Adverse Effects
Cyhalofop-butyl
CAS No.122008-85-9
 
 

Return to Cyhalofop-butyl Index Page

Activity: Herbicide (aryloxyphenoxy propionic acid)
Structure:

Adverse Effects:
Body Weight Decrease
Carcinogenicity:
Kidney
Endocrine: Testicular
Endocrine: Thymus
Eye
Kidney
Liver

As of February 17, 2005, tolerances for Cyhalofop-butyl, Cyhalofop acid and the di-acid metabolite, are permitted in or on 2 food commodities in the United States - listed at the bottom of page

Body Weight Decrease (click on for all fluorinated pesticides)

-- Acute Dermal (Rat) LD50 & 35000 mg/kg (2.5 x the limit dose) 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. There was no dermal irritation. Toxicity Category IV
Ref: Federal Register: June 4, 2002. Cyhalofop-butyl; Time-Limited Pesticide Tolerance. Final Rule.

http://www.fluoridealert.org/pesticides/Cyhalofop-Butyl.FR.June4.02.htm

Carcinogenicity: Kidney (click on for all fluorinated pesticides)

-- Chronic dietary all populations: Carcinogenicity in mice based on kidney effects in females including tubular dilatation, chronic glomerulonephritis, and hyaline casts. LOAEL = 10.06 mg/kg/day.
Ref: Federal Register. September 27, 2001. Cyhalofop-butyl; Pesticide Tolerances for Emergency Exemptions. Final Rule.

http://www.fluoridealert.org/pesticides/Cyhalofop-butyl.FR.Sep27.01.htm

Endocrine: Testicular (click on for all fluorinated pesticides)

"Palatability and Four-Week Dietary Probe Study in Beagle Dogs"; (M.J. Mizell, K.T. Hart and J.W. Crissman; The Toxicology Research Laboratory, Health and Environmental Sciences, The Dow Chemical Company, Midland, MI; Study ID. DR-0298-8876-004; 9/11/90); In a preliminary palatability study, one beagle dog/group received 250, 500 or 1000 mg/kg/day of XRD-537 nBu (Technical) (AGR 276541, purity: 98.2%) for up to 2 weeks... In the second study, 2 beagle dogs/sex/group received targeted doses of 0, 35, 100 or 350 mg/kg/day for 4 weeks. Based on the food consumption, the low dose animals received doses of 36, 36, 34 or 53 mg/kg/day, the intermediate dose animals consumed doses of 85, 86, 133 or 138 mg/kg/day and the high dose animals received doses of 193, 203, 37 or 292 mg/kg/day, respectively... Gross examination of the tissues revealed slight to very severe atrophy of the thymus in a dose-related manner... In the microscopic examination, multifocal vasculitis and thrombosis was noted in the kidneys of the 2 high dose males and one intermediate and one high dose female, respectively. Diffuse atrophy of the thymus ranged from slight to very severe in a dose-related manner for the males in all of the groups and from moderate to severe for the intermediate and high dose females. In the testes, spermatogenesis was moderately to severely reduced in the high dose males with a concomitant increase in multinucleated spermatids. Apparent target organs: thymus and testes; Possible adverse effect: atrophy of the thymus and reduced spermatogenesis in the testes; NOEL can not be determined; Study supplemental. (Moore, 11/20/00)
Ref: February 16, 2001. California Environmental Protection Agency Department of Peticide Regulation. Medical Toxicology Branch. Summary of Toxicological Data. Cyhalofop-Butyl. Chemical Code # 5748, Tolerance # 52840 SB 950 # New A.I.

http://www.fluoridealert.org/pesticides/Cyhalofop.butyl.CA.Tox.2001.pdf

Endocrine: Thymus (click on for all fluorinated pesticides)

"Palatability and Four-Week Dietary Probe Study in Beagle Dogs"; (M.J. Mizell, K.T. Hart and J.W. Crissman; The Toxicology Research Laboratory, Health and Environmental Sciences, The Dow Chemical Company, Midland, MI; Study ID. DR-0298-8876-004; 9/11/90); In a preliminary palatability study, one beagle dog/group received 250, 500 or 1000 mg/kg/day of XRD-537 nBu (Technical) (AGR 276541, purity: 98.2%) for up to 2 weeks... In the second study, 2 beagle dogs/sex/group received targeted doses of 0, 35, 100 or 350 mg/kg/day for 4 weeks. Based on the food consumption, the low dose animals received doses of 36, 36, 34 or 53 mg/kg/day, the intermediate dose animals consumed doses of 85, 86, 133 or 138 mg/kg/day and the high dose animals received doses of 193, 203, 37 or 292 mg/kg/day, respectively... Gross examination of the tissues revealed slight to very severe atrophy of the thymus in a dose-related manner... In the microscopic examination, multifocal vasculitis and thrombosis was noted in the kidneys of the 2 high dose males and one intermediate and one high dose female, respectively. Diffuse atrophy of the thymus ranged from slight to very severe in a dose-related manner for the males in all of the groups and from moderate to severe for the intermediate and high dose females. In the testes, spermatogenesis was moderately to severely reduced in the high dose males with a concomitant increase in multinucleated spermatids. Apparent target organs: thymus and testes; Possible adverse effect: atrophy of the thymus and reduced spermatogenesis in the testes; NOEL can not be determined; Study supplemental. (Moore, 11/20/00)
Ref: February 16, 2001. California Environmental Protection Agency Department of Peticide Regulation. Medical Toxicology Branch. Summary of Toxicological Data. Cyhalofop-Butyl. Chemical Code # 5748, Tolerance # 52840 SB 950 # New A.I.

