PAAG, or hydrophilic polyacrylamide, was first developed in Ukraine more than a decade ago but has never been widely used for breast enlargement, according to a plastic surgeon. It was used to fix scars and wrinkles, said Hong Kong Medical Association vice-president Louis Shih Tai-cho, who is also a private dermatologist. 'It was first found in former Soviet countries more than 10 years ago. Doctors used it as a filler injection to correct scars and wrinkles,' he said. The amounts used in such injections were very limited and the treatment was confined to the surface of the skin. 'No doctor will inject it into the body or use it to enlarge breasts, as the gel cannot be removed once it is inside the body,' Dr Shih said. The Medical Council said plastic surgeons in Hong Kong were reluctant to use the gel because of the health risk. But over the past few years they had treated dozens of Hong Kong patients for side effects, such as infections, inflammation and hardening of tissue. 'In most of the cases, the victims got the injection on the mainland, and we also heard that some people had it done by beauticians in Hong Kong,' Dr Shih said. He pointed out the substance has been banned in Ukraine and had not been approved by the US Food and Drug Administration. 'People should not use such a substance at all,' he said. 'Its safety was not proven; its risk is very high.' Despite all the side effects, it had not been restricted in Hong Kong. Dr Shih advised people to adopt only common breast-enlargement practices such as the insertion of saline or silicon bags. 'The safety of such practices is proven,' he said. 'And the most important point is that these bags can be removed from the body if there is any problem.' He said the gel would also obstruct breast cancer diagnosis.