Jordi Casamitjana, the author of the book “Ethical Vegan”, looks at how antibiotics and hormones are used in animal agriculture, and how this negatively affects humanity

I don’t know how often I had them.

When I grew up in the 60s and 70s, every time I had any infection of any sort my parents would give me antibiotics (prescribed by doctors), even for viral infections antibiotics cannot stop (just in case opportunistic bacteria would take over). Although I can’t remember how many years have been since I had not been prescribed any, I certainly had them as an adult too, especially before I became vegan more than 20 years ago. They became indispensable medicines to cure me of the occasions “bad” bacteria took over parts of my body and threatened my existence, from pneumonia to toothache.  

Globally, since they were “discovered” by modern science in the 1920s — although they were already used for millennia around the world without people realising it, knowing what they were, or understanding how they worked — antibiotics have become a crucial tool to combat disease, which has helped billions of people. However, after their extensive use (and abuse) for so many years, it may be that soon we will not be able to use them anymore because the bacteria they combat have gradually become adapted to resist them, and unless we discover new ones, the ones we have now may no longer be effective. This problem has been made worse by the animal agriculture industry. 

On the other side, I have not taken any hormones as an adult — or at least willingly — but my body has been producing them naturally as these are biochemical molecules necessary for our development, mood, and the functioning of our physiology. However, the chances are that I unwillingly ingested hormones before I became vegan, and I ate animal products that had them, perhaps affecting my body in ways they were not intended to. This problem has been made worse by the animal agriculture industry too. 

The truth is that those who consume animal products think they know what they are eating, but they don’t. Animals raised in the animal agriculture industry, especially in intensive operations, are routinely given both hormones and antibiotics, and this means some of these may end up being ingested by people who eat these animals or their secretions.  Additionally, the massive use of the latter is accelerating the evolution of pathogenic bacteria toward becoming more difficult to stop proliferating when we get infected.   

In most countries, the use of antibiotics and hormones in farming is neither illegal nor a secret, but most people do not know much about it, and how that affects them. This article will dig a little bit into this issue. 

What Are Antibiotics?

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Antibiotics are substances that prevent bacteria from proliferating by either interfering with their reproduction (more common) or directly killing them. They are often found in nature as part of the defence mechanisms living organisms have against bacteria. Some fungi, plants,  parts of plants (like the sabs of some trees), and even animal secretions (such as mammal’s saliva or bee’s honey) have antibiotic properties, and for centuries people have been using them to combat some diseases without understanding how they worked. However, at one point, scientists understood how they prevent bacteria from proliferating, and they were able to manufacture them in factories and create medicines with them. Today, then, people think of antibiotics as drugs to take to combat infections, but you can find them in nature too.  

Technically speaking, antibiotics are antibacterial substances produced naturally (by one microorganism fighting another) which we may be able to transform into medicines by cultivating the organisms that produce them and isolating the antibiotics from them, whereas non-antibiotic antibacterials (such as sulfonamides and antiseptics) and disinfectants are fully synthetic substances created in labs or factories. Antiseptics are substances applied to living tissue to reduce the possibility of sepsis, infection or putrefaction, while disinfectants destroy microorganisms on non-living objects by creating toxic environments for them (too acidic, too alkaline, too alcoholic, etc.).

 Antibiotics only work for bacterial infections (such as infections causing Tuberculosis or Salmonellosis), not for viral infections (such as the flue or COVID), protozoans infections (such as malaria or toxoplasmosis) or fungal infections (such as  Aspergillosis), but they do not directly stop infections, but reduce the chances of bacteria multiplying out of control beyond what our immune systems can cope with. In other words, it is our immune system that hunts down all the bacteria that have infected us to get rid of them, but antibiotics help it by preventing the bacteria from multiplying beyond the numbers our immune system can cope with. 

Many antibiotics used in modern medicine come from fungi (as they are easy to cultivate in factories). The first person to directly document the use of fungi to treat infections because of their antibiotic properties was John Parkinson in the 16th century. The Scottish scientist Alexander Fleming discovered modern-day penicillin in 1928 from Penicillium moulds, which is perhaps the most well-known and widespread antibiotic. 

Antibiotics as medicines would work on many species so the same antibiotics that are used on humans are also used on other animals, such as companion animals and farmed animals. In factory farms, which are environments where infections spread fast, are routinely used as preventive measures, and added to the animals’ feed.

