Adverse Effects
Tefluthrin
CAS No.
79538-32-2
 
 

Return to Tefluthrin Index Page

Activity: Insecticide (pyrethroid)
Structure:


Adverse Effects:
Ataxia
Blood
Body Weight Decrease
Bone
Brain
Cholesterol
Endocrine: Thyroid
Endocrine:
Uterus
Heart
Liver
Tremors
Environmental

As of February 16, 2005, this insecticide and its metabolite is permitted in or on corn in the United States - see list at bottom of page.


Table 6-1. Trends of National Pyrethroid Use

September 2001. Draft Toxicological Profile for Pyrethrins and Pyrethroids. US Department of Health and Human Services. Public Health Service Agency for Toxic Substances and Disease Registry. Organofluorine pyrethroids discussed in the Profile: Bifenthrin (Type 1), Cyfluthrin (Type 2), Cyhalothrin (Type 2), Flucythrinate (Type 2), Flumethrin (Type 2), Fluvalinate (Type 2), Tefluthrin (Type 1).

Note from EC: The following 4 organofluorine pesticides were included in a list of 11 pesticides.

Pyrethroid Amounts applied
(pounds) 1992
Amounts applied
(pounds) 1992
Percent change
Bifenthrin 116,716 110,246 -5
Cyfluthrin 124,360 177,782 +43
lambda Cyhalothrin 205,329 321,284 +57
Tefluthrin 238,429 576,865 +142

Ataxia (click on for all fluorinated pesticides)

-- In a chronic toxicity study, dogs were dosed at dose levels of 0, 0.1, 0.5, and 2 mg/kg/day for 12 months. The LOEL for this chronic study is 2.0 mg/kg/day based on the increased incidence of ataxia in both sexes at the high-dose. The NOEL is 0.5 mg/kg/day.
-- Toxicological Endpoints 1. Acute toxicity. For acute dietary risk assessment, EPA recommends use of a NOEL of 0.5 mg/kg/day based on increased incidence of tremors and ataxia in both sexes of dogs at 2.0 mg/kg/day (LOEL) on day 1 of the study from the 1 year oral chronic toxicity study in dogs.
-- Toxicological Endpoints 2. Short - and intermediate - term toxicity. For short- and intermediate term MOE's, EPA recommends use of a NOEL of 0.5 mg/kg/day based on increased incidence of tremors and ataxia in both sexes of dogs at 2.0 mg/kg/day (LOEL) from the one year oral toxicity study in dogs and use of a dermal absorption rate of 25%. A dermal absorption rate of 25% was recommended based on the weight-of-the-evidence available for structurally related pyrethroids.
-- Chronic toxicity. EPA has established the RfD for tefluthrin at 0.005 milligrams/kilogram/day (mg/kg/day). This RfD is based on increased incidence of tremors and ataxia in both sexes of dogs in a chronic toxicity study and an uncertainty factor of 100 to account for both interspecies extrapolation and intraspecies variability.
Ref: Federal Register: November 26, 1997. Tefluthrin; Pesticide Tolerance. Final Rule.
http://www.fluoridealert.org/pesticides/Tefluthrin.FR.Nov.1997.htm

Blood (click on for all fluorinated pesticides)

In a 3-month rat study, dietary administration of 10 mg/kg/day produced plasma, red blood cell, and brain cholinesterase inhibition. The NOEL was 5 mg/kg/day. In a 6-month dog study, dietary administration of 10 mg/kg/day (LOEL) produced plasma cholinesterase inhibition. The NOEL was 1 mg/kg/day. In a 21-day rat dietary study, administration of 20 mg/kg/day (LOEL for females) produced decreased platelet counts, increased white blood cell, lymphocyte, and neutrophil counts in males and females. The NOEL for females was 5 mg/kg/day... EPA believes that there is sufficient evidence for listing tefluthrin on EPCRA section 313 pursuant to EPCRA section 313(d)(2)(B) based on the available developmental, neurological, hepatic, and hematological toxicity data for this chemical.
Ref: USEPA/OPP. Support Document for the Addition of Chemicals from Federal Insecticide, Fungicide, Rodenticide Act (FIFRA) Active Ingredients to EPCRA Section 313. U. S. Environmental Protection Agency, Washington, DC (1993). As cited by US EPA in: Federal Register: January 12, 1994. Part IV. 40

Body Weight Decrease (click on for all fluorinated pesticides)

