(544b) Nanomaterials: Occupational Exposure and Toxicity in Context

At the forefront of particulate health concerns are nanomaterials. This talk will propose some considerations for evaluating nanomaterials and their health effects.

1. Is the material as prepared truly â??nanoâ?? For example, even though SWNTs satisfy the accepted definition of being nanoscale in 2-dimensions, in practice and certainly as synthesized, they are highly coalesced into aggregates of micron in size.

2. What distinguishing characteristics apply to the particular nanomaterial? High surface area is a universal hallmark of a nanomaterial. Yet fumed silica with a surface area of > 200 m²/g is rated biologically safe and even used a food additive.

3. What are the synthesis methods? Even if synthesis is conducted within a closed system, subsequent processing steps of harvesting and processing can create far greater exposure risk.

3. Do the current markets and/or applications warrant concern? For example quantum dots contain heavy metals, yet they are a commercial product used in limited quantities for biological imaging.

4. What are the exposure routes and levels likely to be encountered in the manufacture, product development and consumer use of nanomaterial based products? Examples in which the nanomaterial, manufacturing process and product are generally considered safe include nanoclays used in various commercial polymers, TiO₂ in sunscreen and carbon black in car tires.

5. Is there any relevant information on related materials and/or nanoparticles and if so, is it applicable?

Examples of nanomaterials and synthesis conditions will be used to address these questions.

The talk will balance these considerations with those nanomaterials derived accidentally such from combustion-based stationary power generation or transportation. For the general population these sources overwhelm their potential exposures to nanomaterials, even after decades of study and emission controls. In fact recent studies have linked soot with asthma, heart arrhythmias and even death.