Thursday, January 13, 2011

The Practically Primal Guide to Conventional Beef, Part 2: Antibiotics, Chemicals, and Pesticides

As an advocate of grass-fed animal products, I have been critical of practices like use of antibiotics in livestock, but not always with adequate information.  Like other people critical of confined animal feeding operations (CAFOs), I started this investigation with the idea that we should raise animals in a manner as close to wild as possible, which would preclude the use of antibiotics.  

People critical of conventional animal products often claim or imply that these products carry harmful residues of antibiotics and other chemicals, particularly pesticides.  I realized that I had accepted these charges without doing investigation myself.   I wanted to find out if this is the case, both to have my facts straight when talking about any possible advantages of grass-fed meats, and to know if I should advise people to avoid these products at all costs, including not eating meat unless you can afford grass-fed animal products. 

Do Livestock Get Overloads of Antibiotics?

Based on data supplied by the FDA, some people have gotten quite upset to find that, by crude weight, 80% of all antibiotics used in the U.S. get used in livestock production, the other 20% getting used in human medicine.  Opponents of antibiotic use claim that this “overuse” of antibiotics in animals constitutes the main cause of antibiotic resistance in bacteria. 

Although I am not a fan of antibiotic use, I find it inappropriate and illogical to evaluate the use of antibiotics on the basis of total tonnage given to either all livestock or all humans in the U.S.  Medical personnel give doses of antibiotics according to weight, not according to head.  In humans, children get smaller doses than adults based on weight.  Pigs, averaging 230 pounds each, would get larger doses than the average 150 pound human, and cattle, averaging 1300 pounds, require even larger doses. 

According to USDA data , in 2008  U.S. livestock included:

  • 96, 035, 000 cattle and calves with a live weight of 41 billion pounds.  
  • 66, 708, 000 hogs and pigs with a live weight of about 30 billion pounds.   
  • 5,950,000 lambs and sheep, weighing 440, 286, 000 pounds.   
  • 9, 000, 000 dairy cattle, which would have an average live weight of about 4 billion pounds.   
  • 450 million chickens at an average weight of 5 pounds gives 22.5 billion pounds of chickens.   
  • 6 billion pounds of turkey   

These numbers have varied only marginally for 10 years spanning 2000-2009.

Using an average weight for humans of 100 pounds (including children), and a U.S. population of 300 million, we can calculate that the total weight of humans in the U.S. comes to about 30 billion pounds.  From the above data, we can see that the weight of livestock in the U.S. is in the range of about 104 billion pounds, about 3.5 times the weight of humans in the U.S..  Adding miscellaneous food animals (bison, ducks, and others) not counted in the USDA data would bring the weight of animals even higher.

Since antibiotics are dosed by body weight, if we used antibiotics in animals at the same rate as in humans, we would expect that we would annually use three to four times as much antibiotics (by gross weight) in treating animals as in treating humans.  The Center for A Livable Future  reports that in 2009 we used about 29 million pounds of antibiotics for food animals, and about 7 million pounds for humans, or just about 4 times as much in food animals in humans.  Calculated by weight, the use of antibiotics in food animals does not vary much from the use in humans; so if we are overusing antibiotics in animals, we’re also overusing them in humans (on a per weight basis).

We don’t administer low doses of antibiotics to children to increase their rate of growth, yet on a weight basis we seem to use nearly as much antibiotics in people as in livestock.  Since it appears that antibiotics get used in food animals at about the same rate per pound that we use them in humans, this should put to rest the Center For A Liveable Future’s speculation that livestock producers “most likely administered them [antibiotics] in continuous low-dosages through feed or water to increase the speed at which their animals grew.”

Antibiotic Resistant Bacteria

I don’t know why veterinarians apparently get most of the heat for supposedly overusing antibiotics in livestock.  As a Chinese medicine provider, I routinely treat people who have received prescriptions for antibiotics from conventional medical doctors for acute upper respiratory conditions without anyone performing cultures to determine whether the infection is bacterial or viral.  The vast majority of such conditions are viral, and viruses are not susceptible to antibiotics. 

