Buckeye Dairy News: Volume 10 Issue 2

Dr. Normand St-Pierre, Dairy Management Specialist, The Ohio State University (top of page)

Summary

• rbST has not been legislatively banned in any country because of human safety concerns.
• Currently, rbST is registered for commercial sale in 20 countries. In addition, 56 countries have confirmed that rbST is safe and pose no human safety threats.
• The current legislation does not allow the use of rbST within European Union (EU) member countries, but it allows imports of milk and dairy products from rbST animals into the EU.

Details

• Technically speaking, no country has a regulatory ban on rbST. Registration of rbST for commercial use has simply not been completed in many countries. Some have imposed a legislative ban.
• No country has banned the importation of milk or milk products from the U.S. or from any of the countries where rbST has been approved and registered. Milk from cows supplemented with rbST can be exported anywhere in the world (U.S. Dairy Export Council).
• There are 20 countries that have a current registration of rbST for commercial sale. Chile is the most recent country to grant registration in 2006.
• There are 56 countries that have confirmed that rbST is safe and does not threaten the human food chain; these include Canada and most countries members of the EU.
• Although there are countries in which rbST has not received registration for commercial sale, the process is generally still open. In some countries, however, the process has been suspended or blocked (banned) through a legislative ban, mostly for political and economic reasons.
• The list of national and international scientific/medical/health/government organizations that have confirmed the human safety of milk and meat products from cows supplemented with rbST is very lengthy and include (not an exhaustive list):

  American Cancer Society; American Council on Science and Health; American Dietetic Association (ADA); American Medical Association (AMA); Canadian Animal Health Institute; Canadian Dietetic Association; Canadian Institute of Biotechnology; Canadian Medical Association; Canadian Network of Toxicology Centres; Canadian Pediatric Society; Children's Nutrition Research Center; Baylor College of Medicine; Council on Agricultural Science & Technology; European Union's Committee for Veterinary Medicinal Products (CVMP); Food and Drug Administration (FDA); Food and Agriculture Organization of the United Nations (FAO); Food and Nutrition Science Alliance; Food Marketing Institute; Grocery Manufacturers of America (GMA); Health Canada; Institute of Food Technologists (IFT); International Dairy Food Association (IDFA); Joint FAO and WHO (World Health Organization), Expert Committee on Food Additive (JECFA); National American Wholesale Grocers' Association; National Dairy Council; National Institute of Health (NIH); Royal College of Physicians and Surgeons; The American Academy of Family Physicians Foundation; The Ohio State University - College of Food, Agricultural and Environmental Sciences; Toronto Biotechnology Initiative; University of California - Berkely; University of California - Davis; U.S. Congress Office of Technology Assessment (OTA); U.S. Food and Drug Administration - Response to Citizen Petition on bST; U.S. Dairy Export Council; U.S. Surgeon General Office

Some have erroneously stated that "Codex Alimentarius, the United Nations main food safety body, TWICE decided it could not endorse the safety of rBGH for human health". This statement is incorrect. The Codex Alimentarius Commission was created in 1963 by FAO and WHO to develop food standards, guidelines, and related texts, such as codes of practice under the Joint FAO/WHO Food Standards Programme. The main purposes of this Programme are protecting the health of the consumers, ensuring fair trade practices in the food trade, and promoting coordination of all food standards work undertaken by international governmental and non-governmental organizations. The FAO/WHO has stated very clearly its position regarding the human safety of rbST:

After examining new evidence, an FAO/WHO independent scientific committee has reconfirmed that the treating of cows with the hormone bovine somatotropins (sic), known as BST, to increase milk production is safe. The Committee concluded that there are no food safety or health concerns related to BST residues in products such as milk and meat from treated animals. (http://www.fao.org/news/1998/980301-e.htm)