The problem with using antibiotics is that some bacteria may mutate and become resistant to them (meaning that the antibiotic no longer prevents them from reproducing), and as bacteria reproduce very fast, those resistant bacteria may end up replacing all the others of their species making that particular antibiotic no longer useful for that bacterium. This issue is known as antimicrobial resistance (AMR). Discovering new antibiotics will be a way around AMR, but not all antibiotics work against the same species of bacteria, so it is possible to run out of antibiotics that work for particular diseases. As bacteria mutate faster than the rate of discovering new antibiotics, it may get to a point where we return to medieval times when we did not have them to combat most infections. 

We have already reached the beginning of this emergency state. The World Health Organization has classified antimicrobial resistance as a widespread “serious threat [that] is no longer a prediction for the future, it is happening right now in every region of the world and has the potential to affect anyone, of any age, in any country”. This is a very serious problem getting worse. A 2022 study concluded that global human deaths attributable to antimicrobial resistance numbered 1.27 million in 2019. According to the US Centers for Disease Control and Prevention, each year in the US at least 2.8 million antibiotic-resistant infections occur, and more than 35,000 people die as a result.

What Are Hormones?

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Hormones are a type of molecules produced by multicellular organisms (animals, plants and fungi) that are sent to organs, tissues, or cells to regulate physiology and behaviour. Hormones are essential to coordinate what different parts of the body do and to make the organism respond coherently and efficiently as a unit (not simply as several cells together) to internal and external challenges. In consequence, they are essential for development and growth, but also for reproduction, sexual dimorphism, metabolism, digestion, healing, mood, thought, and most physiological processes — having too much or too little of a hormone, or releasing it too early or too late, can have many negative effects on all these. 

Thanks to hormones and our nervous system (which works closely with them), our cells, tissues, and organs work in harmony with each other as the hormones and neurones carry the information to them that they need, but while the neurons can send this information very fast,  very targeted, and very briefly, the hormones do it slower, less targeted, and their effects may last longer — if neurones were an equivalent of telephone calls to pass information, hormones would be an equivalent of letters of a postal system.  

Although the information hormones carry lasts longer than the information nervous systems may carry (although the brain has memory systems to keep some information for longer), it does not last forever, so when hormones have passed the information everywhere in the body that needs to get it, they are removed either by excreting them out from the body, sequestering them in some tissues or fat, or metabolising them into something else. 

Many molecules can be classified as hormones, such as eicosanoids (e.g. prostaglandins), steroids (e.g. oestrogen), amino acid derivatives (e.g. epinephrine), proteins or peptides (e.g. insulin), and gases (e.g. nitric oxide). Hormones can also be classified as endocrine (if they act on the target cells after being released into the bloodstream), paracrine (if they act on the nearby cells and do not have to enter general circulation), autocrine ( affect the cell types that secreted it and causes a biological effect) or intracrine (act intracellularly on the cells that synthesised it). In vertebrates, endocrine glands are specialized organs that secrete hormones into the endocrine signalling system.

Many hormones and their analogues are used as medication to solve developmental or physiological problems. For instance, oestrogens, and progestogens are used as methods of hormonal contraception,  thyroxine to combat hypothyroidism,  steroids for autoimmune diseases and several respiratory disorders, and insulin to help diabetics. However, as hormones affect growth, they are also used not for medical reasons, but for leisure and hobbies (such as sports, bodybuilding, etc.) both legally and illegally.

In farming, hormones are used to affect the growth and reproduction of animals. Farmers may apply them on the animals with pads, or give them with their feed, so to make the animals sexually mature sooner, to make them ovulate more frequently, to force labour, to incentivise milk production, to make them grow faster, to make them grow one type of tissue over another (such as muscle over fat), to change their behaviour, etc. Therefore, hormones have been used in agriculture not as part of therapies but as a means to boost production.  

Abuse of Antibiotic Use in Animal Agriculture

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Antibiotics were first used in farming towards the end of WWII (it started with intra-mammary penicillin injections to treat bovine mastitis). In the 1940s, the use of antibiotics in farming for other purposes than simply combating infections started. Studies on different farm animals showed improved growth and feed efficiency when including low (sub-therapeutic) levels of antibiotics in the animals’ feed (possibly by affecting the gut flora, or because with the antibiotics the animals don’t have to have a very active immune system constantly keeping microorganisms at bay, and they can use the energy saved for growing).

