Olympic Doping Controversy Exposes Secret Hormone Abuse in Livestock Farming
Although the Paris Olympics concluded last week, the doping controversies remain far from settled. Amidst the uproar, at least three incidents tied to food safety have surfaced:
The average person has little way of knowing whether these explanations are the whole truth or merely convenient cover-ups. Yet, over the years, the World Anti-Doping Agency (WADA) has documented thousands of similar cases, indicating that doping-related contamination in meat is a widespread issue globally, including across China.
Why do meat products end up containing doping substances? Are ordinary consumers, much like athletes, just as likely to unknowingly consume contaminated meat?
Tracing the trail of the doping substances at the centre of this controversy, and after meticulously reviewing numerous investigative reports, media coverage, and dozens of academic studies, we uncovered overlooked food safety risks within China’s livestock sector. The issues brought to light either stand in stark contrast to the official stance of government food safety authorities, or fall into regulatory blind spots that have yet to be disclosed to the public.
Our key findings are as follows:
- Despite being banned for years, subjected to routine market testing, and strictly policed by regulators, clenbuterol – colloquially known as “lean meat powder” – remains stubbornly in use.
- Growth-promoting hormones such as boldenone are being used illegally to fatten livestock, revealing significant gaps in regulatory oversight;
- Mesterolonealthough primarily prescribed for human use, has been detected in meat products during anti-doping screenings.
I. Clenbuterol: Defying Bans for Twenty Years
“Doping substances” are more accurately described as performance-enhancing drugs (PEDs). This category encompasses both short-acting agents designed to boost an athlete’s immediate alertness and physical capacity, and longer-acting substances – such as “anabolic agents”, which promote muscle mass, strength, and recovery. The specific substances discussed in this article all fall under the anabolic agents category on the World Anti-Doping Agency’s (WADA) prohibited list.
Clenbuterol (Clenbuterol) is a β2-adrenergic receptor agonist. In China, it goes by a more notorious name: lean meat powder.
In the early 1980s, a US pharmaceutical company made an accidental discovery: clenbuterol not only significantly promoted growth and protein synthesis, but also reduced fat and increased lean meat yield. In other words, it could make pigs ‘lean yet heavy’ in a short space of time, leading to its widespread use as a feed additive in the livestock industry.
Operating on the same principle, when taken by humans, clenbuterol can also increase muscle mass or temporarily enhance cardiac function and basal metabolic rate. Consequently, it has been placed on the World Anti-Doping Agency’s (WADA) prohibited list.
However, clenbuterol persists in animal tissue for extended periods, and its chemical structure remains largely stable even under high-heat cooking, which has triggered multiple incidents of food poisoning.
In 2001, nearly 1,000 people in Guangdong were hospitalised after consuming pork tainted with beta-agonists, experiencing symptoms such as dizziness, vomiting and tremours. In 2006, more than 300 individuals in Shanghai suffered poisoning from the same substance after eating pork. In February 2009, a poisoning incident in Guangzhou resulted in over 70 hospital admissions, and subsequent inspections by authorities identified 63 contaminated pigs.
While large-scale incidents of this kind have fallen out of the news in recent years, reports of enforcement actions against illicit beta-agonist use still surface from time to time. In 2021, CCTV’s “3·15” consumer rights programme exposed a farm in Qingxian County, Hebei, for feeding clenbuterol to sheep.
In reality, China’s Ministry of Agriculture explicitly banned two such substances—clebuterol and ractopamine—from animal feed and livestock farming as far back as 1997. Seven further types of beta-agonists were subsequently prohibited in feed and drinking water in 2002.
Yet, illicit use within the animal farming industry has persisted despite repeated bans.
The primary challenge lies in regulating the source. The 2011 Shuanghui ‘lean meat powder’ pork scandal exposed how pharmaceutical companies could manufacture the substance from clenbuterol hydrochloride, an active ingredient in asthma medication. Ultimately, 48 individuals were convicted in connection with the case. The two persons responsible for processing were sentenced to a suspended death penalty and life imprisonment, respectively, for endangering public safety by dangerous methods.
