Chlorhexidine	Last updated: 08/04/2021
(Also known as: chlorohexidine)

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GENERAL INFORMATION

Description	Used mainly as a used topical disinfectant cleanser for skin wounds and as an antibactericide for ear and gum infections killing both gram-positive and gram-negative microbes.
Availability status	-
Introduction & key dates	1953, UK
Examples of species treated	Cattle, Cats, Dogs

Chemical structure

Isomerism	Isomeric
Chemical formula	C₂₂H₃₀Cl₂N₁₀
Canonical SMILES	C1=CC(=CC=C1NC(=NC(=NCCCCCCN=C(N)N=C(N)NC2=CC=C(C=C2)Cl)N)N)Cl
Isomeric SMILES	C1=CC(=CC=C1N/C(=N/C(=NCCCCCCN=C(/N=C(/NC2=CC=C(C=C2)Cl)\N)N)N)/N)Cl
International Chemical Identifier key (InChIKey)	GHXZTYHSJHQHIJ-UHFFFAOYSA-N
International Chemical Identifier (InChI)	InChI=1S/C22H30Cl2N10/c23-15-5-9-17(10-6-15)31-21(27)33-19(25)29-13-3-1-2-4-14-30-20(26)34-22(28)32-18-11-7-16(24)8-12-18/h5-12H,1-4,13-14H2,(H5,25,27,29,31,33)(H5,26,28,30,32,34)
2D structure diagram/image available?	Yes

General status

Veterinary substance type	Antiseptic, Bactericide, Antimicrobial
Substance groups	Unclassified
Minimum active substance purity	-
Known relevant impurities	-
Substance origin	Synthetic
Mode of action	Disrupts the integrity of the cell membrane and causes the leakage of intracellular components of the organisms.
Molecular targets	[Bacterial cell wall]
CAS RN	55-56-1
EC number	200-238-7
CIPAC number	-
US EPA chemical code	-
PubChem CID	-
ATCvet Code	QD08AC52
Therapeutic Class	Dermatogiocals: Antiseptics and disinfectants
Controlled Drug?	No
Regulation 37/2010 MRL Classification	Allowable substance (Table 1: All food producing species)
Molecular mass	505.45
PIN (Preferred Identification Name)	-
IUPAC name	N',N'''''-hexane-1,6-diylbis(N-(4-chlorophenyl)(imidodicarbonimidic diamide))
CAS name	1,6-bis(5-(p-chlorophenyl)biguanidino)hexane
Other status information	-
Relevant Environmental Water Quality Standards	-
Physical state	Colourless to pale yellow crystalline solid

Formulations

Property	Product	Manufacturer	Authorisation Route	UK Legal Class
Example products using this active	Action Actodine	Kilco Chemicals Ltd	UK National authorisation (IC)	Authorised veterinary medicine for general sale (AVM - GSL)
	Deosan SummerTeatcare Plus ( 0.425%w/w ) Teat dip and Teat Spray Emulsion	JohnsonDiversey Ltd	UK National authorisation	Authorised veterinary medicine for general sale (AVM - GSL)
	Propisderm 0.5 % w/w Teat dip solution	Hypred S.A.	UK National authorisation	Authorised veterinary medicine for general sale (AVM - GSL)
	Sebolyse shampoo for dogs and cats	Dechra Veterinary Products A/S	UK National authorisation	Prescription only medicine to be authorised by a veterinarian (POM-V)
Formulation and application details	Available as solutions for topical application

ENVIRONMENTAL FATE

Property		Value	Source; quality score; and other information	Interpretation
Solubility - In water at 20 °C (mg l⁻¹)		800	R3 R = Peer reviewed scientific publications 3 = Unverified data of known source	High
Solubility - In organic solvents at 20 °C (mg l⁻¹)		-	-	-
Melting point (°C)		134	F4 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents (US EPA Databases Related to Pesticide Risk Assessment ) 4 = Verified data	-
Boiling point (°C)		-	-	-
Degradation point (°C)		-	-	-
Flashpoint (°C)		-	-	-
Octanol-water partition coefficient at pH 7, 20 °C	P	1.20 X 1000	Calculated	-
	Log P	0.08	V3 V = ChemID online databases / IPCS INCHEM (ChemID; IPCS INCHEM ) 3 = Unverified data of known source	Low
Fat solubility of residues	Solubility	-	-	-
	Data type	-	-	-
Density (g ml⁻¹)		1.07	Q3 Q = Miscellaneous internet resources 3 = Unverified data of known source	-
Dissociation constant pKa) at 25 °C		10.78	V3 V = ChemID online databases / IPCS INCHEM (ChemID; IPCS INCHEM ) 3 = Unverified data of known source at 25 °C	-
		-
Vapour pressure at 20 °C (mPa)		2.64 X 10-09	V3 V = ChemID online databases / IPCS INCHEM (ChemID; IPCS INCHEM ) 3 = Unverified data of known source as acetate	Low volatility
Henry's law constant at 25 °C (Pa m³ mol⁻¹)		1.25e-25	V3 V = ChemID online databases / IPCS INCHEM (ChemID; IPCS INCHEM ) 3 = Unverified data of known source as acetate	Non-volatile
Maximum UV-vis absorption L mol⁻¹ cm⁻¹		-	-	-
Surface tension (mN m⁻¹)		-	-	-
Refractive Index		-	-	-

