Countries with less restrictive policies for deriving human embryonic stem cells produce a disproportionate share of the field's publications, according to a new study (A. Levine Cell Stem Cell 2, 521–524; 2008).

By this measure, the United States was the worst performer: although 36% of scientific publications on human embryonic stem cells in 2006 had a US-based corresponding author, that compared with 46% of a control set of biomedical publications and 47% of publications on RNA interference, a less controversial 'hot' technology.

The study's author, bioethicist Aaron Levine of the Georgia Institute of Technology in Atlanta, notes that governments in the top five overperforming countries (Singapore, United Kingdom, Israel, China and Australia) support research and permit derivation of new cell lines. Besides the United States, other underperformers included Japan, France and Switzerland. Both France and Japan also have less than the expected share of publications on RNA interference, and Levine suggests that scientists in those countries are less inclined to pursue emerging technologies.