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Keywords:

  • health risk;
  • high pressure carbon monoxide (HiPco);
  • industrial ecology;
  • Monte Carlo simulation;
  • nanotechnology;
  • uncertainty

Summary

Considerable uncertainty exists about occupational risks, future environmental health and safety (EHS) standards, and associated production and compliance costs for single-wall carbon nanotube (SWNT) manufacturing processes. We propose and illustrate the use of risk analysis Monte Carlo (MC) models to assess cost and exposure trade-offs of the high-pressure carbon monoxide (HiPco) SWNT manufacturing process given these uncertainties. Assumptions regarding the timing, frequency, magnitude, and expense of EHS standards are modeled as stochastic events and examined for their impact on the expected values, variances, and probability distributions of total production costs and occupational exposure. With a better understanding of associated risks, these models can help policy makers and manufacturers explore potential EHS benefits, consequences, and trade-offs. For example, results suggest that voluntary implementation of a low level of protection (rather than none at all) can lead to reduced cost and exposure uncertainty with insignificant increases in production costs, as well as lowering total manufacturing and liability costs, depending on the assumptions made. Conversely, slower implementation rates of higher standards produce greater uncertainty in long-term costs and exposure. More generally, the results of this study underscore three important observations: (1) Expected costs alone are insufficient for informed decision making; (2) the best level of standards, overall cost, and optimal voluntary standards are highly dependent on uncertain health effects; and (3) the resultant amount of uncertainty in total costs and exposure can be extreme.