Then, animal agriculture moved toward factory farming where the number of animals kept together skyrocketed, so the risk of infectious diseases spreading increased. As such infections would kill the animals before they can be sent to slaughter, or would make the animals who got infected unsuitable to be used for human consumption, the industry has been using antibiotics not only as a way to combat the infections that were already happening but as preventive measures giving them routinely to animals regardless if they will get infected. This prophylaxis use, plus the use to increase growth, means a huge amount of antibiotics have been given to farmed animals, driving the evolution of bacteria toward resistance.

In 2001, a report by the Union of Concerned Scientists found that nearly 90% of the total use of antimicrobials in the US was for non-therapeutic purposes in agricultural production. The report estimated that farmed animal producers in the US used, every year, 24.6 million pounds of antimicrobials in the absence of disease for nontherapeutic purposes, including about  10.3 million pounds in pigs, 10.5 million pounds in birds, and 3.7 million pounds in cows. It also showed that about 13.5 million pounds of antimicrobials prohibited in the European Union were used in US agriculture for nontherapeutic purposes every year. In 2011, 1,734 tons of antimicrobial agents were used for animals in Germany compared with 800 tons for humans. 

Before the expansion of factory farming from the 1940s onwards, most antibiotics used might have been in humans, and only if individuals combating infections or outbreaks. This meant that, even if resistant strains always appeared, there were enough new antibiotics discovered to deal with them. But the use of antibiotics in farmed animals in many more quantities, and using them routinely all the time for prophylaxis, not only when there are outbreaks, and to help growth, means that bacteria can develop resistance more quickly, far quicker than science can discover new antibiotics.

It has already been scientifically proven that the use of antibiotics in animal agriculture has increased the number of antibiotic resistance because when such usage is significantly reduced the resistance decreases.  A 2017 study about the use of antibiotics said, “Interventions that restrict antibiotic use in food-producing animals are associated with a reduction in the presence of antibiotic-resistant bacteria in these animals. A smaller body of evidence suggests a similar association in the studied human populations, particularly those with direct exposure to food-producing animals.”

The AMR Problem Will Get Worse

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A 2015 study estimated that global agricultural antibiotic usage will increase by 67% from 2010 to 2030, mainly from increases in use in Brazil, Russia, India, and China. Antibiotic use in China, as measured in terms of mg/PCU, is more than 5 times higher than the international average. Therefore, China has become one of the major contributors to AMR because they have a huge animal agriculture industry that uses lots of antibiotics. However, some corrective actions have started to be taken. Several key government policies used to tackle this issue include the maximum residue level monitoring and control, permitted lists, proper use of the withdrawal period, and prescription-only use. 

Legislation to reduce antibiotic use in farm animals is now being introduced in several countries. For instance, the Veterinary Medicinal Products Regulation (Regulation (EU) 2019/6) updated the rules on the authorisation and use of veterinary medicines in the European Union when it became applicable on 28th January 2022. This regulation states, “Antimicrobial medicinal products shall not be used for prophylaxis other than in exceptional cases, for the administration to an individual animal or a restricted number of animals when the risk of an infection or of an infectious disease is very high and the consequences are likely to be severe. In such cases, the use of antibiotic medicinal products for prophylaxis shall be limited to the administration to an individual animal only.” The use of antibiotics for growth promotion purposes was banned in the European Union in 2006. Sweden was the first country to ban all use of antibiotics as growth promoters in 1986. 

In 1991, Namibia became the first African nation to ban the routine use of antibiotics in its cow industry. Growth promoters based on human therapeutic antibiotics are banned in Colombia, which also prohibits the use of any veterinary therapeutic antibiotics as growth promoters in bovids. Chile has banned the use of growth promoters based on all classes of antibiotics for all species and production categories. The Canadian Food Inspection Agency (CFIA) enforces standards by ensuring that foods produced will not contain antibiotics at a level which will cause harm to consumers.

