Abstract
In the last 50 years, various frameworks have been used to control and manage potentially toxic chemical risks; however, these chemicals continue to negatively impact environmental and human health. This work was intended to provide a systematic review of the literature on essential aspects of current risk management frameworks for potentially toxic chemicals. The frameworks were reviewed using Organisation for Economic Co-operation and Development (OECD) principles that focus on elements, successes, shortcomings, similarities, and dissimilarities premised on the experiences of many countries. Keywords such as heavy metals, health risk, industrial chemicals, potentially toxic elements, chemical pollutants, and risk management framework were utilised to search the literature from databases and other sources. Ten risk framework documents selected from an initial yield of 1349 using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow processes met the inclusion criteria. The key elements of risk frameworks that were identified included the risk assessment paradigm, iteration, tiered approach, weight of evidence, uncertainty analysis, and multi-criteria decision analysis among others. Notable gaps in risk frameworks that required improvements to effectively manage health risks posed by potentially toxic chemicals were identified. While existing risk frameworks have made significant contributions to human health and environmental protection, new and comprehensive frameworks are needed to address the novel and dynamic risks posed by toxic industrial chemicals. Also, there is a need to promote the use of risk management frameworks in developing countries through technology transfer and the provision of financial assistance to improve environmental and public health protection from toxic chemicals.
Keywords
Introduction
Over the past 50 years, many risk management frameworks (RMFs) have been used to manage the risks of chemicals through the prevention and control of deleterious chemicals from entering the environment and impairing human health (Jardine et al., 2003; NRC, 2011). Risk management of chemicals involves the selection of options based on health risk assessments and considers scientific, social, economic and policy considerations that require value judgements (Moore et al., 2022; US EPA, 2011). Most broad-based frameworks use OECD guiding principles and best practices on chemical risk evaluation and management that focus on problem formulation, stakeholder involvement, quantitative risk assessment, analysis of the weight of evidence (WoE), iteration and evaluation, risk communication, informed decision-making and flexibility among others (Moore et al., 2022; OECD, 2019a).
Risk assessments are precursors to risk management and use four process steps, which include hazard identification, toxicity or dose-response assessment, exposure assessment and risk characterisation. The WoE elements in the chemical evaluation include problem formulation, evidence collection, evidence evaluation, evidence weighting, and evidence integration and reporting (OECD, 2019b). On the other hand, the use of a tiered and iterative approach in modern risk frameworks ensures that valuation information that may emerge during risk management processes can be repeated (Moore et al., 2022; OECD, 2019a). This gives ‘risk managers and stakeholders the flexibility to revisit early stages of the process when new findings made during later stages shed sufficiently important light on earlier deliberations and decisions’ (Omnenn et al., 1997). The MCDA is used in some frameworks ‘to quantitatively integrate chemical properties and production, use data with expert judgements, stakeholder preferences, risk communication, sustainability and other factors’ (Moore et al., 2022). While qualitative or quantitative uncertainty analysis involves the use of the precautionary principle, which states that ‘lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation in cases where threats can cause serious or irreversible damage’ (Environment Canada, 2007). Other framework evaluation criteria considerations include data transparency, environmental research and monitoring, and adaptive management.
Although, RMFs have resulted in many improvements in reducing novel and existing risks of toxic industrial chemicals, much needs to be done in the future (Gabriela et al., 2022; Moore et al., 2022). There are limited peer-reviewed studies on RMFs for toxic industrial chemicals or contaminants. This study reviewed selected international, regional, national, state and organisational frameworks that were designed for risk management decision-making of novel or existing chemicals. Chemicals that are regulated by RMFs include but are not limited to heavy metals and metalloids, polycyclic aromatic hydrocarbons, pesticides, phenols, cyanide, dioxins and furans, polychlorinated biphenyls, and asbestos among others. Some of these chemicals when taken up by humans negatively impact the central nervous, cardiovascular, endocrine, hepatic and respiratory systems among others (Kamunda et al., 2016; Kwaansa-Ansah et al., 2017; Ngwenya et al., 2023). Some toxic chemicals accumulate in organs such as the liver, bone marrow, brain and kidney after being absorbed by the body, causing acute and chronic health problems (Alidadi et al., 2019; Anyanwu et al., 2018). As a result, the RMF process is essential for identifying, assessing, choosing and implementing measures to reduce and control hazards to human health and the environment (Jardine et al., 2003). The objectives of this review were to identify the existing RMF’s key elements that are essential in addressing risks posed by industrial chemicals exposure, unique features, achievements, and strengths and weaknesses of risk frameworks that can be leveraged for improvements.
