Alpha-hexachlorocyclohexane (Ref: ENT 9232)

Alpha-hexachlorocyclohexane (Ref: ENT 9232)	Last updated: 12/10/2023
(Also known as: alpha-HCH; alpha-benzenehexachloride; alpha-BHC; alpha-lindane)

SUMMARY

Alpha-hexachlorocyclohexane is an insecticide that is not generally approved for use in the developed world. It is moderately toxic to mammals and is likely to be carcinogenic. Alpha-hexachlorocyclohexane has a low aqueous solubility and is highly volatile. It is moderately persistent is soil and slightly mobile. It is moderately toxic to birds and aquatic organisms.

Data alerts

The following alerts are based on the data in the tables below. An absence of an alert does not imply the substance has no implications for human health, biodiversity or the environment but just that we do not have the data to form a judgement.

Environmental fate	Ecotoxicity	Human health
Environmental fate High alert: Potential for particle bound transport: High Warning: Significant data are missing	Ecotoxicity Moderate alert: Fish acute ecotoxicity: Moderate; Daphnia acute ecotoxicity: Moderate; Daphnia chronic ecotoxicity: Moderate Warning: Significant data are missing	Human health Moderate alert: Mammals acute toxicity: Moderate; Possible Carcinogen; Neurotoxicant

GENERAL INFORMATION

Description

Historically an insecticide and a component of the mixed isomer product but now only produced as a byproduct of lindane production. It is also a lindane impurity that has some insecticidal properties

Example pests controlled

Soil-dwelling and plant eating insects

Example applications

Fruit and vegetable crops; Forestry; Public health applications

Efficacy & activity

Availability status

Introduction & key dates

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

Yes

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

Approved for use (✓) under EC 1107/2009 by Mutual Recognition of Authorisation and/or national regulations in the following EEA countries

ISIceland	NONorway

Additional information

Also used in

Chemical structure

Isomerism

There are nine stereoisomers of HCH (eight diastereomers, one of which has two enantiomers).

Chemical formula

C₆H₆Cl₆

Canonical SMILES

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

JLYXXMFPNIAWKQ-LKPKBOIGSA-N

International Chemical Identifier (InChI)

InChI=1S/C6H6Cl6/c7-1-2(8)4(10)6(12)5(11)3(1)9/h1-6H/t1-,2-,3-,4-,5+,6+/m0/s1

2D structure diagram/image available?

Yes

General status

Pesticide type

Insecticide, Other substance

Other constituent type

Impurity

Substance groups

Organochloride insecticide

Minimum active substance purity

Known relevant impurities

Substance origin

Synthetic

Mode of action

Not applicable

CAS RN

319-84-6

EC number

206-270-8

CIPAC number

None allocated

US EPA chemical code

PubChem CID

727

CLP index number

No data found

Molecular mass

290.83

PIN (Preferred Identification Name)

IUPAC name

CAS name

α-hexachlorocyclohexane

Other status information

POP; Water pollutant; Marine pollutant; PAN Bad Actor Chemical; Chemical subject to PIC regulations; Possible groundwater pollutant

Relevant Environmental Water Quality Standards

Herbicide Resistance Class (HRAC MoA class)

Not applicable

Herbicide Resistance Class (WSSA MoA class)

Not applicable

Insecticide Resistance Class (IRAC MoA class)

Fungicide Resistance Class (FRAC MOA class)

Not applicable

Examples of recorded resistance

Physical state

White to beige coloured crystalline powder

Related substances & organisms

lindane

Formulations

Property

Value

Example manufacturers & suppliers of products using this active now or historically

Example products using this active

Formulation and application details

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

Solubility - In water at 20 °C (mg l⁻¹)

2.0

Low

Solubility - In organic solvents at 20 °C (mg l⁻¹)

18000

Ether

Melting point (°C)

159

Boiling point (°C)

288

Degradation point (°C)

Flashpoint (°C)

