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Endrin
Last updated: 21/05/2022
(Also known as: nendrin; OMS 197; aldrin epoxide; Experimental Insecticide 269)

SUMMARY
Endrin is an obsolete, multi-use organochlorine insecticide. It has a low aqueous solubility and is non-volatile. Based on its chemical properties it is not expected to leach to groundwater. Endrin tends to be persistent in soil systems. It is highly toxic to mammals and is a neurotoxin. It is also highly toxic to birds, honeybees and most aquatic organisms but slightly less so to earthworms.
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
High alert:
Birds acute ecotoxicity: High; Fish acute ecotoxicity: High; Fish chronic ecotoxicity: High; Daphnia acute ecotoxicity: High; Bees acute contact ecotoxicity: High
Human health
High alert:
Mammals acute toxicity: High; Endocrine distrupter; Neurotoxicant
GENERAL INFORMATION
Description
A multi-use but now obsolete pesticide used to control insects, rodents, and birds.
Example pests controlled
Aphids; Lygus bugs; Grasshoppers; Small mammals including mice, voles
Example applications
Field crops; Cotton; Grains; Rice; Sugarcane
Efficacy & activity
-
Availability status
Considered obsolete but may be available in some countries; Banned in many countries
Introduction & key dates
1950s
UK regulatory status
UK COPR regulatory status
Not approved
Date COPR inclusion expires
Expired
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
-
Date EC 1107/2009 inclusion expires
Expired
EU Candidate for substitution (CfS)
-
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
                 
Additional information
Also used in
-
Chemical structure
Isomerism
Isomeric
Chemical formula
C₁₂H₈Cl₆O
Canonical SMILES
C1C2C3C(C1C4C2O4)C5(C(=C(C3(C5(Cl)Cl)Cl)Cl)Cl)Cl
Isomeric SMILES
C1[C@@H]2[C@@H]3[C@H]([C@H]1[C@H]4[C@@H]2O4)[C@@]5(C(=C([C@]3(C5(Cl)Cl)Cl)Cl)Cl)Cl
International Chemical Identifier key (InChIKey)
DFBKLUNHFCTMDC-GKRDHZSOSA-N
International Chemical Identifier (InChI)
InChI=1S/C12H8Cl6O/c13-8-9(14)11(16)5-3-1-2(6-7(3)19-6)4(5)10(8,15)12(11,17)18/h2-7H,1H2/t2-,3-,4?,5?,6?,7?,10-,11-/m0/s1
2D structure diagram/image available?
Yes
Cambridge Crystallographic Data Centre diagrams
Common Name Relationship Link
endrin Unstated isomer
General status
Pesticide type
Insecticide, Avicide, Rodenticide
Substance groups
Organochloride insecticide; Cyclodiene insecticide
Minimum active substance purity
-
Known relevant impurities
-
Substance origin
Synthetic
Mode of action
Broad-spectrum, with contact and stomach action. Is a chloride channel-blocking agent.
