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    Will Meat From Cloned Animals Kill You?
    By Lee Silver | February 16th 2007 04:10 PM | 12 comments | Print | E-mail | Track Comments

     On December 28, the Food and Drug Administration issued a draft report stating that "meat and milk from clones of adult cattle, pigs and goats, and their offspring, are as safe to eat as food from conventionally bred animals."   In modern-day America, however, the FDA is not allowed to base its decisions concerning public safety simply on the basis of scientific knowledge.  It must listen to the way people feel -- rationally or not -- about its finding.  And so, the FDA explained, 

     

    • Because the release of the draft risk assessment and proposed risk management plan marks the beginning of our interaction with the public on these issues, we are continuing to ask producers of clones and livestock breeders to voluntarily refrain from introducing food products from these animals into commerce so that we will have the opportunity to consider the public's comments and to issue any final documents as warranted

    Not surprisingly, the response was swift and loud from those who distrust all applications of "unnatural" science to the supposed natural world of food production (which is really not natural at all, as I explained in a previous post).   This is what the Center for Food Safety (which lobbies for the organic farming industry) had to say:

     

    FDA’s action flies in the face of widespread scientific concern about the risks of food from clones . . . What's worse, FDA indicates that it will not require labeling on cloned food, so consumers will have no way to avoid these experimental foods. . .cloning scientists warn that even small imbalances in clones could lead to hidden food safety problems in clones' milk or meat. 

    If you're confused or frightened by the prospect of "cloned food," it is critical to take a step back and understand the fundamental biological principles of cloning and food safety.  Biologists use the word "clone" to describe an individual organism -- microbe, plant, or animal -- that carries the same total genetic information as another organism.   The word was invented about 100 years ago by botanists and  breeders to describe new plants created from cuttings of existing plants.  

     

    The first take-home point is that clones are not copies (science fictions stories notwithstanding).  Identical twins are clones of each other, but they are different people.  The second point is that an adult animal cannot be "cloned" directly.   Rather, the total DNA from one of its cells is used to create an embryo that must undergo the entire process of development before a cloned animal (equivalent to a later-born identical twin) comes to life.

     

    With this scientific primer, we can delve into the question of whether meat from cloned cows poses any risk to a consumer (above and beyond the risk of eating any meat).  The critical point is that cloning doesn't add anything new! The cloned animal -- by definition -- will not contain any substance that was not present in the progenitor animal.  Environmental factors may cause it to produce more or less of some proteins or metabolites, but the natural variation among normal cows is much much greater.    The cloned cow cannot make a new allergenic substance or a new toxin or a new cancer-causing agent in the absence of a very rare mutation (which can occur with just as much likelihood in any cow).   The cloned animal might become infected with a virus or bacteria, but this is true for all animals, and sick animals are not allowed into the food supply.  If nay-sayers persist in claiming that its more risky to eat cloned animals relative to "natural" animals, they should provide some sort of scientific hypothesis to support this claim -- I know of none.

     

    Anyone with a Ph.D. in biology will understand the scientific principles I've just espoused, which is why I am bewildered by the claim of the Center for Food Safety that, "cloning scientists warn that even small imbalances in clones could lead to hidden food safety problems in clones' milk or meat."  Which cloning scientists?  Why don't they actually name names?  The answer is probably because they have no names of actual scientists involved in animal cloning work.

     

    What is the basis for the hysterical reaction taken by the Center for Food Safety against the safety of cloned animals?  Is it just an emotional reaction against the "unnaturalness" of cloning as compared to sexual reproduction, or is there something else at play.  Well, this past week, the Center's Charles Margulis and Joseph Mendelson crowed about legislation introduced by Senators Leahy (D-VT) and Kohl (D-WI) that would exclude milk or meat from cloned animals or their progeny from being used in any product that was labeled organic.

     

    The strategy of the organic food industry is clear.  Frighten people into thinking that cloned food will harm their health, and then tell them that the only way to avoid this harm is by eating organic.  No wonder the organic food market continues to grow by leaps and bounds.