In the US, the Food and Drug Administration’s Center for Veterinary Medicine (CVM) developed a five-year action plan in 2019 for supporting antimicrobial stewardship in veterinary settings, and it aimed to limit or reverse antibiotic resistance arising from the use of antibiotics in non-human animals. On 1st January 2017, the use of sub-therapeutic doses of medically important antibiotics in animal feed and water to promote growth and improve feed efficiency became illegal in the US. However, so far the problem is still there because, without the use of antibiotics, the huge animal agriculture of the country will collapse as it is impossible to prevent infections from spreading in the increasingly cramped conditions of factory farming, so any reduction of use (rather than a total ban of using them) will not solve the problem, but just delay the time it becomes catastrophic. 

A1999 study of the economic cost of the FDA restricting all antibiotic use in farmed animals concluded that the restriction would cost approximately $1.2 billion to $2.5 billion per year in terms of loss of revenue, and as the animal agriculture industry has powerful lobbyists, politicians are unlikely to go for total bans. 

Therefore, it seems that, although the problem is being acknowledged, the solutions attempted are not good enough as the animal agriculture industry is blocking their full application and continues to make the AWR problem worse. This in itself should be a human-based reason to become vegan and not to give any money to such an industry, as supporting it may send humanity back into the pre-antibiotic era, and suffer many more infections, and deaths from them. 

Abuse of Hormonal Use in Animal Agriculture

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Since the mid-1950s, the animal agriculture industry has been using hormones, and other natural or synthetic substances displaying hormonal activity, to boost meat “productivity”  as when given to farmed animals they increase growth rate and the FCE (feed conversion efficiency) is higher, leading to 10–15% increases in daily gains. The first used in cows were DES (diethylstilboestrol) and hexoestrol in the US and the UK respectively, either as feed additives or as implants, and other types of substances also gradually became available. 

Bovine somatotropin (bST) is a hormone also used to increase milk production in dairy cows. This drug is based on the somatotropin naturally produced in cattle in the pituitary gland. Early research in the 1930s and 1940s in Russia and England found that milk production in cows increased by injecting cattle pituitary extracts. it wasn’t until the 1980s that it became technically possible to produce large commercial quantities of bST. In 1993, the US FDA approved a bST product with the brand name “Posilac™” after concluding that its use would be safe and effective.

Other farmed animals also had hormones administered to them for the same reasons, including sheeps, pigs, and chickens. The “classical” natural steroid sex hormones used in animal agriculture are oestradiol-17β, testosterone, and progesterone. Of the oestrogens, the stilbene derivatives diethylstilboestrol (DES) and hexoestrol have been used most widely, both orally and with implants. From the synthetic androgens, the most commonly used are trenbolone acetate (TBA) and methyl-testosterone. Of synthetic gestagens, melengestrol acetate, which stimulates growth in heifers but not in steers, is widely used too. Hexoestrol is used as an implant for steers, sheeps, calves, and chickens, while DES + Methyl-testosterone is used as a feed additive for pigs.

The effects of these hormones on the animals are to force them to either grow too fast or reproduce more often, which stresses their bodies and therefore makes them suffer, as they are treated as production machines and not sentient beings. However, the use of hormones has also some side effects unwanted by the industry. For instance, as early as 1958 the use of oestrogens in steers was observed to cause changes in body conformation such as feminization and raised tail-heads. Bulling (abnormal sexual behaviour in males) was also seen to occur with increased frequency. In a study of the effect of reimplantation of oestrogens in steers, all animals were given a 30 mg DES implant at a live weight of 260 kg, and then reimplanted 91 days later, with either 30 mg DES or Synovex S. Following the second implant, the frequency of the steer-buller syndrome (one steer, the buller, being mounted and persistently ridden by other steers) was 1.65% for the DES-DES group, and 3.36% for the DES-Synovex S group. 

In 1981, with Directive 81/602/EEC, the EU prohibited the use of substances having a hormonal action for growth promotion in farm animals, such as oestradiol 17ß, testosterone, progesterone, zeranol, trenbolone acetate and melengestrol acetate (MGA). This prohibition applied to Member States and imports from third countries alike.

The former Scientific Committee on Veterinary Measures Relating to Public Health (SCVPH) concluded that oestradiol 17ß has to be considered a complete carcinogen.  The EU Directive 2003/74/EC confirmed the prohibition of substances having a hormonal action for growth promotion in farm animals and drastically reduced the circumstances under which oestradiol 17ß could be administered for other purposes to food-producing animals.