The Codex Alimentarius never did question the human safety of rbST. Twice it failed to reach a consensus regarding maximum residue limits (MRL) for products from rbST supplemented animals. During its 22nd session, the commission decided to suspend the consideration of the adoption of MRL for bovine somatotropin. The Chairperson of the Committee on Residues of Veterinary Drugs in Foods reported that the Fiftieth Meeting of JECFA had re-evaluated bST and that the previous MRL "not specified" for bST were confirmed when the substance was used in accordance with good veterinary practice. The Committee on Residues of Veterinary Drugs in Foods, however, had been unable to reach a consensus on the adoption of the MRL because (1) some argued that MRL were unjustified based on JECFA 's finding, and (2) due to the lack of defined methods of analysis.

Statements such as "European nations and Canada have banned rbGH to protect citizens from IGF-I hazards" are grossly incorrect. In 1999, the Council of the European Union (a legislative body) decided to definitely ban the possible use of bovine somatotropin (rbST) in the EU. In support of its ban, it invoked animal welfare reasons. Prior to that decision, the European legislators had invoked different reasons, especially the impact on the European dairy policy, with varying success. Concerns over public safety were always cleared by the competent scientific committee, the Committee of Veterinary Medicinal Products (CVMP). In other instances, European Courts found concerns to be unfounded. Despite the scientific finding of safety to human and public health, which should have led to the establishment of a MRL, the EU legislative body decided to ban rbST. The current legislation does not allow the use of rbST within EU member countries, but it allows imports of milk and dairy products from rbST animals into the EU. If consumer safety was a concern, it would be hard to follow the logic of an approach that considers a product unsafe for consumers in the EU if it is administered within the EU, but safe if it comes from animals treated in other countries.

Adapted from "Bovine Somatotropin Safety around the World" by Dr. Terry Etherton, The Pennsylvania State University.

Dr. Normand St-Pierre, Dairy Management Specialist, The Ohio State University

Summary

• The IGF-I in human plasma is found at concentrations that are 10.5 to 77 times greater than that in bovine milk.
• The IGF-I concentration in bovine milk is quite variable regardless of whether the animals are supplemented with rbST or not. Many factors such as herd, stage of lactation, parity, and diet affect IGF-I concentrations to a greater extent than rbST supplementation.
• Compared to gastrointestinal secretions in adults, bovine milk has in fact a very low IGF-I concentration. Daily ingestion from saliva and other digestive secretions in a normal adult equals the amount of IGF-I found in 95 quarts of milk.
• Endogenous daily IGF-I secretions (i.e., body production) equal the IGF-I found in 3000 quarts of milk.
• There has been some reports documenting an association between serum IGF-I and the risk of certain cancers. It is generally thought that the cancer cells are responsible for the elevated serum IGF-I and not the other way around. Regardless, the total daily IGF-I intake from milk is so low compared to endogenous secretions (less than 1% assuming that all IGF-I consumed is absorbed) that it seems highly unlikely that cancer would be directly related to IGF-I intake.

Details

One area of concern regarding the safety of rbST is that IGF-I in milk results in elevated IGF-I levels in humans after they consume milk from cows supplemented with rbST. The Food and Drug Administration (FDA) maintained and continues to maintain that "levels of IGF-I in milk whether or not from rbGH supplemented cows are not significant when evaluated against the levels of IGF-I endogenously produced and present in humans".

