SETAC Globe - Environmental Quality Through Science
  12 September 2013
Volume 14 Issue 9

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Selecting Materials to Achieve Reduced-Toxicity Products (SMART-Products)

Oladele A. Ogunseitan, Carl W. Lam and Julie M. Schoenung (University of California, Irvine and Davis)

The international diffusion of ideas, products, commerce and manufacturing practices has led to increasing demand for high-volume, user-friendly, multi-capacity, durable and economically affordable products. Designers and manufacturers have responded through rapid innovations in materials science and engineering, electronics, product design and supply chain networks.

One of the unforeseen consequences of product globalization is the accumulation of new categories of high-tech hazardous solid waste in regions of the world that lack appropriate infrastructure to collect, sort and recycle such waste to avoid the concentration of toxicity risk in unprotected populations and ecosystems.  In certain cases, serious pollution of the environment and adverse human health impacts have resulted from toxic materials during manufacturing and after disposal of products at the end of their useful lives.

Policy makers at the regional, national and international levels have responded to the globalization of toxic risks with numerous but disparate legislations and regulations. It is doubtful that policy-making will catch up soon enough to effectively prevent diseases and disabilities among the most vulnerable populations. Therefore, it is imperative that manufacturers are also fully engaged in the selection of alternative materials to reduce the toxicity of their products.

In their recently featured IEAM article, Lam and colleagues (2013) working at the University of California, Davis and Irvine, describe some of their efforts to chart the path for such industrial engagement by working with RIO Tronics, a manufacturer of utility meters, to identify and rank toxic materials and components in the products with the goal of redesigning them to achieve reduced toxicity. One of the major advantages of collaboration between manufacturing industries and university researchers is access to potentially proprietary information. In this case, RIO Tronics provided the complete Bill-of-Materials (BoM) for components in its products, including domestic meters for natural gas and electricity.

The BoM database and information on material mass-per-unit provided by component manufacturers or estimated from component dimensions were then used as input data for a toxicity-rating numerical model called the Toxicity Potential Indicator (TPI). TPI was originally developed at the Fraunhofer Institute in Germany. The advantage of TPI over other publically available models for rating the toxicity risks associated with products includes the integration of ecological and human health impacts in an expanded rating scale that supports the quantification of fine-level differences between materials.

The LAM et al. (2013) paper featured in IEAM includes a TPI innovation that addresses the challenging fact that many manufactured products often consist not only of several individual chemical elements but also of compounds, mixtures and alloys. Hence “Component TPI” was derived from “Material TPI” by aggregating toxicity scores either through a “sum-weighted” method that produced a rating for a single component based on the total sum of the mass-weighted toxicity potential score for each material in the product component; or the “max component” method that is based on the highest toxicity potential rating among different materials present in a component. These two methods give manufacturers the opportunity to pinpoint specific actions needed to reduce the overall toxicity rating of their product, either by completely replacing a component with high “sum weighted” TPI or to remove a particular material with high TPI from a component.

The results of the research revealed that two well-known toxicants, acrylonitrile-based polymers used in shell and grommet components and polyvinyl chloride (PVC) used in the plastic housing and cable wire covers, contributed most to the toxicity profiles of the RIO Tronics utility meters.  The monomeric chemicals upon which these materials are based, are known carcinogens. Somewhat surprisingly, stainless steel, used in brackets, was also identified as a major contributor to the toxicity profile of the products investigated, largely because of the content of nickel and chromium. In particular, chromium in steel can generate highly toxic hexavalent chromium in fumes during the processing of stainless steel. Other notorious toxic materials such as tin-lead (Sn-Pb) solders used in printed wiring boards were also identified as a major contributor to the product toxicity profiles.

The ultimate goal of Lam and colleagues’ research is to provide guidance for manufacturing reduced-toxicity products through the replacement of particular materials or components with less toxic alternatives. In this case, high-density polyethylene (HDPE) and polypropylene are suggested as less toxic alternatives for replacing acrylonitrile-based polymers and PVC, whereas, aluminum-based alloys are suggested as alternatives to stainless steel. Several regulations, including the European Union’s Restriction of the Use of Certain Hazardous Substances (RoHS), have already targeted lead (Pb) for phase-out and alternatives to Sn-Pb solder materials are already commercially available. In addition to the successful assessment and recommendation of less toxic alternative materials, the work also revealed opportunities for further research to improve numerical models for rapid assessment of materials toxicity profiles. For example, gaps remaining in the toxicological data on polymeric substances and alloys necessitated the use of approximate values based on empirical data on related monomers and elemental composition of alloys, even though the physiological responses to these materials may differ markedly.

Access to the BoM data for commercial products may be difficult for investigators aiming to pursue product-toxicity reduction strategies through alternatives assessment. Some jurisdictions have proposed controversial laws, such as California’s Safer Consumer Products regulations (also known as the Green Chemistry Initiative), that mandate the disclosure of toxic substances in products sold within their borders and the chemical identity of alternative materials proposed as less-toxic replacements. To effectively implement such laws, it will be important to provide safeguards against inadvertent disclosure of proprietary information to competing manufacturers, while still facilitating research and complying with consumers’ right-to-know laws.

Advocates for less-toxic consumer products point to the burden of chronic diseases in human populations and ecological disasters as the rationale for the urgent need to standardize methods for toxicity screening of materials and to harmonize international policies that address manufacturing practices and the classification and disposal of hazardous wastes. By focusing on a specific product, collaborating with the manufacturer and exploring various materials toxicity screening models, this work provides a unique framework that advances design-for-environment strategies for envisioning and creating truly “smart” products.

Literature cited
Lam, C., Lim, S.R., O.A. Ogunseitan, A.A. Shapiro, J-D.M. Saphores, A. Brock, and J.M. Schoenung (2013) Integrating Toxicity Reduction Strategies for Materials and Components into Product Design: A Case Study on Utility Meters. Integrated Environmental Assessment and Management, 9 (2): 319 – 328. DOI: 10.1002/ieam.1384.

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