Nanotechnology and the Environment - Chapter 11 (end)

11 Balancing the Risks and Rewards Kathleen Sellers ARCADIS U.S., Inc. CONTENTS 11.1 Life Cycle Analysis (LCA) .........................................................................249 11.2 Adaptations to Nanotechnology ..................................................................250 11.2.1 Screening Approach .........................................................................250 11.2.2 Nano Risk Framework .....................................................................251 11.2.3 XL Insurance Database Protocol .....................................................253 11.3 Summary and Conclusions .........................................................................257 References ..............................................................................................................262 Nanotechnologies offer broad promise to use raw materials and energy more eff i-ciently. Some applications offer medical hope or environmental protection. These rewards, however, must be balanced against the potential risks from manufacturing, using, and disposing of products containing nanomaterials. This chapter discusses tools to evaluate the balance between potential risks and rewards, beginning with the concept of Life Cycle Analysis (LCA). 11.1 LIFE CYCLE ANALYSIS (LCA) Life Cycle Analysis (LCA), an integral part of the ISO environmental management standards (ISO 14040), uses a mass and energy balance to determine the potential effects of product manufacture on human health and the environment. More for-mally [1], “LCA is a technique for assessing the environmental aspects and potential impacts associated with a product by: • Compiling an inventory of relevant inputs and outputs of a product system; • Evaluating the potential environmental impacts associated with those inputs and outputs; • Interpreting the results of the inventory analysis and impact assessment phases in relation to the objectives of the study. 249 © 2009 by Taylor & Francis Group, LLC 250 Nanotechnology and the Environment LCA studies the environmental aspects and potential impacts throughout the product’s life (i.e., cradle to grave) from raw materials acquisition through production, use and disposal.Thegeneralcategoriesofenvironmentalissuesneedingconsiderationinclude resource use, human health, and ecological consequences.” The formal process of LCA uses very specific information to quantify the con-sequences of a particular product’s manufacture, use, and disposal. In the develop-ing world of nanotechnology, such specific information can be difficult to ascertain. Many manufacturing processes are still in scale-up; often, and understandably, these processes are proprietary. Further, as discussed in previous chapters of this book, relatively little quantitative information is known about the potential releases of nanomaterials during the use and disposal of products based on nanotechnology, and the toxicity of those releases if they occur. Relatively few LCAs of nanotechnol-ogy have been published [2–14]. Focusing primarily on safety and environmental protection, several stakeholders have developed paradigms to evaluate the balance between the risks and benef its of nanotechnology. 11.2 ADAPTATIONS TO NANOTECHNOLOGY Three approaches to evaluating nanotechnology are described below: 1. Screening approach developed at a workshop sponsored by The Pew Chari-table Trusts, the Woodrow Wilson International Center for Scholars/Project on Emerging Nanotechnologies, and the European Commission [3] 2. The Nano Risk Framework developed by the Environmental Defense – DuPont Nano Partnership [4] 3. The XL Insurance Database Protocol, applied to nanotechnology by researchers at Rice University, Golder Associates, and XL Insurance [8] The brief summaries that follow illustrate the general mass balance methodolo-gies; critical features that characterize risks; and the uncertainties in evaluating risks from newly developed materials for which little information may be available. These approaches represent two different points of focus: the first two approaches focus on the nanomaterials themselves, and the third approach focuses on the processes used to manufacture the nanomaterials. Either or both of these focal points may be appropriate for balancing the risks and rewards of a particular nanotechnology, depending on the manufacturing process, materials used in that process, quantities of the nanomaterial used in a commercial product, and the potential for exposure (including whether nanomaterials are free or f ixed). Of necessity, this chapter cannot present all the nuances of these models, and the reader is encouraged to consult the cited reference materials for more information. 