Economic studies support the withdrawal of antibiotics in animal feed to protect public health and agricultural environments

Dr. Tanya Roberts, PhD, Chair of the Center for Foodborne Illness Research and Prevention and retired Sr. Economist from Economic Research Service, United States Department of Agriculture

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Antibiotic resistance (AR) is a huge global health challenge. Both the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) have identified the use of antibiotics to promote growth in farm animals as contributing to the development and spread of AR bacteria that are transmitted from animals to humans.  If resistant bacteria contaminate the foods that come from those animals, people who consume these foods can develop serious and sometimes life-threatening AR infections.

Antibiotics must be used judiciously in animals because use contributes to not only the emergence, but also the persistence and spread of AR bacteria globally.  Programs to limit or even ban antibiotic use in animal feed have been implemented in Europe and the United States (EMA and EFSA 2017; FDA 2013).

Until recently, growth promotion was acceptable as a reason for administering antibiotics to animals, and, as a result, over 80 percent of antibiotics that were sold in the United States were used in animal feed. In 2014, however, FDA asked for and obtained voluntary compliance with FDA Guidance Document #213 to withdraw antibiotic use from animal production from all 26 producers of antibiotics used in livestock feed.

While many economic issues are related to antibiotic resistance, in this blog I address the issues related to food animals and compliance with the new FDA directives to withdraw medically important human antibiotics from animal feed. I also address the environmental issues that arise when antibiotics are mismanaged and are allowed to spread into our environments. The most important conclusions from my analysis are as follows.  

1) The cost of producing hogs or chickens need not increase when low-level antibiotics are withdrawn from their feed because equally efficient alternatives for promoting animal growth are readily available; 

2) The U.S. public health benefits of antibiotic withdrawal from animal feed products are significant—$7 billion is saved annually by reducing human cases of AR illnesses due to food and animal sources;  

3) The withdrawal of antibiotics from animal feed reduces the environmental contamination produced by non-metabolized antibiotic residues that are discharged into the U.S. environments;

4)  Manufacturers of antibiotics are causing significant environmental damage in China and India, where most drugs are produced, thereby increasing the risks of creating new multiple drug resistant pathogens that will circulate worldwide.

First, the economic costs of withdrawing antibiotics from animal feed for production-purposes and disease prevention are negligible and not statistically significant for hogs or chickens.  Researchers at the USDA’s Economic Research Service (Sneeringer et al. 2015) used data from U.S. farm surveys to compare the costs of raising hogs and chickens with and without using low level antibiotics in feed. While there may be some short run adjustment costs to raising hogs and chickens without antibiotics in feed, there are no long run differences in farm costs after adopting equally cost-effective husbandry practices.  The alternatives to antibiotic use for growth promotion include increasing the space per animal, tightening biosecurity, optimizing nutrition, improving gut flora, vaccinating herds and flocks, and developing and adopting a systematic management system for improving food safety, called a Hazard Analysis Critical Control Point plan.[1]

Second, the public health benefits of withdrawing antibiotics from feed are significant.  CDC estimates that 20% of U.S. human illnesses with AR pathogens are caused by food and animal sources (CDC 2018). The increased medical costs to treat these illnesses and the productivity costs due to death or morbidity for these ill persons are $7 billion annually in the United States (CDC 2015). 

A potentially important cost that is excluded from CDC’s estimate is the contribution of using antibiotics in animal feed to the creation of  new antimicrobial resistance.  An illustration of what is at stake is the discovery of mobile resistance colistin genes (mcr-1 through mcr-12) in bacteria found in hogs, pork products, and humans in China (Dall 2017, Wang, et al., 2018).  These genes are on plasmids and easily transfered among bacteria, and create resistence to colisten, the antibiotic that is regarded as the last resort for treatment of bacteria that are resistant to many antibiotics.  These gene variants have been found in humans, animals, and the environment in over 40 countries on five continents (Wang et al. 2018).  The rapid development and spread of these genes is of great concern, especially since this bacterial pathogen group is associated with many serious health conditions, such as pneumonia, bloodstream infections or urinary tract infections (Wang et al. 2018).  These mcr mutants threaten public health through both the food chain and environmental routes.

