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Reform No. 5 of the Louisville Charter addresses the pervasive lack of publicly available information about the effects of many chemicals on human health and the environment. This lack of information persists for the majority of chemicals in commerce because the current laws in the United States do not systematically require it to be produced or motivate its voluntary production. These information gaps undermine the effectiveness of the existing environmental statutes, the liability system, the ability of the market to stimulate development of safer chemicals and, if they persist, complete realization of the other elements of the Louisville Charter. Therefore, this Reform calls for manufacturers of chemicals to be required to provide health and safety information as a condition for placing and keeping a chemical on the market.

Close to 400 manufacturer-identified nanotechnology-based consumer products are now on the market (Woodrow Wilson International Center for Scholars 2007). Using increasingly sophisticated levels of control over the assembly of atoms and molecules to form substances and devices, nanotech companies are exploiting the size-dependent properties of nanostructured materials for applications ranging from cosmetics to fuel cells (Colvin 2003). Yet our understanding of the potential toxicity of nanoparticles remains rudimentary (Colvin 2003; Oberdorster et al. 2005b). To determine whether the unique chemical and physical properties of new nanoparticles result in specific toxicologic properties, the nanotechnology community needs new ways of evaluating hazard and ultimately assessing risk (Nel et al. 2006). These new strategies must also consider the complexities inherent to studies of chemical mixtures. This workshop’s assessment of the novel aspects of nanotoxicology built on knowledge gained from prior workshops. In 2004, scientists from many different areas of research came together in Gainesville, Florida, to discuss the emerging field of nanotoxicology (Bucher et al. 2004). They described the challenges facing toxicologists in rigorously characterizing the new materials and in understanding how nanostructures might differentially influence toxicity. This theme was further elaborated in a seminal article by Oberdorster et al. (2005a), which provides a general framework for evaluating the toxicity of engineered nanoparticles. More detailed questions regarding exactly how to evaluate the potential health impact of engineered nanoparticles remain. This report captures some of the critical information that is still needed to understand the human health impact of engineered nanoparticles and defines mechanisms to begin to acquire this information. Building on the insight from those previous meetings and published articles—that the structure of nanoparticles brings many new challenges to toxicological evaluation—workshop participants were asked to identify both factors that make nanoparticles different and information specific to these differences that is needed to assess nanoparticle hazards. The group was further charged with making recommendations on how to gather and use that additional information to evaluate health hazards associated with these scale-specific properties. Because of the short duration of this workshop, the scope was limited to consideration of toxic properties of nanoparticles. A full evaluation of human health risks will require development of sufficient techniques for assessing exposure to nanoparticles in addition to consideration of toxicity. E. Silbergeld of Johns Hopkins University opened the workshop with a presentation that explored ways of thinking about and evaluating the potential hazards of nanoparticles. She emphasized focus on the nanoscale interactions that take place in the normal functioning of biological systems in order to understand the positive and negative effects that engineered nanoparticles could have on humans. For example, because the immune system functions through nanoscale intercellular communications, Lynch et al. (2006) hypothesized that engineered nanoparticles can disrupt these processes with deleterious end results. Specifically, they considered unique interactions between native proteins and the highly curved surfaces of nanoparticles, speculating that the protein shape could be modified after binding. This deformation could expose amino acid residues that are normally buried in the core of the protein, and the immune system would then recognize these newly exposed residues as “cryptic epitopes” and mount an unwanted immune response. A 2005 study by Zhao et al. (2005) predicted that DNA repair, another vital biological system that operates at the nanoscale, is also susceptible to modification by nanoparticles. Specifically, this study found through computer modeling that the association in water between C60 and DNA is stronger than the association between two C60 molecules. Therefore, when DNA is damaged, fullerenes can occupy the damaged site, possibly impeding the self-repairing processes of the double-strand DNA and thus negatively impacting the structure, stability, and biological functions of DNA molecules. These unique interactions between nanoparticles and biological systems afford great promise for medicinal applications, but the unintended consequences could be harmful. We know, for instance, that natural and unintentionally produced ultrafine particulate matter, which is in the same size range as engineered nanoparticles, can carry a broad range of compounds, including polycyclic aromatic hydrocarbons, endotoxin, metals, and other toxic chemicals. These complexes can then damage biological systems (Penn et al. 2005; Schwarze et al. 2006). Gutierrez-Castillo et al. (2006) found that particulate matter with chemicals adsorbed to the surface can damage DNA. These examples suggest that the myriad possible interactions between nanoparticles and harmful environmental chemicals may lead to unique exposures and health risks. Conventional knowledge about exposure assessment, fate and transport, and current computer models is not necessarily applicable to nanoparticles. But alternative methods such as toxicogenomic technologies, lower-order animal and in vitro testing, and ultimately the development of structure activity models could prove useful, providing more rapid testing than traditional animal toxicology tests and allowing for explicit experimental design based on mechanism. The development of alternative methods is an ambitious but necessary goal if the large and growing numbers of nanoparticles are to be adequately assessed for toxicity. Silbergeld ended her presentation with a charge for the group: to frame its dialogue both to inform the industry on how to look before leaping into the production of new nanoparticles and to provide guidance for those who have already taken that leap.

