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Scientific, policy and consumer concerns regarding the health and environmental impacts of toxic substances have resulted in increased pressures to restrict potentially hazardous chemicals in processes and products.1 However, selecting chemical alternatives without regard to their hazard profiles can have regrettable consequences when substitutes are as toxic or are even more toxic than the chemicals they replace. Examples of regrettable substitutions include flame retardants (eg, substituting tris(1,3-dichloro-2-propyl) phosphate for polybrominated diphenyl ether), solvents (eg, substituting n-propyl bromide for methylene chloride and trichloroethylene (TCE)) and replacements for endocrine disrupting plastics components (eg, substituting bisphenol-S for bisphenol-A).2 These mistakes occur, in part, because performance and cost are elevated over health and safety in chemical selection decisions. They also occur because the environmental health community has been slow to provide strategies and guidelines for identifying, evaluating and adopting alternatives that include a thoughtful examination of environmental health and safety alongside cost and performance considerations.
When public health scientists identify problematic chemicals, scientific justification for substituting that chemical based on identifying a safer alternative is rarely pursued. In a previous JECH commentary, we noted the challenges related to an over-reliance on studying environmental problems versus solutions in environmental health science, using the example of bisphenol-A.3 We argued that the ‘problem-centred’ approach to chemicals management is often reactive, extremely resource intensive, fosters extended debates over regulatory benchmarks, and inaction that benefits neither health nor innovation. This reactive approach is fortified by a number of factors including policies that require significant evidence of risk before action can be taken, which then focuses research and agency resources on risk assessment, risk management and enforcement; the lack of interdisciplinary collaboration between those designing molecules, materials, and products and those evaluating their risks; and the fact that many chemicals of concern have important functionality and cost benefits that are not easily replaced.
In response to challenges and limitations in this approach, there has been a significant growth in the science policy field of alternatives assessment. Alternatives assessment is defined as a process for identifying, comparing and selecting safer alternatives to chemicals of concern (including those in materials, processes or technologies) on the basis of their hazards, performance and economic viability.1 The goal of alternatives assessment is to support the informed transition to safer chemicals by comparing a range of options to substitute a chemical of concern—it is directly linked to decisions about adoption. This action-oriented process is different than the risk assessment process, which focuses on quantifying the risk (or safety) of a chemical for a specific hazard end point (eg, cancer) associated with a given level of exposure, but is not intrinsically linked to any action.
The value of the alternatives assessment approach is well demonstrated through the example of TCE, identified as a priority chemical under the revised federal Toxic Substances Control Act. TCE is a widely used solvent in degreasing operations, adhesives and electronics. It works exceptionally well as a degreaser, but is a known human carcinogen, developmental toxicant and neurotoxicant and is frequently found in hazardous waste sites.4–6 The US Environmental Protection Agency (EPA) spent millions of dollars and more than two decades conducting a risk assessment for TCE under its Integrated Risk Information System (IRIS) programme. US EPA has taken steps to reduce risks from TCE use in some processes and products and, in some cases, these actions have led to its regrettable substitution by n-propyl bromide, an even more potent carcinogen that remains unregulated.7
In contrast to this ‘problem-centred’ approach to addressing risks, the Massachusetts Toxics Use Reduction Act requires manufacturing firms to ask another set of questions about TCE—‘Is it necessary?’ and ‘Are there safer alternatives?’ These questions encourage companies to think about why they are using TCE, whether there are feasible safer options (alternative degreasers or process designs) that fulfil the same function, and the costs (handling, transportation, liability) associated with continued use of TCE.8 The law, combined with technical support to evaluate the performance and toxicity of alternatives and adoption support led to a 96% reduction in TCE use in manufacturing in the state, saving industry millions of dollars.9
In 2014, the US National Research Council (NRC) published its ‘Framework to Guide the Selection of Chemical Alternatives’.2 This seminal report outlines a set of steps for the alternatives assessment process that are adaptable to different decision contexts, data sources and inputs. The NRC framework builds on the field as it has emerged since the 1990s. Indeed, a recent review of 20 different alternatives assessment frameworks found consistency in the steps of the alternatives assessment methods with some important differences in how exposure, economics, performance and life cycle attributes are addressed.10
The NRC report helped to elucidate: (1) how alternatives assessment addresses exposure as compared with the standard risk assessment process; and (2) the importance of predictive toxicology data streams (eg, high throughput in vitro assays such as Tox 21 or in silico approaches) for addressing data gaps. The report noted that considerations of exposure should be included in alternatives assessments, ‘not to demonstrate “safe” levels of exposure’ but as an additional basis for comparing alternatives that is ‘focused on the intrinsic potential for exposure without physical or administrative controls’. Thus, consideration of physiochemical data, such as vapour pressure, solubility, and molecular size, as surrogates for direct exposure measures in the alternatives assessment process is essential as well as use characteristics that can elucidate potential routes of exposure. The NRC framework supports the generation and incorporation integration of data from predictive toxicology in alternatives assessment processes and encourages the integration of these data with more traditional data sources to reduce the need for expensive animal experimentation and to expedite informed decision-making. Finally, given that superior alternatives to certain chemicals or uses may not be available, the report recommends increased research and development in green chemistry solutions that eliminate the chemical and engineering design flaws that result in environmental and health hazards.
