1,4-naphthoquinone

Endpoint summary

Description of key information

An acute oral toxicity study is available for the substance which indicates that the substance is toxic to rats via the oral route. An acute study conducted via the inhalation route is also available indicating the the substance is toxic to rats via this route. However, the experimental data and test report is not available and accordingly this is only used in the consideration of Classification and Labelling.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Deviations:

no

Principles of method if other than guideline:

Although conducted before the OECD Guideline 401 came into effect, the procedures used on this study were comparable in terms of species used, number of animals, dose selection and observations made.

GLP compliance:

not specified

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Shizuoka Laboratory Animal Agriculture Co-operative association.
- Females (if applicable) nulliparous and non-pregnant: Yes
- Age at study initiation: Around 9 weeks
- Weight at study initiation: Males (260 to 300 g) and females (170 to 205 g).
- Fasting period before study: Witheld overnight prior to dosing
- Housing: No details
- Diet (e.g. ad libitum): Pelleted diet provided freely
- Water (e.g. ad libitum): tap water provided freely
- Acclimation period: At least one week

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23 to 25°C
- Humidity (%): 50 to 60%
- Air changes (per hr): Not detailed
- Photoperiod (hrs dark / hrs light): Not detailed

Route of administration:

oral: gavage

Vehicle:

other: 0.5% (w/v) gum tragacanth water solution

Details on oral exposure:

VEHICLE
- Concentration in vehicle: Varies depending on dosage
- Amount of vehicle (if gavage): 5 mL/kg

Doses:

130, 169 and 220 mg/kg

No. of animals per sex per dose:

5 males and 5 females per sex per group

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Bodweight was measured on the day of exposure and Days 7 and 14.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, and gross necropsy.

Statistics:

LD50 calculated using Litchfield-Wilcoxon analysis

Sex:

male/female

Dose descriptor:

LD50

Effect level:

124 mg/kg bw

Based on:

test mat.

Mortality:

100% of animals that received 220 mg/kg were found dead by 1 day after dosing.
90% of animals that received 169 mg/kg were found dead by 1 day after dosing.
60% of animals that received 130 mg/kg were found dead by 1 day after dosing.

Clinical signs:

other: Staggered gait was observed 5 minutes after treatment with lethargy and lack of spontaneous movement observed by 10 minutes in all dose groups. These findings were observed until 1 hour after treatment. Around half of the animals that received 169 or 220

Gross pathology:

Congestion and erosion was observed at the fundus of the stomach in animals which died shortly after treatment.Oedema was observed in animals which died up to 4 hours after treatment. Thickening and hardening of the cardia of the stomach was noted in all surviving animals on Day 14. In addition adhesion of the cardia of the stomach, liver and spleen was noted in one animal in each group receiving 130 or 169 mg/kg.

Interpretation of results:

Category 3 based on GHS criteria

Conclusions:

A reliable near guideline study is available which provides a LD50 value of 124 mg/kg bw after a single dose of the substance. The test substance was considered to be highly stimulative to the stomach and induced acute gastritis which was regarded as the cause of death alongside CNS depression. Some evidence of recovery was noted in animals that survived until the end of the observation period.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

124 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

The substance has been tested for acute toxicity in a study equivalent to the OECD 401 guideline. This provided an LD50 value of 124 mg/kg/day which indicates that classification as Acute Toxicity Category 3 (H301) is appropriate for this substance when considering the CLP regulation (1272/2008, as amended).

Data is available on the acute inhalation toxicity of the substance providing a 4 hour LC50 value of 0.046 mg/L indicating Classification as Acute Toxicity Category 1 (H330). However, access to the source data is not available and accordingly this data is not considered sufficiently reliable or required for REACH purposes owing to the corrosive nature of the test substance.

When considering specific target organ toxicity - single exposure (STOT SE 1 & 2) classification, the effects observed in the relevant acute oral toxicity study were considered a result of the corrosive nature of the substance (inducing acute gastritis). As the substance is already classified for skin/eye corrosive effects and acute oral toxicity for the same effect, this classification is not deemed appropriate. The test substance also induced > 50% mortality in all concentrations tested in the acute oral toxicity study, whereas STOT SE is only considered relevant when toxicity to specific organs are noted in the absence of mortality.