CAS RN
72-20-8
EC number
200-775-7
CIPAC number
28
US EPA chemical code
041601
PubChem CID
12358480
Molecular mass
380.91
PIN (Preferred Identification Name)
(1aR,2R,2aR,3R,6S,6aS,7S,7aS)-3,4,5,6,9,9-hexachloro-1a,2,2a,3,6,6a,7,7a-octahydro-2,7:3,6-dimethanonaphth[2,3-b]oxirene
IUPAC name
1,2,3,4,10,10-hexachloro-6,7-epoxy-1,4,4a,5,6,7,8,8a-octahydro-exo-1,4-exo-5,8-dimethanonaphthalene
CAS name
(1aR,2R,2aR,3R,6S,6aS,7S,7aS)-rel-3,4,5,6,9,9-hexachloro-1a,2,2a,3,6,6a,7,7a-octahydro-2,7:3,6-dimethanonaphth(2,3-b)oxirene
Other status information
WFD priority substance; POP - regulated by Stockholm Convention; LRTAP Annex I; PAN Dirty Dozen; OSPAR soc; Severe Marine Pollutant; Subject to the provisions of the UK Poisons Act 1972
Relevant Environmental Water Quality Standards
EU Directive 2008/105/EC EQS for the sum of all cyclodiene pesticides in: inland surface waters: 0.01 µg l⁻¹; Other surface waters; 0.005 µg l⁻¹ as annual average
Herbicide Resistance Classification (HRAC)
Not applicable
Herbicide Resistance Classification (WSSA)
Not applicable
Insecticide Resistance Classification (IRAC)
2A
Fungicide Resistance Classification (FRAC)
Not applicable
Examples of recorded resistance
Many recorded cases, Aphis gossypii, Culex pipiens pipiens, Empoasca biguttula, Leptocorisa oratorius, Spodoptera littoralis, many others
Physical state
White crystals
Formulations
Property
Value
Example manufacturers & suppliers of products using this active now or historically
  • Shell Chemical Company
  • Velsicol
Example products using this active
  • Endrex
  • Mendrin
  • Nendrin
  • Hexadrin
Formulation and application details
Available in a variety of formulations including wettable powders and emulsifiable concentrates
ENVIRONMENTAL FATE
Property
Value
Source; quality score; and other information
Interpretation
Solubility - In water at 20 °C (mg l⁻¹)
0.24
H4 H = The US ARS pesticide properties database (click here )
4 = Verified data
Low
Solubility - In organic solvents at 20 °C (mg l⁻¹)
- - -
Melting point (°C)
200
V3 V = ChemID online databases / IPCS INCHEM (ChemID; IPCS INCHEM )
3 = Unverified data of known source
-
Boiling point (°C)
- - -
Degradation point (°C)
- - -
Flashpoint (°C)
- - -
Octanol-water partition coefficient at pH 7, 20 °C
P
1.58 X 1003 Calculated -
Log P
3.2
H4 H = The US ARS pesticide properties database (click here )
4 = Verified data
High
Fat solubility of residues
Solubility
Soluble
A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
5 = Verified data used for regulatory purposes
-
Data type
Observed in metabolism and farm animal feeding studies
A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
5 = Verified data used for regulatory purposes
-
Density (g ml⁻¹)
1.84
Q2 Q = Miscellaneous internet resources
2 = Unverified data of unknown source
-
Dissociation constant pKa) at 25 °C
- - -
-
Vapour pressure at 20 °C (mPa)
2.0 X 10-07
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
Low volatility
Henry's law constant at 25 °C (Pa m³ mol⁻¹)
1.48 X 10-01
H4 H = The US ARS pesticide properties database (click here )
4 = Verified data
Moderately volatile
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)
4300
M4 M = GLEAMS Model database (Groundwater Loading Effects of Agricultural Management Systems) (click here )
4 = Verified data
Very persistent
DT₅₀ (lab at 20 °C)
- - -
DT₅₀ (field)
- - -
DT₉₀ (lab at 20 °C)
- - -
DT₉₀ (field)
- - -
DT₅₀ modelling endpoint
- - -
Note
Other sources: DT₅₀ up to 12 years (R3); FAO state DT₅₀ 4-14 days
Dissipation rate RL₅₀ on plant matrix
Value
3.3
R3 R = Peer reviewed scientific publications
3 = Unverified data of known source
-
Note
Birdsfoot trefoil leaves, n=1
Dissipation rate RL₅₀ on and in plant matrix
Value
4.0
R4 R = Peer reviewed scientific publications
4 = Verified data
-
Note
Published literature RL₅₀ range 1.0-7.0 days, 2 field crops, various matrices, n=2
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
-
H3 H = The US ARS pesticide properties database (click here )
3 = Unverified data of known source
Non-mobile
Koc
10000
Notes and range
Other sources: 31623 mL g⁻¹ (R3)
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
0.00 Calculated Low leachability
SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate
Value
5.35 X 10-03 Calculated -
Note
