Introduction
The risk to human health posed by hazardous chemicals depends on the hazardous properties of the chemical and the likelihood of being exposed. Therefore, the most efficient way to reduce the risk is to eliminate the hazard or the exposure or to reduce it by substituting or replacing them with less dangerous alternatives[1]. Substitution is a general legal requirement for managing occupational safety and health (OSH) in the workplace as set out in the OSH Framework Directive (89/391/EEC)[2] and daughter Directives. In addition, Regulation No 1907/2006 (REACH)[3] sets rules for placing chemicals on the EU market and requires hazard and exposure information from manufacturers or importers and encourages substitution of substances of very high concern (SVHCs) with safer alternatives. Tools useful for substitution are available as well as shared knowledge to help in the process.
What is substitution?
Substitution, in this article, refers to the replacement of hazardous chemicals or processes and handling methods by safer alternatives.
Substitution is a key principle of managing the risks posed by chemicals in the workplace[4]. Substitution of hazardous chemicals is a way to transpose into chemical risk management the general principle of ‘replacing the dangerous by non-dangerous or less dangerous’, as stated in the Directive 89/391/EEC (Framework Directive)[2]. Substitution of hazardous substances and mixtures with less hazardous alternatives is a basic principle of any good chemical risks management and legal requirement according to OSH legislation. According to the Chemical Agents Directive 98/24/EC[4] “substitution should be by preference undertaken” to eliminate or reduce the risk from a hazardous chemical agent. The Carcinogens, Mutagens and Reprotoxic substances Directive 2004/37/EC[5] stipulates that employers have the obligation to reduce the use of a carcinogen, mutagen or reprotoxic substance at the place of work, by replacing it, “in so far as is technically possible, by a substance, mixture or process which, under its conditions of use, is not dangerous or is less dangerous to workers’ health or safety”.
The legal provisions on OSH place substitution at the top of the hierarchy of control measures[6].
The Chemical Agents Directive 98/24/EC recommends following a hierarchy or ‘order of priority’ of control measures for preventing or reducing exposure to dangerous substances based on the STOP principle[1]:
- S - Substitution = complete elimination of the dangerous substance or substitution with a safer alternative
- T - Technological measures = minimising the concentration of dangerous substance in the exposure zone
- O - Organisational measures = minimising the number of exposed workers and/or the duration and intensity of exposure
- P - Personal protective equipment = wearing protective clothing or equipment such as goggles and gloves as a barrier to exposure.
The progressive substitution of substances of very high concern (SVHCs) with suitable alternatives is one of the key requirements of authorisation under REACH[7].SVHCs are substances that are carcinogenic, mutagenic and toxic to reproduction (CMR) persistent, bioaccumulative and toxic (PBT), very persistent and very bioaccumulative (vPvB) or substances of equivalent level of concern, like endocrine disruptors. Substitution is directly linked with the main objectives of REACH: ensuring a high level of protection for human health and the environment.
REACH states that when applying for the authorisation of substances of very high concern the registrant has to provide an analysis of the alternatives, considering their risks and the technical and economic feasibility. If suitable alternatives are available, a substitution plan, including a timetable of the applicant’s proposed actions, has to be submitted.
In addition, the European Green Deal has set up a goal to protect human health and the environment as part of an ambitious approach to tackle pollution from all sources and move towards a toxic-free environment. To achieve this goal the EC has published a chemical strategy for sustainability with the aim of achieving chemicals and materials inherently safe and sustainable, from production to end of life[8]. The strategy puts chemical substitution at first by encouraging companies to design chemicals that are safer and therefore those that are toxic can be substituted.
Substitution can also refer to an alternative process re-organisation of the work process or procedures, as well as product revision. This is in line with the definition used by Lohse & Lissner: ‘The replacement of hazardous substances in products and processes by less hazardous or non-hazardous substances maintaining an equivalent functionality via technological or organizational measures’[9].
For example, substitution may be done by:
- Using different and safer substance(s) instead of the initial one (substitution by substance/s or material), e.g. glycerol acetate as an alternative to phthalate plasticisers in coatings;
- Using a technological alternative instead of the initial substance (substitution by process), e.g. deep freezing instead of formaldehyde for preserving biological samples;
- Using an organisational measure as replacement for a hazardous substance (substitution by procedure), e.g. replacing mercury switches in some X Ray machines with manual adjustment by the operator;
- Changing the product so that the substance is no longer needed (substitution by re-design). A known example is eliminating adhesives by redesigning product shapes so they can be assembled manually (e.g. flooring click systems).
