Is Milk from Cows Treated with rBGH Safe to Drink? Unpacking the Controversy

December 9, 2025 •

4 min read

In 1993, the FDA approved the commercial use of recombinant bovine growth hormone, or rBGH, sparking decades of debate. The central question for many consumers remains: is milk from cows treated with rBGH safe to drink? The answer involves understanding both the regulatory stance and ongoing scientific discussions.

Quick Summary

Decades after its FDA approval, the safety of milk from rBGH-treated cows is still debated. While regulatory bodies consider it safe, concerns persist regarding elevated IGF-1 levels, potential antibiotic use, and animal welfare implications. Understanding these issues helps consumers make informed choices.

Key Points

rBGH is a synthetic hormone: It is a genetically engineered version of a naturally occurring hormone used to increase milk production in cows.
FDA has approved rBGH as safe: Since 1993, the U.S. Food and Drug Administration has maintained that milk from rBGH-treated cows is safe for human consumption.
International bans exist: Many countries, including Canada and the European Union, have banned rBGH due to animal welfare concerns and ongoing human health debates.
IGF-1 levels are elevated: Milk from rBGH-treated cows contains higher levels of the growth hormone IGF-1, though the human absorption and long-term effects are disputed.
Potential for increased antibiotic use: Cows treated with rBGH are at a higher risk of udder infections (mastitis), which may lead to more frequent antibiotic treatments.
Clear labeling helps consumers choose: Consumers can look for specific labels like 'rBGH-free' or 'USDA Organic' to ensure they are purchasing milk from untreated cows.
Animal welfare is a key factor: Beyond human health, the use of rBGH raises significant ethical concerns regarding the health, comfort, and lifespan of dairy cows.

Understanding Recombinant Bovine Growth Hormone (rBGH)

Recombinant bovine growth hormone (rBGH), also known as recombinant bovine somatotropin (rBST), is a synthetic, genetically engineered hormone. It is manufactured to mimic the natural bovine somatotropin (bST), a hormone naturally produced by a cow's pituitary gland that regulates milk production. When injected into dairy cows, rBGH stimulates increased milk synthesis in the mammary glands, allowing for a boost in milk yield by approximately 10-15% per cow. The FDA first approved rBGH for commercial use in 1993.

The Science Behind rBGH

When a cow is treated with rBGH, it leads to higher levels of insulin-like growth factor-1 (IGF-1) in the cow's system. This, in turn, boosts milk production. Importantly, IGF-1 is naturally present in all cow's milk, as well as human milk, and is essential for normal growth and development. The key difference in rBGH milk is the potentially elevated concentration of IGF-1. However, IGF-1 concentrations can vary naturally due to factors such as a cow's breed, stage of lactation, and age, making direct comparisons difficult.

Regulatory Approvals vs. International Bans

While the FDA maintains its position that rBGH is safe for human consumption, many other countries have taken a different approach. The use of rBGH has been banned in Canada, the European Union, Australia, New Zealand, and Japan, largely due to concerns over animal welfare and potential human health implications. In Canada, for instance, the ban was enacted in 1999 primarily due to health risks to cows, such as increased rates of mastitis and lameness.

Health Concerns for Humans

The primary human health concerns associated with drinking milk from rBGH-treated cows center on the elevated IGF-1 levels and the increased potential for antibiotic use.

Increased IGF-1 Levels and Cancer Risk

Some research has suggested a correlation between higher blood levels of IGF-1 and an increased risk of certain cancers, including breast, prostate, and colorectal cancers. Milk from rBGH-treated cows contains higher levels of IGF-1, and some studies indicate that pasteurization can increase the amount of free, bioactive IGF-1. Opponents of rBGH argue that while the human digestive system is thought to break down most IGF-1, chronic exposure could still pose a risk, especially for populations with compromised intestinal permeability. However, the FDA and organizations like the American Cancer Society state that there is no conclusive evidence linking milk from rBGH-treated cows to an increased risk of cancer in humans, and that ingested IGF-1 is largely broken down during digestion.

The Link to Antibiotic Use

A well-documented effect of rBGH on cows is an increased risk of mastitis, a painful udder infection. To treat these infections, farmers must administer antibiotics. This raises a twofold concern for consumers: potential antibiotic residues in milk and the contribution to antibiotic resistance. While milk is tested for antibiotic residues, and any contaminated milk is not permitted for sale, the broader issue of promoting antibiotic-resistant bacteria through overuse remains a public health concern.

