Therapeutic cloning will put vulnerable women in poorly regulated countries at risk of medical and financial exploitation, says an Australian sociologist. Assoc Professor Catherine Waldby, of the University of Sydney, says that poor women already supply eggs to IVF clinics catering for rich clients and that the demand for eggs for stem-cell research will increase the pressure on them.

"There have been serious medical problems in women involved in selling eggs," she says. The growth in IVF, combined with cheap international air travel has promoted clinics which trade eggs across borders. "They actually function as brokers between people in countries where they can't get ova and where it's very regulated, and countries where it's not," she says.

To remedy this, Professor Waldby proposes international regulation. This woud ensure that scientists are banned from using any eggs procured in the absence of ethical guidelines and oversight. Her survey of the field will be published in the journal New Genetics and Society.