    Comments

    i think I am going to make fun of anyone who thinks that milk from a cloned cow is different than regular milk. how many stomachs in a cow do they think need to be non-cloned to produce regular milk? 2, 3?

    Er... but haven't there been problems with cloned animals living much shorter lives than their "donors"? Wouldn't that require something to be very different about them? Can we be sure that that difference doesn't include alterations in the animal's chemistry that might produce harmful substances... or even reduce the nutritional value of the meat, which is also a valid issue?

    Lee Silver
    The frequency of birth defects is greater than with naturally-conceived cows (although much less than is commonly imagined), but it's critical to distinguish between developmental defects/disease and infectious disease.   Many tens of thousands of naturally-conceived cows are born with developmental defects every year as well. Development defects do not imply any new chemicals or substances -- they are simply manifestations of biological structures that are not properly organized.  They may hurt the animal (in which case, the animal is always put to sleep), but they can't harm you.  Remember -- meat is just cooked muscle containing an assortment of protein, fats, carbohydrates and small metabolites.  Cloning cannot -- I repeat, cannot -- add anything that isn't there already.



    Hank

    From other news sites that read this:

    Djehuty also writes a column here on ethics/culture and he wrote elsewhere on this article:

     


    I know very little about the details of this, so here's a question:

    It's my understanding that cell duplication and differentiation "shortens" the DNA a little every time (as opposed to sexual reproduction of a cell), so that for example the skin cells on my arm when freshly grown are different in some sense to skin cells behind my ear when freshly grown - because the cells on my arm have reproduced many more times than those behind my ear. Therefore if a clone is made from a cell from my arm its DNA will be composed of the "older" (and possibly sun-damaged, but let's ignore that) shorter DNA.

    Now I understand that the tail-area of DNA strands is not used to make proteins, so the shorter tail isn't a problem per se. But compare "Dolly the Sheep" to a sheep grown from a fertilized ovum: all her cells' DNA have this shortened tail. Does that mean that Dolly is in some ways (I realise not in most ways, but with reference to DNA tail length) the age of her cell donor plus her own age?

    If so I imagine her quick-reproducing cells (skin for example) would be most affected. Will she have liver spots and dry skin as a teenager, for example?

    Now I'm not arguing that (if the above is true - is it?) that means Dolly's milk or meat is affected. It's not even saying that in most ways the milk or meat is from an "old" animal. Developmentally Dolly is her age, not that of her "mother" plus her age. I can't see there would be too many issues - after all our stomachs break down food to the constituent proteins and the length of the dna strands isn't going to matter, but it's not the lay down mazaire cloning advocates suggest. And the above discussion ignores other issues I know less about. Mitochondrial DNA. RNA. Are their others?

    I know people who have grown plants from cuttings through many generations. Some plants in fact can only be cultivated this way, but it's a well known urban myth (does it have truth?) that in the end it's better to occasionally grow a generation from seed because doing so restores vigor which cloning loses.

    Dr. Jack Heinmann of the Centre for Integrated Research at the University of Canterbury (Christchurch, New Zealand) wrote on Newsvine ( you can respond without having an account here but not there so I copied it here): 

     


    FDA has concluded that cloned animals may be safe to eat. That is a different conclusion than which Dr. Silver draws when he says that the cloning process does not "add anything new". If Dr. Silver were correct, then the FDA conclusion, based on a physical description of the product, would be easy to arrive at. In my view, Dr. Silver's standard has not been achieved through scientific experiment (at least not yet). Just as importantly, when it comes to food for humans, gross compositional equivalence is not the only important factor. For example, it may be safe to eat other humans, but there are important other reasons to not include them in the human food supply. Dismissing other public concerns because they are not in comfort zone of "science" is too restrictive a view.

    Silver says that "Anyone with a Ph.D. in biology will understand the scientific principles I've just espoused." I have a PhD in molecular genetics and do understand the basis for animal cloning, but that is much different from his other extrapolations that are suggested to be obvious derivatives.

