Nearly half of Australia’s cattle is treated with growth hormones. Is it safe to eat?

A potential increase in exports to the UK of Australian beef pumped with hormones has raised alarm food safety standards could be compromised.

In Australia, the use of veterinary drugs to make cattle grow bigger is widespread and deemed safe by regulatory bodies. But hormonal growth promotants have long been banned in Europe, and the UK government has pledged not to allow hormone-treated beef into British supermarkets.

It’s unclear if that ban will be upheld under a potential UK-Australia trade deal, including proposals for zero-tariff beef, which has some farmers and environmental groups worried.

default

Related: ‘Irresponsible’ Australia trade deal will bring ruin for UK farmers, critics warn

So what are the effects of hormone treatment in cattle and is it safe to eat Australian beef?

How widespread is hormone treatment?

Hormone-treated beef is common in Australia: an estimated 40% of cattle in the country is treated with growth promotants to boost weight gain in the animals.

However, in 2011, major Australian supermarket chain Coles announced that it would move away from using hormonal growth promotants in its own-brand beef products.

Many farmers in Australia are economically reliant on growth promoters because they improve the efficiency of meat production by around 15%, says Peter Wynn, an adjunct professor at the Graham Centre for Agricultural Innovation at Charles Sturt University.

Treated animals have an implant inserted at the back of the ear, containing a combination of oestrogen and androgen steroid hormones.

Female animals seem to grow faster when they are given mostly male hormones, and vice versa, says Wynn. “We don’t really understand why that is.”

The hormones can be either natural or synthetic. Common synthetic hormones include trenbolone acetate, an androgen, and estradiol benzoate, which mimics natural oestrogens.

The synthetic compounds produce a similar effect to natural hormones in the body, but are between five and 20 times more potent, says Frederic Leusch, a professor at Griffith University’s school of environment and science.

Is it safe to eat?

While it may sound like cause for alarm, the amount of hormone that ends up as residues in the meat we consume is extremely low.

“What we get from meat is 1,000 times lower than what you would produce in your own body,” says Leusch. “As a human health issue, it really doesn’t seem to be much of a concern.”

Wynn points out that all beef has small amounts of hormones in it, regardless of whether it has been treated with hormone implants. What is often overlooked in discussions about the safety of using growth promotants – synthetic or natural – is that our diets typically contain many other sources of hormones, he says.

“You’ll get more oestrogen out of an egg than you will out of 10kg of beef that has been treated with a steroid implant,” he says. “There’s a whole heap more oestrogen in soy milk.”

Vegetables including cabbage and corn contain phytoestrogens – plant oestrogens – that bind to the same hormone receptors in our bodies, he adds.

What are the rules around hormone use?

Maximum residue limits in meat are set by the Australian Pesticides and Veterinary Medicines Authority (APVMA), a government body tasked with assessing and registering agricultural chemicals in Australia.

A spokesperson for the APVMA said in a statement: “The APVMA undertakes a dietary exposure evaluation at the time maximum residue limits are set to ensure the levels do not pose an undue hazard to human health.”

A statement from Food Standards Australia New Zealand, a government body that develops food safety standards, said: “Upon request, FSANZ may play a supporting role in this process by confirming that dietary exposure to any residues do not pose a risk to the Australian population.”

Why is it banned in some places?

The use of hormonal growth promotants in meat production has been banned in the European Union since 1989 – and has also been incorporated into UK law recently as part of its withdrawal from the EU. The 1989 ban on hormonal growth promotants in the EU was likely influenced by historical community concerns about diethylstilbestrol (DES), a potent synthetic oestrogen that disrupts the endocrine system and has been linked to some cancers. DES was detected in meat residues in Europe in the 1970s and 80s, sparking public anger.

Speaking to the Guardian in a personal capacity, David Hopkins, an adjunct professor also at Charles Sturt University, says every hormonal growth promotant now used in animal production undergoes exhaustive testing before it is launched to market.

“The ban on such meat [in the EU and UK] is not based on science, but perceptions and marketing,” says Hopkins.

Wynn agrees: “They’re really a non-tariff trade barrier to keep our products out of their marketplace.”

In 1996, the US opposed the EU’s ban on the grounds of a lack of scientific evidence for health risks associated with common hormonal growth promotants. The Americans took the dispute to the World Trade Organization, which ruled in the US’s favour.

Environmental impacts

Environmental concerns may also be a factor in the ban on growth promotants in the UK, says Dr Mike Williams at the CSIRO.

Synthetic compounds are particularly slow to break down, so can pass through an animal’s digestive and urinary systems into the surrounding environment.

“If these compounds are released and environmental organisms are exposed to them at a high enough concentration, that can have an effect on their reproduction,” Williams says.

For fish, says Leusch, “Exposure to nanogram-per-litre concentrations usually can cause changes in endocrine function in the short term, which can then in the long term lead to developmental and reproductive issues.”

The half-life for the synthetic compounds used can be as long as 200 days, so runoff from feedlots can have concerning flow-on effects if not properly managed. The wastewater either needs to be held for a period of time so that the compounds degrade, or are heavily diluted to lower the concentrations entering the environment, says Leusch.

Hormonal growth promotants do, however, have an environmental benefit. “They allow you to obviously get the cattle to market a lot faster,” says Leusch. “The cow therefore spends less time in the environment, which means we have less nutrient runoff and we also have less greenhouse gas emissions.”