Regardless of the type, substitution should reduce the risk for health and safety. Shifting hazards (e.g. from chemical to physical), or using inappropriate control measures for the alternative, may lead to situations in which the overall risk is higher than before substitution. Failing to distinguish between a lack of data on certain hazards and the absence of those hazards could also make substitution ineffective. Although substitution examples may be transferrable, they need to be assessed on a case-by-case basis. This requires consideration of the specific conditions of the workplace, the characteristics of the workers, production processes and work procedures, as well as the conditions arising during maintenance and in the event of foreseeable malfunctions. There cannot be a “generic" approach to substitution.
As well as being a legal requirement, substitution can also be done voluntarily. Many companies have lists of substances that are banned or restricted in their products or activities (‘grey or black lists’). Some of these substances are not (yet) restricted by law.
Though this article refers to substitution of hazardous chemicals, hazardous processes, like those mentioned in annex I of the Carcinogens, Mutagens and Reprotoxic substances Directive[5], should also be considered for substitution. Examples of such processes are work involving exposure to hardwood dusts, to respirable crystalline silica dust generated by a work process or to diesel engine exhaust emissions. In these cases, companies also have a legal obligation to look for safer alternatives.
Drivers for substitution
Legal banning or restricting of a substance has proven to be one of the strongest drivers for substitution. Faced with the impossibility to produce, distribute, use or import/export a substance, interested parties have found one or more substitutes6. REACH has a significant influence in this respect when substances are included as candidates for restriction and authorisation. A survey carried out by ECHA among companies affected by an authorisation and/or restriction process showed that 34 % indicated that their company had already substituted the use(s) of a substance of concern, while 26 % were in the process of substituting and 29 % had plans to substitute in the future[7]. An example of the impact of REACH on the use and substitution of substances is trichloroethylene. This substance was added to the REACH Candidate List in June 2010 and to the Authorisation List in 2013. Its use has since decreased by around 95%, from approximately 53,000 tonnes in 2010 to 2,650 tonnes in 2022[10].
Stakeholder requirements may support substitution. Whether internal (workers, OSH specialists, trade unions) or external (NGOs, sector organisations, financiers, mass-media) they may put pressure to stop working with hazardous substances and find safer alternatives.
Cost cutting may be achieved by reducing expenditure caused by workers’ ill-health, and on end-of-pipe measures like neutralisation of emissions and wastes. Substitution has the advantage of addressing the root cause of the problem. It may change the working process to the point of reducing or even making redundant some protective measures. Also, alternatives may be (or become) cheaper than the initial substances.
Competitive advantage: placing a new, safer substance on the market before competitors may have immediate economic benefits for the company, offer new market opportunities and promote further developments.
Creating a responsible and modern image for the company by demonstrating care for workers, clients and the environment, improves credibility. On the other hand, pretending to care (e.g. by ‘window dressing’ or ‘greenwashing’) will rapidly deteriorate the image and confidence, first internally and eventually externally.
Contributing to a toxic-free environment and ensuring a safer, healthier and more sustainable future for the next generations.
Technical progress may lead to safer alternatives and improved methods for testing their properties and their effects on health and the environment.
Common barriers to implementing substitution are economical (direct and indirect costs), technological, performance (technical requirements, client expectations), lack of knowledge on dangerous properties of alternatives, lack of enforcement (inefficient control from authorities), lack of motivation (no incentives, reduced public interest) and awareness (ignoring hazards, unknown costs of not substituting), fear of change.
The substitution process
General considerations
Substitution may be an isolated event in a company although ideally it should be part of a more systematic approach or policy at company/sector or local/regional level.
It should be integrated in the general policies and plans of companies, making good use of existing knowledge within the companies and of the relations with external stakeholders (partners, authorities, shareholders, supply chain, clients).
Making substitution part of the preventive culture of the company helps to identify problems earlier - spotting opportunities, acting in a coherent way and gaining broader support.
Multidisciplinary teams are generally needed, depending on the nature and complexity of the substitution. Such teams should include preventive services and occupational physicians, technical personnel, and workers representatives. These teams are crucial to prevent regretful substitution where the risk is shifted.
Workers have to be informed, encouraged and involved in identifying possible substitutions and discussing the appropriateness of their implementation, as well as when putting them into practice. The fact that substitution is a change (sometimes an innovation) may be stimulating in some cases, but in others it will challenge companies’ and workers´ capacities to adapt, to change mindsets, and to control things while under development. Information exchange along the supply chain or at sector level can promote substitution initiatives and share practical experience[11].