There is an increasing number of government and industry policies supporting alternatives assessment. Examples include: (1) the California Safer Consumer Products regulation that will require firms to undertake comprehensive alternative assessments for chemicals of concern in specific product uses,11 and (2) the European Union's Registration, Evaluation, and Authorization of Chemicals (REACH) regulation that requires an analysis of alternatives for firms seeking authorisation for continued use of Substances of Very High Concern.12 While the US EPA has encouraged alternatives assessment and safer chemistry through its voluntary Safer Choice programme, it remains to be seen whether the new premarket testing, assessment and risk management provisions under the revised Toxic Substances Control Act will provide a regulatory impetus for such activities. A review of existing regulatory mandates for alternatives assessment found that given the variety of contexts in which substitution decisions are made, overly detailed requirements and high standards of evidence can stymie the action orientation of alternatives assessment, leading to the paralysis by analysis that is often the case in risk assessment.2 In addition, alternatives assessment requirements need to be married with carefully designed incentives and disincentives as well as research funding that support the innovation in and adoption of safer chemistries. A recent report conducted for the European Chemicals Agency found that while mandates under REACH and other European legislation are important drivers for substitution, these have to be connected with adequate government resources, innovation support to firms, and education of government and industry professionals.13
The public and environmental health research, policy and practice communities have a critical role and responsibility to play in shaping the field of alternatives assessment by engaging in the development of policies, scientific methods, and practice that advance the thoughtful, effective assessment and adoption of safer chemistries. For example, given the speed with which decisions regarding substitutes often need to be made in industry, there is a critical need for improved rapid screening methods focused on adverse outcome pathways leading to pathophysiology that translates data from multiple types of toxicity testing into actionable data sets that can be useful for decisions on chemical design and application. Hence, the science and tools underlying the study of problems—rapidly characterising chemical hazards and exposures—will still play an essential role in evaluating solutions.
Nonetheless, this work cannot effectively advance in a vacuum. There is an important need to interface and collaborate with scientists who are researching and designing the chemicals and products of tomorrow—chemists and chemical/material engineers. Together, these communities can be a powerful voice for research, smart policy and investment, and action on safer chemistry that can overcome current systemic challenges to this field. We foresee a time when all public health scientists, chemists and chemical engineers are trained in the thought processes and specific practices that underpin alternatives assessment. Through these interdisciplinary collaborations, such as those undertaken by the non-profit Beyond Benign and the American Institute of Chemical Engineers, we can use our evolving knowledge about how chemical exposures may lead to health impacts to help inform environmentally conscious design criteria and curriculum for undergraduate and graduate chemistry and chemical engineering programmes. This will require changes in education and professional training as well as expanded collaborations and thinking. This evolution is critical to reaching our common goal of improving health with the innovation benefits of safer chemicals and products.
Competing interests None declared.
Provenance and peer review Commissioned; externally peer reviewed.
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