CAS No. 122008-85-9

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Adverse Effects

ACTIVITY: Herbicide (aryloxyphenoxy propionic acid)


Adverse Effects:

Body Weight Decrease
Carcinogenicity: Kidney
Endocrine: Testicular
Endocrine: Thymus

Regulatory Information
(only comprehensive for the US)
US EPA Registered: Yes 
US EPA PC Code: 082583 
California Chemical Code 5748 
Registered use in
(includes only a limited list of countries)

Japan, Phillipines, US, Vietnam  
Japan's Maximum Residule Level (MRL) Rice  
US Maximum Residue Levels permitted in food commodities
Tolerances for Cyhalofop-butyl, Cyhalofop acid and the di-acid metabolite:

Rice (grain and straw)
Other Information
Entry Year: 1992 
Molecular formula: C20H20FNO4
Inventing Company: Dow Elanco 
Manufacturers: Dow Agro  
Other Names: Clincher, DEH-112,
XDE 537
Of special interest:
PAN Data 
July 2005 - Evaluation of the new active Cyhalofop-Butyl in the product Barnstorm Herbicide. Australian Pesticides and Veterinary Medicines Authority (APVMA). Canberra, Australia. Barnstorm herbicide is proposed to be used for the post emergence control of barnyar grasses and silver top grass in rice. Cyhalofop-butyl is manufactured in Japan. Barnstorm Herbicide will be formulated in New Zealand and transported to Australia fully packed. The label recommends both ground and aerial applications. Almost all applications (~95%) are expected to be aerially applied with just ~5 % applied by groundrigs.

February 16, 2001 - Summary of Toxicological data (Cyhalofop-Butyl). California Environmental Protection Agency. Department of Pesticide Regulation. Medical Toxicology Branch.

September 18, 2002: European Commission Health & Consumer Protection Directorate-General. Review report for the active substance cyhalofop-butyl. Finalised in the Standing Committee on the Food Chain and Animal Health at its meeting on 19 April 2002 in view of the inclusion of cyhalofop-butyl in Annex I of Directive 91/414/EEC. 
February 18, 2002 - European Commission decision to extend provisional authorisation for new active substances including cyhalofop-buty
Glossary of Pesticide Chemicals, October 2001. A listing of pesticides subject to analysis of residues in foods and feeds by the US Food and Drug Administration. Also available at: 
August, 2001 - IR-4: New Products/Transitional Solution List - This list contains brief descriptions of numerous new pest control materials that have been introduced over the last several years. Additionally, it contains information on some "older" crop protection chemicals that are believed to have room for new uses. This List includes Cyhalofop-butyl.

(page 12,
Name Chemical Name
Cyhalofop-Acid [R-(+)-2-(4-(2-fluoro-4-cyanophenoxy)phenoxy)propanoic acid] O
Cyhalofop-Diacid [R-(+)-2-(4-(4-carboxyl-2-fluoro-4hydroxy-phenoxy)phenoxy)propanoic acid] O
Cyhalofop DP 4-(2-fluoro-4-cyanophenoxy)phenol

US Federal Register

•• Note: Not all entries are listed below. Click here to view all FR entries.

Date Published Docket Identification Number Details
June 4. 2002 OPP-2002-0087

5-Year pesticide tolerance for combined residues of cyhalofop (cyhalofop-butyl plus cyhalofop-acid) and the di-acid metabolite in or on rice grain at 0.03 ppm and rice straw at 8.0 ppm. Final Rule.

  • Dermal, Long-Term, Carcinogenicity in Mice: Kidney effects in females including tubular dilatation, chronic glomerulonephritis, and hyaline casts at the LOAEL of 10.06 / 10.28 mg/kg/day, M/F.
  • Inhalation, Short- Term (1-30 days), Subchronic Feeding Mice: Enlarged kidneys in Enlarged kidneys in swelling of the proximal tubule cells in 4/12 mice at the LOAEL of 14.1 mg/kg/ day.
  • Inhalation, Long- Term ( 6 months), Carcinogenicity in Mice: Kidney effects in females including tubular dilatation, chronic glomerulonephritis, and hyaline casts at the LOAEL of 10.06 / 10.28 mg/kg/day, M/F.
  • Cancer: This herbicide has not been classified. The rat and mouse carcinogenicity studies are identified as data gaps. Since the doses tested in these studies were too low to assess the carcinogenic potential of cyhalofop- butyl, the cancer dietary risk assessment was conducted using the potency factor (Q1*) of 2.3 x 10-\1\ for the structural analog diclofop- methyl.
  • Special Study Hepatocellular Proliferation in Rats: In a subchronic oral toxicity study in rats (MRID 45000413), satellite rats dosed for 4 weeks had hepatocellular hypertrophy and focal necrosis at all dose levels... An initial dramatic increase in DNA synthesis during the first week of treatment was followed by hepatocellular hypertrophy at subsequent observations. This was the reason for enlarged livers.
  • In Vitro Chromosomal Aberration in Chinese Hamster Lung: Polyploidy was induced when CHL (V79) cells were treated for 48 hours in the absence of S9, but there was no clastogenic effect on DNA.
    [FAN Note:
    is when the number of chromosomes in a cell becomes doubled. One obvious consequence is that the resulting creature has no one it can breed with. Ref: ]
  • Acute Dermal (Rat): Chromodacryorrhea was observed in 2/ 5 males on day 2 only. Delayed weight gain was observed in all rats, with the females being most affected.

    [FAN Note:
    or red tears due to excessive production of Harderian gland secretions. The glands, named after the Swiss physician Johann Jakob Harder, are exocrine glands located deep within the orbit. The Harderian gland secretes mostly lipids in the rat. Further products include porphyrin and melatonin. Various physiological functions have been attributed to the rat Harderian gland. The lipid-containing part of the secretion may serve to lubricate the eye. Some observations suggest a behavior related odoriferous (pheromonal) role. The Harderian gland is also considered to serve, like the pineal gland, as an extraretinal photoreceptor. Harderian porphyrin may have a photoprotective role, as it is increasingly secreted in response to light exposure and as porphyrins show an intense absorption of light. Chromodacryorrhea is a consequence of acute-onset stress such as pain, illness, restraint, or poisoning. Red tears are often an indication of a chronic underlying disease, and warrant a thorough evaluation of affected animals. Ref: ]

Feb 13, 2002 na Cyhalofop-butyl: Emergency Exemptions:
Arizona. EPA authorized the use of cyhalofop-buty on rice to control bearded sprangletop; April 15, 2002 to August 15, 2002.

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