You contend that most nanotechnology researchers now acknowledge that some areas of their work raise legitimate environmental, health and safety concerns (Nature 488, 576–579; 2012). This was not the case a decade ago, when we at the Action Group on Erosion, Technology and Concentration (ETC) called for a moratorium on the commercialization of products containing engineered nanoparticles.

In 2002, scientists could point us to only one peer-reviewed study of nanotube toxicity, and companies were still sending a Material Safety Data Sheet for graphite with carbon nanotube shipments. ETC's concerns were dismissed as alarmist. We welcome the change in attitude.

ETC's central concern has always been the economic impact on populations in developing countries resulting from the market disruptions that are expected with the advent of new nanoproducts and processes. We have consistently dismissed the hypothetical concept of 'grey goo' — uncontrolled self-replicating nanorobots — as a red herring.

Finally, ETC has no connection to ITS, the group that claimed responsibility for the nanotech-related bombings in Mexico. ETC opposes violence in all forms.