Methods and materials
A systematic review of RMF literature from databases such as CINAHL, EBSCO, Google Scholar, PUBMED, PROSPERO, Science Direct and Web of Science was carried out. The review used OECD principles, which provide an understanding of the successes, similarities, dissimilarities and shortcomings of frameworks premised on the experiences of many countries (OECD, 2019a). The chemical risk frameworks identified represented a relatively wide range of industry, national, regional and international programs. The search used Boolean operators ‘AND’ and ‘OR’ with a combination of the following keywords: chemical pollutants, cyanide, health risk, heavy metals, industrial chemicals, potentially toxic metals, priority substances and risk management framework. Additional literature was also found through snowballing using initially identified published articles and their reference lists. Both grey and published literature were included in this systematic review. The grey literature was in the form of general, voluntary and regulatory frameworks found on the internet and these documents were obtained from a variety of sources that include governments, regulators and private organisations. The documents from different geographical settings published 20 years ago in English were found to be relevant for inclusion in the review; however, the reviewed literature excluded letters, and short communications. We acknowledge the review’s limitations, which include the limited use of peer-reviewed risk framework literature on chemical risks, and the exclusion of risk frameworks written in languages other than English that could have fitted our selection criteria.
The first author evaluated the literature that satisfied the inclusion criteria and discussed the findings with the co-authors. Disagreements on the selection of RMFs were resolved through dialogue between the first author and the co-authors to reach a consensus. The review was done from October 2022 to August 2023 and the reviewed frameworks apply to chemically contaminated sites, standards setting, and different environmental media, and covered a diverse geographic representation. The literature articles and documents were identified and selected based on the authors’ professional judgement, evaluated for suitability and incorporated in the review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow process shown in Figure 1.
A two-stage screening flow chart depicting the document and article selection process was utilised. A total of 946 peer-reviewed articles and 403 risk management documents were chosen by scanning through the titles, abstracts and full documents found on the internet and other sources. Of these articles and documents, a total of 158 duplicates were excluded from the review and the first screening led to the exclusion of 198 documents and 708 articles that were irrelevant. The second screening resulted in the exclusion of 209 articles and 66 risk documents that did not meet the inclusion criteria. As shown in Table 1, a total of 10 risk documents were found to be relevant and were ulitised in the appraisal.
Results
The review scope and parameters included RMFs’ purpose, use, achievements, and key elements applied in risk assessment and management. The evaluation criteria for the risk frameworks adopted from OECD guidelines included the use of a risk assessment paradigm, tiered and iterative approach, weight of evidence approach, multi-criteria decision analysis (MCDA) and uncertainty analysis among others.
Toxic substances control act, 2016
The United States Environmental Protection Agency (US EPA) uses the Toxic Substances Control Act (TSCA) to manage chemicals in commerce utilising pre-manufacture notices for new chemicals that are not included in the TSCA inventory. Chemicals regulated under TSCA include but are not limited to heavy metals, metalloids, polychlorinated biphenyls (PCBs), asbestos, formaldehyde, and per and poly-fluoroalkyl substances. This framework provides screening reviews to evaluate whether a further assessment of hazards and exposure potential is required. More risky chemicals identified through the prioritisation of existing chemicals are often subjected to more rigorous risk assessments. Also, the chemicals are evaluated for undesirable properties like carcinogenicity, toxicity, bioaccumulation, persistence in the environment and other characteristics. According to Moore et al., (2022), chemicals are evaluated in tiers and the WoE approach is used in higher tiers, MCDA and uncertainty analysis are explicitly applied under TSCA.
Australian industrial chemicals introduction scheme (AICIS), 2020
The AICIS is used to regulate the manufacture and importation of industrial chemicals and applies to chemicals such as polymers, and ingredients of products used in plastics, paints, printing, adhesives, cosmetics, mining, construction and consumer goods (Australian Department of Health, 2020). However, AICIS excludes chemicals for veterinary, food, agricultural and therapeutic use that are regulated under different schemes (Gabriela et al., 2022). The framework provides for post-introduction risk assessment and introducers are given reporting obligations for adverse effects. The AICIS principle is risk proportionate regulation that bases regulatory decisions on the level of risk at the time of a chemical’s introduction (Gabriela et al., 2022). The framework provides for carrying out risk assessments and risk management decisions such as tracking and monitoring industrial chemicals post-introduction and enforcing statutory compliance. Also, it imposes conditions on the use of highly risky new chemicals and forbids the use of hazardous chemicals if risks materialise after the chemical’s introduction (Australian Department of Health, 2020). The AICIS uses the principles of tiered and iterative evaluation of chemicals, stakeholder consultation and risk communication.