Estimated concentrations of chemicals with Koc values greater than 9995 ml g⁻¹ are beyond the scope of the regression data used in SCI-GROW development. If there are concerns for such chemicals, a higher tier groundwater exposure assessment should be considered, regardless of the concentration returned by SCI-GROW
Potential for particle bound transport index
High Calculated -
Potential for loss via drain flow
Non-mobile Calculated -
Bio-concentration factor
BCF (l kg⁻¹)
3970
R3 R = Peer reviewed scientific publications
3 = Unverified data of known source
Whole body (Literature values log BCF range 2.2-3.4 (
R3 R = Peer reviewed scientific publications
3 = Unverified data of known source
))
Threshold for concern
CT₅₀ (days)
Not available -
Other known metabolites
Metabolite name and reference
Aliases
Formation medium / Rate
Estimated maximum occurrence fraction
Metabolising enzymes
endrin aldehyde
Note: Persistent
- Soil - -
ECOTOXICOLOGY
Terrestrial ecotoxicology
Property
Value
Source; quality score; and other information
Interpretation
Mammals - Acute oral LD₅₀ (mg kg⁻¹)
> 7.5
R3 R = Peer reviewed scientific publications
3 = Unverified data of known source
Rat
High
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)
5.6
R3 R = Peer reviewed scientific publications
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)
- - -
Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹)
> 66
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
Lumbricus terrestris
Moderate
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)
> 0.46
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
High
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)
0.00073
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
Oncorhynchus mykiss
High
Fish - Chronic 21 day NOEC (mg l⁻¹)
0.00012
P3 P = Other governments and regulators
3 = Unverified data of known source
Cyprinodon variegatus
High
Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)
0.0042
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
Daphnia magna
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)
4.22
R3 R = Peer reviewed scientific publications
3 = Unverified data of known source
Cironomus dilutus as 10d LC₅₀
Moderate
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)
> 7.5
R3 R = Peer reviewed scientific publications
3 = Unverified data of known source
Rat
High
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)
5.0
R3 R = Peer reviewed scientific publications
3 = Unverified data of known source
Rat
-
Mammals - Inhalation LC₅₀ (mg l⁻¹)
- - -
Other Mammal toxicity endpoints
- - -
ADI - Acceptable Daily Intake (mg kg⁻¹ bw day⁻¹)
0.0002
A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
5 = Verified data used for regulatory purposes
-
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; List II - -
Exposure Routes
Public
-
Occupational
-
MRLs
European
EU MRL pesticide database 
Great Britain
GB MRL Register 
Notes
-
Drinking Water Standards
Non-statutory WHO drinking water guideline 0.0006 mg l⁻¹
B5 B = UK CRD and ACP evaluation documents / and other Defra (UK) documents (click here )
5 = Verified data used for regulatory purposes
UK EA QS database 2018
-
Drinking Water MAC (μg l⁻¹)
- - -
Mammalian dose elimination route and rate
- - -
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
Yes, known to cause a problem
Reproduction / development effects Acetyl cholinesterase inhibitor Neurotoxicant
?Possibly, status not identified
XNo, known not to cause a problem
Yes, known to cause a problem
Respiratory tract irritant Skin irritant Skin sensitiser
XNo, known not to cause a problem
XNo, known not to cause a problem
No data found
Eye irritant Phototoxicant  
XNo, known not to cause a problem
No data found  
General human health issues
Highly toxic
Endocrine issues - Competitive binding to androgen receptors
Handling issues
Property
Value and interpretation
General
No information available
CLP classification 2013
Health: H300, H311
Environment: H400, H410
WHO Classification
O (Obsolete substance)
UN Number
2761
Waste disposal & packaging
-
TRANSLATIONS
Language
Name
English
endrin
French
endrine
German
Endrin
Danish
endrin
Italian
endrin
Spanish
endrin
Greek
endrin
Polish
endryna
Swedish
-
Hungarian
-
Dutch
endrine

Record last updated: 21/05/2022
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