Cesium tungsten oxide

Endpoint summary

Description of key information

LD50 > 2000 mg/kg bw, OECD 423, Poole 2005

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

Study period:

13 Apr-11 May 2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 423 (Acute Oral toxicity - Acute Toxic Class Method)

Version / remarks:

adopted 17 December 2001

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.1 tris (Acute Oral Toxicity - Acute Toxic Class Method)

Version / remarks:

Commision Directive 2004/73/EC

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

The Department of Health of the Government of the United Kingdom, London, England

Test type:

acute toxic class method

Limit test:

yes

Species:

rat

Strain:

Sprague-Dawley

Remarks:

CD (Crl: CD® (SD) IGS BR)

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River (UK) Ltd., Margate, Kent, UK
- Females nulliparous and non-pregnant: yes
- Age at study initiation: 8 to 12 weeks
- Weight at study initiation: 191 - 213 g (females)
- Fasting period before study: overnight
- Housing: rats were housed in groups of three in suspended solid-floor polypropylene cages furnished with woodflakes.
- Diet: Certified Rat and Mouse Diet (Code 5LF2), BCM IPS Limited, London, UK, ad libitum
- Water: mains drinking water, ad libitum
- Acclimation period: at least five days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3
- Humidity (%): 30 - 70
- Air changes (per hr): at least 15
- Photoperiod (hrs dark / hrs light): 12 hrs / 12 hrs

IN-LIFE DATES: From: 13 Apr 2005 To: 11 May 2005

Route of administration:

oral: gavage

Vehicle:

arachis oil

Details on oral exposure:

VEHICLE
- Concentration in vehicle: 30 mg/mL (starting) and 200 mg/mL (study)
- Justification for choice of vehicle: The test material did not dissolve/suspend in distilled water.
- Lot/batch no. (if required): batch number 050214

MAXIMUM DOSE VOLUME APPLIED: 10 mL/kg bw

DOSAGE PREPARATION: same as starting material, freshly prepared, as required

CLASS METHOD: Acute Toxic Class Method
- Rationale for the selection of the starting dose: Three fasted females were treated at a starting dose level of 300 mg/kg bw. Based on the results from this dose level further groups of fasted females were treated at a dose level of 2000 mg/kg bw.

Doses:

300, 2000 mg/kg bw

No. of animals per sex per dose:

3 females (starting)
6 females (study)

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: The animals were observed for deaths or overt signs of toxicity ½, 1, 2 and 4 hours after dosing and subsequently once daily for fourteen days. Individual bodyweights were recorded prior to dosing and seven and fourteen days after treatment.
- Necropsy of survivors performed: Yes
- Other examinations performed: No

Preliminary study:

300 mg/kg bw to three fasted female rats. No clinical signs of toxicity were noted up to the end of the 14-day observation period. No mortality occurred during the study period.

Key result

Sex:

female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Mortality:

No mortality occurred during the study period.

Clinical signs:

other: No clinical signs of systemic toxicity were observed up to the end of the 14-day observation period.

Gross pathology:

All animals were killed Day 14 and no abnormalities were detected at necropsy.

Interpretation of results:

other: CLP/EU GHS criteria are not met, no classification required according to Regulation (EC) No 1272/2008

Conclusions:

The acute oral LD50 of the test substance in female Sprague-Dawley CD rats was estimated according to this OECD 423 to be greater than 2000 mg/kg bw.

Executive summary:

This study was conducted to assess the acute toxicity of the test item, following a single oral administration to small groups of rats. The study design provides information for hazard assessment and classification and enables a chemical to be assigned to toxicity classes but severely restricts animal usage.

A group of three female fasted rats were given the test item as a single dose by oral gavage at 300 mg/kg bw. Based on the results from this dose level, a further dose level at 2000 mg/kg bw was performed using 6 rats. 


The test item was dispersed in arachis oil. All animals underwent a full necropsy. No clinical, gross pathological or body weight changes were seen in the test item dosed rats. 

There were no deaths at 2000 mg/kg bw, the LD50 is considered to be > 2000 mg/kg bw. 

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 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 adverse effect observed

Additional information

OECD 423 (2005) - This study was conducted to assess the acute toxicity of the undissolved test item, following a single oral administration to small groups of rats. The study design provides information for hazard assessment and classification and enables a chemical to be assigned to toxicity classes but severely restricts animal usage.

A group of three female fasted rats were given the test item as a single dose by oral gavage at 300 mg/kg bw. Based on the results from this dose level, a further dose level at 2000 mg/kg bw was performed using 6 rats. 


The test item was dispersed in arachis oil. All animals underwent a full necropsy. No clinical, gross pathological or body weight changes were seen in the test item dosed rats. 

There were no deaths at 2000 mg/kg bw, the LD50 is considered to be > 2000 mg/kg bw. 

The study was conducted on the particulate nanoform (i.e. not the dissolved form). Based on dissolution study results (Rosenfeldt, 2021, Section 4) this aligns with the draft ECHA guidance (Appendix R7-1 for nanoforms applicable to Chapter R7a and R7c Endpoint specific guidance, draft v3.0, 2021), whereby testing on the nanoform should be conducted if the nanoform is not highly soluble in water (>33,3 g/L) and/or does not have a half-life of water dissolution ≤ 10 min (Appendix R7-1 for nanoforms applicable to Chapter R7a and R7c Endpoint specific guidance, draft v3.0, 2021; Figure 1).  This is further supported by the lack of dissolution seen in any vehicle and at pH 4 (relevant gut pH) seen during the dissolution study (Section 4, Rosenfeldt, 2021). 

Justification for classification or non-classification

In accordance with the CLP regulation (Regulation (EC) No 1272/2008), no acute toxicity classification is required as the LD50 is > 2000 mg/kg bw.