Guide on sustainable chemicals (GSC), 2016
The GSC is a voluntary framework that aids in the selection of sustainable chemicals by providing criteria for distinguishing between sustainable and non-sustainable substances (Umweltbundesamt, 2016). The application of use-specific criteria for chemicals denoted by different colours aids in the prioritisation of measures required. When chemicals are classified in the yellow and red bands (problematic properties), measures such as substitution, boosting energy efficiency and substitution risk management must be implemented. The scheme covers a wide range of substances and compounds that are classified as contributors to greenhouse emissions, energy consumption and water consumption. If a chemical is listed under specified conventions and regulatory frameworks like the Water Framework Directive on hazardous substances, REACH candidate substances, Oslo and Paris Conventions, Helsinki Commission priority substances, Montreal Protocol on Ozone depleting substances, and ‘Substitute It Now’ (SIN) lists, it is a strong indication that the substance is not sustainable (Umweltbundesamt, 2016). Key elements of the guide used include sustainability analysis, risk assessment, risk prevention and reduction, and emergency preparedness and response.
Chemicals management plan (CMP), 2016
The CMP assists with the assessment and management of risks caused by chemicals found in food and food products, consumer goods, cosmetics, medicines, drinking water and industrial emissions (Government of Canada, 2020). The CMP has a well-developed performance measurement system (Gabriela et al., 2022) and is modelled on Canada’s Toxic Substances Management Policy and guided by the 1999 revisions to the Canadian Environmental Protection Act. It brings together all prevailing federal programs into a combined scheme. The CMP has all key elements, which include risk assessment paradigm, MCDA, uncertainty analysis, tiered iterative evaluation and WOE among others. The strategy has improved public health protection by setting priorities and administrative deadlines for actions on chemicals of concern, integrating chemicals management activities in the country enabling the selection of the most appropriate federal law for action; and improving research, and surveillance activities (Government of Canada, 2020).
Risk management strategy for lead (RMSL), 2013
The RMSL was developed after research showed that while the blood Pb levels of Canadians had declined sharply over the past 40 years, its negative health effects still manifested at very low concentrations (Health Canada, 2013). In response, Health Canada initiated a rigorous review of existing toxicological and toxicokinetic data on Pb to further reduce its exposure to Canadians with a focus on particularly vulnerable special population groups. This created a need for improved Pb risk management to continue to support existing government control measures under RMSL. Risk management measures that are part of the strategy include water characterisation, corrosion control, infrastructure replacement, administrative controls and public education. The framework contains key elements such as a risk assessment paradigm, tiered and iterative approach, WoE, stakeholder consultation, risk communication, and uncertainty analysis.
Australian environmental health risk assessment (EHRA): guidelines for assessing human health risks from environmental hazards, 2012
The EHRA framework combines quantitative risk assessment and risk management and is used for evaluating health risks caused by environmental hazards. The EHRA can be either generic or situation-specific and is critical in informing the risk management process. In instances such as defining environmental standards for additives or contaminants in environmental media or deciding whether specific chemicals are safe for use, generic risk assessments may be undertaken (enHealth Council, 2012). Where there is an actual or possible environmental hazard, such as contaminated soil or industrial pollutants from a proposed facility, situation-specific risk assessments can be performed. Uncertainty analysis is conducted at all levels of risk assessment and the MCDA (economic, social and political aspects, stakeholder engagement, and risk communication) is also incorporated into the framework. Monitoring and evaluation of the effectiveness of actions are also undertaken. This paradigm addresses the health needs of underprivileged subpopulation groups like the elderly, children, gender and lifestyle status among others (Jardine et al., 2003).
Framework for the management of contaminated land (FMCL), 2010
The FMCL describes standards for the practical implementation of incentives under the Waste Management Act in South Africa for cleaning contaminated sites. The site assessment protocol is based on the concept of pathway-receptor linkages and is used to provide a conceptual risk-based decision support tool for use by promoters and regulators (Department of Environmental Affairs, 2010). The target contaminants include potentially toxic metals, organics, petroleum organics and asbestos among others. Due to many factors, including the high costs of treatment resources, the FMCL is essentially a multi-level and risk-based approach to address remediation coherently across South Africa. The RMF gives decision-making guidance on how to deal with polluted land and is premised on important criteria for successful implementation. The FMCL’s primary components include quantitative risk assessment, a tiered and iterative methodology, WoE, and MCDA.
