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paclobutrazol (Ref: PP 333)
** paclobutrazole ** Translations

Environmental Fate - Ecotoxicology - Human Health - A to Z Index - Home

GENERAL INFORMATION Click here for an explantaion of the general chemical status information
for paclobutrazol

Description: A conazole plant growth regulator with some fungicidal activity for ornamentals, fruit and other crops to inhibit vegetative growth

Example pests controlled: Vegetative growth - cell division

Example applications: Mango; Cotton; Corn; Chilli; Bonzi production; Grape vines

Efficacy & activity: -

Availability status: Current

Introduction & key dates: 1986

EC Regulation 1107/2009 (repealing 91/414):
Status Approved
Dossier rapporteur/co-rapporteur UK/Romania
Date inclusion expires 31/05/2021
EU Candidate for substitution (CfS) Yes - two 'Persistent-Bioaccumulative-Toxic' criteria
Listed in EU database Yes

Approved for use () or known to be used () in the following European countries: Click to access a note on the approvals information on this site

AT

BE

BG

CY

CZ

DE

DK

EE

EL

ES

FI

FR

HR

HU

IE

IT

LT

LU

LV

MT

NL

PL

PT

RO

SE

SI

SK

UK

Also used in: Australia

Chemical structure: Click here for further information on the general chemical status information used on this site
Isomerism A molecule with two chiral centres. The technical material is a racemate comprising equimolar amounts of (2R,3R)- and (2S,3S)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)pentan-3-ol.
Chemical formula C15H20ClN3O
Canonical SMILES CC(C)(C)C(C(CC1=CC=C(C=C1)Cl)N2C=NC=N2)O
Isomeric SMILES CC(C)(C)[C@H]([C@@H](CC1=CC=C(C=C1)Cl)N2C=NC=N2)O
International Chemical Identifier key (InChIKey) RMOGWMIKYWRTKW-UHFFFAOYSA-N
International Chemical Identifier (InChI) InChI=1S/2C15H20ClN3O/c2*1-15(2,3)14(20)13(19-10-17-9-18-19)8-11-4-6-12(16)7-5-11/h2*4-7,9-10,13-14,20H,8H2,1-3H3/t2*13-,14-/m10/s1
2D structure diagram/image available? Yes

General status: Click here for further information on the general chemical status information used on this site
Pesticide type Plant growth regulator; Fungicide
Substance group Triazole
Minimum active substance purity 930 g/kg
Known relevant impurities EU dossier - None declared
Substance origin Synthetic
Mode of action Absorbed through leaves, stem and roots and translocated
CAS RN 76738-62-0
EC number 266-325-7
CIPAC number 445
US EPA chemical code 125601
PubChem CID 158076
Molecular mass (g mol-1) 293.8
PIN (Preferred Identification Name) -
IUPAC name (2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)pentan-3-ol
CAS name (αR,βR)-rel-β-((4-chlorophenyl)methyl)-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol
Other status information -
Relevant Environmental Water Quality Standards -
Herbicide Resistance Classification (HRAC) Not applicable
Herbicide Resistance Classification (WSSA) Not applicable
Insecticide Resistance Classification (IRAC) Not applicable
Fungicide Resistance Classification (FRAC) Not applicable
Examples of recorded resistance -
Physical state White crystalline solid
Related substances & organisms

Formulations:
Property Click here for information on the general product and branding information used on this site Value
Example manufacturers & suppliers of products using this active now or historically
  • Agrovista
  • Fine
  • Syngenta
Example products using this active
  • Bonzi
  • Cultar
  • Parlay
  • Piroutte
UK LERAP status None
Formulation and application details Often supplied as a suspension concentrate that is mixed with water and used as a spray.