Degradation

Property		Value	Source; quality score; and other information	Interpretation
Soil degradation (days) (aerobic)	DT₅₀ (typical)	-	-	-
	DT₅₀ (lab at 20 °C)	-	-	-
	DT₅₀ (field)	-	-	-
	DT₉₀ (lab at 20 °C)	-	-	-
	DT₉₀ (field)	-	-	-
	Note	-
Manure DT₅₀ (days)		-	-	-
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	-	V3 V = ChemID online databases / IPCS INCHEM (ChemID; IPCS INCHEM ) 3 = Unverified data of known source	Non-mobile
	Koc	31600
	Notes and range	Literature estimate
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		-	-	-
Bio-concentration factor	BCF (l kg⁻¹)	-	-	-
	CT₅₀ (days)	-		-

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property		Value	Source; quality score; and other information	Interpretation
Mammals - Acute oral LD₅₀ (mg kg⁻¹)		> 1800	R3 R = Peer reviewed scientific publications 3 = Unverified data of known source Mouse as the digluconate	Moderate
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)		-	-	-
Birds - Short term dietary (LC₅₀/LD₅₀)		-	-	-
Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)		-	-	-
Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹)		-	-	-
Earthworms - Chronic NOEC, reproduction (mg kg⁻¹)		-	-	-
Soil micro-organisms		-	-	-
Collembola	Acute LC₅₀ (mg kg⁻¹)	-	-	-
	Chronic NOEC (mg kg⁻¹)	-	-	-
Non-target plants		-	-	-
		-	-	-
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)	-	-	-
	Chronic	-	-	-
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	-
Beneficial insects (Ladybirds)		-	-	-
Beneficial insects (Lacewings)		-	-	-
Beneficial insects (Parasitic wasps)		-	-	-
Beneficial insects (Predatory mites)		-	-	-
Beneficial insects (Ground beetles)		-	-	-

Aquatic ecotoxicology

Property		Value	Source; quality score; and other information	Interpretation
Fish - Acute 96 hour LC₅₀ (mg l⁻¹)		> 1.4	Q3 Q = Miscellaneous internet resources 3 = Unverified data of known source Danio rerio	Moderate
Fish - Chronic 21 day NOEC (mg l⁻¹)		-	-	-
Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)		> 0.06	Q3 Q = Miscellaneous internet resources 3 = Unverified data of known source Daphnia magna as acetate	High
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)		-	-	-
Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)		-	-	-
Algae - Chronic 96 hour NOEC, growth (mg l⁻¹)		-	-	-
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)		> 1800	R3 R = Peer reviewed scientific publications 3 = Unverified data of known source Mouse as the digluconate	Moderate
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)		500	Q3 Q = Miscellaneous internet resources 3 = Unverified data of known source Rat	-
Mammals - Inhalation LC₅₀ (mg l⁻¹)		> 2.03	Q3 Q = Miscellaneous internet resources 3 = Unverified data of known source Rat	-
Other Mammal toxicity endpoints		Subcutaneous LD₅₀ = 1000 mg kg⁻¹	V3 V = ChemID online databases / IPCS INCHEM (ChemID; IPCS INCHEM ) 3 = Unverified data of known source Rat	-
		Intraperitoneal LD₅₀ = 60 mg kg⁻¹	V3 V = ChemID online databases / IPCS INCHEM (ChemID; IPCS INCHEM ) 3 = Unverified data of known source Rat	-
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	-
Mammalian dose elimination route and rate		Excretion is primarily through the faeces (~ 90%). Also found in breast milk.	Q3 Q = Miscellaneous internet resources 3 = Unverified data of known source	-

Health issues

Specific human health issues		Carcinogen Genotoxic Endocrine disruptor No data found 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 ?Possibly, status not identified No data found No data found Respiratory tract irritant Skin irritant Skin sensitiser ✓Yes, known to cause a problem ✓Yes, known to cause a problem ✓Yes, known to cause a problem Eye irritant Phototoxicant   ✓Yes, known to cause a problem No data found
General human health issues		No further information available

Handling issues

Property	Value and interpretation
General	May decompose on heating emiting dangerous gaseous substances - halogenated compounds, oxides of nitrogen
CLP classification 2013	-
WHO Classification	NL (Not listed)
UN Number	3077
Waste disposal & packaging	Packaging Group III (minor danger)

TRANSLATIONS

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

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Record last updated:	08/04/2021
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