The “Beef” “Hormone War

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To make cows grow faster, for many years the animal agriculture industry used “artificial beef growth hormones”, in particular estradiol, progesterone, testosterone, zeranol, melengestrol acetate and trenbolone acetate (the last two are synthetic and not naturally occurring). Cow farmers were legally allowed to administer synthetic versions of natural hormones for cost-reduction and to synchronise the oestrus cycles of dairy cows. 

In the 1980s, consumers began expressing concern over the safety of hormone use, and in Italy there were several “hormone scandals” exposés, claiming that children eating meat from cows who had received the hormones showed signs of the premature onset of puberty. No concrete evidence linking premature puberty to growth hormones was found in the subsequent enquiry, in part because no samples of the suspect meals were available for analysis. In 1980 the presence of diethylstilbestrol (DES), another synthetic hormone, in veal-based baby foods was exposed as well.  

All these scandals, although did not come with a scientific consensus based on irrefutable evidence that people consuming meat from animals who were given such hormones suffered more unwanted effects than people consuming meats from animals whom the hormones were not given, that was enough for EU politicians to attempt to control the situation. In 1989, the European Union banned the import of meat that contained artificial beef growth hormones approved for use and administered in the United States, which created tensions between both jurisdictions with what is known as the “beef hormone war” (the EU often applies the precautionary principle concerning food safety, while the US does not). Originally, the ban only provisionally banned six cow growth hormones but in 2003 permanently banned estradiol-17β. Canada and the United States opposed this ban, taking the EU to the WTO Dispute Settlement Body, which in 1997 ruled against the EU.

In 2002, the EU Scientific Committee on Veterinary Measures Relating to Public Health (SCVPH) concluded that the use of beef growth hormones posed a potential health risk to humans, and in 2003 the EU enacted Directive 2003/74/EC to amend its ban, but the US and Canada rejected that the EU had met WTO standards for scientific risk assessment. The EC has also found high amounts of hormones in the surrounding areas of intensive cow farms, in the water, affecting waterways and wild fish. One of the hypotheses of why synthetic hormones could cause negative effects in humans who eat meat from animals who received them, but this may not be the case for natural hormones, is that the natural metabolic inactivation by the body of the hormones may be less effective for synthetic hormones as the body of the animal does not possess the necessary enzymes to eliminate these substances, so they persist and may end up in the human food chain.

Sometimes animals are exploited to produce hormones and then used in animal agriculture. “Blood Farms” in Uruguay and Argentina are used to extract Pregnant Mare Serum Gonadotropin (PMSG), also known as Equine Chorionic Gonadotropin (eCG), from horses to sell it as a fertility hormone used in factory farms in other countries. There have been calls to ban the external trade of these hormones in Europe, but in Canada, it is already approved for use by factory farms looking to trick the bodies of mother pigs into having larger litters.

Currently, the use of hormones in animal farming remains legal in many countries, but many consumers try to avoid meat from farms that use them. In 2002, a study showed that 85% of US respondents wanted mandatory labelling on cow’s flesh produced with growth hormones, but even if many showed a preference for organic meats, meats produced with the standard methods remained the majority consumed. 

The use of antibiotics and hormones in animal agriculture has now become a form of abuse as the sheer numbers involved are creating all sorts of problems. Problems for the farmed animals whose lives have been messed to force them into unnatural medical and physiological situations that make them suffer; problems for the natural habitats surrounding farms where these substances may end up contaminating the environment and negatively affecting wildlife; and problems for humans as not only could found their bodies negatively affected when consuming the flesh of animals farmers gave such substances to, but soon they may no longer be able to use antibiotics to combat bacterial infections as the animal agriculture industry is making the antimicrobial resistance problem reach a critical threshold we may not be able to overcome. 

Becoming vegan and stopping supporting the animal agriculture industry is not only the right ethical choice for the animals and the planet, but it is the sensible choice for those who are concerned with human public health.

The animal agriculture industry is toxic.

Jordi Casamitjana
“Originally from Catalonia, but resident in the UK for several decades, Jordi is a vegan zoologist and author, who has been involved in different aspects of animal protection for many years. In addition to scientific research, he has worked mostly as an undercover investigator, animal welfare consultant, and animal protection campaigner. He has been an ethical vegan since 2002, and in 2020 he secured the legal protection of all ethical vegans in Great Britain from discrimination in a landmark employment tribunal case that was discussed all over the world. He is also the author of the book, ‘Ethical Vegan: a personal and political journey to change the world’.