Considerations of Environmentally Relevant Test Conditions for Improved Evaluation of Ecological Hazards of Engineered Nanomaterials.

Engineered nanomaterials (ENMs) are increasingly entering the environment with uncertain consequences including potential ecological effects. Various research communities view differently whether ecotoxicological testing of ENMs should be conducted using environmentally relevant concentrations-where observing outcomes is difficult-versus higher ENM doses, where responses are observable. What exposure conditions are typically used in assessing ENM hazards to populations? What conditions are used to test ecosystem-scale hazards? What is known regarding actual ENMs in the environment, via measurements or modeling simulations? How should exposure conditions, ENM transformation, dose, and body burden be used in interpreting biological and computational findings for assessing risks? These questions were addressed in the context of this critical review. As a result, three main recommendations emerged. First, researchers should improve ecotoxicology of ENMs by choosing test end points, duration, and study conditions-including ENM test concentrations-that align with realistic exposure scenarios. Second, testing should proceed via tiers with iterative feedback that informs experiments at other levels of biological organization. Finally, environmental realism in ENM hazard assessments should involve greater coordination among ENM quantitative analysts, exposure modelers, and ecotoxicologists, across government, industry, and academia.

Anticipating the perceived risk of nanotechnologies.

Understanding emerging trends in public perceptions of nanomaterials is critically important for those who regulate risks. A number of surveys have explored public perceptions of their risks and benefits. In this paper we meta-analyse these surveys to assess the extent to which the following four hypotheses derived from previous studies of new technologies might be said to be valid for nanotechnologies: risk aversion will prevail over benefit appreciation; an increase in knowledge will not result in reduced aversion to risks; judgements will be malleable and subject to persuasion given risk-centric information; and contextual, psychometric and attitudinal predictors of perceived risk from prior studies can help anticipate future perceptions of nanotechnologies. We find that half the public has at least some familiarity with nanotechnology, and those who perceive greater benefits outnumber those who perceive greater risks by 3 to 1. However, a large minority of those surveyed (44%) is unsure, suggesting that risk judgements are highly malleable. Nanotechnology risk perceptions also appear to contradict some long-standing findings. In particular, unfamiliarity with nanotechnology is, contrary to expectations, not strongly associated with risk aversion and reduced 'knowledge deficits' are correlated with positive perceptions in this early and controversy-free period. Psychometric variables, trust and affect continue to drive risk perceptions in this new context, although the influence of both trust and affect is mediated, even reversed, by demographic and cultural variables. Given the potential malleability of perceptions, novel methods for understanding future public responses to nanotechnologies will need to be developed.