ENVIRONMENTAL FATE
for paclobutrazol

Property Click here for information on the parameters used to describe environmental fate on this site Value Source/Quality Score/Other Information Click here for information on the primary data sources used to populate this database with fate data Interpretation Click here for information on the way in which we interpret environmental fate data
Solubility - In water at 20oC (mg l-1) 22.9 A5 Low
Solubility - In organic solvents at 20oC (mg l-1) 72400 A5 - Acetone -
5670 A5 - Xylene -
150000 A5 - Methanol -
199 A5 - n-Heptane -
Melting point (oC) 164 A5 -
Boiling point (oC) 384 A5 -
Degradation point (oC) - - -
Flashpoint (oC) Not expected to self ignite; Not highly flammable A5 -
Octanol-water partition coefficient at pH 7, 20oC P 1.29 X 1003 Calculated -
Log P 3.11 A5 High
Bulk density (g ml-1)/Specific gravity 1.23 A5 -
Dissociation constant (pKa) at 25oC - - -
Note:
Vapour pressure at 20oC (mPa) 0.0019 A5 Low volatility
Henry's law constant at 25oC (Pa m3 mol-1) 2.39 X 10-05 A5 Non-volatile
GUS leaching potential index Click here for a note on the limitations of the GUS index 3.49 Calculated High leachability
SCI-GROW groundwater index (μg l-1) for a 1 kg ha-1 or 1 l ha-1 application rate Click here for a note on the limitations of the SCI-GROW index Value 6.39 X 10-01 Calculated -
Note -
Potential for particle bound transport index Click here for a note on the limitations of the potential for particle bound transport index - Calculated Medium
Maximum UV-vis absorption L mol-1 cm-1 Neutral solution: 222nm = 10900, 260nm = 233, 267nm = 294, 276nm = 236; [Acidic solution: 221nm = 17500, 260nm = 228, 267nm = 284, 276nm = 229; [Basic solution: 221nm = 12800, 260nm = 222, 267nm = 280, 276nm = 225; [No absorbance > ca 280nm A5 -
Surface tension (mN m-1) 66.0 A5 at 20.5 oC] -

Degradation:
Property Click here for information on the parameters used to describe substance degradation Value Source/Quality Score/Other Information Click here for information on the primary data sources used to populate this database with degradation data Interpretation Click here for information on the way in which we interpret substance degradation data
General biodegradability -
Soil degradation (days) (aerobic) DT50 (typical) 112 B5 Persistent
DT50 (lab at 20oC) 120 A5 Persistent
DT50 (field) 29.5 A5 Non-persistent
DT90 (lab at 20oC) 876 A5 -
DT90 (field) 98.1 A5 -
DT50 modelling endpoint - - -
Note EU dossier lab studies DT50 range 27.1-618 days, DT90 range 143-2053 days, field studies DT50 range 27.2-60.8 days, DT90 range 46.7-202 days; Other studies: DT50 (1) lab 84-140 days, field 6-13 months (B4), (2) US sources: 200 days (DW4)
Dissipation rate RL50 on plant matrix Value 4.4 R3 -
Note Wheat, whole plant, n=1
Dissipation rate RL50 on and in plant matrix Value 6.0 R3 -
Note OSR, whole plant, n=1
Aqueous photolysis DT50 (days) at pH 7 Value Stable A5 -
Note -
Aqueous hydrolysis DT50 (days) at 20oC and pH 7 Value Stable A5 -
Note Stable pH 4 to pH 9 over 30 days at 25 degC
Water-sediment DT50 (days) 787 A5 Stable
Water phase only DT50 (days) 164 A5 Stable

Soil adsorption and mobility:
Property Click here for information on the parameters used to describe substance adsorption and mobility Value Source/Quality Score/Other Information Click here for information on the primary data sources used to populate this database with adsorption and mobility data Interpretation Click here for information on the way in which we interpret substance adsorption and mobility
Linear Kd - DW3 Moderately mobile
Koc 400
Notes and range -
Freundlich Kf 4.3 A5 Moderately mobile
Kfoc 210
1/n 0.93
Notes and range EU dossier kf range 0.68-15.1 mL/g, Kfoc range 34.7-665.3 mL/g, 1/n range 0.87-0.97, Soils=13
pH sensitivity No

Key metabolites:
Metabolite Formation medium Estimated maximum occurrence fraction 1107/2009 relevancy Click here for further information on 1107/2009 relevancy
(2RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)pentan-3-one (Ref: CGA 149907) This metabolite may cause environmental pollution, click here for further information Soil   0.274   Major fraction, Relevant
1,2,4-triazole (Ref: CGA 71019) Soil   0.03   Minor fraction, Relevant
1H-1,2,4-triazol-1-ylacetic acid (Ref: CGA 142856) Soil   -   Not relevant

