Today, arsenic is known to be a dangerous toxin. However, arsenic compounds have been used in medicine for over 200 years. H.W. Thomas, for example, working in the early 1900’s, found that Atoxyl (sodium hydrogen 4-aminophenylarsonate) could cure experimental trypanosomiasis. During the 1950’s, it was discovered that certain arsenic compounds could affect the growth of broiler chickens, control cecal coccidiosis in poultry, swine, and other domestic animals, as well as promote better feathering in chickens while increasing egg production and pigmentation. 1
As of these and other findings, arsenic-based drugs were used in U.S. animal feeds for chicken, turkey, and pigs for over 60 years, after approval in 1944. Now, however, approval for use of these drugs has been withdrawn by the FDA and the companies that made such drugs have removed them from the market.
Prior to removal of arsenic-based drugs from the market, there were several common ones used, all based on organic forms of arsenic: Roxarone, aranilic acid, nitarsone, and carbasone. Aranilic acid was also approved for use in swine feeds. These four main compounds were formulated into over 100 drugs that were used in chicken, turkey, and pig feed. See PDF report of withdrawal of many drugs.
At least 1.7 to 2.2 million pounds of these arsenic compounds were given to broiler chickens each year — almost 1000 tons. After the withdrawal of approval for animal drugs containing aranilic acid, carbasone, or roxarsone, many drugs were withdrawn from the market. This withdrawal of approval was initiated at the request of the manufacturing companies.
The arsenic in drugs like 3-Nitro (roxarsone) was an organic form of arsenic considered to be less toxic than inorganic arsenic. However, studies indicated that this organic arsenic could be transformed into inorganic arsenic. As a result, scientists from the FDA developed a test to check for very low levels of inorganic arsenic in animal tissue. Using this method, they found increased levels of inorganic arsenic in the livers of chickens treated with roxarsone.
Alpharma, a subsidiary of Pfizer, Inc. then voluntarily suspended the sale of 3-Nitro® and took steps to suspend the use of the product in the U.S. Zoetis, Inc. later acquired ownership of the drug but continued to suspend its sale and on February 27, 2014, voluntarily withdrew all new animal drug applications involving 3- Nitro®. Along with Huvepharma AD the company simultaneously withdrew two other drugs, arsanilic acid and carbarsone for use in animal feed. In April 2015 Zoetis withdrew the only remaining arsenic-based drug on the market, Histostat (nitarsone), which was no longer available by the 2016 growing season. 2
As of this time, there are no longer any arsenic-based drugs approved for use in food animals. Arsenic is, however, naturally occurring in the environment and is found in soil, water, air, and in our food, usually in trace amounts. Higher arsenic levels are found in certain geographic areas, however, which can lead to higher levels of arsenic in crops or animals raised for food. 3
You can read more here at CulinaryLore about arsenic and other toxins in foods, as well as how arsenic is used as medicine.
- Abernathy, Charles M., et al. Arsenic Exposure and Health Effects IV: Proceedings of the Fourth International Conference on Arsenic Exposure and Health Effects, June 18-22, 2000, San Diego, California. Elseriver, 2001.
- Medicine, Center for Veterinary. “Product Safety Information – Arsenic-Based Animal Drugs and Poultry.” U S Food and Drug Administration Home Page, Center for Veterinary Medicine, www.fda.gov/AnimalVeterinary/SafetyHealth/ProductSafetyInformation/ucm257540.htm.
- Chakrabarty, Narayan. Arsenic Toxicity: Prevention and Treatment. CRC Press, Taylor & Francis Group, 2016.