Third, environmental spread of antibiotic residues to soil and water is another area of concern for the United States and elsewhere.  Not all drugs fed or administered to food animals are metabolized, so a high percentage of these antibiotics can be discharged into manure and urine (Aga et al. 2016).  In 2013, tetracyclines were the most widely used antibiotic sold for veterinary use in the United States at 6.5 million mg/yr. Tetracycline has a low metabolization rate, leaving 60-80% of the drug as a residual in the animal’s manure and urine.  These drug residues originating on the farm can contaminate the soil and water and increase the antibiotic resistance of human pathogens both in the United States and globally.

Fourth, the international nature of antibiotic drug manufacturing is a major challenge. The two most populous countries in the world, China and India, produce most of the world’s antibiotics (Armbruster & Roberts 2018).  China produces most of the ingredients and India produces most of the final products.  Both countries have minimal oversight over the production of antibiotics and limited enforcement tools to implement the few regulations that they do have.  Contamination of the water (and sometimes soil) with these antibiotic residues is common in both countries.  Economists call this contamination of the environment a negative externality, meaning that the companies that manufacture these antibiotics do not pay the full costs of making these drugs, since they are not compensating the citizens of China and India for the increased risk of AR infections arising from environmental contamination. As a result, these drug companies – both U.S. and international – are getting a “free ride.”

In sum, the economic evidence is clear. Routine administration of antibiotics to animals causes substantial costs without delivering any benefits than cannot be obtained by equally effective alternatives that are not more costly. The U.S. Food and Drug Administration has taken some important steps to protect antibiotics, thereby delivering huge public health benefits by reducing the number of human illnesses caused by AR bacteria. Finally, we must do more to protect our environments – both within the United States and elsewhere throughout the world – if we hope to combat the threats posed by AR bacteria.

 

References

Aga DS, Lenczewski M, Snow D, Muurinen J, Sallach JB, Wallace JS (2016). Challenges in the measurement of antibiotics and in evaluating their impacts in agroecosystems: A critical review. Journal of Environmental Quality, 45: 407-19. DOI: 10.2134/jeq2015.07.0393

Armbruster W and T Roberts. (2018). Food Safety Economics, Chapter 15, Springer Nature, in press.

European Medicines Agency and European Food Safety Authority (2017) EMA and EFSA joint scientific opinion on measures to reduce the need to use antimicrobial agents in animal husbandry in the European Union, and the resulting impacts on food safety. EFSA J. 2017; 15: 1–245 http://www.ema.europa.eu/docs/en_GB/document_library/Report/2017/01/WC500220032.pdf. Accessed 08/24/18.

Centers for Disease Control and Prevention. (2015).  Antibiotic resistance threats in the United States, 2013, p.11. https://www.cdc.gov/drugresistance/threat-report-2013/pdf/ar-threats-2013-508.pdf. Accessed 07/26/18.

CDC. (2018). Protecting the food supply. https://www.cdc.gov/drugresistance/protecting_food-supply.html. Accessed 08/24/18

Dall, C. (2017). New colistin resistance gene identified in China. CIDRAP News, June 28.  http://www.cidrap.umn.edu/news-perspective/2017/06/new-colistin-resistance-gene-identified-china. Accessed 07/26/17.

Food and Drug Administration. (2013). #213 Guidance for industry: New animal drugs and new animal drug combination products administered in or on medicated feed or drinking water of food producing animals: Recommendations for drug sponsors for voluntarily aligning product use conditions with GFI.  https://www.fda.gov/download/AnimalVeterinary%20GuidanceComplianceEnforcement/GuidanceforIndustry/UCM299624.pdf.  Accessed 07/26/18.

Liu, Y. et al. (2016). Emergence of plasmid-mediated colistin resistance mechanism MCR-1 in animals and human beings in China: a microbiological and molecular biological study. Lancet Infect. Dis. 16, 161–168.  https://www.ncbi.nlm.nih.gov/pubmed/26603172. Accessed 08/24/18.

Sneeringer SE, MacDonald J, Key N, McBride WD, and Mathews K. (2015). Economics of antibiotic use in U.S. livestock agriculture. ERR-200, U.S. Department of Agriculture, Economic Research Service, November. https://ageconsearch.umn.edu/bitstream/229202/2/err200.pdf.

Wang X, Wang Y, Zhou Y et. al. (2018). Emergence of a novel mobile colistin resistance gene, mcr-8, in NDM-producing Klebsiella pneumoniae. Emerging Microbes & Infections, Volume 7, Article number: 122. https://www.nature.com/articles/s41426-018-0124-z. Accessed 08/24/18.

[1] See https://www.fda.gov/food/guidanceregulation/haccp/ucm2006801.htm.