http://www.fluoridealert.org/pesticides/Cyhalofop.butyl.CA.Tox.2001.pdf

Eye (click on for all fluorinated pesticides)

Based on the findings of acute toxicology studies with two similar products, and by extrapolation from the characteristics of the individual constituents in the product, it is expected that Barnstorm Herbicide would be of low acute oral, dermal and inhalational toxicity. It is likely to be a slight skin irritant and a severe eye irritant, but not to be a skin sensitiser (page 5). ... Barnstorm Herbicide is expected to be of low oral, dermal and inhalational toxicity. It is expected to be a severe eye, and slight skin irritant, but not a skin sensitiser (page 9).
... Risks to workers during use. The main acute risks arising from exposure to Barnstorm Herbicide are slight skin irritation and severe eye irritation. Mixer/loaders may be exposed to the product by inhalation or by skin and ocular contact. The main risk during this activity is skin and eye and respiratory tract irritancy (page 17). ...Eye protection is indicated for handling undiluted product due to the potential for severe acute eye irritation (page 18). ... SAFETY DIRECTIONSWill damage the eyes (page 35).
Ref: July 2005 - Evaluation of the new active Cyhalofop-Butyl in the product Barnstorm Herbicide. Australian Pesticides and Veterinary Medicines Authority (APVMA). Canberra, Australia.
http://www.fluorideaction.org/pesticides/cyhalofop.butyl.aust.2005.pdf

Kidney (click on for all fluorinated pesticides)

-- Chronic dietary all populations: Carcinogenicity in mice based on kidney effects in females including tubular dilatation, chronic glomerulonephritis, and hyaline casts. LOAEL = 10.06 mg/kg/day.
Ref: Federal Register. September 27, 2001. Cyhalofop-butyl; Pesticide Tolerances for Emergency Exemptions. Final Rule.

http://www.fluoridealert.org/pesticides/Cyhalofop-butyl.FR.Sep27.01.htm

-- 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 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.
Ref: June 4, 2002. Federal Register. Cyhalofop-butyl; 5-Year Time-Limited Pesticide Tolerance. Final Rule.

http://www.fluorideaction.org/pesticides/cyhalofop-butyl.fr.june4.02.htm

Liver (click on for all fluorinated pesticides)

5. Subchronic and chronic toxicity, and oncogenicity. Cyhalofop- butyl caused increases in liver and kidney weights, microscopic hepatocellular hypertrophy, renal tubular microscopic effects, and distended gallbladders when given at sufficiently high dose levels to the appropriate species for 13 weeks. Similar increases in liver and kidney weights, hepatocellular hypertrophy, and renal effects were also observed in chronic toxicity studies in rodents. In addition, mice had liver inflammation (microgranulomas). Chronic toxicity in dogs was limited to decreased body weight and the occurrence of concretions in the gallbladder. Using the Guidelines for Carcinogen Risk Assessment published September 24, 1986 (51 FR 33992), it is proposed that cyhalofop and cyhalofop-butyl be classified as Group E for carcinogenicity (no evidence of carcinogenicity) based on the results of carcinogenicity studies in two species. Dow AgroSciences LLC believes that there was no evidence of carcinogenicity in an 18-mouse feeding study and a 24-month rat feeding study at all dosages tested.
Ref: Federal Register. April 25, 2001. [PF-1009; FRL-6774-7]

