Josephine Quintavalle, of Comment on Reproductive Ethics, said: "We still don't know the dangers of taking a biopsy from an early stage embryo, whether it has any effect on the baby's future development. On paper it looks like an ethical solution, but that requires the biopsy to be completely harmless."In other words, we have no evidence whatsoever that the biopsy is harmful, but because it might be, this is still not a good solution. A second example, same article (emphasis added):
Prof [Peter] Braude [of ob/gyn in King's College London] said he doubted whether the controversy could be avoided by the American breakthrough. "We don't undertake embryo biopsy willy-nilly, as it is better not to remove a cell from a developing embryo unless one really has to," he said. "I certainly cannot see why one would wish to try and remove a cell from a healthy embryo with such low odds of developing a stem line from it when many thousands of useful cells are harvested from a baby's placenta at birth, if one needed to do it. Equally, I'm not persuaded by arguments that this is a more ethical way of getting stem cell lines, as it is not impossible that biopsy compromises the developing embryo from which one removes the cell."Again, since there's a non-zero probability of harming the embryo, this is still a poor solution. (As an ethical principle, this is crap, incidentally. If a zero probability of harm is required before one acts, then one will never act.)
There's no pleasing the dogmatic; I really wonder how long rational people will continue to try.