Nanotechnology, the design and manipulation of materials at the atomic scale, may well revolutionize many of the ways our society manufactures products, produces energy, and treats diseases. Innovative nanotechnology products are already reaching the market in a wide variety of consumer products. Some of the observed properties of nanomaterials call into question the adequacy of current methods for determining hazard and exposure, and for controlling resulting risks. Given the limitations of existing regulatory tools and policies, two distinct kinds of initiatives are urgently needed: first, a major increase in the federal investment nanomaterial risk research, and second, rapid development and implementation of voluntary standards of care pending development of adequate regulatory safeguards. The U.S. government should increase federal funding for nanomaterial risk research under the National Nanotechnology Initiative to at least $100 million annually for the next several years. Several voluntary programs are currently at various stages of evolution, though the eventual outputs of each of these are still far from clear. Ultimately, effective regulatory safeguards, harmonized globally, are necessary to provide a level playing field for industry while adequately protecting human health and the environment.

Nanotechnology has the potential to deliver considerable benefits to society. Some of the properties of nanomaterials, however, call into question the adequacy of current methods for determining hazard and exposure and for controlling risks. Given the limitations of existing regulatory tools and policies, three distinct initiatives are urgently needed: first, a major increase in nanomaterial risk research; second, rapid development and implementation of voluntary standards of care; and third, development of adequate regulatory policies on nanomaterial risk management.

▪ Abstract This paper reviews and analyzes the major recent North American studies that have compared on an environmental basis the major options used to manage the materials that comprise municipal solid waste (MSW). The reviewed studies provide quantitative comparative information on one or more of the following environmental parameters: solid waste output, energy use, and releases of pollutants to the air and water. The review finds that all of the studies support the following conclusions: Systems based on recycled production plus recycling offer substantial system-wide or “life-cycle” environmental advantages over systems based on virgin production plus either incineration or landfilling, across all four parameters examined. Only when the material recovery or waste management activities are analyzed in isolation—which does not account for the system-wide consequences of choosing one system option over another—do the virgin material–based systems appear to offer advantages over recycled production plus recycling.

Pulverized-coal pyrolysis experiments have been conducted in an inert gas, Ar, under conditions of high heating rate (10 5 –10 6 K/s), and high temperature (2000–2800 K). The dry-ash-free (daf) mass loss was calculated on the basis of a seeded-tracer, tungsten carbide powder, and on the basis of a natural tracer, titanium. The former method gave consistently higher daf mass loss. The data indicate that under these test conditions mineral elements in the coal, including some major and minor species, leave the parent coal and therefore cannot serve as a tracer for the determination of mass loss as is often done conventionally. The loss of some mineral elements is correlated with the daf mass loss. Criteria for the selection of a seeded tracer are discussed.