Reproductive and developmental toxicity. In a rat developmental study, [[Page 50363]] delayed ossification was noted in the highest dose group (5 mg/kg/day), along with significant maternal toxicity (decreased body weight (bwt)). The developmental no observed effect level (NOEL) for this study was established at 3 mg/kg/day.
Ref: Federal Register: September 25, 1997 [Page 50337-50367]. Notice of Filing of Pesticide Petitions.
http://www.fluori
dealert.org/pesticides/Bifenthrin.FR.Sept.25.1997.htm

Bone (click on for all fluorinated pesticides)

Reproductive and developmental toxicity. In a rat developmental study, [[Page 50363]] delayed ossification was noted in the highest dose group (5 mg/kg/day), along with significant maternal toxicity (decreased body weight (bwt)). The developmental no observed effect level (NOEL) for this study was established at 3 mg/kg/day.
Ref: Federal Register: September 25, 1997 [Page 50337-50367]. Notice of Filing of Pesticide Petitions.

http://www.fluoridealert.org/pesticides/Bifenthrin.FR.Sept.25.1997.htm

-- In a developmental toxicity study, rats were dosed at 0, 1, 3, or 5 mg/kg/day from days 7 through 16 of gestation. The maternal LOEL is 3 mg/kg/day, based on treatment-related decrease body weight gains during dosing. The maternal NOEL is 1 mg/kg/day. Developmental toxicity was demonstrated at 5 mg/kg/day as an increase in the fetal incidence of bilaterally unossified calcanea (92.9% vs. 87.5% in controls, p<0.05; litter incidence was not shown) and a slight increase in the pes score (3.05 vs. 2.96 in controls) indicating slight inhibition of ossification at these sites. There were no treatment-related effects on the number, growth, and survival of the young in utero. In addition, the inter-group differences in the mean numbers of corpora lutea, implantations, pre- and post- implantation deaths, live fetuses, proportion of male fetuses, and fetal weights were not remarkable. The developmental LOEL is 5 mg/kg/day, based on inhibited ossification. The developmental NOEL is 3 mg/kg/day.
-- In a developmental toxicity study, rabbits were dosed at 0, 3, 6, or 12 mg/kg/day from days 7 through 19 of gestation. The maternal LOEL is 3 mg/kg/day, based on treatment-related clinical signs of toxicity (tremors). The maternal NOEL is <3 mg/kg/day. There was no developmental toxicity demonstrated at any dose level. There were no treatment-related effects on in utero survival and growth or on litter size and sex ratio of the fetuses. The skeletal
variant data showed significant (p<0.01 or 0.05) increases in incidence of extra thoracic ribs and 27 pre-sacral vertebrae among fetuses in the dosed groups; however, when the litter was used as the unit for comparison, the incidences of these respective variants were comparable between all groups. The incidences of these variants were not biologically significant. The NOEL for developmental toxicity is 12 mg/kg/day. The developmental LOEL was not observed.
Ref: Federal Register: November 26, 1997. Tefluthrin; Pesticide Tolerance. Final Rule. http://www.fluoridealert.org/pesticides/Tefluthrin.FR.Nov.1997.htm

Brain (click on for all fluorinated pesticides)

In a 3-month rat study, dietary administration of 10 mg/kg/day produced plasma, red blood cell, and brain cholinesterase inhibition. The NOEL was 5 mg/kg/day. In a 6-month dog study, dietary administration of 10 mg/kg/day (LOEL) produced plasma cholinesterase inhibition. The NOEL was 1 mg/kg/day.
Ref: USEPA/OPP. Support Document for the Addition of Chemicals from Federal Insecticide, Fungicide, Rodenticide Act (FIFRA) Active Ingredients to EPCRA Section 313. U. S. Environmental Protection Agency, Washington, DC (1993). As cited by US EPA in: Federal Register: January 12, 1994. Part IV. 40 CFR Part 372. Addition of Certain Chemicals; Toxic Chemical Release Reporting; Community Right-to-Know; Proposed Rule.