Although routine national monitoring of agricultural product quality and safety in 2019 indicated a 99.9% pass rate for clenbuterol tests in livestock products, laboratory data with higher detection precision tells a different story: clenbuterol has never truly disappeared from our dinner tables.
Also in 2019, research teams from two universities in Jilin Province analysed hundreds of meat samples across the region. The combined detection rate for three types of ‘lean meat powder’ stood at 11.36%, with clenbuterol specifically found in 6.37% of samples. The average residue level was 0.85μg/kg, exceeding the maximum safe residue limit of 0.2μg/kg recommended by the Codex Alimentarius Commission (CAC).
Currently, the lowest detectable concentration of clenbuterol under national standard laboratory methods is 0.5μg/kg, which is higher than the maximum safe residue limit of 0.2μg/kg. The precision of rapid testing kits commonly used by market regulators is even lower. Consequently, a ‘not detected’ result does not mean the food is free of clenbuterol, nor does it guarantee food safety.
Higher-precision testing employed by the World Anti-Doping Agency (WADA) has further laid bare the widespread contamination of meat products with doping agents.
WADA has previously cited a 2012 study from the German Sport University Cologne. Researchers collected urine samples from 28 volunteers who had recently returned from China and used a testing method with a limit of detection of 1 pg/ml (200 times more sensitive than WADA’s stipulated minimum limit of 0.2 ng/ml), detecting clenbuterol in 79% of the samples.
In the 2016 and 2017 cases involving Chinese swimmers who tested positive for clenbuterol, which drew scrutiny from the New York Times, WADA’s review found that the concentrations in the three athletes were extremely low and concluded the positives resulted from consuming contaminated meat. According to WADA statistics, clenbuterol contamination in meat has been linked to 420 adverse analytical findings for athletes worldwide.
A 2021 WADA document explicitly noted widespread clenbuterol contamination in meat from Guatemala, Mexico, and China, even though the substance had been banned domestically for 24 years by that point.
Similar independent studies prompted WADA to amend its standards in 2019: positive results for low-dose clenbuterol in urine (below 5 ng/ml) no longer need to be reported.
II. Trenbolone and Hormone-Fed Beef
The trenbolone that triggered a positive doping test for US track athlete Erriyon Knighton this March tells a similar story.
Dubbed the ‘competition prep wonder drug’ in bodybuilding circles, trenbolone is an androgen and a type of anabolic-androgenic steroid (AAS). It works by boosting protein synthesis and slowing its breakdown, thereby promoting muscle growth. While it has not been approved for clinical use in humans, some individuals still use it privately for bodybuilding.
The adverse health effects of AAS include harmful shifts in cholesterol levels, acne, hypertension, liver damage, and left ventricular hypertrophy. Cardiac complications can lead to myocardial infarction and stroke. AAS can also cause conditions linked to hormonal imbalance, such as gynecomastia and testicular atrophy, as well as irreversible masculinisation in women and children.
In livestock farming, trenbolone is routinely administered during the finishing phase of beef cattle to increase muscle mass and shorten the time to market. The United States is one of the few countries that permits its use in livestock.
Since the 1950s, the United States has authorised a number of growth-promoting hormones for livestock, including clenbuterol. These encompass natural androgens, oestrogens, and progestogens, alongside their synthetic counterparts, and are often collectively termed “Hormonal Growth Promotants” (HGPs).
Figures indicate that around 90% of US livestock operations use these hormones, with adoption rates nearing 100% among large-scale farms.
While the United States and other nations maintain that residual synthetic hormones in beef pose no risk to human health, the European Union has consistently adopted a cautious stance.
The European Commission’s Scientific Committee on Veterinary Measures Relating to Public Health noted in a report: “The human endocrine system is highly delicate, and [these hormones] along with their metabolites possess potential genotoxicity… exposure to exogenous hormones could upset this subtle equilibrium.” In simpler terms, such compounds risk triggering endocrine disruption.
