imidacloprid (ISO); 1-(6-chloropyridin-3-ylmethyl)-N-nitroimidazolidin-2-ylidenamine

Acute Toxicity: oral

Administrative data

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

10 Oct 1990 - 23 Jan 1991

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1991

Report date:

1991

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Version / remarks:

adopted 1987

Deviations:

no

GLP compliance:

yes

Test type:

standard acute method

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

428-040-8

EC Name:

-

Cas Number:

138261-41-3

Molecular formula:

C9H10ClN5O2

IUPAC Name:

2-chloro-5-{[2-(nitroimino)imidazolidin-1-yl]methyl}pyridine

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Laboratory animal breeder Winkelmann (Borchen, Germany)
- Females nulliparous and non-pregnant: Yes
- Age at study initiation: 7 - 8 weeks (males), 10 - 11 weeks (females)
- Weight at study initiation: 167 - 186 g (males), 170 - 183 g (females)
- Fasting period before study: 15 - 17 hours before administration
- Housing: in groups of 5 in Type III Makrolon cages equipped with type S 8/15 low-dust wood granules (Rettemaier & Söhne Füllstoff-Fabriken, Ellwangen-Holzmühle, Germany) as bedding material
- Diet: Altromin 1324 Diet for Rats and Mice (Altromin GmbH and Co KG, Lage, Germany), ad libitum
- Water: tap water, ad libitum
- Acclimation period: at least 5 days
- Method of randomisation in assigning animals to test and control groups: randomized lists generated by a computer program

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19.5 - 22.5
- Humidity (%): 40 - 70
- Air changes (per hr): at least 10
- Photoperiod (hrs dark / hrs light): 12 / 12

IN-LIFE DATES: From: 10 Oct 1990 To: 23 Jan 1991

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: 2 % v/v Cremophor EL in demineralized water

Details on oral exposure:

VEHICLE
- Amount of vehicle: 10 mL/kg bw

Doses:

50, 200, 300, 350, 400, 500, 600 mg/kg bw (males)
100, 200, 300, 350, 400, 500 mg/kg bw (females)

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: appearance and behavior were recorded several times in the day of administration, and at least once a day thereafter. Body weights were recorded before administration, on days 4 and 8 and then weekly.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight, gross pathological examination

Statistics:

Not reported.

Results and discussion

Effect levels

Effect levels 1

Key result

Sex:

male

Dose descriptor:

LD50

Effect level:

504 mg/kg bw

Based on:

test mat.

95% CL:

> 372 - < 684

Effect levels 2

Key result

Sex:

female

Dose descriptor:

LD50

Effect level:

379 mg/kg bw

Based on:

test mat.

95% CL:

> 324 - < 445

Mortality:

Mortalities occurred at doses from 300 mg/kg bw. The LD50 was determined to be 504 mg/kg bw for males and 379 mg/kg bw for females. For details on mortality please see attached tabular results.

Clinical signs:

other: A dose of 50 mg/kg bw (males) and 100 mg/kg bw (females) was tolerated without symptoms. At higher doses apathy, staggering and spastic gait, labored breathing, reduced motility, spasmodic state (periodic in some cases), periodic tremors, soft feces and

Gross pathology:

No test substance-related gross pathological changes were observed in the animals which were sacrificed at the conclusion of the post-treatment observation period. The following findings were determined in animals which died during the post-treatment observation period: lung distended, mottled, dark; liver dark, bladder distended with clear urine.

Applicant's summary and conclusion

Interpretation of results:

Category 4 based on GHS criteria

Conclusions:

The study was performed in accordance to OECD TG 401 under GLP conditions and is considered reliable. Under the conditions chosen, the acute oral LD50 was determined to be 504 mg/kg bw for male rats and 379 mg/kg bw for female rats. According to criteria of the CLP Regulation (EU) No. 1272/2008, classification of the test item for acute oral toxicity category 4 is needed.