http://www.fluoridealert.org/pesticides/Cyhalofop-butyl.FR.Apr.2001.htm

SUBCHRONIC STUDIES (90-day feeding study) 52840-028; 172924; "XRD-537 NBU: Four-Week and 13-Week Dietary Toxicity Studies in Sprague-Dawley Rats"; (R.A. Corley, K.T. Haut, and L.G. Lomax; The Toxicology Research Laboratory, Health and Environmental Sciences, The Dow Chemical Company, Midland, MI; Study ID. DR-0298- 8876-003; 3/7/91); Two studies were performed at the same time. In the first study, five Sprague-Dawley rats/sex/group (unless otherwise noted) were dosed orally in the diet with 0, 25, 400 (M only), 800 (F only) or 1600 mg/kg b. wt./day of XRD-537 NBU (n-butyl ester; AGR 276541, purity: 98.2%) for 4 weeks. In the second study, 10 rats/sex/group (unless otherwise noted) were dosed orally in the diet with 0, 3 (M only), 10 (F only), 25 (M only), 100, 400 or 800 (F only) mg/kg b.wt./day of the test material for 13 weeks. In the 4-week study, mean body weight for the animals in the 1600 mg/kg group was less than that of the control. The target organ was the liver with increased liver weight noted for the 25 mg/kg males and the 800 mg/kg females (p<0.05). Diffuse hepatocellular hypertrophy was noted for the males at 25 mg/kg and above and for the females at 800 mg/kg and above. In the 13-week study, the mean body weight of the females in the 800 mg/kg group was lower than that of the control (p<0.05). However, there was no apparent treatment-related effects upon food consumption. For the males in the 100 and 400 mg/kg groups, the mean red blood count, hemoglobin concentration and hematocrit were less than that of the control (p<0.05). The serum alkaline phosphate activity was increased for both sexes at 100 mg/kg and above (p<0.05). The mean plasma albumin levels for males in the 400 mg/kg and the females in the 400 and 800 mg/kg groups were increased (p<0.05) in contrast to the globulin levels which were lower for 400 mg/kg males and the 800 mg/kg females (p<0.05). The liver was the target organ with increased liver weights noted for the 100 mg/kg groups and above (p<0.05). Multifocal and/or diffuse hepatocellular hypertrophy was reported for the males in the 25 mg/kg group and above and for the females in the 100 mg/kg group and above (p<0.05). No adverse effect indicated; Reported NOEL: (4-week study) (M) < 25 mg/kg/day (based upon increased mean liver weight and the incidence of diffuse hepatocellular hypertrophy in the 25 mg/kg/day treatment group), (F) 25 mg/kg/day (based upon increased mean liver weight and incidence of diffuse hepatocellular hypertrophy in the 800 mg/kg/day treatment group; (13-week study) (M) 3 mg/kg/day (based upon the incidence of multifocal hepatocellular hypertrophy in the 25 mg/kg/day treatment group, (F) 10 mg/kg/day (based upon the increased mean liver weight and incidence of multifocal and diffuse heptocellular hypertrophy at 100 mg/kg); Study unacceptable. possibly upgradeable with the submission of the concentrations of the test material in the dietary preparations and a calculation of the actual doses which the study animals received. (Moore, 11/16/00)
Ref: Summary of Toxicological Data for Cyhalofop-butyl. California EPA, Department of Pesticide Regulation, Medical Toxicology Branch. February 16, 2001.

http://www.fluorideaction.org/pesticides/cyhalofop.butyl.ca.tox.2001.pdf

A February 17, 2005, check at the Code of Federal Regulations for Cyhalofop-butyl, cyhalofop acid and the di-acid metabolite: this herbicide is permitted in or on 2 food commodities in the United States. The following list identifies these crops for which EPA has set pesticide tolerances. 

[Code of Federal Regulations]
[Title 40, Volume 22]
[Revised as of July 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR180.576]
[Page 511]

TITLE 40--PROTECTION OF ENVIRONMENT

CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)

PART 180_TOLERANCES AND EXEMPTIONS FROM TOLERANCES FOR PESTICIDE CHEMICALS
IN FOOD--Table of Contents

Subpart C_Specific Tolerances

Sec. 180.576 Cyhalofop-butyl; tolerances for residues.
(a) General. Time-limited tolerances are established for combined
residues of cyhalofop
(cyhalofop-butyl, R-(+)-n-butyl-2-(4(4-cyano-2-
fluorophenoxy)-phenoxy)propionate, plus cyhalofop acid, R-(+)-2-(4(4-
cyano-2-fluorophenoxy)-phenoxy)propionic acid) and the di-acid
metabolite
, (2R)-4-[4-(1-carboxyethoxy)phenoxy]-3-fluorobenzoic acid,
from the application of the herbicide cyhalofop-butyl in or on the
following raw agricultural commodities:

Commodity

As of
September 26,
2003

PPM

As of
February 17,
2005

PPM

Expiration/ Revocation Date

Rice, grain 0.03 0.03 6/1/2007 
Rice, straw 8.0 8.0 6/1/2007 
(b) Section 18 emergency exemptions. [Reserved]
(c) Tolerances with regional registrations. [Reserved]
(d) Indirect or inadvertent residues. [Reserved]
 
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