Registration, evaluation, authorisation, and restriction of chemicals (REACH), 2007
The framework protects human health and the environment from chemical risks and applies to all chemicals that are manufactured, imported, marketed or used within the EU. It regulates chemicals that are restricted in products under REACH including Pb, Azo dyes, dimethylformamide, polycyclic aromatic hydrocarbons, perfluorooctane sulfonic acid, phthalates and nickel among others. However, other chemicals that are partly or fully exempted from REACH regulation include radioactive substances, chemicals under customs supervision, non-isolated intermediates, transport of substances and wastes, medicinal products for human or veterinary use, food or feeding stuff, plant protection products, and biocides. The regulation obligates the industry to collect chemical safety data and use it to develop risk management plans, which are then communicated to all stakeholders (Jardine et al., 2003; US DoD, 2019). For the registration of a chemical, the industry provides a chemical safety assessment of potential risks to the European Chemicals Agency (ECHA) and proposes management measures if necessary (ECHA, 2021). REACH manages chemical risks through the imposition of restraints on manufacturing, marketing, chemical use, and permits to ensure that toxic substances of very high concern are identified and used safely while encouraging substitution with less risky alternatives (Moore et al., 2022). In the assessment phase, the ECHA and the EU member states assess the chemical dossier for compliance and carry out substance evaluation to verify the risk assessments and conclusions (ECHA, 2021). Since 2007, over ten annual reviews of the framework have been carried out to evaluate its effectiveness and to verify if objectives were being met, while the EU periodically carries out policy audits of the framework. The WoE approach is applied in chemical evaluation, especially in exposure assessment of properties like adverse environmental and human health properties like carcinogenicity, reproductive toxicity, persistence and bio-accumulative properties. Uncertainty is also provided for the ‘use of conservative assessment factors in exposure and effects evaluations or qualitatively in the classification of substances’ (Moore et al., 2022). The framework also incorporates MCDA and tiered and iterative approaches in chemical evaluation.
Nano risk framework (NRF), 2007
The NRF is a voluntary framework that assists companies, governments, public-interest non-governmental organisations, academia and the general public to assess and discuss the potential risks of engineered nanomaterials (ENMs) (Wang et al., 2021). ENMs can cross cell membranes, encumber cell activity and accumulate in organs, resulting in neurotoxicity, and genotoxicity, among others (US EPA, 2021). The framework comprises six steps covering the description of the material and the intended application; the material’s lifecycle profiling; the assessment of risks involved; assessing risk management options; deciding and documenting measures; and regularly reviewing new information and adapting actions accordingly (Environmental Defence and DuPont, 2007). The NRF does not have the element of the WoE approach; however, it has an in-built tiered approach that allows the early use of incomplete or uncertain information to facilitate subsequent data collection and analysis (US EPA, 2021).
Canadian environmental protection act (CEPA), 2004
The CEPA aims to decrease environmental pollution and safeguard public health via research and monitoring, risk assessment, risk management, and compliance promotion and enforcement (Government of Canada, 2004; Registry CEPA, 2004). In scientific research and monitoring, the WoE method is applied, and it entails taking into consideration evidence of adverse health effects and environmental contamination (OECD, 2019b). Other important components of the framework include tiered and iterative evaluation, MCDA, and uncertainty analysis. Substance manufacturers are required to disclose specified information for risk assessment purposes. When it comes to toxic chemicals, the government implements risk management measures such as prohibiting their manufacturing or import within a specified time frame.
Discussion
While frameworks such as CEPA, REACH, FMCL and EHRA are not flawless, they have incorporated most OECD principles and have greatly contributed to the improvement of human health and environmental protection while some RMFs have significant gaps that need to be addressed to improve their effectiveness and usefulness. Notwithstanding the achievement of significant milestones under TSCA (which include the forcing of substantiation of Confidential Business Information claims) and the conclusion of guidelines on chemical risk evaluation (US DoD, 2019), the framework provides for the exemption of manufacturers from submitting toxicity data or can request limited data to fast-track approvals that can create potential health problems (Gabriela et al., 2022). One milestone of the AICIS is that it reduced the number of industrial chemical categories to 6 from 30 that were under its predecessor, the National Industrial Chemicals Notification and Assessment Scheme, so this has administratively simplified the assessment process. The AICIS has been criticised for ‘increased introducer self-regulation and lack of reporting requirements and monitoring tools which are not systematically applied and updated’ (Gabriela et al., 2022). On the other hand, the GSC’s non-prescriptiveness encourages organisations and stakeholders to be accountable and responsible in developing and selecting sustainable chemicals that protect human health and the environment. Nonetheless, the GSC is not a statutory creation, and compliance enforcement may be problematic as it bestows responsibility for compliance on individuals, organisations and stakeholders. The RMSL performance review process has assisted the government in effectively evaluating progress in protecting public health from the effects of Pb exposure (OECD, 2018); however, Cooper and McClenghan (2002) criticised the strategy, stating that the assertion made under RMSL that Pb exposure is not a risk for children from consumer products such as Pb-containing jewellery because that they are not ‘intended for children’ is not only irrational but irresponsible. The strategy has also been criticised for allowing the Liquid Coating Materials Regulation to permit the use of leaded paint in interior spaces on the basis that it is not ‘frequented by children’. On the other hand, the GSC is similar to the NRF in that it is a soft law that provides for ‘self-regulation and public engagement’ and is ‘framed as means for technology development and is socially robust’ (Kurath, 2010). The implementation of such frameworks can present compliance glitches that vitiate the attainment of desirable preventive and control outcomes.
