As is well illustrated in PlasticsEurope, a hazard property that makes a substance “capable” of having an adverse effect on human health or the environment can, for instance, lead to including it in the REACH Candidate List of SVHCs and making it subject to the related immediate regulatory requirements.Footnote ⁷⁸ Similarly, a waste that is found to be hazardous according to the conditions set out in WFD becomes subject to specific requirements concerning traceability, packaging and labelling and the ban on mixing that waste with any other waste, and it must be treated in specifically designated hazardous waste treatment facilities.Footnote ⁷⁹

The risk of repeated skin contact of a hiker with the hazardous substances that the recycled telecommunication pole underlay of duckboards on a wetland contains, as examined in Lapin luonnonsuojelupiiri, is an example of a purely hypothetical risk.Footnote ⁸⁰ The ECJ found that if those poles are merely used as an underlay for those duckboards without being part of the surface crossed under normal conditions by users, repeated skin contact with the treated wood would appear unlikely. As the referring court concluded in its final judgment, such exposure could occur only if the hiker was barefoot and intentionally stepped on the underlay of these duckboards.Footnote ⁸¹

The precautionary principle also is not applied in the case of simple risk problems, where the level of protection is defined and the risk can be quantified so that the policymakers can respond with a normal risk management approach (eg by setting thresholds). The necessary measures can be adopted without invoking the precautionary principle because there is a consolidated scientific basis concerning the adverse effects in question. The interventions are thus preventative.

A risk problem is complex if it is difficult to accurately predict the performance of the system as a whole based on knowledge of the specific functions and states of its individual components.Footnote ⁸² There may be many intervening variables between a trigger and its effects. In the recent EU case law related to material circulation, such dimensions can be found in the ClientEarth case. In that case, ClientEarth contested the decision by which the Commission had authorised the use of recycled PVC containing bis(2-ethylhexyl) phthalate (DEHP), which is subject to an authorisation requirement under REACH due to its reproductive toxicity and endocrine-disrupting properties. Both authorising and prohibiting the use of secondary plastic materials containing such a hazardous substance have different consequences that interconnect; thus, the overall outcome as regards the related risks is difficult to predict. Under the REACH authorisation procedure, this complexity is assessed in an analysis of the available alternatives and via a socio-economic analysis. Under Article 60(4) of REACH, the Commission may grant authorisation if the socio-economic benefits outweigh the risk to human health or the environment arising from the use of the respective substance and if there are no suitable alternative substances or technologies. In ClientEarth, the GC and subsequently the ECJ held that, contrary to the applicant’s arguments, the Commission’s authorisation decision was based on sufficient examination of the available alternatives and the socio-economic benefits and risks of the use of the recycled PVC.Footnote ⁸³

If it is difficult to accurately predict the occurrence of events or their consequences, a risk problem is uncertain. In Verlezza and Others, which is our example in this category, the ECJ examined the conditions for classifying wastes as hazardous under WFD. The case concerned mechanically treated municipal waste, which, under WFD, has a hazardous waste mirror code. As Advocate General (AG) Sánchez-Bordona points out, such waste may contain hazardous substances originating, for example, from batteries that have been disposed of incorrectly.Footnote ⁸⁴ The uncertainty related to the potential hazardous properties of such waste may therefore be large, and at the same time the consequences of the presence of hazardous substances to human health or the environment could be extreme. In such a situation, the precautionary principle requires that the uncertainty is narrowed down by acquiring such further information as is technically feasible and economically viable. The waste holder must determine the composition of the waste and ascertain the hazardous substances that may reasonably be found in that waste.Footnote ⁸⁵ However, if it remains impossible to determine whether the waste contains hazardous substances or has hazardous properties, the (pre)cautious approach requires that the hazardousness is presumed and the waste is classified as hazardous.Footnote ⁸⁶

Different views on the relevance, meaning and implications of the basis for the decision-making or on the values to be protected and priorities to be established result in interpretative or normative ambiguity, respectively.Footnote ⁸⁷ Ambiguity is usually the result of complexity and uncertainty, so ambiguous risk problems also have features of these categories, and the boundary between the categories is not precise.Footnote ⁸⁸ With regards to interpretative ambiguity, knowledge available can be viewed as justified beliefs, which are founded on data, information, analysis, argumentation or testing (evidence) but may never be conclusive, resulting in ambiguity. A key issue to consider is whether the knowledge and lack of knowledge have been properly addressed. The solidness (eg compliance with all rules and assumptions, limitations or constraints introduced) of the assessments behind the knowledge, as well as the degree to which the results obtained are reliable and valid, should be considered in decision-making.Footnote ⁸⁹ Poor solidness, reliability and/or validity may lead to different understandings of what the risk characterisation expresses.