    "The critical point is that cloning doesn't add anything new!" This is a critical point that has not been subject to any large scale test. After all, we are still trying to characterise the genome (we know how many genes of a certain description-those that encode recognised proteins-but the number of genes that produce other active gene products is still very much unknown. For example, the number of genes that encode regulatory RNAs is still uncertain.) We still are trying to characterise both the transcriptome and the proteome, each of which have an untold number of components. We arguably know less about the components and variance in the components of large animal genomes than we do the single-celled yeast and even bacteria, and these are still far from fully described.

    I am excited by what we don't know, and find it contrary to the process to assign knowledge by assertion to something that we are both capable of answering with experiments and that we can wait for answers on. Surely the world's hungry are not so because currently cloned cows and sheep are not in the human food supply. It surprises me a bit when there is a rush to dismiss questions of fundamental biological interest (eg, how does an animal made by cloning techniques develop as compared to one formed by breeding? Is the variance between any two bred individuals larger than the variance between bred cows and cloned cows? What size experiment would give us confidence that our comparisons were generalisable?) with "common sense" when the timetable for those questions could conflict with commercialisation.

    There was a very nice paper (reference below) recently that looked at some of these questions. The epigenome of developing cloned and natural cow embryos were characterised. Cloned and natural bovine zygotes were stained with antibodies that revealed the extent of methylation (the patterned addition of chemical groups to DNA; some of these patterns are of clear genetic importance). Significant differences in the amount of methylation at different stages of development were seen. This was hypothesised to be due to failure to fully reprogram the nuclear DNA of donor cells in clones.

    Those authors concluded based on experimental evidence that: “Our results suggest that the type of reprogramming needed for cloning success is ‘foreign’ and unlikely to be readily achieved in the oocyte because epigenetic marks characteristic of somatic cells may differ substantially from those in the egg and sperm, which are efficiently reprogrammed in normal development. This would explain the consistently low rate of cloning efficiency in all species in which it has been achieved…The rare successful development of clones to term may be partly explained by accidental or stochastic erasure of the somatic epigenetic marks.” Clearly, cloning techniques do not create a perfect mimic of the natural breeding process and this has clear biological effects. That some individuals have been cloned is not evidence that they are equivalent to bred animals, only that they were similar enough to not die.

    This is evidence in direct contrast to the assertion that "[t]he cloned animal -- by definition -- will not contain any substance that was not present in the progenitor animal". The genome isn't just the order of deoxribonucleotides, but the interacting network of DNA and epigenes (all of which interact with the environment). On one level, the methyl groups on the DNA are not different substances, but the pattern and its presence at different developmental stages is different from the natural embryo. The effects that this may have on the activity of higher order units of the network (the transcriptome and proteome) can't be guessed. In my opinion, they can't be dismissed but should be tested. Genes are about the information, and thus the arrangement of the components and their temporal regulation is important too.

    Finally, Dr. Silver aggressively calls for evidence of harm rather than more basic research on the fundamental biology of cloned animals when he says "If nay-sayers persist in claiming that its more risky to eat cloned animals relative to "natural" animals, they should provide some sort of scientific hypothesis to support this claim -- I know of none." Again, in my view, it is incumbent upon those that seek to commercialise the benefits of cloning to bear the responsibilty for evidence of safety. It is not the public's responsibility to prove that a technology has been properly characterised. Of course, what constitutes proper is a grey area. What Dr. Silver and I might also take as evidence of risk may also differ, as it does between any two people. But my reading of literature says that there are plausible scientific reasons to hypothesise differences between some cloned and natural animals and that is platform upon which hazard assessment should begin. Not from the perspective that hazards must be proved.

    Santos, F., Zakhartchenko, V., Stojkovic, M., Peters, A., Jenuwein, T., Wolf, E., Reik, W. and Dean, W. (2003). Epigenetic marking correlates with developmental potential in cloned bovine preimplantation embryos. Curr. Biol. 13, 1116-1121

    Lee Silver

    It's my understanding that .  .  .  if a clone is made from a cell from my arm its DNA will be composed of the "older" (and possibly sun-damaged, but let's ignore that) shorter DNA.