The right timing for substitution is influenced by the availability and the costs of substitution. Big companies can afford to make a competitive advantage of putting on the market or using a new and safer alternative, even while prices are still high. Small companies might need to wait for prices to go down.
A critical issue is the current state of knowledge on the long-term effects of substances. In some notorious cases, like asbestos, chemicals were proven unsafe after many years of intensive use. Such cases make it hard to decide on implementing alternatives, especially when they are not supported by long-term epidemiological studies.
Constant improvement of laboratory tests and modelling methods are expected to provide more reliable data and in shorter time. A precautionary approach is recommended, and substitution by unknown substances should be avoided until clarification is forthcoming, in particular if the current risk is low and may not justify such a step.
A risk assessment for the alternative should determine if risk is reduced and ensure no new risks are created, and what protective measures are required. An alternative will rarely be the safest for all hazard endpoints. Decision on what alternative to adopt should consider which hazard is more likely to generate high risks levels, and which one the company is better able to control. As well as chemical risks, other risks should also be considered that could impact negatively on health and safety (e.g. risk of fire and explosion). The impact on the main working processes and on auxiliary activities like maintenance should be considered, as well as the consequences of possible accidents. Working procedures, protective and preventive measures already in place may need to be amended or supplemented. Companies could develop purchasing procedures to select for safer chemicals and products as they become available.
The principle of substitution of hazardous chemicals can also be applied to the design of new products or processes, which is a preferable preventive approach.
Substitution steps
Substitution requires a systematic approach that generally includes the following steps[12]:
- Organising a working group
Identify all the relevant stakeholders and their interests such as the purchasing department, maintenance, production, facility management, health and safety department etc. Be sure to include workers, as they have practical knowledge and experience. Set up a working group and and integrate all required expertise. Make a work plan with well-defined roles for all stages, time limits and resources. Take measures to ensure an efficient information flow between the group, the rest of the company and its stakeholders. Maintain a collaborative, open–minded atmosphere.
Identify the substances to be substituted and why. Be clear on why you make these choices. Prioritise substitution according to legal provisions, company policy and stakeholder perspective. It is important to have a broad view of the function of the substance, in order to look for not only alternative substances, but also alternative processes or organisational changes that might avoid the need to use chemicals at all[12].
Describe the role of the substance and how it is integrated in the process or product. List the conditions for the substance to perform its role adequately (temperature, acidity, pressure, chemical compatibility, etc). An alternative should fit these conditions, or the system/product will need to be changed, to a greater or lesser degree. Identify the property that the substance contributes to the process or to the final product. If this property is not essential (e.g. some commercial attributes) the substance may be eliminated. Otherwise, an alternative is needed.
- Setting substitution criteria
Set criteria for selecting possible alternatives. Initially, use preliminary criteria to eliminate at an early stage alternatives that are not safe (CMRs, sensitisers or neurotoxicants). Other criteria may be added to differentiate between alternatives that have passed the preliminary screening criteria such as cost, functionality, availability on the local market, and other advantages.
- Searching for alternatives
Look for alternatives that have already been developed and implemented, as this could reduce innovation costs and risks. Search in internet sources, ask authorities and consult with stakeholders (e.g. supply chain, professional or sectorial associations). Another approach is to ask the supplier to formulate a safer alternative. Some companies offer support in selecting the right product and may even be willing to reformulate the initial one, particularly for important clients.
- Assessing and comparing alternatives
Compare and assess all alternatives in terms of their usefulness, applicability and safety. The following aspects must be assessed[12]:
1. Environmental and health and safety impact: ensuring that the alternative is actually safer for health and environment.
2. Technical viability: assessing the functionality of alternatives to ensure they are equal to or better than the products they are replacing. This includes research and detailed technical examinations by users, as well as market analysis.
3. Economic viability: a cost assessment and a cost/benefit analysis, not only by comparing purchase costs but including all costs and benefits associated with the product.
4. Social impact:
It involves the impact of an alternative product on other workers, human rights, society, etc.
Select those alternatives that best fit the nature and dimension of the problem and that provide indeed an overall risk reduction.
- Experimenting on pilot scale
Try substitution on a smaller scale. Plan the technological and organisational changes required. Assess the impact of substitution on functional performance, workers, the environment and consumers. Pay special attention to any shifts in risk and the necessary control measures. Consult with the workers. Compare costs against those initially forecast, and estimate if feasible when transposed at full scale.
- Implementing and evaluating
Plan carefully for full-scale implementation. Evaluate the risks and take appropriate measures. Update your supply chain and inform your downstream users. Review training needs, monitoring and other work procedures. Collect feedback from workers and customers. Evaluate and identify points to improve.