Guided by this precautionary approach, the EU has prohibited the import of beef treated with six specific growth-promoting hormones since 1989, clenbuterol among them. The restriction sparked a protracted trade dispute between the EU and the United States. For nearly two decades, both sides clashed over whether the ban contravened principles of free trade, a conflict widely dubbed the “beef war” by the press.
III. Ban = Zero Use?
In 2021, a research team led by Professor Ying Guangguo from South China Normal University detected traces of clenbuterol in the wastewater and faeces of two pig farms in South China. Two additional papers co-authored by Professor Ying in 2012 also reported the presence of clenbuterol in several other farms across the region.
Because clenbuterol cannot be synthesised through natural animal metabolism, its detection unequivocally points to illicit addition during the rearing process.Furthermore, these studies also identified other prohibited hormones, namely methyltestosterone and diethylstilbestrol.
Although the Ministry of Agriculture and Rural Affairs has prohibited the addition of hormonal compounds to water and feed, a 2015 study detected multiple synthetic steroids, including clenbuterol, in feed samples from aquaculture facilities near Hailing Island, Yangjiang, Guangdong. This provides clear evidence of the illegal addition of hormones to feed. Moreover, several studies have identified synthetic hormones in the water surrounding farms in South China.
The hormones used in livestock and aquaculture eventually discharge into water bodies, causing pollution and subsequent human exposure through environmental pathways and the food chain. Research indicates that in high-density farming areas, steroid hormone concentrations in rivers can exceed safe thresholds, adversely affecting the growth and reproduction of aquatic life. In 2016, the clenbuterol detected in Taihu Lake was directly linked to the influx of farm wastewater.
Beyond unauthorised use, what other practices in livestock farming could lead to hormone misuse?
While hormones are prohibited for promoting growth in livestock, they are permitted for therapeutic purposes. Yet “treatment” extends beyond curing illness; it can also encompass reproductive management: an injection to induce oestrus, another to trigger ovulation, with hormones also administered to maintain pregnancy, induce labour, and stimulate lactation. Whether current veterinary hormones are used strictly for their authorised purposes, and whether safe dosages and withdrawal periods are properly observed, remains a grey area.
Another grey area involves synthetic endogenous hormones. For instance, hormones such as testosterone and oestradiol, which can be used to increase weight during the fattening period, are difficult to verify for unauthorised addition because animals naturally produce them.
IV.The Unknown Risks of Methandienone’s “Human Medicines for Veterinary Use”
In October 2022, two Chinese swimmers tested positive for methandienone. WADA confirmed that the Chinese Anti-Doping Agency examined hundreds of meat samples from various sources, detecting methandienone residues in dozens of them. Based on these findings, they concluded that the low doses detected originated from food contamination.
If clenbuterol represents “veterinary drugs for human use,” then methandienone represents “human medicines for veterinary use.” Like clenbuterol, methandienone is a type of androgen widely used by bodybuilding enthusiasts, yet it is not a conventional veterinary hormone. Few researchers have previously examined its application in livestock farming, leaving the extent of methandienone-related food contamination virtually a blind spot.
A study published in 2023 detected methandienone residues in beef available on the Russian market. The authors suggest that although methandienone is not a standard veterinary drug, its low cost and ready availability make its use in animal husbandry a distinct possibility.
Reports indicate that WADA launched an investigation earlier this year to assess the prevalence of methandienone contamination in meat across China and other countries.
From clenbuterol to nandrolone, and from synthetic growth hormones to a host of yet-to-be-identified drug risks, the efficacy of oversight is constrained by testing accuracy and costs, as well as the sluggish pace at which regulations and standards are updated.
Faced with a sheer proliferation of problematic chemicals, the system readily falls into a cycle where “those policing the substances” cannot outpace “those administering them”, leaving regulators perpetually playing catch-up. How to restrict hormone abuse at the source and eradicate food safety hazards remains a long and arduous journey.
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Editors: Ze’en & Tianle