Cycloheximide	Last updated: 05/01/2021
(Also known as: naramycin; U-4527; isocycloheximide )

---

GENERAL INFORMATION

Description	An obsolete antibiotic fungicide used in horticultural mainly in combination with other fungicides
Example pests controlled	Powdery mildew; Rusts; Leafspot; Petal blight
Example applications	Ornamentals including roses, azaleas, lawn grass; Citrus
Efficacy & activity	-
Availability status	Obsolete
Introduction & key dates	1946, first reported

UK regulatory status

UK COPR regulatory status	Not approved
Date COPR inclusion expires	Not applicable
UK LERAP status	No UK approval for use

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status	Not approved
Dossier rapporteur/co-rapporteur	Not applicable
Date EC 1107/2009 inclusion expires	Not applicable
EU Candidate for substitution (CfS)	Not applicable
Listed in EU database	No
Approved for use (✓) under EC 1107/2009 in the following EU Member States	ATAustria BEBelgium BGBulgaria CYCyprus CZCzech Republic DEGermany DKDenmark EEEstonia ELGreece                   ESSpain FIFinland FRFrance HRCroatia HUHungary IEIreland ITItaly LTLithuania LULuxembourg                   LVLatvia MTMalta NLNetherlands PLPoland PTPortugal RORomania SESweden SISlovenia SKSlovakia

Also used in

Also used in	-

Chemical structure

Isomerism	A chiral molecule
Chemical formula	C₁₅H₂₃NO₄
Canonical SMILES	CC1CC(C(=O)C(C1)C(CC2CC(=O)NC(=O)C2)O)C
Isomeric SMILES	C[C@H]1C[C@@H](C(=O)[C@@H](C1)[C@@H](CC2CC(=O)NC(=O)C2)O)C
International Chemical Identifier key (InChIKey)	YPHMISFOHDHNIV-FSZOTQKASA-N
International Chemical Identifier (InChI)	InChI=1S/C15H23NO4/c1-8-3-9(2)15(20)11(4-8)12(17)5-10-6-13(18)16-14(19)7-10/h8-12,17H,3-7H2,1-2H3,(H,16,18,19)
2D structure diagram/image available?	Yes

General status

Pesticide type	Fungicide, Plant growth regulator
Substance group	Unclassified
Minimum active substance purity	-
Known relevant impurities	-
Substance origin	Synthetic
Mode of action	A protein biosynthesis inhibitor
CAS RN	66-81-9
EC number	-
CIPAC number	-
US EPA chemical code	043401
PubChem CID	6197
CLP index number	613-140-00-8
Molecular mass	281.16
PIN (Preferred Identification Name)	4-{(2R)-2-[(1S,3S,5S)-3,5-dimethyl-2-oxocyclohexyl]-2-hydroxyethyl}piperidine-2,6-dione
IUPAC name	4-{(2R)-2-[(1S,3S,5S)-3,5-dimethyl-2-oxocyclohexyl]-2-hydroxyethyl}piperidine-2,6-dione
CAS name	4-((2R)-2-((1S,3S,5S)-3,5-dimethyl-2-oxocyclohexyl)-2-hydroxyethyl)-2,6-piperidinedione
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 known
Examples of recorded resistance	-
Physical state	Colourless crystalline solid

Formulations

Property	Value
Example manufacturers & suppliers of products using this active now or historically	Acti-Aid Acti-dione Actispray
Example products using this active	Upjohn Co Nor-Am
Formulation and application details	Usually formulated as a wettable powder or concentrated liquid

