Nearly half of Australia’s cattle is treated with growth hormones to speed up weight gain. Australian regulators say these hormones are safe and legal, but in the EU and the UK, they’re banned. However a new free-trade agreement currently under negotiation could see a change in policy in the UK, and cause Australia’s beef exports to the UK to rise tenfold. Science writer Donna Lu speaks to Laura Murphy-Oates about this trade agreement, and the impact of hormone-treated beef on humans, animals and the environment