US Food and Drug Administration
Center for Food Safety and Applied Nutrition
SOURCE: http://vm.cfsan.fda.gov/~ear/CORbST.html

Are milk and meat from bST-supplemented cows safe?

YES! Extensive studies of the safety of bST have been conducted world-wide and reviewed by the Food and Drug Administration (FDA). The FDA concluded that both milk and meat are safe. A separate review of the data has been conducted by the National Institute of Health, the World Health Organization, the Office of the Inspector General of the Department of Health and Human Services, and reviews by the Journal of the American Medical Association, Pediatrics, and the Journal of the American Dietetic Association all independently have arrived at the same conclusion, milk and meat from bST supplemented cows are safe. In addition, regulatory agencies from countries around the world have reached the same conclusion, milk and meat from bST supplemented cows are safe. In addition, regulatory agencies from countries around the world have reached the same conclusion.

What is bST?

bST is an abbreviation for bovine somatotropin or what is also called bovine growth hormone. The term rbST has been used to refer to bST that is produced using fermentation technology and injected into dairy cows to increase efficiency of milk production.

Is bST a hormone?

Yes. However, there are two types of hormones: steroids and proteins. bST is a protein hormone. Protein hormones have no activity when taken by mouth, while steroid hormones do have activity. For example, insulin is a protein hormone.

Insulin has no activity if taken orally. Therefore, a diabetic has to have injections of insulin. Like insulin, the protein hormone bST has no activity when taken by mouth. In contrast, hormones used in birth control pills are steroids and therefore are effective when taken by mouth. Again, bST has no effect when taken by mouth.

Furthermore, studies were conducted in the 1950's to determine if children suffering from dwarfism could be given direct injections of high levels of bST to stimulate growth. The conclusion of the study was that somatotropin from cows is not active in humans even if injected. Why? The structure of human somatotropin is so different from bovine somatotropin, that injections of high levels of bovine somatotropin into children have no influence on growth and development.

How does bST work?

The pituitary gland of the dairy cow normally produces bST. bST is one of a group of hormones produced naturally in the cow that controls milk production. Supplemental rbST can be injected into a dairy cow. Both sources of bST (that produced by the cow herself and supplemental) are carried to the liver of the cow via the blood stream. bST in the liver stimulates this organ to produce insulin-like growth factor (IGF-1), another protein hormone that plays an important role in helping regulate the conversion of dietary nutrients into milk.

Supplemental bST helps increase the efficiency of conversion of feed to milk in the cow's body. It has been shown that to support increased milk production, a cow supplemented with rbST automatically consumes more feed. The amount of nutrients required for the cow's body maintenance remain unchanged, therefore, the cow's increased nutrient intake is used primarily for milk production. bST is found in trace amounts in milk from all cows, unsupplemented and supplemented.

Milk from cows given supplemental bST contains no more bST than milk from cows not given the supplement.

Is there any difference between milk from bST suplemented cows and unsupplemented cows?

For all practical purposes no. There are no differences in nutrient content (i.e., fat, protein, calcium, vitamins, etc.) or sensory characteristics (flavor, color, etc.). There is no difference in bST content.

The concentration of IGF-1 in milk from supplemented cows is slightly higher than from unsupplemented cows. However, the average increase in concentration in milk is small compared to normal variations in concentration of this compound from cow-to-cow in milk from unsupplemented animals. The average increase of IGF-1 in milk produced by supplemented cows is also small compared to the variation in amounts that occur normally from the beginning to end of the cow's lactation period.

Should I be concerned about the small difference in concentration of IGF-1 in milk?

No. IGF-1 is normally present in milk. It is a protein hormone and is digested just like any other protein in milk, meat, or other foods that you eat. IGF-1 is not active when consumed by mouth. IGF-1 is a normal component in human milk. The average amount of IGF-1 in human milk is higher than that found in milk from bST supplemented cows. IGF-1 is also present in human saliva and the average person consumes IGF-1 from this source each day that is equivalent to the amount consumed from any source of milk.

How much more milk does a bST supplemented cow produce?

On average about 10%. After having a calf, a cow produces milk for about 300 days. The highest daily milk production will occur at about 8 weeks after calving and then the level of milk production per day gradually declines during the rest of the lactation period. Not all cows give the same amount of milk. Cows that produce the highest amounts of milk generally have about the same peak milk production per day as lower producing cows. However, the rate of decline in daily production of milk during the rest of lactation is slower in these high-producing cows.

Administration of supplemental bST is started after the peak of milk production occurs and causes the cow to maintain a higher level milk production per day during the period when milk production is normally declining. Therefore, a cow supplemented with bST will not be producing more milk per day than it produced per day at peak production prior to the start of bST supplements.

Won't higher milk production trigger mastitis in cows?

The question of animal health has been reviewed extensively by the FDA and was the subject of a special FDA Expert Advisory Panel hearing on March 31, 1993. The Panel reported that based on extensive research results, any increase in mastitis that may result from use of bST is insignificant compared to the increase in mastitis that occurs normally for other reasons, such as seasonal variation, extremes of weather conditions, age of the cow, and stage of lactation. The influence of season of the year changes the incidence of mastitis 9 times more that the influence of bST.

Doesn't treating mastitis require antibiotics which might find their way into milk and affect milk safety?