ENVIRONMENTAL FATE

Property		Value	Source; quality score; and other information	Interpretation
Solubility - In water at 20 °C (mg l⁻¹)		21000	CA3 CA = Medical and toxicological databases and information systems e.g. TOXNET (click here ) 3 = Unverified data of known source	High
Solubility - In organic solvents at 20 °C (mg l⁻¹)		70000	CA3 CA = Medical and toxicological databases and information systems e.g. TOXNET (click here ) 3 = Unverified data of known source Amyl acetate	-
		330000	CA3 CA = Medical and toxicological databases and information systems e.g. TOXNET (click here ) 3 = Unverified data of known source Acetone	-
		190000	CA3 CA = Medical and toxicological databases and information systems e.g. TOXNET (click here ) 3 = Unverified data of known source Cyclohexanone	-
Melting point (°C)		120	Q3 Q = Miscellaneous internet resources 3 = Unverified data of known source	-
Boiling point (°C)		492	V3 V = ChemID online databases / IPCS INCHEM (ChemID; IPCS INCHEM ) 3 = Unverified data of known source	-
Degradation point (°C)		-	-	-
Flashpoint (°C)		251	V3 V = ChemID online databases / IPCS INCHEM (ChemID; IPCS INCHEM ) 3 = Unverified data of known source	-
Octanol-water partition coefficient at pH 7, 20 °C	P	3.55 X 1000	Calculated	-
	Log P	0.55	R3 R = Peer reviewed scientific publications 3 = Unverified data of known source	Low
Bulk density (g ml⁻¹)		-	-	-
Dissociation constant pKa) at 25 °C		-	-	-
		-
Vapour pressure at 20 °C (mPa)		-	-	-
Henry's law constant at 25 °C (Pa m³ mol⁻¹)		-	-	-
Maximum UV-vis absorption L mol⁻¹ cm⁻¹		-	-	-
Surface tension (mN m⁻¹)		-	-	-

Degradation

Property		Value	Source; quality score; and other information	Interpretation
General biodegradability		-
Soil degradation (days) (aerobic)	DT₅₀ (typical)	-	-	-
	DT₅₀ (lab at 20 °C)	-	-	-
	DT₅₀ (field)	-	-	-
	DT₉₀ (lab at 20 °C)	-	-	-
	DT₉₀ (field)	-	-	-
	DT₅₀ modelling endpoint	-	-	-
	Note	-
Dissipation rate RL₅₀ on plant matrix	Value	-	-	-
	Note	-
Dissipation rate RL₅₀ on and in plant matrix	Value	1.1	R3 R = Peer reviewed scientific publications 3 = Unverified data of known source	-
	Note	Cherry fruits, n=1
Aqueous photolysis DT₅₀ (days) at pH 7	Value	-	-	-
	Note	-
Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7	Value	-	-	-
	Note	-
Water-sediment DT₅₀ (days)		-	-	-
Water phase only DT₅₀ (days)		-	-	-

Soil adsorption and mobility

Property		Value	Source; quality score; and other information	Interpretation
Linear	Kd	-	CA2 CA = Medical and toxicological databases and information systems e.g. TOXNET (click here ) 2 = Unverified data of unknown source	Mobile
	Koc	47
	Notes and range	Estimated
Freundlich	Kf	-	-	-
	Kfoc	-
	1/n	-
	Notes and range	-
pH sensitivity		-

Fate indices

Property		Value	Source; quality score; and other information	Interpretation
GUS leaching potential index		-	-	-
SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate	Value	Cannot be calculated	-	-
	Note	-
Potential for particle bound transport index		-	-	-
Potential for loss via drain flow		-	-	-