Normative ambiguity extends beyond the scientific domain. Whether a risk problem that is characterised with high uncertainty deserves attention depends on the values at stake: the potential for serious consequences and different views on how to handle them. Normative ambiguity does not reflect features related to knowledge but concerns how one values these features. The differences in values are influenced by several factors, including the geographical dispersion of potential damage, the temporal extension of potential damage, its reversibility, the latency period between the initial event and the actual impact (delayed effect) and the potential for the mobilisation of individuals and affected groups.Footnote ⁹⁰

Tallinna Vesi concerned the recognition of the EoW status of biologically treated sewage sludge and the Member States’ margin of discretion in a case-by-case application of the EoW criteria. There were no EoW criteria at the EU or national level. Tallinna Vesi AS wished to market the treated (anaerobic digestion, drying, aerobic digestion) sludge as a greening soil.Footnote ⁹¹ The main legal question was whether and under what conditions Member State authorities are obliged to adopt case-by-case EoW decisions. The ECJ ruled that a Member State is not obliged to recognise EoW status on a case-by-case basis and that Article 6(4) of WFD does not allow a waste holder to demand the recognition of EoW status by the competent authority or by a court of the Member State.Footnote ⁹²

The cases Tallinna Vesi and Prato Nevoso underlined that the safety of secondary raw materials is at the heart of the circular economy. The ECJ stated in Tallinna Vesi that “the recovery of sewage sludge entails certain risks for the environment and human health, in particular those linked to the presence of hazardous substances”, and that a Member State may refrain from recognising EoW status or from laying down standards that would lead to EoW status.Footnote ⁹³ However, the Member State must ensure that such a measure does not amount to an obstacle to the attainment of the objectives of WFD, such as encouraging the application of the waste hierarchy or enabling the development of a circular economy.Footnote ⁹⁴ Therefore, the Member States may have grounds for refraining from recognising the EoW status of certain wastes, but they cannot apply such a policy as a rule to all wastes. The duty of the Member States to ensure that EoW is applied was introduced in Article 6(1) in the 2018 amendment of WFD.Footnote ⁹⁵ However, for the sake of legal certainty and proper functioning of the internal market, the preference should be given to adopting EU-wide EoW criteria for specific waste streams.Footnote ⁹⁶

The ECJ also recalled that fulfilling the EoW criteria set out in Article 6(1) of WFD cannot in itself directly establish that certain wastes or waste categories must no longer be regarded as such.Footnote ⁹⁷ This was also stated in Prato Nevoso, in which the ECJ underlined that “the fact that the competent national authority finds that, provided that certain criteria are met, a given waste loses the status of waste for a certain use does not imply that it ceases to be waste when used for other purposes”.Footnote ⁹⁸ The ECJ stated that Member States have a wide margin of discretion as regards the establishment of appropriate procedural arrangements and the substantive examination of compliance with the conditions for EoW status, involving complex technical and scientific assessments by the competent national authorities.Footnote ⁹⁹

These two cases also highlight clearly the uncertainties related to decision-making in ambiguous risk problems. For example, sludge originating from a municipal wastewater treatment plant, such as in our example case Tallinna Vesi, typically contains residues of hazardous substances, such as persistent industrial chemicals, pesticides and pharmaceuticals, from various industrial and domestic sources. The World Health Organization (WHO) has indicated that there are potential negative health implications of the use or sewage sludge in agriculture, including a wide range of direct health end points, such as typhoid, dysentery and diarrhoeal diseases, as well as direct or indirect changes in soil or water quality.Footnote ¹⁰⁰ Inappropriate reuse practices may, for example, contaminate surface and groundwater sources that are used for the production of drinking water, as well as spread antimicrobial agents and potentially toxic metals in the environment, increasing the risk of the development of antimicrobial resistance.Footnote ¹⁰¹ The risk level depends on, for example, how the sludge is treated and how it is used on the soil.Footnote ¹⁰² In wastewater treatment systems, monitoring of many of these substances is limited or lacking.Footnote ¹⁰³ In addition, the lack of comprehensive toxicological data regarding the potential impacts on human health and the environment results in interpretative ambiguity. Such uncertainty may be related to hazard identification (whether a certain substance is hazardousFootnote ¹⁰⁴ or is a direct or indirect hazardFootnote ¹⁰⁵ ), the existence of the substance in a secondary material, the fate of the substance in the environment in a specific useFootnote ¹⁰⁶ and the actual risk to human health and the environment.Footnote ¹⁰⁷ These uncertainties may result from complexity or a lack of knowledge regarding the underlying phenomena or processes, giving rise to interpretative ambiguity,Footnote ¹⁰⁸ but they may also lead to the balancing of different values (normative ambiguity) and environmental impacts.Footnote ¹⁰⁹