I also have many people tell me that their physician prescribed antibiotics for their chronic sinusitis, but Mayo Clinic research suggests that most chronic sinus infections are fungal.  Antibiotics don’t affect fungi, in fact they enhance fungal growth by killing off harmless flora that would otherwise keep fungal infections at bay.  Thus, I would guess that widespread, essentially indiscriminate use of antibiotics in humans is the most likely cause of antibiotic resistant strains of bacteria that commonly infect humans. 

Then, how about people flushing antibiotics and other drugs down their toilets or sinks?  Whether done intentionally (disposal) or by urination and defecation after using the drugs, it contributes to antibiotics and other drugs occurring in tap water.  This direct deposit of drugs into municipal water supplies can in part account for the multiple antibiotic resistant (MAR) bacteria found in drinking water

Further, it seems to me that anyone who has the idea that we could prevent bacteria from developing antibiotic resistance has failed to understand the basic biological principle of evolution by natural selection.  If you understand this principle, you will see that any use of antibiotics at all contributes to the development of antibiotic resistant strains, and that it is only a matter of little time before fast-reproducing microbes develop resistance to all of our antibiotics. 

Here’s the view based in understanding of the principle of natural selection:  Antibiotics present a environmental stress to bacteria.  In any bacteria population, there will exist a variation in susceptibility to any one antibiotic.  Some will have little or no resistance, and some will have complete resistance.  Whenever we use an antibiotic, we will kill off the bacteria that have insufficient resistance, and those with resistance will remain to reproduce.  This will happen whether we use the antibiotics on a herd of cattle or a human population, even on one individual. 

In short, the principle of natural selection predicts the eventual failure of antibiotics.  As an alternative, I could suggest that we curtail our use of antibiotics, and instead put attention on fortifying host resistance by hygiene, proper diet (for vitamin A and numerous other nutrients) and sun exposure (for vitamin D), use herbs that contain multiple natural antimicrobials for routine antimicrobial purposes, and leave the high dose antibiotics for a last resort.

However, taking another perspective,  I can’t control the actions of other people, and we will adjust to super microbes as surely as we have adjusted to conventional microbes.  If we exhaust the usefulness of antibiotics, this may indeed serve us better in the long run by forcing us to look for better ways to control infectious disease, like increasing host resistance in the manner I have suggested. 

By the way, although we have a great outcry about the supposed increase of antibiotic resistant microbes in developed nations, I haven’t seen any dramatic increase in infectious disease in these nations.  Infectious disease still wreaks its greatest toll in poorly nourished developing nations. 

Antibiotic and Chemical Residues in Meats and Dairy?

The Food Safety Inspection Service of the USDA performs random tests of animal products for residues of antibiotics and fifteen other chemicals or classes of chemicals, and publishes the findings annually.  Below I have copied the page from the 2008 edition of the FSIS National Residue Program Data (aka “Red Book” ) .

Click for larger version.

According to this data, of 4146 samples tested for antibiotic residues, 276, or about 7%, had antibiotic residues that did not exceed residue limits (i.e. non-violative), and only 2 samples, or 0.05%, had violative residues.  Since the USDA impounds products that violate the residue limits, not allowing their sale, this suggests that 93% of animal products on the market have NO antibiotic residues, and the other 7% have residues that have no health effects because they are not large enough. 

If you survey the rest of the list, the FSIS found violations of residue limits for only 5 other chemicals or classes of chemicals:  arsenic, avermectins,  carbadox, chlorinated hydrocarbons or organophosphates, or sulfonomides.  In each case, the violations occurred in much less than 1% of samples. 

Based on production class (i.e. type of animal) the FSIS found violations occurred in beef cows, boars/stags, bob veal, bulls, goats, heavy calves, heifers, market hogs, non-formula fed veal, roaster pigs, and sows, with the highest numbers of violations occurring in heavy calves—2 violations out of 456 samples, or 0.44 percent.  The following graph depicts the number of samples of each production class (in the hundreds, up to nearly 1500 samples in some classes) along with the percent violations (red dots, all less than half of a percent) in each class :

Click for larger version.

The USDA FSIS page "Beef: Farm to Table" explains the regulation of antibiotic use in livestock:

“Antibiotics may be given to prevent or treat disease in cattle. A "withdrawal" period is required from the time antibiotics are administered until it is legal to slaughter the animal. This is so residues can exit the animal's system. FSIS randomly samples cattle at slaughter and tests for residues. Data from this Monitoring Plan have shown a very low percentage of residue violations. Not all antibiotics are approved for use in all classes of cattle. However, if there is a demonstrated therapeutic need, a veterinarian may prescribe an antibiotic that is approved in other classes for an animal in a non-approved class. In this case, no detectable residues of this drug may be present in the edible tissues of the animal at slaughter.”