11.2.1 SCREENING APPROACH The 2006 workshop “Nanotechnology and Life Cycle Assessment: A Systems Approach to Nanotechnology and the Environment” brought together stakehold-ers from industry, government, academia, and nongovernmental organizations to talk about the life cycle analysis of nanomaterials [3]. Recognizing the limitations © 2009 by Taylor & Francis Group, LLC Balancing the Risks and Rewards 251 of applying rigorous LCA to nanotechnology, workshop participants developed an alternative approach. This five-step screening process combines elements of LCA, risk analysis, and scenario analysis: 1. Check for obvious harm. Consider compliance with health, safety, and environmental regulations using conventional analyses. 2. Perform a traditional LCA, excluding toxicity impact assessment. Instead, focus on potential impacts such as global climate change, eutrophication, etc. If the benefits appear to be substantial, then proceed; if not, stop prod-uct development. 3. Perform a thorough toxicity and risk assessment (RA) of the product. The assessment must consider possible exposures in each life-cycle stage. 4. Combine the results of Steps 2 (LCA) and 3 (RA) to determine overall impacts. 5. Perform a scenario analysis to extrapolate the results of Step 4 to large-scale usage (e.g., look at the implications of using a very small quantity of a nanomaterial in billions of products). The authors of this approach acknowledge its current limitations: unavailability of proprietary information, limited hazard and exposure data, and lack of standard tools to combine LCA and RA (Step 4). 11.2.2 NANO RISK FRAMEWORK Environmental Defense, a U.S.-based non-profit environmental advocacy group, and the multi-national chemical company DuPont collaborated to develop the Nano Risk Framework [4]. In the words of the developers, “The purpose of this Framework is to def ine a systematic and disciplined process for identifying, managing, and reducing potential environmental, health, and safety risks of engineered nanomaterials across all stages of a product’s ‘life cycle’ — its full life frominitialsourcingthroughmanufacture,use,disposalorrecycling,andultimatefate. The Framework offers guidance on the key questions an organization should consider in developing applications of nanomaterials, and on the information needed to make sound risk evaluations and risk-management decisions. The Framework allows users flexibility in making such decisions in the presence of knowledge gaps — through the application of reasonable assumptions and appropriate risk-management practices. Further, the Framework describes a system for guiding information generation and updating assumptions, decisions, and practices with new information as it becomes available. And the Framework offers guidance on how to communicate information and decisions to key stakeholders.” The Framework differs from LCA, as def ined in Section 11.1, in that it focuses on potential environmental, health, and safety risks. It does not consider resource inputs. The Nano Risk Framework comprises six steps, as described briefly below. Step 1: Describe Material and Application.Thisstepgeneratesanoverviewofthe physical and chemical properties of the material, sources and manufacturing © 2009 by Taylor & Francis Group, LLC 252 Nanotechnology and the Environment processes, and possible uses. The overview includes existing materials that the nanomaterial may replace, and bulk counterparts of the nanomaterial. Step 2: Profile Life Cycle(s). This step includes three components. Each relies on compiled “base set” data to def ine the characteristics and hazards of a nanomaterial. Where those data are not available, the Framework suggests using reasonable worst-case default values or assumptions. Analysts can replace those default values with actual data as they become available. This approach will provide an initially conservative estimate of risk that can be refined if appropriate. a. Profile Life Cycle Properties. Develop base set data on physical and chemical properties of the nanomaterial, including property changes throughout the full product life cycle. (See Section 2.3.2.) b. Profile Life Cycle Hazards. Characterize the potential hazards to human health, the environment, and safety from exposure to this mate-rial throughout its life cycle. In this step, analysts compile four base sets ofdata:healthhazards,environmentalhazards,environmentalfate,and safety. Standard methods are not yet available to measure some of these base set parameters for nanomaterials. Base set data on health hazards include short-term toxicity, skin sensitization/irritation, skin penetra-tion, genetic toxicity tests, and other data. Base set environmental haz-ard data include acute aquatic toxicology