Hormones in Food
The artificial hormones that underpin the mass production of food are sparking new concerns about how they affect our bodies. Though government tests in the United States show that almost all residues fall within safety margins, there is growing concern that hormone residues in meat and milk might be harmful to human health and the environment.
Recombinant bovine growth hormone (rBGH), for example, increases milk production in cows. Canada has not approved its use and many scientists are worried that the hormone-laced milk is a potential health risk. But dairy farmers swear by rBGH. Injections every 14 days for Jim Mlsna’s (a dairy farmer from Hillsboro, Wisconsin) 300 cows, increases daily milk production by 10 pounds an animal. The Food and Drug Administration (FDA) and the United States Department of Agriculture (USDA) deem milk from hormone-treated cows safe, and Mlsna says: “I wouldn’t let my children drink the farm milk if I didn’t think it was safe.”
What’s in the Beef?
According to the European Union’s (EU) Scientific Committee on Veterinary Measures Relating to Public Health, the use of six natural and artificial growth hormones in beef production poses a potential risk to human health. These six hormones include three that are naturally occurring — Oestradiol, Progesterone and Testosterone — and three that are synthetic — Zeranol, Trenbolone and Melengestrol.
The EU committee also questioned whether hormone residues in the meat of “growth enhanced” animals can disrupt human hormone balance, causing developmental problems, interfering with the reproductive system, and even leading to the development of breast, prostate or colon cancer.
Children, pregnant women and the unborn are thought to be most susceptible to these negative health effects. Hormone residues in beef have been implicated in the early onset of puberty in girls, which could put them at greater risk of developing breast and other forms of cancer. The EU committee reported that as of 1999, no comprehensive studies had been conducted to determine whether hormone residues in meat can be cancer-causing.
Scientists are also concerned about the environmental impacts of hormone residues in cow manure. Growth promoting hormones not only remain in the meat we consume, but they also pass through the cattle and are excreted in their manure. When manure from factory farms enters the surrounding environment, these hormones can contaminate surface and groundwater. Aquatic ecosystems are particularly vulnerable to hormone residues. Recent studies have demonstrated that exposure to hormones has a substantial effect on the gender and reproductive capacity of fish, throwing off the natural cycle.
In one of the EU-funded studies, research teams led by Louis J. Guillette Jr. of the University of Florida and Ana M. Soto of Tufts University School of Medicine in Boston collaboratively investigated the environmental fate of hormones running off feedlots (where animals get beefed up on high-protein food) in Nebraska. Soto compared the hormonal activity of water sites downstream of feedlots with that of water collected upstream. In her tests, she added water samples to cells that react in various ways to steroids. In one assay, estrogen turns on cell growth; in another, androgens inhibit cell growth.
At a meeting in Copenhagen in May 2000, Soto reported her findings that concentrations of estrogenic pollutants at two of the downstream sites were sometimes almost double those at the upstream site. And water from all three downstream sites was significantly more androgenic than the samples collected upstream. One downstream sample exhibited nearly four times the androgenicity of the upstream water.
Toxicologist L. Earl Gray Jr., of the Environmental Protection Agency (EPA), also analyzed water from those Nebraska sites. He uses a different assay for androgenicity, but like Soto, he finds evidence of masculinizing steroids. The steroids may not be just sitting benignly in the water. In a report sent to the EU, Guillette reports adverse hormonal changes in fathead minnows.
Males just downstream of the feedlots “had a significantly reduced testes size” — which, he says, appears to explain why they also produced less testosterone than males upstream. He also found that the heads of these fathead minnows weren’t all that fat — which also makes sense, he notes, since testosterone helps determine skull size. What appears to be happening, he says, is that the water-borne androgens provide some signal that tells the males’ bodies to produce less testosterone. In females, the researchers observed a significant increase in the ratio of androgenic to estrogenic hormone concentrations in blood. The biological significance remains unknown.
These observations indicate that wild fish “are being nailed by polluting hormones”, Guillette said — with males becoming somewhat feminized and females somewhat masculinized.
Despite international scientific concern, the US and Canada continue to allow growth promoting hormones in cattle. The EU, however, does not allow the use of hormones in cattle production, has prohibited the import of hormone-treated beef since 1988, and has banned all beef imports from the US.
Moreover, because Soto has not yet identified the particular steroids in downstream waters, Guillette notes, “we can’t rule out that these effects are due to natural androgens and estrogens in manure”. Even untreated cattle, horses and chickens excrete natural estrogens, testosterone and other steroids. However, Guillette adds, when one considers new German data on how long steroidal growth-promoting drugs can persist in the environment, “it’s highly likely that what we’re seeing in these wild fish is a pharmaceutical effect” derived from the farm use of these agents.
At the Copenhagen meeting, Stephen F. Sundlof, director of the FDA’s Center for Veterinary Medicine, noted that although “it is my role to regulate these substances … I was only made aware at this workshop that we may be having some environmental issues to consider”. That was nearly seven years ago. In the interim, Soto and Guillette have briefed Sundlof on their studies. Sundlof has also learned of the German findings. From these, he now concludes that the environmental fate of livestock-steroid use “is something that we [at the FDA] are definitely concerned about”.
The Center for Veterinary Medicine at the FDA has approved the use of these hormones because they tend to leave only small concentrations — ones believed to be harmless — in the meat consumed. However, the regulators haven’t considered what effect the hormones might have after being excreted into the environment.