This Purdue University video describes what happens when the FSIS discovers that a producer has product that contains violative residues:

In short, producers stand to lose their businesses if they produce animals with antibiotic or chemical residues exceeding USDA limits.

I know some may not trust the USDA, considering it in league with the producers to cover-up their misdemeanors.  I myself fall into that class.  You might want to consider the report of Schnell et al, entitled Pesticide Residues in Beef Tissues from Cattle Fed Fruits, Vegetables and Their By-products, from The Journal of Muscle Foods.  The abstract:

“Muscle, adipose, liver and kidney tissue samples were collected from cattle fed potato processing residue (n=20), apple pomace (n=20), pear pomace (n=10), cannery corn waste (n=20), cotton gin trash (n=20), tomato pomace plus almond hulls (n=16), dried grape solids (n=10) or dried citrus pulp (n=6) as well as from control cattle which were not fed fruits, vegetables or their byproducts (n=21). All adipose tissue samples (n=143), representative samples of the above feeds (n=24) and representative samples of muscle (n=35), liver (n=35) and kidney (n=35) tissues were assayed for acephate, benomyl, captafol, cypermethrin, folpet, azinphos-methyl, captan, chlorothalonil, ethyl parathion, and permethrin. In 2,720 tests for the aforementioned oncogenic pesticides, eight tests were positive, but no residue amount that would be considered violative was detected. The only pesticide detected was benomyl and it was detected at nonviolative levels in the adipose tissue of cattle that had been fed either apple pomace or pear pomace.”

Thus, Schnell et al found pesticide residues in only 8 of 2,720 samples, i.e. 0.29%, from cattle fed several different foods that may have pesticide residues.  This gives some indication of the low levels of residues on these particular crops (apples, pears, corn, cotton, tomato, grape, and citrus), or of the efficiency with which the liver and kidneys of bovines get rid of residues.  Note also that they tested liver samples, confirming my long held belief that liver does not store but transforms and eliminates toxins from the body.

Vazquez-Moreno et al tested for pesticide residues in adipose tissue of beef, pork, and poultry from plants located in northwestern Mexico and published the results in the Journal of Muscle Foods (5 May 2007).  According the the abstract:

“This study involved testing of adipose tissue from beef (208 samples), pork (112 samples) and poultry (39 samples) for pesticide residues, including nine different chlorinated hydrocarbons (CHC) and nine organophosphates (OP). Tissues were collected during a two-year period (1996–1997) from plants located in the Northwestern Mexico, and determinations conducted by gas chromatography under international performance criteria. While none of the pork samples contained CHC residues, 17 (1996) and 11 (1997) beef samples contained either hexacholorobenzene, heptachlor, aldrin or dieldrin. Also, poultry samples (three in one year and four in the other) contained residues of either hexachlorobenzene, heptachlor or dieldrin. None of the tissues tested contained organophosphate residues above the detection limit. CHC incidences and concentrations were lower than those reported for other Mexican and Latin American regions, but higher than reports from the U.S. Based on the Mexican or U.S. tolerances, all concentrations of CHC found were nonviolative.”

In this study, no pork samples, 13% of beef samples, and 18% of poultry samples from Mexican processing plants contained CHC, while none of any samples contained OP, and in no case was the concentration of CHC above limits. 

Compare this to cabbage:  100% of cabbage samples contain at least 49 naturally occurring pesticides.
As documented by Bruce Ames (PNAS pdf), 99.99% of the pesticide load consumed by the typical American consists of pesticides that naturally occur in plant foods, which when tested have a toxicity and carcinogenicity similar to synthetic pesticides. This slide from Ames's paper lists 49 pesticides naturally occurring in cabbage (click on image for larger version):

So if you avoid conventional meats in favor of plant foods, you don't avoid pesticides or antibiotics (plants contain natural antibiotics also), and you probably increase your pesticide and antibiotic load.  But when you eat meat, as shown by Schnell et al (above), you have put a filter between yourself and the plant sources of toxins.  Relatively speaking, it appears that fresh conventional meat presents a much lower pesticide and antibiotic load than organically grown cabbage. 