Other known metabolites:
Metabolite name and reference Aliases Formation medium / Rate Estimated maximum occurrence fraction Metabolising enzymes
2-amino-3-1,2,4-triazole-1-yl-propionic acid
(Ref: CGA 131013) 		triazole alanine Plant - -
2-hydroxy-3-[1,2,4]-triazole-1-yl-propionic acid
(Ref: CGA 205639) 		triazole lactic acid Plant - -
3-hydroxy-1H-1,2,4-triazole, hydroxy triazole
(Ref: NOA 457654)
Note: Potenial groundwater pollutant 		- Water/sediment; Soil - -
(2RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1H, 1,2,4-triazole-1-yl)-1-hydroxy-pentan-3-one
(Ref: R117117) 		hydroxy ketone Water/sediment - -
(2RS, 3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1H, 1,2,4-triazole-1-yl)pentan-1,3-diol
(Ref: SYN 536408) 		diol Water/sediment - -


ECOTOXICOLOGY
for paclobutrazol

Property Click here for information on the parameters used to describe substance ecotoxicology Value Source/Quality Score/Other Information Click here for information on the primary data sources used to populate this database with ecotoxicology data Interpretation Click here for information on the way in which we interpret substance ecotoxicology
Bio-concentration factor BCF (l kg-1) 44 A5 Low potential
CT50 (days) Not available -
Mammals - Acute oral LD50 (mg kg-1) 1336 A5 Rat Moderate
Mammals - Short term dietary NOEL (mg kg-1) 2.5 B5 Rat High
(ppm diet) 50 -
Birds - Acute LD50 (mg kg-1) > 2100 A5 Colinus virginianus Low
Birds - Short term dietary (LC50/LD50) > 2000 mg kg feed-1 A5 Colinus virginianus -
Fish - Acute 96 hour LC50 (mg l-1) 23.6 A5 Lepomis macrochirus Moderate
Fish - Chronic 21 day NOEC (mg l-1) 3.3 A5 Salmo gairdneri Moderate
Aquatic invertebrates - Acute 48 hour EC50 (mg l-1) 33.2 B5 Daphnia magna Moderate
Aquatic invertebrates - Chronic 21 day NOEC (mg l-1) 0.32 A5 Daphnia magna Moderate
Aquatic crustaceans - Acute 96 hour LC50 (mg l-1) - - -
Sediment dwelling organisms - Acute 96 hour LC50 (mg l-1) - - -
Sediment dwelling organisms - Chronic 28 day NOEC, static, water (mg l-1) - - -
Sediment dwelling organisms - Chronic 28 day NOEC, sediment (mg kg-1) - - -
Aquatic plants - Acute 7 day EC50, biomass (mg l-1) 0.0082 A5 Lemna gibba High
Non-target plants 58.3 A5 Tomato
Seedling emergence, ER50
as g/ha 		-
- - -
Algae - Acute 72 hour EC50, growth (mg l-1) 7.2 A5 Pseudokirchneriella subcapitata Moderate
Algae - Chronic 96 hour NOEC, growth (mg l-1) - - -
Honeybees (Apis spp.) Contact acute LD50 (worst case from 24 , 48 and 72 hour values - μg bee-1) > 40 A5 Moderate
Oral acute LD50 (worst case from 24 , 48 and 72 hour values - μg bee-1) > 2 A5 Moderate
Unknown mode acute LD50 (worst case from 24 , 48 and 72 hour values - μg bee-1) - - -
Bumblebees (Bombus spp.) Contact acute LD50 (worst case from 24 , 48 and 72 hour values - μg bee-1) - - -
-
Oral acute LD50 (worst case from 24 , 48 and 72 hour values - μg bee-1) - - -
-
Mason bees (Osmia spp.) Contact acute LD50 (worst case from 24 , 48 and 72 hour values - μg bee-1) - - -
Oral acute LD50 (worst case from 24 , 48 and 72 hour values - μg bee-1) - - -
Other pollinators (1) Acute LD50 (worst case from 24 , 48 and 72 hour values - μg insect-1) - - -
Mode of exposure -
Other pollinators (2) Acute LD50 (worst case from 24 , 48 and 72 hour values - μg insect-1) - - -
Mode of exposure -
Earthworms - Acute 14 day LC50 (mg kg-1) > 500 A5 Eisenia foetida, corr Moderate
Earthworms - Chronic 14 day NOEC, reproduction (mg kg-1) 0.68 A5 Eisenia foetida, corr Moderate
Other soil macro-organisms - e.g. Collembola LR50 / EC50 / NOEC / % Effect - - -
Other arthropod (1) LR50 g ha-1 16.7 48 hour
A5 Aphidius rhopalosiphi 		-
% Effect - - -
Other arthropod (2) LR50 g ha-1 1000 >, 7 day
A5 Typhlodromus pyri 		-
% Effect - - -
Soil micro-organisms Nitrogen mineralisation: No significant adverse effect @ 77 days
Carbon mineralisation: No significant adverse effect @ 21 days 		A5
Dose: 20 kg ha-1 		-
Mesocosm study data NOEAEC mg l-1 - - -
NOEAEC mg l-1 - - -


