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” ) .
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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 :
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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.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):
Compare this to cabbage: 100% of cabbage samples contain at least 49 naturally occurring pesticides.
Compare this to cabbage: 100% of cabbage samples contain at least 49 naturally occurring pesticides.
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.