1,4-Benzenediol, 2-(6-oxido-6H-dibenz[c,e][1,2]oxaphosphorin-6-yl)-

Endpoint summary

Description of key information

One Acute toxicity study is available, via the oral route.

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:

19 June 2019- 11 July 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Required by REACH

Qualifier:

according to guideline

Guideline:

OECD Guideline 420 (Acute Oral Toxicity - Fixed Dose Method)

Deviations:

yes

Remarks:

relative humidity in the animal room was between 38-83% instead of 45-65% and the temperature was between 20-26°C instead of 20-24°C for several hours due to insufficient capacity of the air conditioning system during a summer heat wave

Qualifier:

according to guideline

Guideline:

EU Method B.1 bis (Acute Oral Toxicity - Fixed Dose Procedure)

Version / remarks:

EEC Methods for the determination of toxicity and other health effects. Commission Regulation No. 440/2008, Part B, Method B.1 bis. Acute Oral Toxicity: Fixed Dose Procedure. 30 May 2008

Deviations:

yes

Remarks:

relative humidity in the animal room was between 38-83% instead of 45-65% and the temperature was between 20-26°C instead of 20-24°C for several hours due to insufficient capacity of the air conditioning system during a summer heat wave

GLP compliance:

yes (incl. QA statement)

Test type:

fixed dose procedure

Limit test:

no

Specific details on test material used for the study:

Purity: 99.7%
Physical description: white powder
Storage conditions: room temperature
Expiration date: March 20, 2020

Species:

rat

Strain:

Wistar

Sex:

female

Details on test animals or test system and environmental conditions:

The animals were distributed into the test groups at random. If possible, all animals belonging to the same experimental group were kept in one cage. The animals were individually marked by fur clippings. A colour-coded card was prepared for each project, giving details of the test type, project number, treatment start, dose level, sex and number of animals.
Acclimatization: At least 5 days prior to the start of dosing under test conditions after health examination. Only animals without any visible signs of illness were used for the study.

Housing: groups of one to five rats (of the same sex and dose group)
Cage Type: Makrolon Type IV, with wire mesh top
Bedding: granulated soft wood bedding
Feed: 2018C Teklad Global 18% protein rodent diet (certified), ad libitum (except for overnight fasting prior to dosing; diet was returned immediately after dosing was complete)
Water: tap water, ad libitum
Environment: temperature 22 + 2°C (except for deviation) relative humidity approx. 45-65% (except for deviation) (with the aim of 50 – 60%) artificial light 6.00 a.m. - 6.00 p.m.
Environmental enrichment: provided throughout the study period (e.g., wooden chew blocks, fun tunnels or suitable nesting material)

Route of administration:

oral: gavage

Vehicle:

CMC (carboxymethyl cellulose)

Details on oral exposure:

Dose administration was once orally by gavage (feeding needle). The volume administered did not exceed 10 mL/kg b.w.
Based on available information on the toxicity of the test item, 300 mg/kg was chosen as the initial starting dose, since a severe toxicity which may necessitate humane euthanasia was not expected at this dose level.
Two single animals were treated as follows:
Dose level (mg/kg) 300, 2000
Concentration (mg/mL) 30, 200 respectively
Dose volume (mL/kg) 10, 10 respectively
Number of rats Female 1, 1 respectively

In the absence of mortality or toxicity at a dose level of 2000 mg/kg, an additional group of animals was treated as follows:
Dose level (mg/kg) 2000
Concentration (mg/mL) 200
Dose volume (mL/kg) 10
Number of rats Female 4

A total of five animals were therefore treated at a dose level of 2000 mg/kg in the study.