No. Federal and state milk safety and quality assurance programs, as well as testing by farmers and processors, ensure the safety and wholesomeness of milk. When a farmer treats a cow with an antibiotic, the milk from that cow is discarded by the farmer for several days as defined on the label of the antibiotic. In many cases today, a concerned farmer sends a sample of milk from that cow to the dairy plant to be tested for antibiotics before the milk from that cow is allowed to go in with the milk to be sold.

When milk is picked up at dairy farms, the truck driver must take a sample of milk from the farm bulk tank at every farm before the milk is pumped into the truck. When every truck arrives at a milk processing plant, a milk sample is taken from the milk in the truck and tested for antibiotics. If the load is positive, the truck is not unloaded. Another sample is taken and the positive test is confirmed. If the load of milk is positive for antibiotics, then all of the individual farm samples that the driver collected are tested to identify

which farm's milk contained the antibiotics. In addition, the dairy plant must notify the local regulatory agency that milk is being discarded and they need to document the manner in which is was discarded.

There are very large financial penalties imposed on dairy farmers that contaminate a truck load of milk with antibiotics. Many processing plants have offered incentives to their farmers to avoid contamination of tank trucks of milk with antibiotics. If a farmer thinks a mistake has been made and his/her milk is contaminated, he/she can call the plant and have a milk sample picked up and tested. If the tank of milk is positive and the farmer prevented it from contaminating a full truck load, then some plants have a program to pay the farmer for one tank of milk during some period of time (for instance, 1 year).

What impact will the approval of bST have on the economy and the environment in the US?

The US Office of Management and Budget recently reported that the use of bST will likely have a small but positive impact on the US economy and environment. Use of bST will reduce the amount of animal waste per unit of milk produced and will reduce the amount of feed required to produce a unit of milk. This will be an environmental benefit.

Will some dairy products be labeled as "from cows not treated with rbST" and what does it mean?

This type of label will be allowed by the US FDA. FDA also requires that all statements on food product labels must be truthful and not misleading. The FDA recommends that the company also put information on the label to inform the consumer that "no significant difference has been shown between milk derived from rbST-treated cows and non-rbST-treated cows". FDA says that this will put the statement "from cows not treated with rbST in proper perspective so it is not misleading. The FDA recommends that firms that make such claims establish a plan and maintain records to substantiate their claims, and make those records available for inspection by regulatory agencies responsible to verify the accuracy of the label claim.

Will the commercialization of bST hurt the small dairy farmer?

The effective use of bST has nothing to do with farm size. Unlike many new technologies, there is no up-front capital costs before a farmer starts using this technology. Thus, small farms will have equal access to this technology. The Office of Technology Assessment has concluded that "quality of management" on the dairy farm, not farm size, will be the major factor affecting the magnitude of milk production response from bST. Better farm managers will benefit most from bST, regardless of farm size. Milk price is derived from many factors including consumer demand, business costs, and government regulations.

Will bST create a large surplus of dairy products?

No. The signal to a dairy farmer that triggers the production of more or less milk is the difference between the price of milk paid to the dairy farmer and the cost of producing that milk. Farmers will continue to respond to these signals. The larger the spread between cost of production and price paid to the farmer for milk, the greater the incentive for dairy farmers to produce more milk. Prior to the introduction of bST there have been times of short and surplus milk supply and times of high and low milk prices. This will continue with or without bST use.

Use of supplemental bST will provide dairy farmers with a production management tool to produce the same amount of milk that would have been produced without bST with fewer cows and at lower cost. The signal to the dairy farmer to produce more or less milk will continue to be based on the difference between the price paid for milk and the cost of milk production. For the well-managed dairy farm that adopts bST technology (just like any other technology that improves efficiency), profitability should be enhanced.

Over the period from 1982 to 1992 (when most of the research on bST has taken place), new technology and better dairy farm management without supplemental bST has increased the annual milk production per cow from 12,306 to 15,423 pounds per year (25% increase in productivity per cow), while the number of cows has decreased.

Increased production efficiency has kept the rate of increase of dairy product prices to consumers lower than increases in prices of other foods. Thus, excellent food value for the price, new product offerings (such as low fat products) developed through dairy product research that meet changing consumer needs, and promotion of dairy products have increased total sales of milk for commercial use from 122 billion pounds to 142 billion pounds over the same 10 year period.

Should I buy raw milk from a local farmer and pasteurize it at home to be sure I don't drink milk from bST supplemented cows?

While it is possible to do this, there are several risks involved that a consumer should be aware of before they begin this practice. About 2 to 10% of raw milk contains harmful bacteria (such as, Salmonella, Listeria, Campylobacter, E. coli 0157:H7 and possibly other pathogens). These disease causing bacteria are all killed by commercial pasteurization. There is very strict regulatory inspection, control, and testing of milk processing equipment and personnel to ensure that commercially pasteurized milk does not contain pathogenic bacteria and that milk is not recontaminated after it is pasteurized. When pasteurization of milk is done at home, there is always a possibility that the milk will not be fully pasteurized or that it will be contaminated after pasteurization.

In addition, all milk from commercial processing plants is tested for the presence of antibiotics prior to processing and bottling. If a consumer buys raw milk directly from a dairy farmer, that consumer has abandoned the dairy industry's quality and safety assurance system designed to protect them from antibiotic contaminated milk. The food safety risks of home pasteurization could be large compared with the low level of risk that has been enjoyed by consumers of commercially pasteurized milk.

For answers to additional questions, contact Professor David M. Barbano
Department of Food Science Cornell University, (607) 255-5482.

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