Life Cycle Assessment and Release Studies for 15 Nanosilver-Enabled Consumer Products: Investigating Hotspots and Patterns of Contribution

Increasing use of silver nanoparticles (AgNPs) in consumer products as antimicrobial agents has prompted extensive research toward the evaluation of their potential release to the environment and subsequent ecotoxicity to aquatic organisms. It has also been shown that AgNPs can pose significant burdens to the environment from life cycle emissions associated with their production, but these impacts must be considered in the context of actual products that contain nanosilver. Here, a cradle-to-gate life cycle assessment for the production of 15 different AgNP-enabled consumer products was performed, coupled with release studies of those same products, thus providing a consistent analytical platform for investigation of potential nanosilver impacts across a range of product types and concentrations. Environmental burdens were assessed over multiple impact categories defined by the United States Environmental Protection Agency’s Tool for the Reduction and Assessment of Chemical and Other Environmental Impacts (TRACI 2.1) method. Depending on the product composition and silver loading, the contribution of AgNP synthesis to the overall impacts was seen to vary over a wide range from 1% to 99%. Release studies found that solid polymeric samples lost more silver during wash compared to fibrous materials. Estimates of direct ecotoxicity impacts of AgNP releases from those products with the highest leaching rates resulted in lower impact levels compared to cradle-to-gate ecotoxicity from production for those products. Considering both cradle-to-gate production impacts and nanoparticle release studies, in conjunction with estimates of life cycle environmental and health benefits of nanoparticle incorporation, can inform sustainable nanoenabled product design

Material Flow Analysis of Carbon Nanotube Lithium-Ion Batteries Used in Portable Computers

Engineered nanomaterials are finding application in a wide range of consumer electronics. In particular, carbon nanotubes (CNTs) are candidate materials for use in enhancing the performance of lithium-ion battery anode and cathodes. However, past studies indicate that some toxicological effects exist for CNTs, although full evaluation may yet take time. Appraisals of material flows of potential products containing CNTs are useful for early recognition of environmental problems, for investment planning in production and waste management infrastructures, and for government policy formulation. This material flow analysis (MFA) study uses a stock dynamics and logistic model to forecast the technology transition from conventional Li-ion batteries in portable computers to CNT Li-ion batteries and the subsequent waste generation of CNTs in obsolete laptop batteries. State-specific recycling rates for electronic waste are projected to determine the quantities of CNTs in laptop batteries destined for recycling, incineration, or landfilling. As markets for CNT-enabled electronics begin to expand, United States collection and recycling facilities may consider establishment of new processes or controls to reduce the potential for CNT emissions and exposures