Doses:

300 mg/kg
2000 mg/kg

No. of animals per sex per dose:

300 mg/kg - one rat
2000 mg/kg- five rats

Control animals:

no

Details on study design:

Morbidity/Mortality Inspection and Clinical Observations:
Clinical observations and inspections for morbidity / mortality were performed at least three times within the first six hours after application (i.e., 30 minutes and 1 hour, 2 hours and 4 hours after dosing), thereafter at least once daily for 14 days. All animals were observed for 14 days after dosing.
The nature and severity, where appropriate, of the clinical signs and the time were recorded at each observation for all individual animals. If applicable, the time of death/humane kill was recorded as precisely as possible.
Observations included changes in the skin and fur, eyes and mucous membranes, and respiratory, circulatory, autonomic and central nervous system, and somatomotor activity and behavior pattern. Particular attention was directed to the observation of tremors, convulsions, salivation, diarrhea, lethargy, sleep and coma.
Fate of the Animals:
Animals were sacrificed by carbon dioxide asphyxiation followed by cervical dislocation.
Determination of Body Weight:
Body weights were recorded on Day 0 (prior to dosing), Day 7, and 14, or (if applicable) at death (unscheduled).
Necropsy:
A gross necropsy was performed on all animals that died or were humanely killed during the study (if applicable) and at the end of the in-life part. Any macroscopic abnormalities were recorded. Routinely no organs or tissues were retained.

Statistics:

Data Evaluation:
The test item is classified according to Annex 3 of the OECD Guidelines for Testing of Chemicals No. 420 ‘Acute Oral Toxicity – Fixed Dose Procedure’ (adopted 17 December 2001) as shown in the Flow Chart in Annex 2.
Evaluation of data includes the identification of the number of animals that died during the study (or that were killed for humane reasons), and determination of the nature, severity, onset and duration of the toxic effects. If possible, the signs of toxic effects of evident toxicity are described. Evident toxicity refers to the toxic effects of sufficient severity that administration of the next higher dose level could result in development of severe signs of toxicity and probable mortality. Effects on body weights and abnormalities noted at necropsy were identified.
Using the mortality data obtained, an estimate of the acute oral median lethal dose (LD50) of the test item was made.

Preliminary study:

Dose Level – 300 mg/kg b.w.
There were no deaths during the study.
Clinical signs observed were closed eyes. These signs were only noted on day 1 after dosing. Recovery of the animal, as judged by external appearance and behavior, was complete by day 2.
The animal showed expected gains in body weight over the observation period.
No abnormalities were noted in any animal at the macroscopic examination at study termination on Day 14.

Key result

Sex:

female

Dose descriptor:

LD50

Effect level:

>= 2 000 mg/kg bw

Based on:

test mat.

95% CL:

>= 99.7

Mortality:

There were no deaths during the study.

Clinical signs:

other: There were no clinical signs of reaction to treatment throughout the study.

Gross pathology:

No abnormalities were noted in any animal at the macroscopic examination at study termination on Day 14.

Other findings:

no

Interpretation of results:

GHS criteria not met

Conclusions:

The acute median lethal oral dose (LD50) to rats of DOPO-HQ was demonstrated to be greater than 2000 mg/kg body weight.
DOPO-HQ is included in Category 5/Unclassified, according to the Globally Harmonised System (GHS), as described in Annex 2.

Executive summary:

The study was performed to assess the acute oral toxicity of DOPO-HQ to the rat.

Methods

Following a sighting test at dose levels of 300 mg/kg b.w. and 2000 mg/kg b.w. in one female rat per dose group, a further group of four fasted females was given a single oral dose of DOPO-HQ, as a suspension in 1% CMC (carboxy methyl cellualose), at a dose level of 2000 mg/kg body weight. Clinical signs and body weight development were monitored in all animals during the study. All animals were subjected to gross necropsy.

Results

Mortality: There were no deaths.

Clinical Observations: Closed eyes were noted on day 1 after application only in the animal treated at a dose level of 300 mg/kg. There were no signs of systemic toxicity noted in the remaining animals.

Body Weight: All animals showed expected gains in body weight.

Necropsy: No abnormalities were noted at necropsy.

Conclusion

The acute median lethal oral dose (LD50) to rats of DOPO-HQ was demonstrated to be greater than 2000 mg/kg body weight.

DOPO-HQ is included in Category 5/Unclassified according to the Globally Harmonised System (GHS), as described in Annex 2.