(209a) Human Health and 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 "nano"?  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?

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.