    Like many other highly publicized claims about the problems inherent in cloning technology, this one turns out to be false (as explained in this Science paper, cloned animals actually have longer chromosome ends because the ends get lengthened every generation in the embryo.)  Sun-damaged DNA, though, would raise the mutation rate.

    I can't see there would be too many issues - after all our stomachs break down food to the constituent proteins and the length of the dna strands isn't going to matter, but it's not the lay down mazaire cloning advocates suggest. And the above discussion ignores other issues I know less about. Mitochondrial DNA. RNA. Are their others?

      Whether these are issues for animal development or not doesn't matter in terms of whether the muscle=meat will be safe to eat.  Every time we eat a salad, we are putting lots of intact DNA and RNA into our mouths.

    I know people who have grown plants from cuttings through many generations. Some plants in fact can only be cultivated this way, but it's a well known urban myth (does it have truth?) that in the end it's better to occasionally grow a generation from seed because doing so restores vigor which cloning loses.

    Well, then we'd have a real problem with bananas because they don't make seeds. People have been cloning bananas for thousands of years and they still taste good to me. 

    FDA has concluded that cloned animals may be safe to eat. That is a different conclusion than which Dr. Silver draws when he says that the cloning process does not "add anything new". If Dr. Silver were correct, then the FDA conclusion, based on a physical description of the product, would be easy to arrive at. 

    Just because the FDA decides to review something doesn't mean that it is inherently more likely to be risky than products that do not undergo review. These kinds of decisions have as much to do with politics as science.  Case in point:  the FDA has no right to pre-review new "natural" botanical products even though many plants synthesize toxins and other chemicals with significant drug activity.

    In my view, Dr. Silver's standard has not been achieved through scientific experiment (at least not yet). 

    You are right -- my claim is not based on empirical experiments. It is based on a generalized theoretical understanding of how cloning works, how developmental defects are formed, and what substances might be dangerous to eat.  I never made the claim that meat from cloned cows is risk-free.   My claim is simply that eating any kind of meat is associated with a certain level of risk and there is no theoretical basis for the belief that cloned meat would be significantly more risky.

    Just as importantly, when it comes to food for humans, gross compositional equivalence is not the only important factor. For example, it may be safe to eat other humans, but there are important other reasons to not include them in the human food supply. 

    I agree with this point completely, but this issue is completely unrelated to the safety issue.

    Dismissing other public concerns because they are not in comfort zone of "science" is too restrictive a view.

    I didn't dismiss non-safety public concerns.  It's fine for society to debate animal welfare and ethical issues, but proper debate is not aided by confusing ethics and safety.

    "The critical point is that cloning doesn't add anything new!" This is a critical point that has not been subject to any large scale test. 

    I am not sure how you can disagree with my statement that nothing new is added.  Unlike genetic engineering (which often does add something new), no new coding sequence or molecule is *put into* a cloned embryo that didn't already exist in the animal's cells.

    We still are trying to characterise both the transcriptome and the proteome, each of which have an untold number of components. We arguably know less about the components and variance in the components of large animal genomes than we do the single-celled yeast and even bacteria, and these are still far from fully described. I am excited by what we don't know, and find it contrary to the process to assign knowledge by assertion to something that we are both capable of answering with experiments and that we can wait for answers on. Surely the world's hungry are not so because currently cloned cows and sheep are not in the human food supply. It surprises me a bit when there is a rush to dismiss questions of fundamental biological interest (eg, how does an animal made by cloning techniques develop as compared to one formed by breeding? 

    Again, I have no disagreement with you on this point. But it actually bolsters my argument.  We've been eating uncharacterized cow muscle for a long time, and there is huge variation from one cow to another, but it doesn't really matter for food safety.

    Is the variance between any two bred individuals larger than the variance between bred cows and cloned cows? What size experiment would give us confidence that our comparisons were generalisable?) with "common sense" when the timetable for those questions could conflict with commercialisation.

    The experiments you describe have been done (in mice for certain, I will look into cows) and the answers are as theory would predict.  Muscle tissue from cloned animals has an expression and protein pattern that is less variant compared to unrelated animals.