Tools and information sources
Collecting and assessing data on alternatives are key elements in the substitution process. Several tools can be used during the substitution process. SMEs mostly benefit from tools that are easy to use and for which entry data can be obtained from the Safety Data Sheets of substances or products (e.g. the Column Model). Tools that require more detailed (eco)toxicological data are also freely available but using them may require a specialist or experienced operator (Green Screen, P2Oasys).
Examples of tools, information sources and databases that may be used for substitution:
- OECD SAAToolbox: Substitution and Alternatives Assessment Toolbox for chemicals and nanomaterials. The toolbox compiles resources relevant to chemical selection including substitution and alternatives assessment, as well as the OECD SSIA (Safe(r) and Sustainable Innovation Approach) for nano-enabled and other emerging materials. It includes tools and data sources to help users to evaluate potential hazards of chemicals with a subset focused on materials, processes and products. Additional tools address exposure assessment, life-cycle assessment and economic and social considerations[13].
- Road Map on carcinogens[14]: the webpage includes a search engine with useful links to guidance documents and tools on chemical substitution including specific examples of successful substitution for a number of carcinogens
- Column Model for Chemical Substitutes Assessment - an easy to use method that compares alternatives, ranking hazards according to severity levels, and considering emission factors, and considering the process employed[15].
- Technical Rules for Hazardous Substances (TRGS 600) – is an easy to use guidance that structures information on: identification of substitution possibilities (with examples of information sources), criteria for pre-selecting substitutes (with examples of series that rank health/physicochemical hazards and release potential) and decision on substitution (criteria for technical suitability and criteria for health and physicochemical risk). TRGS 600 was developed by the German Committee on Hazardous Substances (AGS) and is available in German and English[16].The Green Screen for Safer Chemicals[17] is a hazard-based assessment tool developed by the NGO Clean Production Action (US). The Green Screen defines four benchmarks with each benchmark defining a progressively safer chemical:
Benchmark 1: Avoid. Chemical of high concern
Benchmark 2: Use but search for safer substitutes
Benchmark 3: Use but still opportunity for improvement
Benchmark 4: Safe chemical.
Each benchmark includes a set of hazard criteria that a chemical must pass, including persistence, bioaccumulation, ecotoxicity, carcinogenicity and reproductive toxicity. - Pollution Prevention Options Analysis System (P2OASys)[18] helps organising information to compare the environmental, health and safety attributes of chemicals, formulated products and production process changes. P2OASys was developed by the Toxic Use Reduction Institute of Massachusetts (TURI)
- PRIO[19] is a hazard-based tool developed by the Swedish Chemicals Agency to help companies and other actors to identify and phase out hazardous substances. PRIO provides information the hazards of substances and which substances should be prioritised for substitution.
- SUBSPORTplus[20] is a webportal offering information for supporting the substitution process including a database on substances of concern and case studies.
- The Chemsec SIN List (Substitute It Now)[21] contains hazardous chemicals that are widely used, but which should be phased out as soon as possible due to the threat they pose to human health and the environment.
More examples of tools and databases are available in the EU-OSHA training course for OSH practitioners on substitution of dangerous substances in workplaces[12].
Success stories
The variety of substitutions and their context are presented in the examples below.
Construction sector - substitution by non-chemical alternative - personal initiative in an SME: A worker in a SME proposed the use of an electric, infrared (IR) heater to soften old paint, instead of the usual chemical procedure for stripping, based on dichloromethane. Initially, the proposal had nothing to do with occupational safety or environmental protection. The IR stripper was easier to transport, store and use than the chemicals. The substitution was well received by co-workers, who soon also noticed the OSH advantages. Moreover, unlike torch stripers, the IR device does not reach temperatures high enough to volatilise hazardous components such as lead; nor does it create dusts, like mechanical methods (e.g. blasting). When the SME proposed it in its next subcontract offer as a “green solution’’, it made a good impression on the contractor and the beneficiary.
Health care sector - substitution by product changes (packaging) and organisational measures - part of a broader risk reduction plan. As part of the process to eliminate mercury in health care units, a hospital decided to use thimerosal free vaccines. Thimerosal (or thiomersal) is a mercury-containing preservative that stabilises vaccines. Using preservative free vaccines meant changing the supplying procedure: single vials instead of multiple vial vaccines were used, and the storing time was shortened. The hospital reduced chemicals risks and hazardous waste, and patients that rejected vaccines containing mercury were reassured.
More case studies are available on the EU-OSHA website[22], in the Case story database of SUBSPORTplus[23], Road map on carcinogens[24] and in the OECD SAAToolbox[13].