Making an Informed Choice

For consumers, navigating the rBGH issue requires understanding the nuances between different dairy products and labels. Labels can provide important clues about the milk's production method.

Conventional vs. Organic Milk Production

Conventional Milk: Can come from cows treated with rBGH. The use of rBGH is not required to be labeled in the United States, but many brands voluntarily label their milk as rBGH-free or rBST-free.
Organic Milk: By USDA regulation, organic dairy cows cannot be treated with rBGH or antibiotics. Therefore, all certified organic milk is rBGH-free. Organic cows must also have access to pasture and be given organic feed.

Identifying rBGH-Free Products

To ensure you are purchasing rBGH-free milk, look for labels with claims such as:

“rBGH-free” or “rBST-free”
“No artificial hormones”
“USDA Organic”


Comparison: rBGH-Treated Milk vs. Organic Milk	Feature	rBGH-Treated (Conventional) Milk	Organic Milk
Hormone Use	Cows may be injected with synthetic rBGH to boost production.	Cows are prohibited from being treated with rBGH or other artificial hormones.
IGF-1 Levels	Potentially elevated levels compared to untreated cows, though within natural physiological range.	Reflects natural IGF-1 levels, with no artificial boosting.
Antibiotic Use	Increased risk of mastitis requires higher antibiotic use, raising concerns about resistance.	Prohibited from using antibiotics. Illnesses are treated, but milk is not sold.
Animal Welfare	Associated with greater stress, health problems like mastitis and lameness, and a shorter lifespan for cows.	Strict regulations regarding animal treatment, including pasture access and humane care.
Nutritional Profile	Largely the same as untreated milk in terms of macro-nutrients like fat and protein.	Can contain higher levels of certain beneficial nutrients like omega-3s, depending on the cow's diet.

Conclusion: Weighing the Evidence

Decades after its introduction, the debate over the safety of milk from cows treated with rBGH continues, pitting regulatory approval against persistent consumer concerns and animal welfare issues. While major regulatory bodies like the FDA have repeatedly affirmed its safety for human consumption, acknowledging that the hormone is largely inactive in humans and that any residues are typically degraded, other influential voices and international bodies remain cautious. The concerns regarding increased IGF-1 levels in milk, potential links to cancer, and the downstream effect of increased antibiotic use to combat rBGH-related infections in cows are valid points raised by critics. Ultimately, for consumers in the US where rBGH use is permitted, the decision of whether to opt for rBGH-free or organic milk rests on a personal assessment of the available evidence, their comfort with potential risks, and their concern for animal welfare practices. With many dairy companies now offering rBGH-free options, and with clear labeling on organic products, consumers have more choices than ever to align their purchasing decisions with their personal values and health considerations.

For more detailed scientific and regulatory analysis, you can consult the American Cancer Society's overview of rBGH.

Frequently Asked Questions

rBGH, or recombinant bovine growth hormone, is a man-made, synthetic version of the natural bovine growth hormone that some dairy farmers inject into cows to increase their milk production.

The FDA approved rBGH in 1993 based on its assessment that milk from treated cows was safe for human consumption. The agency concluded that the hormone is inactive in humans and that IGF-1 levels in the milk do not pose a significant health risk.

While rBGH is mostly destroyed by pasteurization and digestion, milk from treated cows does contain elevated levels of another hormone, IGF-1. However, regulatory bodies state this increase is not significant enough to cause a health risk.

Look for labels that explicitly state 'rBGH-free', 'rBST-free', 'No artificial hormones', or 'USDA Organic'. Organic certification prohibits the use of rBGH.

Several countries, including Canada and many in the EU, banned rBGH due to concerns about animal welfare, as the hormone increases the risk of health issues like mastitis in cows.

While both are free of rBGH, organic milk has additional regulations that prohibit the use of antibiotics and require cows to have pasture access and eat organic feed. The 'best' choice depends on your priorities regarding animal welfare and other practices.

The most well-documented risk for cows treated with rBGH is an increased incidence of mastitis, a painful infection of the udder. This leads to increased antibiotic use in the herds.