Lure of the Lucre
The cattleman’s perspective is easily understood — the financial lure of hormones. It costs farmers about $1 to $3 per head to treat their livestock, notes animal scientist Michael J. Fields of the University of Florida. Treatment increases animals’ growth by 20 per cent, so each cow in a feedlot typically gains 3 pounds per day, he says. Moreover, for each pound that it gains, it consumes 15 per cent less feed than an untreated animal does. “This feed efficiency works out to a cost savings of about $40 per head, so you get more protein at a cheaper cost,” Fields says.
Some farmers are trying to inform others of the benefits that would come to the environment from stopping the use of pharmaceutical growth promoters in cattle, such as having a tenderer product to market. An under-reported side effect of the use of growth stimulants is about a 25 per cent increase in toughness of the meat. If the beef industry would eliminate growth-enhancing drugs, their market would expand. Many producers have calculated that this increased demand for beef would more than make up economically for less weight gain by untreated cattle.
What’s in the Milk?
Industrial farms use a number of methods for increasing milk production in dairy cows, including selective breeding, feeding grain-based diets (instead of grass) and exposing cows to longer periods of artificial light. Yet, one of the most common and controversial ways to force greater milk production is to inject them with rBGH, a genetically engineered artificial growth hormone. The hormone has been seen to alter how cows use nutrients, causing them to divert more of their energy intake into milk generation rather than growth. Developed and manufactured under the brand names Posalic® by Monsanto Corporation, rBGH has been controversial from the start. rBGH is also referred to as rBST, or recombinant Bovine Somatotropin.
FDA approval for rBGH came in 1993, in spite of strong opposition from scientists, farmers and consumers. According to detractors, rBGH was never properly tested. The FDA relied solely on a study done by Monsanto in which rBGH was tested for 90 days on 30 rats. The study was never published and the FDA stated the results showed no significant problems. But a review by the Canadian health agency on rBGH found the 90-day study showed a significant number of issues which should have triggered a full review by the FDA.
By the summer of 1994, the Wisconsin Farmers Union and the National Farmers Union set up a joint hotline for dairy farmers to use when reporting problems with the artificial growth hormones in cattle. One New York dairy farmer reported losing a quarter of his herd to severe mastitis (a painful bacterial infection of the udder that causes inflammation and swelling) after beginning rBGH injections. He also reported a drastic drop in production after taking his cows off rBGH; they suddenly produced less milk than they had before going on the drug. A year later, he had to replace 135 of his original 200 cows. Other farmers using rBGH have reported similar problems, in addition to hoof diseases, open sores and cows that died from internal bleeding.
A 1991 report by Rural Vermont, a non-profit farm advocacy group, revealed serious health problems with the rBGH-injected cows that were part of a Monsanto-financed study at the University of Vermont. Among the problems was an alarming rise in the number of deformed calves and dramatic increases in mastitis. To treat mastitis outbreaks, the dairy industry has relied on antibiotics. Critics of rBGH point to the subsequent increase in antibiotic use (which contributes to the growing problem of antibiotic resistant bacteria) and inadequacies in the federal government’s testing programme for antibiotic residues in milk, as further reasons why the hormone should never have been approved.
Additionally, cows forced to produce unnaturally high quantities of milk will often become malnourished because they lose more nutrients through their milk than they ingest in their feed, and are, therefore, more susceptible to disease.
Over the years, some scientists have worried that the hormone treatments seed milk with rBGH residues. According to the International Dairy Foods Association, all milk “contains naturally occurring BGH. Milk from rBGH-supplemented cows contains no more BST than milk from cows not supplemented with rBGH”.
Critics of the therapy have also argued that milk from rBGH-treated cows may develop elevated concentrations of insulin-like growth factor-1 (IGF-1). This protein is important to milk production, bone growth and cell division in all animals, including humans. These higher levels of IGF-1 have been linked to colon and breast cancer. Even though no direct connection has been made between elevated IGF-1 levels in milk and cancer in humans, scientists have expressed concern.
A stunning report linked twin-births to milk diets. Using data obtained from mothers by way of questionnaires, physician Gary Steinman of the Long Island Jewish Medical Center and his colleagues compared the number of twin births from moms who consumed meat and/or milk and those who consumed no animal products at all. They found that the omnivores and vegetarians were five times more likely to have fraternal twins than the vegans.
Faced with mounting evidence to the contrary, the FDA has stubbornly continued to assure consumers that rBGH is safe for cows and humans. In fact, in 1994, the FDA prohibited dairies from claiming there was any difference between milk from rBGH-injected cows and milk produced without the artificial hormone. Critics of rBGH ask why so many US dairies choose to inject their livestock with the engineered hormone when the nation is already experiencing a milk glut. The answer, agricultural economists say, is that dairying doesn’t offer farmers much profit. So any treatment that allows dairies to get hundreds to thousands more gallons from a herd each year looks mighty attractive.
What You Can Do
There are many small family farmers who don’t use artificial hormones on their animals. By purchasing your milk and meat from local and sustainable farms, you are supporting a system that ensures the health and welfare of the farm animals, and protects you and your family from hormone-related health risks.
Choose hormone-free beef and rBGH-free dairy products at the supermarket. Foods that carry the “USDA-certified organic” label cannot contain any artificial hormones. When purchasing sustainably raised foods without the “organic” label, be sure to check with the farmer to ensure no additional hormones have been administered.
References and Useful Websites
- The Scientific Committee on Veterinary Measures Relating to Public Health. “Assessment of Potential Risks to Human Health from Hormone Residues in Bovine Meat and Meat Products.” European Commission, April 30, 1999
- Science News, Vol. 164 and Vol. 161
- Embassy of the United States of America, Stockholm, Sweden – Foreign Agricultural Service, Issue 1999
- National Geographic, May 2002
- Organic Consumer’s Association – Associated Press April 23, 2002