Consider also that antibiotics and  persistent pesticides are ubiquitous hazards these days, and may occur in “organic” and grass-fed animal products as well as conventional.  For example, a company producing organic chicken in the UK found residues of nitrofuran, a banned pesticide, in meat from their birds

 All in all, although a part of me would prefer to have "pure" animal products without residues of any potentially toxic chemical, the reality is nothing is "pure."  From my perspective, it seems that most conventional animal products have no antibiotic, pesticide, or chemical residues, and in the small percentage (less than 0.5%) that has residues, they occur in amounts that present no hazard to health.


Thomas said...

Very nice post! It is refreshing to get "the rest of the story" about what most of us traditionally think in knee-jerk fashion. It is fascinating how much information we blindly accept as truth turns out to be cultural mythology.

Eva said...

Very interesting! Thank you. It's so easy to fall victim to assumptions. I'm glad you looked into this for us and shared your findings.

Greg said...

Great Post!

Let me question a point- that antibiotic use in animal feed was always just speculation- I don't think you can state that based on your math.

I talk to farmers that raise cattle in pasture and they say that it is rare for an animal to ever need antibiotics. If this were the case, then there is a large class of animals with close to no antibiotics.

Likewise, among chicken producers some seem to use antibiotics frequently and others have decided it is not cost effective:

So averaging across every animal is going to lead to a misleading situation.

Also, averaging across animals of different sizes can mislead. If antibiotic usage is actually fairly low in cattle, that will make the average low even if there are chicken producers that constantly add antibiotics to their feed.

On the point of evolution of antibiotic resistance- I think it is still pragmatic to reduce antibiotics in animal feed as much as possible. Natural selection doesn't just select for genes, but also selects against them. An organism can easily lose a useful trait if it goes many generation without using it- especially if there is a cost associated with the trait. So if maintaining a trait of resistance to an antibiotic takes even a slight amount of extra energy, that trait will be selected against in future generations. Evolution can only guarantee the failure of antibiotics if their use crosses a threshold which makes it profitable for bacteria to maintain their antibiotic resistant genes.

We aren't going to get rid of antibiotic resistant genes, but we can certainly try to keep them at bay.

Certainly, none of these corrections overturn evidence showing low traces of antibiotics in cattle, and you are still building a case that there are few practical health concerns with factory raise meat (I am hoping part 3 discusses omega imbalances and other nutritional aspects). However, I think these corrections have real implications as to how bad the effects of factory raised animals are to our society as a whole, even if not directly to ourselves.

Chris Kresser said...

Excellent work, Don. A fair and balanced examination of a contentious issue. I'm enjoying this series a lot!

Toban said...

Excellent work once again. Greatly appreciated. You've shone much light on this much overlooked topic.

Al said...

fabulous work. I will support your efforts.

However, I choose to never transmit funds over the internet.

If you mention a postal address and a payee name, i will mail a money order.

Aitor Calero GarcĂ­a said...

Awesome post. I've been always skeptical regarding the presence of antibiotics in cattle. We've had in Spain a shocking doping case involving Tour de France winner Alberto Contador. He was found gultty of doping by clembuterol, but he blamed an steak coming from a farm. Automatically, farmers protested a lot showing convincing proofs that the cattle they raise are very strictly monitorized and that they face prison otherwise.
The point you make about the role of the liver was unknown for me. I've never realized the implications that plants lack of it.
Looking forward to read your nexts post regarding omegas

rob said...

Yes- my bias leads me to instantly-indict the industry when such headlines appear - and i hav ot re-check myself that i am not just embracing the headlines i like and damning the ones i don't-

that said, i see no reason to eat more conventional meat because it's cheaper - i still and always will eat a smaller piece of humanely-raised grass-fed - to err on the side of both my ideals and the much lower chance taht ANY antibiotics are getting though (since organic producers pull the animals that need antibiotic treatment from their "organic" line).

Thanks for the "fair and balanced" (i'm trying to redeem that phrase... ;-) )


Don said...


As I pointed out in the post, conventional producers also have to comply with a withdrawal period for any of their animals given antibiotics, since they aren't allowed to sell animal products containing residues.