    The genome isn't just the order of deoxribonucleotides, but the interacting network of DNA and epigenes (all of which interact with the environment). On one level, the methyl groups on the DNA are not different substances, but the pattern and its presence at different developmental stages is different from the natural embryo. The effects that this may have on the activity of higher order units of the network (the transcriptome and proteome) can't be guessed. In my opinion, they can't be dismissed but should be tested. Genes are about the information, and thus the arrangement of the components and their temporal regulation is important too.

    Important for what?  Development - no question.  But not for food safety -- there's no theoretical basis.  Cow muscle contains about 5,000 different proteins.  Cows are genetically heterogeneous and from one cow to another there is sure to be differences in gene expression and splicing, and metabolite levels.  Yet, the FDA does not require farmers to analyze every single cow because the identity of the proteins is irrelevant -- it's all broken down in our digestive tracts, and there is no evidence that differences in metabolite levels among cows has any effect on food safety.  If you know of research contrary to this, I'd like to see it.

    But my reading of literature says that there are plausible scientific reasons to hypothesise differences between some cloned and natural animals and that is platform upon which hazard assessment should begin. Not from the perspective that hazards must be proved.

    Your conclusion doesn't hold up -- there are plausible scientific reasons to hypothesize differences among "natural" cows and yet we don't demand that every individual cow be analyzed before it is turned into meat.  You still haven't told me what substance in a cloned cow could possibly cause added harm.  New proteins? No.  New nucleic acids - no.  New carbohydrates - no.   New fats -- the old ones are dangerous enough.  New small molecules could only be made by new enzymes and a cloned animal is not going to make an enzyme that isn't already made in a "natural" animal.    You may not cloning for ethical reasons or for animal welfare reasons -- and we can disagree about that, but you shouldn't suggest that food safety is the issue.





    "The critical point is that cloning doesn't add anything new!" This is a critical point that has not been subject to any large scale test. I am not sure how you can disagree with my statement that nothing new is added. Unlike genetic engineering (which often does add something new), no new coding sequence or molecule is *put into* a cloned embryo that didn't already exist in the animal's cells.I think you cannot conclude that since the coding sequence is the same, nothing new is added. It could be that some protein that is usually expressed at a very low level in 'naturally bred organisms' is in fact expressed at a much higher level in cloned individuals. Surely, this counts as adding something new?Similarly, I don't think its obvious that developmental differences don't translate into food safety differences. After all, developmental differences are caused in part due to different expression profiles and could conceivably lead to differences in composition and hence differences in safety.While it may be true that there is no known theoretical basis for developmental differences translating into food safety differences, all I'm arguing is that it is not a logical deduction either.

    Lee Silver
    You are right that a scientist should never say never. But the question is whether a cloned animal is any more likely to have a significant change in the expression of a gene compared to a normal uncloned, heterogenous animal. Traditional cows are not inbred; every one is genetically distinct from every other cow that ever existed (just based on recombining parental genes), and every one could potentialy carry a new mutation that alters gene expression.  If you wanted to be perfectly safe, you would have to perform a sophisticated analysis on every single one of the millions of cows used every year for meat or milk.  But the risk is so incredibly low that we don't do that.  There is no reason to believe -- none whatsoever -- that random events taking place in a cloned cow are any more likely to impact food safety than random events taking place in your average non-cloned cow.



    SCIENTIFIC RESEARCH ON ANIMALS IS WRONG AND IT SHOULD BE ILLIGAL

    sick animals are not allowed into the food supply

    Two words:
    Mad Cow

    A few more words regarding how
    sick animals are not allowed into the food supply

    "Steve Mendell, chief executive of Westland/Hallmark, on March 12, 2008, admitted to a House subcommittee that cows too sick to stand apparently were forced into the food supply at his plant."
    - Herrera pleads guilty

    Where there is money to be made, somewhere, inevitably, that will trump public health concerns.

    Cloning animals may be good, or bad. If the animals are being harmed, I am totally against it. If the animals are NOT being harmed, then I am for it.

    Now what we need are animals being bred without nerves. This will cause no pain to the animals.
    That's what I'm waiting for.

    sorry buddy but thats never going to happen