Although risk assessment, a precursor to risk management has been instrumental in reducing the number of environmental and public health risks caused by toxic chemicals over the last 50 years, it has limitations in that it works optimally for chemical agents that have already been released into the environment, whose ‘nature and degree of exposure is better understood and can be monitored’ (NRC, 2011). Risk assessment in public health is beneficial in secondary prevention that is when a problem has already occurred rather than preventing it from occurring. Other shortcomings of risk assessment paradigms, according to the NRC (2009), include their failure to scientifically confirm low-level concerns; significant delays in risk assessment, mainly at the national level; and a lack of data on hazard or exposure for quantitative risk assessment. The ‘toxicological basis underlying risk assessment presented by agents such as nanoparticles or endocrine disruptors’ (NRC, 2011) is also under scrutiny. Also, RMFs are largely used in developing countries and barely or minimally used in developing countries. Previous studies on the paucity of RMF use have linked this to the ‘cultural theory of risk, roles of experts as policy advisors, psychometric paradigms, different risk assessment paradigms, and participatory approaches to risk assessment and risk management in different jurisdictions’ among other reasons (Clahsen et al., 2019). Also, the continuous development of new substances or chemicals with new and diverse properties poses challenges in the development and use of RMFs (Gabriela et al., 2022). On the one hand, the process of assessing chemical risks and weighing their toxicity to make informed decisions is not only a challenge but inherently uncertain, especially where new data and methods are continuously evolving (de Bruin et al., 2022; Moore et al., 2022). There is a great need for science and technology transfer to assist developing countries to develop and promote the use of risk management frameworks to improve the protection of their environments and public health. This can be done by helping them to ‘establish national surveillance and chemical residue monitoring systems, harmonising risk assessment and management systems across jurisdictions, carrying out chemical review efficiency, and developing regular performance review mechanisms to ensure that human health is protected’ (Gabriella et al., 2022). We propose that the direction for future research focus on producing more peer-reviewed work on risk management frameworks to increase the amount of scholarly work on the subject and contribute to improved global environmental and public health protection from toxic industrial chemicals.
Conclusions
While RMFs differ in their purposes, applications and features, they have several common elements such as risk assessment paradigms, tiered and iterative approaches, stakeholder involvement, weight of evidence, multi-criteria decision analysis, and uncertainty analysis among others. There is a need to promote the use of RMFs at national levels in developing countries that are currently limited through technology and knowledge transfer, provision of development, and financial assistance from the developed countries, which have made great strides in improving the environment and public health protection of their people.
Supplemental Material
Supplemental Material - A systematic review of the risk management frameworks for potentially toxic chemical elements
Supplemental Material for A systematic review of the risk management frameworks for potentially toxic chemical elements by Sheunesu Ngwenya, Ntsieni S Mashau, Sphiwe E Mhlongo and Afsatou N Traoré in Toxicology and Industrial Health
Supplemental Material
Supplemental Material - A systematic review of the risk management frameworks for potentially toxic chemical elements
Supplemental Material for A systematic review of the risk management frameworks for potentially toxic chemical elements by Sheunesu Ngwenya, Ntsieni S Mashau, Sphiwe E Mhlongo and Afsatou N Traoré in Toxicology and Industrial Health
Footnotes
Acknowledgements
Special thanks are due to Prof. Wilfred Nunu from the National University of Science & Technology (NUST) in Zimbabwe for his invaluable guidance offered to the Principal Investigator during the preparation of this article.
Author contributions
SN conceptualised the review study in partial fulfilment of the requirements of the PhD study. NSM is the Principal Promoter of the PhD study while SEM and ANT are Co-promoters. The three co-promoters equally contributed by guiding the student in the preparation of the manuscript. All authors read and approved the final manuscript.
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The study is part of a PhD work for the first author who is financially supported by the Kwekwe City Council under the Staff Development Support Program and University of Venda under the South African Library and Information Consortium (SANLiC) agreement for the publication of this article.
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References
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