Cholesterol (click on for all fluorinated pesticides)

In a subchronic oral toxicity study, rats were dosed at 0, 50, 150, or 350 ppm (2.5, 7.5, or 17.5 mg/kg/day) for 90 days. The LOEL for this 90-day feeding study is 150 ppm (equivalent to approximately 7.5 mg/kg/day) based on changes in hemoglobin, cholesterol, and liver weight in the mid-dose animals. The NOEL is 50 ppm (equivalent to approximately 2.5 mg/kg/day).
Ref: Federal Register: November 26, 1997. Tefluthrin; Pesticide Tolerance. Final Rule. http://www.fluoridealert.org/pesticides/Tefluthrin.FR.Nov.1997.htm

Heart (click on for all fluorinated pesticides)

Abstract. This report describes for the first time a novel anionic background current (I(AB)) identified in guinea-pig isolated ventricular myocytes. It also shows that I(AB) has both novel and differential pharmacology from other (cardiac) chloride currents. Using the whole-cell patch-clamp technique and external anion substitution, I(AB) was found to be outwardly rectifying and highly permeable to NO(-)(3), with a relative permeability sequence of NO(-)(3) > I(-) > Cl(-). I(AB) was not blocked by 50 microM DIDS, by hypertonic external solution, or by the nonselective protein kinase inhibitor H7-DHC. Exposure to the pyrethroid agent tefluthrin (10 microM) increased the current density of I(AB) significantly at positive voltages (P < 0.05), but had no significant effect on other cardiac chloride currents. We conclude that I(AB) possesses a distinct pharmacology and does not fall into the three major classes of cardiac chloride conductance commonly reported. (C)2002 Elsevier Science (USA).
Ref: Borg JJ et al. (2002). Tefluthrin modulates a novel anionic background conductance (I(AB)) in guinea-pig ventricular myocytes. Biochem Biophys Res Commun. Mar 22;292(1):208-15.

Abstract: Pyrethroid insecticides are known to modify neuronal sodium channels, inducing persistent, steady-state sodium current at depolarized membrane potentials. Cardiac myocytes are also rich in sodium channels but comparatively little is known about the effect of pyrethroids on the heart, or on the cardiac sodium channel isoform. In the present study therefore, we determined the actions of type I and type II pyrethroids against rat and guinea pig ventricular myocytes under current and voltage clamp, and on isolated perfused rat hearts. In myocytes, tefluthrin (type I) and fenpropathrin and alpha-cypermethrin (type II) prolonged action potentials and evoked afterdepolarizations. The time course of sodium current (I(Na)) was also prolonged by these compounds. Pyrethroids delayed I(Na) inactivation, when measured under selective conditions as current sensitive to 30 microM tetrodotoxin, by increasing the proportion of slowly inactivating current at the expense of fast inactivating current. Further experiments, focusing on fenpropathrin, revealed that its effects on I(Na) inactivation time course were dose-dependent, and the Na(+) "window-current" was increased in its presence. In unstimulated, isolated hearts perfused with the same pyrethroids, the variability in contraction amplitude increased due to variations in the intervals between heartbeats. These potentially arrhythmogenic changes are consistent with the effects observed at the cellular level. The type I pyrethroid tetramethrin had little effect in any of the preparations. These findings suggest that some pyrethroids possess considerable mammalian cardiac arrhythmogenic potential, the manifestation of which in vivo may depend on the route of exposure.
Discussion from full paper: The principal findings of the present study at the cellular level are that the type I pyrethroid tefluthrin and the type II pyrethroids fenpropathrin and -cypermethrin
1) prolonged ventricular action potentials and evoked afterdepolarizations;
2) modified the time course of INa by altering the relative proportions of fast and slowly inactivating current; and
3) altered the voltage dependence of INa. At the whole heart level, these effects corresponded with a pyrethroid-induced increase in the variability of contractile force, suggestive of proarrhythmic activity. Several aspects of these findings merit detailed consideration.
Ref: Spencer CI et al. (2001). Actions of pyrethroid insecticides on sodium currents, action potentials, and contractile rhythm in isolated mammalian ventricular myocytes and perfused hearts. J Pharmacol Exp Ther. 2001 Sep;298(3):1067-82. Erratum in: J Pharmacol Exp Ther 2001 Oct;299(1):399.
Full free report available at
http://jpet.aspetjournals.org/cgi/content/full/298/3/1067

Endocrine: Thyroid (click on for all fluorinated pesticides)

