Arsenic in Animal Feed: The Good News and the Bad News
Arsenic is a naturally occurring substance in the environment and is considered a contaminant in soil, water, air, and even food. While the compound is not for consumption, it’s less toxic organic form was commonly used in popular poultry and swine feeds to promote weight gain and prevent parasitic infections in poultry and swine. Popular poultry and swine feed additives that contain arsenic include roxarsone, arsanilic acid, and carbarsone.
Why Arsenic Was Used in Poultry and Swine Feed
While arsenic it’s not used as an active ingredient in food or any food product, it is fed to poultry and swine for the sole purpose of enhancing growth, improving feed efficiency, prevention of parasitic diseases, and overall providing the farmer bigger returns on their livestock. In chicken, roxarsone or “Rox” was specifically fed to control coccidiosis, a disease of birds and mammals that target the intestines that are caused by coccidia.
Concerns About Arsenic in Poultry and Swine Feed
Despite the “safety” claims of organic arsenic, the FDA found that the use of arsenic-based food additives, such as roxarsone, was linked to high levels of inorganic arsenic in chicken livers  compared to chickens who weren’t fed with roxarsone. The main concern was how the metabolites were found in chicken livers despite the five-day preslaughter safety window used in the poultry industry to clear all additives.
A market basket study in 2013 also confirmed high levels of inorganic arsenic in chicken breast meat from those fed with arsenic-based feeds. This caused concerns for human exposure, especially from food that make use of chicken liver as its main ingredient. Chronic exposure is known to cause bladder, lung, and skin cancers as well as other diseases including type 2 diabetes,  cognitive deficits,  cardiovascular disease,  and increased pregnancy risks. 
The Good News and the Bad News About Arsenic-based Feed
The good news is that arsenic-based feeds are currently banned in the EU and that following the news, roxarsone, carbarsone, and arsanilic acid was pulled from the US market in 2014 by their respective companies.  In 2015, the only remaining arsenic-based feed nitarsone would also cease production. 
The bad news is that the historical use of nitarsone in turkey production and of roxarsone in chicken production may thus have been a chronic source of arsenic exposure  for the U.S. population. And unfortunately, exposure may still be ongoing in other parts of the world. 
Common Substitutes for Arsenic-based Animal Feed Additives
Outside of growth, the main use of arsenic-based feed additives is to prevent poultry-specific diseases like histomoniasis. Histomoniasis is also known as blackhead disease and is a parasitic infection of Histomonas meleagridis. The most successful alternative so far, based on a study,  is a product called Natustat.
Natustat is a natural, plant-derived proprietary blend composed of essential oils, extracts, and polysaccharides obtained from yeast and other organic minerals. Natustat is manufactured by ALLTECH but is currently exclusively sold to large companies. 
1. Halford, B. (2018). Arsenic poultry feed additive may be more problematic than believed | Chemical & Engineering News. [online] Cen.acs.org. Available at: https://cen.acs.org/articles/95/i20/Arsenic-poultry-feed-additive-problematic.html [Accessed 8 Jun. 2018].
2. Fda.gov. (2018). Arsenic-based Animal Drugs and Poultry. [online] Available at: https://www.fda.gov/AnimalVeterinary/SafetyHealth/ProductSafetyInformation/ucm257540.htm [Accessed 8 Jun. 2018].
3. Nachman KE, Baron PA, Raber G, Francesconi KA, Navas-Acien A, Love DC. Roxarsone, Inorganic Arsenic, and Other Arsenic Species in Chicken: A U.S.-Based Market Basket Sample. Environmental Health Perspectives. 2013;121(7):818-824. doi:10.1289/ehp.1206245.
4. International Agency for Research on Cancer. Arsenic and arsenic compounds. IARC Monogr Eval Carcinog Hum 100C:41–93. 2012. Available: http://monographs.iarc.fr/ENG/Monographs/vol100C/mono100C-6.pdf [accessed 8 June 2018]
5. Navas-acien A, Silbergeld EK, Pastor-barriuso R, Guallar E. Arsenic exposure and prevalence of type 2 diabetes in US adults. JAMA. 2008;300(7):814-22.
6. Wasserman GA, Liu X, Parvez F, et al. Water Arsenic Exposure and Intellectual Function in 6-Year-Old Children in Araihazar, Bangladesh. Environmental Health Perspectives. 2007;115(2):285-289. doi:10.1289/ehp.9501.
7. Chen Y, Graziano JH, Parvez F, et al. Arsenic exposure from drinking water and mortality from cardiovascular disease in Bangladesh: a prospective cohort study. The BMJ. 2011;342:d2431. doi:10.1136/bmj.d2431.
8. Ahmad SA, Sayed MH, Barua S, et al. Arsenic in drinking water and pregnancy outcomes. Environmental Health Perspectives. 2001;109(6):629-631.
9. Fda.gov. (2018). [online] Available at: [Accessed 8 Jun. 2018].
10. Nigra AE, Nachman KE, Love DC, Grau-Perez M, Navas-Acien A. Poultry Consumption and Arsenic Exposure in the U.S. Population. Environmental Health Perspectives. 2017;125(3):370-377. doi:10.1289/EHP351.
11. Yao L, Huang L, He Z, Zhou C, Li G. Occurrence of impurities in organoarsenic and animal feeds. J Agric Food Chem. 2013 Jan 16; 61(2):320-4.
12. Efsa.europa.eu. (2018). [online] Available at: http://www.efsa.europa.eu/sites/default/files/scientific_output/files/main_documents/121.pdf [Accessed 8 Jun. 2018].
Duffy CF, Sims MD, Power RF. Evaluation of dietary Natustat for control of Histomonas meleagridis in male turkeys on infected litter. Avian Dis. 2005;49(3):423-5.
13. Alltech, Inc. (2018). Alltech – Animal Nutrition, Animal Feed Supplements, Animal Health. [online] Available at: https://www.alltech.com/ [Accessed 8 Jun. 2018].
14. BackYard Chickens. (2018). Natustat availability?. [online] Available at: https://www.backyardchickens.com/threads/natustat-availability.1111409/#post-17114390 [Accessed 8 Jun. 2018].