Meat and Dairy and Antibiotics and Hormones, Oh My!

ANTIBIOTICS

Antibiotics have been used since the 1940s to treat diseases in farm animals. Over time, these drugs were given to promote growth and prevent infection. Many food growers add antibiotics to the livestock feed or water to prevent illness. This also stimulates weight gain in the animal.

Colorful antibiotic capsules. The majority of antibiotics made are used in farm animals.

The antibiotics these animals consume remain in the final food products, such as milk, meat, and eggs. These are considered reservoirs of antibiotics, which, when consumed by humans, can lead to allergic reactions and antibiotic resistance. The antibiotics used commercially in food production contribute to the current spread of antibiotic-resistant bacteria.

Photo of raw meat, milk, and eggs. These foods can act as antibiotic reservoirs if the animals they came from were treated with antibiotics.

The World Health Organization has recommended stopping the routine use of antibiotics for growth and disease prevention in healthy animals. They estimate in some countries, about 80% of antibiotic use is in animals for food production. Antibiotic resistance is a problem everywhere, leading to the death of about 700,000 people worldwide annually. Estimates in this country show that more than 2.8 million people are infected each year with antibiotic-resistant bacteria. Among these are 35,000 deaths.

Antibiotic sales have steadily risen in the United States as there are no clear guidelines for their use in animals, and no limits are set for antibiotic residues in food. There are 89 different antibiotics used in animal production.

Europe has taken steps to reduce this use. In 2006, the EU banned the use of antibiotics in farm animals for growth promotion. In 2022, they banned the routine use of antibiotics in farming and for preventive measures. They allow them to be given to sick animals. They also do not allow the import of animals or animal products treated with antibiotics to promote growth and have set limits for antibiotic residues in food, unlike here.

Unfortunately, manufacturers are not required to label their products as raised with antibiotics. Sometimes a label states “no antibiotics” or “antibiotic-free” but this is not mandatory. The only way to guarantee this is to buy products with an organic label, which is not always affordable. 

STEROIDS

The Food and Drug Administration (FDA) approved the use of steroid hormones in beef, cattle, and sheep in the 1950s. Natural and synthetic estrogen, progesterone, and testosterone were included. These are used to increase the growth, meat, or milk production of these animals. Increasing production means an increase in profit.

Steroid vials of testosterone and estrogen, both used in animals to increase meat and milk production.

The FDA determines the safe, acceptable limits for these hormone levels in meat. In other words, they determine the level of drug that is expected to have no harmful effect on humans. The Freedom of Information Summary is published on the FDA website and gives the public the information they used to determine safety. The FDA also requires that food manufacturers show how much hormone remains in any edible tissue after treatment to ensure it is below the safe level.

Synthetic estrogen and testosterone pellets are implanted in a young animal’s ear, releasing hormones as the animal ages. These hormones increase milk production and make the animal gain weight more quickly.

In the 1950s and 1960s, the estrogen compound used was diethylstilbestrol (DES). This was the same hormone given to pregnant women during that time to prevent miscarriages. DES was banned in 1979 due to it causing a higher risk of vaginal cancer in the daughters of women who received this steroid. This was decades after it was first shown to cause cancer.

In the 1980s, in Puerto Rico, a high rate of precocious puberty (early sexual development) was reported. This was traced to high levels of estrogen in the meat and chicken they consumed. The age of puberty has gradually decreased in this country over the past century, but this is thought to be due to the increase in obesity rather than from external hormones. 

Europe maintains stricter standards and regulations for food products, as seen with food dyes and the far fewer additives allowed than in the US. In 1981, the EU prohibited using hormones for growth promotion in farm animals. They prohibit the same hormones the United States uses (estradiol, progesterone, testosterone, and their synthetic versions. They also prohibited the use of growth hormones in 1985.

Flag of the European Union (EU). The EU banned the use of antibiotics in healthy animals and the use of steroids in farm animals years ago, determining them unsafe for human consumption.

The EU prohibited hormone use in animals in Europe and in imported meats. In 1999, an independent advisory council in the EU concluded that NO acceptable daily intake (ADI) could be established for any of the six hormones. This was reconfirmed in 2000 and 2002. The greatest concern was estradiol, which was considered a carcinogen. In 2008, the European Parliament prohibited all uses of estradiol. The United States protested these rulings since their meat export to Europe dropped dramatically. 

The EU has been concerned about health risks to its citizens; the US’s concerns are lost profit. Unlike the United States, Europe prioritizes consumer protection, even opposing the World Trade Organization, which tried to overturn Europe’s rulings. In the USA, the estrogenic effects of pesticides and plastics (endocrine disruptors) are being researched, yet hormone treatment of animals is not. Whether or not this could be related to increasing cancer rates in young adults remains to be seen. 

There are substantial gaps in our knowledge.