-- In a subchronic oral toxicity study, dogs were dosed at 0, 0.1, 0.5, or 1.5 mg/kg/day for 90 days. The LOEL for this 90-day oral toxicity study is 1.5 mg/kg/day based on thyroid changes, and increased levels of plasma triglycerides and aspartate transaminase observed at the high-dose. The NOEL is 0.5 mg/kg/day.
-- Endocrine Disrupter Effects. EPA is required to develop a screening program to determine whether certain substances (including all pesticides and inerts) ``may have an effect in humans that is similar to an effect produced by a naturally occurring estrogen, or such other endocrine effect...'' The Agency is currently working with interested stakeholders, including other government agencies, public interest groups, industry and research scientists in developing a screening and testing program and a priority setting scheme to implement this program. Congress has allowed 3 years from the passage of FQPA (August 3, 1999) to implement this program. At that time, EPA may require further testing of this active ingredient and end use products for endocrine disrupter effects.
Ref: Federal Register: November 26, 1997. Tefluthrin; Pesticide Tolerance. Final Rule. http://www.fluoridealert.org/pesticides/Tefluthrin.FR.Nov.1997.htm

Endocrine: Uterus (click on for all fluorinated pesticides)

-- In a chronic/oncogenicity study, mice were dosed at 0, 25, 100, or 400 ppm (actual dose levels were equivalent to 3.4, 13.5, or 54.4 mg/kg/day) for 104 weeks. The chronic LOEL is 13.5 mg/kg based on hemangiomatous changes of the uterus and liver necrosis observed in the mid- and high-dose females. The chronic NOEL is 3.4 mg/kg. Under the conditions of this study, there was no evidence of carcinogenic potential.
-- In a developmental toxicity study, rats were dosed at 0, 1, 3, or 5 mg/kg/day from days 7 through 16 of gestation. The maternal LOEL is 3 mg/kg/day, based on treatment-related decrease body weight gains during dosing. The maternal NOEL is 1 mg/kg/day. Developmental toxicity was demonstrated at 5 mg/kg/day as an increase in the fetal incidence of bilaterally unossified calcanea (92.9% vs. 87.5% in controls, p<0.05; litter incidence was not shown) and a slight increase in the pes score (3.05 vs. 2.96 in controls) indicating slight inhibition of ossification at these sites. There were no treatment-related effects on the number, growth, and survival of the young in utero. In addition, the inter-group differences in the mean numbers of corpora lutea, implantations, pre- and post- implantation deaths, live fetuses, proportion of male fetuses, and fetal weights were not remarkable. The developmental LOEL is 5 mg/kg/day, based on inhibited ossification. The developmental NOEL is 3 mg/kg/day.
Ref: Federal Register: November 26, 1997. Tefluthrin; Pesticide Tolerance. Final Rule.
http://www.fluoridealert.org/pesticides/Tefluthrin.FR.Nov.1997.htm

Liver (click on for all fluorinated pesticides)

-- In a chronic/oncogenicity study, mice were dosed at 0, 25, 100, or 400 ppm (actual dose levels were equivalent to 3.4, 13.5, or 54.4 mg/kg/day) for 104 weeks. The chronic LOEL is 13.5 mg/kg based on hemangiomatous changes of the uterus and liver necrosis observed in the mid- and high-dose females. The chronic NOEL is 3.4 mg/kg. Under the conditions of this study, there was no evidence of carcinogenic potential.
Ref: Federal Register: November 26, 1997. Tefluthrin; Pesticide Tolerance. Final Rule.
http://www.fluoridealert.org/pesticides/Tefluthrin.FR.Nov.1997.htm

Tremors (click on for all fluorinated pesticides)

-- In a developmental toxicity study, rabbits were dosed at 0, 3, 6, or 12 mg/kg/day from days 7 through 19 of gestation. The maternal LOEL is 3 mg/kg/day, based on treatment-related clinical signs of toxicity (tremors). The maternal NOEL is <3 mg/kg/day. There was no developmental toxicity demonstrated at any dose level. There were no treatment-related effects on in utero survival and growth or on litter size and sex ratio of the fetuses. The skeletal variant data showed significant (p<0.01 or 0.05) increases in incidence of extra thoracic ribs and 27 pre-sacral vertebrae among fetuses in the dosed groups; however, when the litter was used as the unit for comparison, the incidences of these respective variants were comparable between all groups. The incidences of these variants were not biologically significant. The NOEL for developmental toxicity is 12 mg/kg/day. The developmental LOEL was not observed.
-- Toxicological Endpoints 1. Acute toxicity. For acute dietary risk assessment, EPA recommends use of a NOEL of 0.5 mg/kg/day based on increased incidence of tremors and ataxia in both sexes of dogs at 2.0 mg/kg/day (LOEL) on day 1 of the study from the 1 year oral chronic toxicity study in dogs.
-- Toxicological Endpoints 2. Short - and intermediate - term toxicity. For short- and intermediate term MOE's, EPA recommends use of a NOEL of 0.5 mg/kg/day based on increased incidence of tremors and ataxia in both sexes of dogs at 2.0 mg/kg/day (LOEL) from the one year oral toxicity study in dogs and use of a dermal absorption rate of 25%. A dermal absorption rate of 25% was recommended based on the weight-of-the-evidence available for structurally related pyrethroids.
-- Chronic toxicity. EPA has established the RfD for tefluthrin at 0.005 milligrams/kilogram/day (mg/kg/day). This RfD is based on increased incidence of tremors and ataxia in both sexes of dogs in a chronic toxicity study and an uncertainty factor of 100 to account for both interspecies extrapolation and intraspecies variability.
Ref: Federal Register: November 26, 1997. Tefluthrin; Pesticide Tolerance. Final Rule. http://www.fluoridealert.org/pesticides/Tefluthrin.FR.Nov.1997.htm

