Formal Recommendation 

From: National Organic Standards Board (NOSB)

To: the National Organic Program (NOP)

Date: October 30, 2020

Subject: Fenbendazole - petitioned for amendment 

NOSB Chair: Steve Ela

The NOSB hereby recommends to the NOP the following: 

Other: None

Statement of the Recommendation: 

The NOSB voted to not approve the petition seeking to amend the listing of fenbendazole to expand its 

use to include use in laying hens or replacement chickens intended to be laying hens

Rationale Supporting Recommendation

Fenbendazole is an antiparasitic drug that works at the sub-cellular level preventing cell division. 

Benzimidazoles bind to the β-tubulin, inhibiting the cell’s microtubule assembly responsible for 

intracellular transport and required for mitotic cellular division. The targeted organisms of Fenbendazole 

for laying hens and replacement laying hens are the parasitic roundworms Ascaridia galli and Heterakis 

gallinarum. Chickens infected with A. galli and H. gallinarum become unthrifty, weak and emaciated and 

exhibit weight loss proportional to the parasite load. Young birds are more susceptible to the parasites 

than are mature hens, but mature hens will exhibit significant loss of egg production when infected with 

A. galli and H. gallinarum. Histomoniasis, also known as Blackhead Disease, is a disease caused by 

infection with Histomonas meleagridis. 

A request was submitted to FDA by Ivervet, Inc. to expand the use of Fenbendazole to chickens. In 

October 2015, the FDA gave formal approval for the use of fenbendazole in treatment and control of 

adult A. galli in broiler chickens and replacement chickens intended to become breeding chickens and 

for the treatment and control of adult A. galli and H. gallinarum in breeding chickens. The FDA allowed a 

total of 2.4 ppm residual of Fenbendazole in eggs with no withdrawal time from application. 

Public Comments: 

There were many public comments received for the proposed annotation change to 7 CFR 

§205.603(a)(23)(i) during the Fall 2019 and Spring 2020 NOSB meetings when the annotation change 

was presented as a discussion document and during the Fall 2020 NOSB meeting when it was presented 

as a proposed annotation change. 

The public comments were divided into two segments: 

(1) Many producers stated that the presence of worms in their laying hens was becoming more 

prevalent as cooler and more wet climate conditions have become the “normal” weather 

pattern. They also said that the worm population was increasing due to granting more 

outdoor access to the birds, which then scratched in the dirt and picked up the worm oocyts. 

They stated that the worms were causing health issues in the birds, resulting in pain, 

suffering, and death. They expressed their fears of erosion of the public’s confidence if they 

cracked an egg and found worms in the eggs. 

(2) Consumers and organic industry leaders expressed concerns about potential health risks 

associated with the residual of fenbendazole in the eggs at a rate of 2 ppm for eight days 

after application. They feared that residual fenbendazole could cause health issues in more 

susceptible populations, especially in children, pregnant women, and the elderly. They 
expressed their fears of erosion of the public’s confidence if it became public knowledge that 

organic eggs had residual levels of fenbendazole.

During the NOSB Fall 2020 meeting, an NOSB member stated that among the producers and egg 

processors that he had inspected, none had expressed the need for the use of fenbendazole for their 

laying hen operations.

The NOSB proposal to amend the listing for Fenbendazole at 7 CFR §205.603 (23)(1) to include the use 

of Fenbendazole for use in laying hens or replacement chickens intended to be laying hens failed due to 

the following OFPA sections of the statute: based on the following criteria in the Organic Foods 

Production Act (OFPA) and/or 7 CFR 205.603(a).

OFPA § 6517(c)(1)(A)(i) - Harmful to human health or the environment - Concern was expressed by 

NOSB board members that there could be adverse human health impact due to the 2.4 ppm residue 

of fenbendazole in the eggs after application of the fenbendazole to the active laying hens.

OFPA § 6517(c)(1)(A)(ii) Necessary to the production or handling of the agricultural product 

because of unavailability of wholly natural substitute products – The NOSB concluded that there 

were natural products and cultural practices that were available to control the parasitic worm 

infestations without adding the synthetic fenbendazole to the poultry producers’ toolbox.

As such, the NOSB overwhelmingly voted to not amend the proposed annotation at §205.603(23)(1).

NOSB Vote: 

Motion to amend the listing for fenbendazole to include: Fenbendazole-for use in laying hens or 

replacement chickens intended to be laying hens at 7 CFR §205.603(a)(23)(i).

Motion by: Sue Baird

Seconded by: Kimberly Huseman

Yes: 1 No: 14 Abstain: 0 Absent: 0 Recuse: 0

 

Motion Failed

[Fall 2020 Original Subcommittee Proposal - Fenbendazole]