• The IGF-I is normally found in human plasma at concentrations much higher than those found in bovine milk (Schaff-Blass et al., 1984). The levels in human plasma range from a low in neonates of 14 ng/mL to a high of 686 ng/mL in late pubertal females. The mean values of IGF-I concentrations in human plasma are between 42 and 308 ng/mL.
• The mean serum IGF-I concentration in cows not supplemented with rbST is approximately 4 ng/mL at mid lactation (Collier et al., 1991). In this survey of 100 bulk tanks from farms not utilizing exogenous somatotropin supplementation, the mean IGF-I concentration was found at 4.3 1.1 ng/mL, with a range of 1.3 to 8.1 ng/mL. In another study (Juskevich and Guyer, 1990), milk samples from 5 commercial dairy herds not supplemented with rbST had a mean IGF-I concentration of 2.54 ng/mL.
• Reported percentage increases in IGF-I concentrations in milk of rbST supplemented cows are deceiving and misleading because the levels of IGF-I in milk are so low prior to any increase. The IGF-I concentration in milk of rbST supplemented cows is increased by 2 to 3 ng/mL (Juskevich and Guyer, 1990; Torkelson et al., 1988), thus leading to the 50 to 100% increase often stated. Nowhere can one find in the scientific literature a 10- fold increase (1000 %) in serum IGF-I concentration from rbST supplementation as has been stated in public comments and various internet sites. In addition, the effect of farm, parity, and stage of lactation have a greater effect on serum IGF-I concentrations than rbST supplementation (Collier et al., 1991).
• The total daily production of IGF-I (the endogenous production) in an adult is approximately 10,000,000 ng/day (Guler et al., 1989). Gastrointestinal secretions in adults are estimated at 357,400 ng/day (Chaurasia et al. 1994; Vander, Sheman and Luciano (ed.), 1990). Thus, the daily IGF-I from saliva and other digestive secretions equal the IGF-I in 95 quarts of milk. The IGF-I from whole body production equal to the IGF-I in 3,000 quarts of milk. Milk is just a very low source of oral IGF-I. In fact, the IGF-I concentration in saliva is more than 50% greater than that of milk.
   

Table 1. Volume and IGF-I concentrations in gastrointestinal secretions of human adults.

• The IGF-I comprise one-tenth of one millionth of total milk proteins. It is digested in the gastrointestinal tract like other dietary protein. There is little to no direct absorption of IGF-I (NIH, 1990; Houle et al, 1995; Phillips et al., 1995). In fact, a massive dose of IGF-I administered orally (8.45 µg/day) resulted in an increase of less than 5 nmol/L in serum IGF-I in training athletes (Mero et al. 1997). Interestingly, a one hour training session has a greater impact on serum IGF-I than the oral supplement.
• The IGF-I is normally found in human breast milk in concentrations higher than those found in bovine milk. The IGF-I concentrations in human milk ranged between 13 and 40 ng/mL (Corps et al., 1988; FDA, 2000). These levels are 3.25 to 15.7 times greater than those of bovine milk.
• There has been some reports of increased IGF-I serum concentrations after humans consume milk (e.g., Heaney et al. 1999). The IGF-I increased observed in this study must be viewed in light of the total daily adult endogenous production of IGF-I, which is in the milligram range while the daily levels of IGF-I consumed in milk are in the microgram range - this is a thousand fold difference (FDA, 2000). Even if all the IGF-I in 1.5 liters of milk was directly absorbed - which it is not - the plasma IGF-I would be altered by a maximum of 1%. Well-controlled studies have reported no significant change in serum IGF-I levels over a 2 year period for women supplemented with four 8-ounce glass of milk for the duration of the trial (Storm et al., 1998).
• Some have asserted a connection between increases in levels of IGF-I and breast, prostate, and lung cancer (Chan et al., 1998; Hankinson et al., 1998; Yu et al., 1999). These papers note a possible relationship between increased risks for these cancers and elevated levels of IGF-I, but none of them showed a causal relationship. In fact, one paper states "that the increased IGF-I plasma levels may be part of the phenotype [i.e., expression] of certain types of cancer." Thus, the cancerous cells themselves may promote IGF-I to maintain accelerated cell cycle (FDA, 2000). The presence of oxygen (air) is essential to start and maintain a fire, but it does not cause the fire. In addition, these cancers generally appear much later in life than peak IGF-I which occurs in late puberty. Also, strenuous exercise increases IGF-I concentrations without having any positive association with these cancers.

(References are available on request.)