Octanol-water partition coefficient at pH 7, 20 °C

6.61 X 10⁰³

Calculated

Log P

3.82

High

Fat solubility of residues

Solubility

Likely to be soluble

Data type

Based on chemical group

Density (g ml⁻¹)

1.87

Dissociation constant pKa) at 25 °C

Vapour pressure at 20 °C (mPa)

5.99

Moderately volatile

Henry's law constant at 25 °C (Pa m³ mol⁻¹)

Maximum UV-vis absorption L mol⁻¹ cm⁻¹

No absorption > 290nm

Surface tension (mN m⁻¹)

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

175

Persistent

DT₅₀ (lab at 20 °C)

DT₅₀ (field)

DT₉₀ (lab at 20 °C)

DT₉₀ (field)

DT₅₀ modelling endpoint

Note

DT₅₀ sandy loam 55 days in subtropical conditions (R2), temperate climate data suggests 150-200 days (R3)

Dissipation rate RL₅₀ on plant matrix

Value

Note

Dissipation rate RL₅₀ on and in plant matrix

Value

Note

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Note

Not thought to be a major degradation route

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

K_d

Slightly mobile

K_oc

1888

Notes and range

Literature gives K_oc range 1780-1995 mL g⁻¹

Freundlich

K_f

K_foc

¹/_n

Notes and range

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

1.62

Calculated

Low leachability

SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate

Value

4.93 X 10^-02

Calculated

Note

Potential for particle bound transport index

High

Calculated

Potential for loss via drain flow

Slightly mobile

Calculated

Bio-concentration factor

BCF (l kg⁻¹)

CT₅₀ (days)

Known soil metabolites

Metabolite

Major/Minor fraction

$Click here for further information on Major/Minor fraction$

Estimated maximum occurrence fraction

Notes

pentachlorocyclohexane

tetrachlorobenzene

trichlorobenzene

dichlorobenzene

Known groundwater metabolites

None

Other known metabolites

None

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

177

Rat

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 bee species (1)

Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)

Mode of exposure

Other bee species (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)

> 0.820

Danio rerio

Moderate

Fish - Chronic 21 day NOEC (mg l⁻¹)

Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)

0.370

Daphnia magna

Moderate

Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)

0.1

Daphnia magna 25 day EC₅₀

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)

Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)

> 10

Chlorella pyrenoidosa

Low

Algae - Chronic 96 hour NOEC, growth (mg l⁻¹)

Mesocosm study data

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)

177

Rat

Moderate

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

List I

Exposure Routes

Public

May be absorbed through the skin

Occupational

May be absorbed through the skin

MRLs

European

EU MRL pesticide database

Great Britain

GB MRL Register

Notes

Drinking Water Standards

Drinking Water MAC (μg l⁻¹)

Mammalian dose elimination route and rate

Health issues

Specific human health issues

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

Reproduction / development effects

Acetyl cholinesterase inhibitor

Neurotoxicant

Respiratory tract irritant

Skin irritant

Skin sensitiser

No data found

Eye irritant

Phototoxicant

No data found

General human health issues

Exposure may cause dyspnoea, anorexia, tremors, convulsions and cramps
Liver, kidney and heart toxicant
Induces a carcinogenic response in rodents via aberrant cell proliferation; CLP data - suspected carcinogen; US NTP - suspected carcinogen; OSHA - anticipated human carcinogen

Handling issues

Property

Value and interpretation

General

Flammable
IMDG Transport Hazard Class 6.1

CLP classification 2013

Health: H301, H312, H351
Environment: H400, H410

WHO Classification

Not listed (Not listed)

UN Number

UN2811

Waste disposal & packaging

Packaging Group III (minor danger)

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

alpha-hexachlorocyclohexane

French

German

alpha-Hexachlorocyclohexan

Danish

Italian

Spanish

Greek

Polish

Swedish

Hungarian

Dutch

Norwegian

Record last updated:	12/10/2023
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