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

---

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

GENERAL 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:

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:

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:

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	propylene glycol

Formulations:

Property	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		Value	Source/Quality Score/Other Information	Interpretation
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		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	Value	6.39 X 10-01	Calculated	-
	Note	-
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		Value	Source/Quality Score/Other Information	Interpretation
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		Value	Source/Quality Score/Other Information	Interpretation
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
(2RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)pentan-3-one (Ref: CGA 149907)		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		Value	Source/Quality Score/Other Information	Interpretation
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	Contact acute 48 hour LD50 (μg bee-1)	> 40	A5	Moderate
	Oral acute 48 hour LD50 (μg bee-1)	> 2	A5	Moderate
	Unknown mode acute 48 hour LD50 (μg bee-1)	-	-	-
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		Value	Source/Quality Score/Other Information	Interpretation
Threshold of Toxicological Concern (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 Limits		-	-	-
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	Mutagen	Endocrine disrupter	Reproduction / development effects	Cholinesterase inhibitor	Neurotoxicant
	-	-
Respiratory tract irritant	Skin irritant	Skin sensitiser	Eye irritant	Phototoxicant
		-		-
General human health issues		Harmful if inhaled or swallowed

: Yes, known to cause a problem
: No, known not to cause a problem
: Possibly, status not identified
- : No data found

Handling issues:

Property		Value	Source/Quality Score/Other Information	Interpretation
General		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		Reproduction risk category 3: R63 Xn - Harmful: R20/22 N - Dangerous for the environment: R51, R53
EC Safety Classification		S60, S61
WHO Classification		II	-	Moderately hazardous
US EPA Classification (formulation)		IV	-	Caution - Not acutely toxic
UN Number		Usually 1325
Waste disposal & packaging		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: Thursday 13 September 2018
Contact: aeru@herts.ac.uk