EU Scientific Committee Warns of Human Health & Cancer Hazards
of Monsanto's recombinant Bovine Growth Hormone (rBGH)

Scientific Committee of European Union on Veterinary Measures relating to
Public Health
Outcome of discussions

Report on Public Health Aspects of the Use of Bovine Somatotrophin -
15-16 March 1999
4. Summary and Conclusions

Numerous reports have indicated that the application of recombinant growth
hormones (rBST, rbST) increases productivity of dairy cows measured as
total milk yield per animal per lactation period. The application of rBST
therefore may result in economic benefits although no therapeutic
indications have been considered in the target animal species to date.

Based on its peptide nature, rBST has to be applied parenterally and the
concept of species - specificity implies that residual amounts of
unchanged rBST fail to induce a biological response in species (including
humans) other than bovines. However, the nature of rBST cleavage products
and their biological activity has not been
investigated in detail.

Comparably to the endogenous growth hormone, rBST is known to increase the
level of circulating IGF-I in the target animal followed by an increased
excretion of IGF-I in milk. Consequently increased levels of IGF-I in milk
have to be included in the estimation of potential health hazards
originating from the zootechnical use of rBST.

IGF-I is a physiological constituent of bovine milk. Data on the actual
amount of IGF-I in milk are inconsistent as physiological levels show a
considerable variation depending on the age of the animals, state of
lactation and nutritional status. The highest IGF-concentrations in milk
are found at the initial phase of lactation (colostrum) and decline as
lactation progresses.

The various analytical techniques for the determination of IGF-I and its
truncated forms need to be evaluated in validated procedures. Present data
do not provide a conclusive answer to whether or not previously applied
analytical techniques have underestimated the actual IGF-I level in milk
by neglecting the protein-bound fraction, and to what extent the ratio
between free and bound IGF-I in milk has changed as a consequence of rBST
treatment resulting in a relative increase of the free IGF-I
fraction.

Application of rBST increases the amount of excreted IGF-I in milk by
25-70 % in individual animals. The Committee noted that bovine milk may
contain truncated IGF-I (des(1-3)IGF-I) which was found to be even more
potent than IGF-I in the anabolic response when given subcutaneously to
rats. No quantitative data are available indicating the additional level
of this truncated form of IGF-I in milk from rBST-injected dairy cows.

The biological activity of IGF-I comprises endocrine, paracrine and
autocrine effects and IGF-I has been identified as cellular growth factor
with mitogenic, anti-apoptotic properties and may thus directly interfere
with physiological mechanisms involved in the removal of transformed
cells. Evidence on the physiological essentiality of IGF-I
in foetal and perinatal development is accumulating. Biomedical research
focuses on the possible use of IGF-I in the therapy of distinct diseases,
whereas the detrimental role of IGF-I in tumour progression is disputed.

Experimental evidence for an association between IGF-I and breast and
prostate cancer is supported by epidemiological studies. The bimodal
activity of IGF-I being essential in the process of cellular
differentiation regulating the expression of several genes, and acting as
cellular growth factor with anti-apoptotic properties hinders the
definition and establishment of a no-adverse-effect level, a paradigm in
conventional risk assessment.

Advocates of the medical (therapeutic) use of IGF-I refer to the short
half-life and the auto-regulatory mechanisms sequestering free
biologically active IGF-I via endogenous binding proteins (IGFBPs).

Opponents refer to the epidemiological evidence arising from the recently
published cohort studies indicating an association between circulating
IGF-I levels and the relative risk of breast and prostate cancer,
respectively.

Elevated plasma IGF-levels may be considered as a predictive marker for
breast and prostate cancer. However, it should be emphasised that all
these epidemiological studies refer to a time interval in which exposure
to dairy products originated exclusively from non-rBST treated animals.
Whether or not the use of rBST will modify the level of risk, remains to
be substantiated.

Following the globally accepted concept of risk assessment it is concluded
that:

- Direct risks associated with the use of rBST in dairy cows appear to be
related to the possible increase of IGF-I levels in milk. The diverse
biological effects attributable to the intrinsic activity of IGF-I,
exerting a broad variety of metabolic responses through endocrine,
paracrine and autocrine mechanisms, make the definition of an in vivo
quantitative dose-effect relationship virtually impossible.

- Risk characterisation has pointed to an association between circulating
IGF-I levels and an increased relative risk of breast and prostate cancer.
In addition, the possible contribution of life span exposure towards
dietary IGF-I and related proteins, present in milk from rBST treated
cows, to gut pathophysiology particularly of infants, and to gut
associated cancers need to be evaluated.

- The available data basis for exposure assessment, i.e. the amount of
IGF-I and/or its truncated forms excreted in milk following the
administration of rBST to dairy cows, is incomplete.

In addition secondary risks associated with the use of rBST in dairy cows
are:

- Potential changes in milk protein composition which might favour
allergic reactions.

- An increased use of antimicrobial substances in the treatment of rBST
related mastitis which might lead to an increased risk of residue ormation
in milk and to the selection of resistant bacteria.

Full text on website
http://europa.eu.int/comm/dg24/health/sc/scv/out19_en.html
We (the Greens) will now demand a ban not only on the use of rBST here but
a stop to all imports of milk and dairy produce from rBST/rBGH using
countries.

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Steve Emmott
Advisor, Genetic Engineering
Green Group in the European Parliament
1047 Brussels

Tel/fax (00 32) (0) 2 284 2026