Nanoparticles are small-scale substances (<100 nm) with unique properties and, thus, complex exposure and health risk implications. This symposium review summarizes recent findings in exposure and toxicity of nanoparticles and their application for assessing human health risks. Characterization of airborne particles indicates that exposures will depend on particle behavior (e.g., disperse or aggregate) and that accurate, portable, and cost-effective measurement techniques are essential for understanding exposure. Under many conditions, dermal penetration of nanoparticles may be limited for consumer products such as sunscreens, although additional studies are needed on potential photooxidation products, experimental methods, and the effect of skin condition on penetration. Carbon nanotubes apparently have greater pulmonary toxicity (inflammation, granuloma) in mice than fine-scale carbon graphite, and their metal content may affect toxicity. Studies on TiO2 and quartz illustrate the complex relationship between toxicity and particle characteristics, including surface coatings, which make generalizations (e.g., smaller particles are always more toxic) incorrect for some substances. These recent toxicity and exposure data, combined with therapeutic and other related literature, are beginning to shape risk assessments that will be used to regulate the use of nanomaterials in consumer products.

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Decades of study indicate that copper oral exposures are typically not a human health concern. Ingesting high levels of soluble copper salts can cause acute gastrointestinal symptoms and, in uncommon cases, liver toxicity in susceptible individuals with repeated exposure. This focused toxicological review evaluated the current literature since the last comprehensive reviews (2007)(2008)(2009)(2010). Our review identified limitations in the existing United States and international guidance for determining an oral reference dose (RfD) for essential metals like copper. Instead, an alternative method using categorical regression analysis to develop an optimal dose that considers deficiency, toxicity, and integrates information from human and animal studies was reviewed for interpreting an oral RfD for copper. We also considered subchronic

SummaryWe examined heritabilities and correlations among measures of locomotor performance (speed, stamina) and among possible morphometric determinants of performance (hindlimb span, tail length) in families of hatchling lizards (Sceloporus occidentalis). We were particularly interested in determining whether these traits were heritable and thus might potentially respond genetically to selection. Moreover, we wished to determine whether speed and stamina are negatively genetically correlated, as suggested by a priori physiological and empirical considerations. All four traits appeared to be significantly heritable. Broadsense heritabilities were 0.33-0.36 for speed, 0.35-0.36 for stamina, 0.45-0.51 for hindlimb span, and 0.46--0.47 for tail length. Contrary to expectations, speed and stamina were not negatively genetically correlated. Hindlimb span and tail length, however, were negatively genetically correlated (but not phenotypically correlated). Hindlimb span and stamina were positively phenotypically correlated. Thus, for example, selection for longer hindlimb span could potentially result in shorter tails, contrary to evolutionary predictions based only on phenotypic correlations.