ECOTOXICOLOGY

Property		Value	Source; quality score; and other information	Interpretation
Bio-concentration factor	BCF (l kg⁻¹)	Low risk	Q3 Q = Miscellaneous internet resources 3 = Unverified data of known source Based on LogP < 3	Low risk
	CT₅₀ (days)	-		-
Mammals - Acute oral LD₅₀ (mg kg⁻¹)		-	-	-
Mammals - Short term dietary NOEL	(mg kg⁻¹)	-	-	-
	(ppm diet)	-		-
Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)		-	-	-
Birds - Acute LD₅₀ (mg kg⁻¹)		82.5	CA3 CA = Medical and toxicological databases and information systems e.g. TOXNET (click here ) 3 = Unverified data of known source Anas platyrhynchos	High
Birds - Short term dietary (LC₅₀/LD₅₀)		-	-	-
Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)		-	-	-
Fish - Acute 96 hour LC₅₀ (mg l⁻¹)		-	-	-
Fish - Chronic 21 day NOEC (mg l⁻¹)		-	-	-
Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)		-	-	-
Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)		-	-	-
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)		-	-	-
Non-target plants		-	-	-
		-	-	-
Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)		-	-	-
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)	-	-	-
	Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)	-	-	-
	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)		-	-	-
Earthworms - Chronic NOEC, reproduction (mg kg⁻¹)		-	-	-
Other soil macro-organisms	Acute LC₅₀ (mg kg⁻¹)	-	-	-
	Chronic NOEC (mg kg⁻¹)	-	-	-
Other arthropod (1)	LR₅₀ g ha⁻¹	-	-	-
	% Effect	-	-	-
Other arthropod (2)	LR₅₀ g ha⁻¹	-	-	-
	% Effect	-	-	-
Soil micro-organisms		-	-	-
Mesocosm study data	NOEAEC mg l⁻¹	-	-	-
	NOEAEC mg l⁻¹	-	-	-

HUMAN HEALTH AND PROTECTION

General

Property		Value	Source; quality score; and other information	Interpretation
Threshold of Toxicological Concern (Cramer Class)		High (class III)	-	-
Mammals - Acute oral LD₅₀ (mg kg⁻¹)		-	-	-
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)		-	-	-
Mammals - Inhalation LC₅₀ (mg l⁻¹)		-	-	-
Other Mammal toxicity endpoints		-	-	-
ADI - Acceptable Daily Intake (mg kg⁻¹ bw day⁻¹)		-	-	-
ARfD - Acute Reference Dose (mg kg⁻¹ bw day⁻¹)		-	-	-
AAOEL - Acute Acceptable Operator Exposure Level (mg kg⁻¹ bw day⁻¹)		-	-	-
AOEL - Acceptable Operator Exposure Level - Systemic (mg kg⁻¹ bw day⁻¹)		-	-	-
Dermal penetration studies (%)		-	-	-
Dangerous Substances Directive 76/464		-	-	-
Exposure Routes	Public	-
	Occupational	-
European MRLs		EU MRL pesticide database
Drinking Water Standards		-	-	-
Drinking Water MAC (μg l⁻¹)		-	-	-

Health issues

Specific human health issues		Carcinogen Genotoxic Endocrine disruptor ?Possibly, status not identified A0 A = Chromosome aberration (EFSA database) 0 = No data ; B0 B = DNA damage/repair (EFSA database) 0 = No data ; C0 C = Gene mutation (EFSA database) 0 = No data ; D0 D = Genome mutation (EFSA database) 0 = No data ; E0 E = Unspecified genotoxicity type (miscellaneous data source) 0 = No data No data found Reproduction / development effects Acetyl cholinesterase inhibitor Neurotoxicant ✓Yes, known to cause a problem No data found No data found Respiratory tract irritant Skin irritant Skin sensitiser No data found ✓Yes, known to cause a problem No data found Eye irritant Phototoxicant   ✓Yes, known to cause a problem No data found
General human health issues		Highly toxic Bone marrow toxicant

Handling issues

Property	Value and interpretation
General	Avoid generation of dust Gives off irritating or toxic fumes in a fire
CLP classification 2013	-
EC Risk Classification	T = Toxic: R26, R27, R28
EC Safety Classification	S45, S53, S61
WHO Classification	O (Obsolete substance)
UN Number	2588 (solid); 2902 (liquid)
Waste disposal & packaging	-

TRANSLATIONS

Language	Name
English	cycloheximide
French	-
German	-
Danish	-
Italian	-
Spanish	-
Greek	-
Polish	-
Swedish	-
Hungarian	-
Dutch	-

---

Record last updated:	05/01/2021
Contact:	aeru@herts.ac.uk
Please cite as:	Lewis, K.A., Tzilivakis, J., Warner, D. and Green, A. (2016) An international database for pesticide risk assessments and management. Human and Ecological Risk Assessment: An International Journal, 22(4), 1050-1064. DOI: 10.1080/10807039.2015.1133242