Senta said...

Isn't the main concern with the use of antibiotics in animals not the residues in meat, which are required to be just about nil, but the antibiotic-resistant strains of bacteria produced by the use of said antibiotics? So even if you don't get a dose of antibiotics with your meat, you get the resistant bacteria, yum. Then there is also the factory farm run-off loaded with the resistant strains, often blamed for contaminating produce.

Scotlyn said...

Thanks for putting in the work, Don. It is useful, when making a less than popular argument to be as accurate as possible and you've done a great job of ferreting out the facts.

From my perspective as a farmer, raising a small flock of grass-fed sheep, though, I would add some anecdotal data to Greg's point. Our flock numbers around 40. The flock's antibiotic requirement averages 2 to 3 occasions (one sheep, one course of treatment = an occasion) per year, usually for complications of lambing or feeding (uterine infection, mastitis, things of that nature).

Nevertheless, it is probably true to say that "conventionally" raised (can we not reclaim the word "conventional" for old-fashioned grass-rearing, though?) cattle do not have much in the way of harmful residues in their meat. But, to me the issue goes beyond the health of the individual human, to the health of our whole ecosystem.

Choosing grass-fed meat is probably only marginally healthier in terms of one's own body. But choosing grass-fed is a choice to support the "perennial polyculture," sustainable model of human food production - and to promote the health of the soil, the water, and the local wildlife, including microbes, mammals, birds, amphibians and fish. Choosing CAFO meat is a vote for the "annual monocrop" (grain) model of human food production (these animals are raised as they are purely as a way of hoovering up grain surplusses). It is this bigger picture that makes the grass-fed choice a critical consumer vote of confidence for long-term sustainability, bio-diversity, and health.

Don said...


I agree with you completely, I prefer the environment created by grass-farming vs. conventional grain-farm supported meats.


As I noted in the article, we have good reason to believe that use of antibiotics in humans creates the resistant strains of most concern to humans. No one has shown that use of antibiotics in livestock is the primary cause of antibiotic resistant bacteria.

For example, in this Science News article:

You find this:

“We’re speculating that there may be a possibility of a link,” said Daniel Fung, a food science professor at Kansas State University who led research into the question for the Food Safety Consortium. “We are looking at it from the food scientist’s standpoint. The resistant cultures may get into the food supply and may get into human beings. But those are speculations only.”

Speculations only....

Jim Sutton said...

Great post, Don, and timely for me and my wife.

We have been trying to decide how big this problem is, and what to do about it. This informative article helps us in both respects. My donation via PayPal is about to occur.

Publius said...

"In short, the principle of natural selection predicts the eventual failure of antibiotics."

There will always be something that can kill a particular bug. Science will have to catch up to the bacteria once again. They breed so darn fast...

Publius said...

"In short, the principle of natural selection predicts the eventual failure of antibiotics."

There will always be something that can kill a particular bug. Science will have to catch up to the bacteria once again. They breed so darn fast...

lisao said...

I don't think you should be embarrassed about having written this article. I think you have helped a lot of people by doing so and reporting the truth rather than the hype that is accepted as fact that is promoted by fear mongers. We know that you recognize the superiority of pastured meat and are promoting it to.people. But the reality is that sometimes conventional is what people must eat, because of financial issues or availability issues. I think we should all do what we can to support healthier practices. Many people can afford some pastured products at least. If we do what we can maybe eventually a change in practices will occur. For the times that we must settle for conventional or semi conventional such as store bought organic, I think you have done a service by separating truth from fiction and by making clear the gross exaggerations or outright lies that are being told and believed. I have read loads of authoritative sounding dispensers of natural health info. telling people they are getting poisoned and damaged by copious quantities of hormones and antibiotics that are in all the conventional products they have eaten. Apparently, someone thought this sounded logical and just started believing it and promoting it without making sure they had their facts straight. Yes, pastured is better in many ways, but let's not falsely scare the crap out of people making them think that they will be drowning themselves in hormones, antibiotics and pesticides when the facts say it isn't true, and that in fact they are probably getting more toxins from their organic cabbage than from conventional meat. I thank you for relieving me of this great fear and lack of ease and peace which is probably far more damaging to health than conventional meat or other supposed bad things.