and terrestrial toxicology (i.e., earthworms and plants), and may include additional data if needed. Recommended base set data on the environmental fate of nanomateri-als include physical-chemical properties, adsorption-desorption coef-ficients (soil or sludge), and nanomaterial aggregation or disaggregation in applicable exposure media. They also include data pertaining to per-sistence, characterizing biodegradability, photodegradability, hydroly-sis, and bioaccumulation. Finally, base set safety hazard data include flammability, explosivity, incompatibility, reactivity, and corrosivity. c. Profile Life Cycle Exposure. Quantifythepotentialforhumanandenviron-mentalexposuresthroughouttheproductlifecycle.Thisdefinitionisdecep-tively simple. The analyst must consider opportunities for direct contact or release to the environment at multiple stages: manufacture, processing, use, distribution/storage, andpost-usedisposal, reuse,orrecycling. Step 3: Evaluate Risks. The information collected in Step 1 and Step 2 is com-bined to estimate the risks to human health and the environment for each life cycle stage. Depending on the availability of base set data, the initial estimates may range from qualitative to quantitative. The analyst must determine gaps in the life cycle prof iles and either generate data to f ill the gaps or make reasonable worst-case assumptions. Step 4: Assess Risk Management. For each life cycle stage, determine the actions needed to reduce and control risks from known and reasonably anticipated activities. These actions could include product modifica-tions, engineering or management controls, protective equipment, or risk communication such as warning labels. The product developer might even decide to abandon the product. © 2009 by Taylor & Francis Group, LLC Balancing the Risks and Rewards 253 Step 5: Decide, Document, and Act. At this stage, a review team critically analyzes the results to decide how to proceed. The team documents and communicates the results, and determines the course of action for refining or updating the conclusions. Step 6: Review and Adapt. This step ensures that the risk characterization and risk management protocols continue to evolve as new information becomes available. The authors of the Framework developed several case studies to test the Frame-work. Three of the case studies pertained to materials targeted in this book: nano titanium dioxide, zero-valent iron, and carbon nanotubes. Tables 11.1 through 11.3 summarize those case studies [5–7]. 11.2.3 XL INSURANCE DATABASE PROTOCOL The preceding adaptations of LCA focused on the nanomaterials themselves. In con-trast, researchers at Rice University, Golder Associates, and XL Insurance focused on the materials and processes used to manufacture nanomaterials [8, 9]. Their risk analysis used the XL Insurance Database Protocol, which is used to calculate insur-ance premiums for the chemical industry, to examine the industrial fabrication of five nanomaterials. Those included three of the nanomaterials discussed at length in this book: single-walled carbon nanotubes, C60 fullerenes, and nano-titanium diox-ide. The risk analysis entailed the following steps, as shown in Figure 11.1. 1. Identify process and materials: a. Determine synthesis methods, based on process currently used for com-mercial production or on processes likely to be scaled up for commercial production. b. Create block f low diagram showing inputs to and outputs from the man-ufacturing process, omitting energy use. 2. Characterize materials and processes: a. Collectandcharacterizedataonmaterialproperties.Notethatthesedata pertain to the raw materials used to manufacture the nanomaterials and the byproducts of fabrication; they do not pertain to the nanomaterials themselves. Critical data include toxicity, as expressed by LC50 and LD50, water solubility, log Kow, flammability, and expected emissions. These initial data may trigger the need for additional information according to the protocol, so characterization of material properties is an iterative step. The protocol uses the collected data on material prop-erties to rank substances by relative risk. b. Define manufacturing processes according to characteristics that deter-mine risks, that is, temperature, pressure, and enthalpy. Then, for each point in the process and for each of the substances involved in the manufacturing process (except the nanomaterial), identify these char-acteristics: amount present, role in the process, physical phase at the temperature and pressure specified; and potential emissions. This step allows the model to calculate the probability of exposure from an in-process accident and from normal operations. © 2009 by Taylor & Francis Group, LLC ... - tailieumienphi.vn