HUMAN HEALTH AND PROTECTION
for paclobutrazol

General:
Property Click here for information on the parameters used to describe human health and protection issues Value Source/Quality Score/Other Information Click here for information on the primary data sources used to populate this database with human health and protection data Interpretation Click here for information on the way in which we interpret human health and protection data
Threshold of Toxicological Concern (Cramer Class) Click here for a note on the limitations of the Cramer class High (class III) - -
Mammals - Acute oral LD50 (mg kg-1) 1336 A5 Rat Moderate
Mammals - Dermal LD50 (mg kg-1 body weight) > 2000 A5 Rat -
Mammals - Inhalation LC50 (mg l-1) 3.13 A5 Rat, 4 hr (nose only) -
Other Mammal toxicity endpoints - -
ADI - Acceptable Daily Intake (mg kg-1bw day-1) 0.022 A5 -
ARfD - Acute Reference Dose (mg kg-1bw day-1) 0.1 A5 SF=100 -
AAOEL - Acute Acceptable Operator Exposure Level (mg kg-1 bw day-1) - - -
AOEL - Acceptable Operator Exposure Level - Systemic (mg kg-1bw day-1) 0.1 A5 SF=100 -
Dermal penetration studies (%) - - -
Dangerous Substances Directive 76/464 - - -
Exposure Routes Public No unacceptable risks to bystanders identified
Occupational No unacceptable risks to operators or other workers identified
European MRLs Click here for the EU MRL pesticide database
Drinking Water Standards - - -
Drinking Water MAC (μg l-1) 0.1 EU Dir 89/778/EC limit; A5 Calc MAC=300 μg l-1 -

Health issues:
Carcinogen Genotoxic Endocrine disrupter Reproduction / development effects Cholinesterase inhibitor Neurotoxicant

A3; B3; C3; D0; E0

-

Respiratory tract irritant Skin irritant Skin sensitiser Eye irritant Phototoxicant

-

-

General human health issues Harmful if inhaled or swallowed
Key: Genotoxicity
A: Chromosome aberration (EFSA database)
B: DNA damage/repair (EFSA database)
C: Gene mutation (EFSA database)
D: Genome mutation (EFSA database)
E: Unspecified genotoxicity type (miscellaneous data source)
0: No data
1: Positive
2: Mixed/ambiguous results
3: Negative		 Key: Other
: Yes, known to cause a problem
: No, known not to cause a problem
: Possibly, status not identified
- : No data found

Handling issues:
Property Click here for information on the parameters used to describe substance handling issues Value Source/Quality Score/Other Information Click here for information on the primary data sources used to populate this database with data on handling issues Interpretation Click here for information on the way in which we interpret data on handling issues
General Click here for a description of the International Maritime Dangerous Goods (IMDG) codes Not explosive or oxidising
IMDG Transport Code is usually 4.1
CLP classification 2013 Health: H302, H319, H332, H361d
Environment: H400, H410
EC Risk Classification Click here to view information omn the EU risk phrases Reproduction risk category 3: R63
Xn - Harmful: R20/22
N - Dangerous for the environment: R51, R53
EC Safety Classification Click here to view information omn the EU safety phrases S60, S61
WHO Classification II - Moderately hazardous
UN Number Usually 1325
Waste disposal & packaging Click here for a description of UN packaging marks Packaging Group II (medium danger)


TRANSLATIONS
for paclobutrazol

Language Name
English paclobutrazol
French paclobutrazol
German Paclobutrazol
Danish paclobutrazol
Italian paclobutrazolo
Spanish paclobutrazol
Greek -
Slovenian paklobutrazol
Polish paklobutrazol
Swedish -
Hungarian paklobutrazol
Dutch paclobutrazool

Record last updated: Wednesday 26 June 2019
Contact: aeru@herts.ac.uk