Environmental (click on for all fluorinated pesticides)

Aquatic acute toxicity values for tefluthrin include a rainbow trout 96-hour LC 50 of 0.06 ppb, a bluegill 96-hour LC50 of 0.13 ppb, a sheepshead minnow 96-hour LC50 of 0.13 ppb, a daphnid 48-hour EC50 of 0.07 ppb, and a mysid 96-hour EC 50 of 0.053 ppb. EPA believes that there is sufficient evidence for listing teflurin on EPCRA section 313 pursuant to EPCRA section 313(d)(2)(C) based on the available environmental toxicity data for this chemical.
Ref: USEPA/OPP. Support Document for the Addition of Chemicals from Federal Insecticide, Fungicide, Rodenticide Act (FIFRA) Active Ingredients to EPCRA Section 313. U. S. Environmental Protection Agency, Washington, DC (1993). As cited by US EPA in: Federal Register: January 12, 1994. Part IV. 40 CFR Part 372. Addition of Certain Chemicals; Toxic Chemical Release Reporting; Community Right-to-Know; Proposed Rule.

Ref: Acute Aquatic Ecotoxicity Summaries for Tefluthrin on All Taxa Groups. PAN Pesticides Database - Chemical Toxicity Studies on Aquatic Organisms
http://www.pesticideinfo.org/List_AquireAcuteSum.jsp?Rec_Id=PC34532
Common Name Scientific Name Avg Species LC50 (ug/L) LC50 Std Dev Number of Studies Avg Species Rating

Fish

Bluegill Lepomis macrochirus 4.47 4.34 2 Very Highly Toxic
Rainbow trout,donaldson trout Oncorhynchus mykiss 3.78 3.72 2 Very Highly Toxic

A  February 16, 2005, check at the Code of Federal Regulations for Teflulthrin (and its metabolite): this insecticide is permitted in or on 7 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: 40CFR180.440]
[Page 453]

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. 180.440 Tefluthrin; tolerances for residues.
(a) General. Tolerances are established for the combined residues of
the insecticide tefluthrin
(2,3,5,6 tetrafluroro-4-methylphenyl)methyl-
(1 alpha, 3 alpha)-(Z)-()-3(2-chloro-3,3,3-
trifluoro-1-propenyl)-2,2-diemthylcyclopropanecarboxylate) and its
metabolite
(Z)-3-(2-chloro-3,3,3-trifluroro-1-propenyl)-2,2-
dimethylcyclopropanecarboxylic acid in or on the following commodities:
Commodity

As
of October 15,
2003

PPM

As of
February16,
2005

PPM


Corn, field, fodder and forage, pop and sweet
Not Listed in this way 0.06
Corn, fresh (including sweet K and corn with husk removed 0.06 (CWHR) 0.06 0.06
Corn, field, grain and pop Not Listed 0.06
CORN, FIELD, FORAGE 0.06 Not Listed in this way
CORN, FIELD, GRAIN 0.06 Not Listed in this way
CORN, FIELD, STOVER 0.06 Not Listed
CORN, POP, FODDER 0.06 Not Listed in this way
CORN, POP, FORAGE 0.06 Not Listed in this way
CORN, POP, GRAIN 0.06 Not Listed in this way
CORN, SWEET, FODDER 0.06 Not Listed in this way
CORN, SWEET, FORAGE 0.06 Not Listed in this way
(b) Section 18 emergency exemptions. [Reserved]
(c) Tolerances with regional registrations. [Reserved]
(d) Indirect or inadvertent residues. [Reserved]
 
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