4-Butoxy-2,3-difluorophenylboronic Acid (contains varying amounts of Anhydride)

Endpoint summary

Description of key information

GLP compiant OECD 423 ATC Study: LD50 between 300 and 2000 mg/kg bw

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:

Aug 07, 2018 - Aug 21, 2019

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)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test type:

acute toxic class method

Limit test:

yes

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: F. Winkelmann, 33178 Borchen
- Age at study initiation: about 9 weeks
- Weight at study initiation: 166 g (range from 155 to 182 g).
- Fasting period before study: yes, overnight (17 hours before - 4 h after treatment)
- Housing: the rats were housed in an air-conditioned room of ca. 25 m² in the Institute of Toxicology in Macrolon cages type III with a shelter, placed on mobile racks. Animals were kept on conventional softwool granulate as bedding which was changed 2x per week.
- Diet: Provimi Kliba 3433.0, ad libitum
- Water: tap water from Makrolon drinking bottles, ad libitum
- Acclimation period: at least 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21.7 – 23.2
- Humidity (%): 43.2 – 58.5
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: gavage

Vehicle:

methylcellulose

Details on oral exposure:

VEHICLE
- Amount of vehicle (if gavage): 10 mL/kg bw
Directly before the preparation the test metariel was solved in the vehicle using a shaking device (Vortex Genie) and and Ultra Turrax device.

The vehicle chosen was Methocel(R) K4M Premium solution

MAXIMUM DOSE VOLUME APPLIED: 10 mL/kg bw

Doses:

2000 mg/kg bw

No. of animals per sex per dose:

3

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing:
The behaviour and general condition of all animals was monitored for at least 6 h after administration of the test material and then checked daily. All animals were weighed before treatment and on days 2, 4, 6, 8, 11, 13, and 15 of the experimental part.
- Necropsy of survivors performed: yes, At the end of the experimental part, all surviving rats were sacrificed by an air carbon dioxide mixture and exsanguination after opening the abdominal vessels (Vena cava caudalis, Aorta abdominalis). All rats (survivors and rats found dead) were subjected to a gross pathological investigation and macroscopic findings were noted manually on a necropsy record sheet.

Statistics:

Body weight data were recorded with the PC software "akudat", the statistical evaluation of the body weight were carried out with the software "Tox 511A", the body weight development of each rat and group was determined. The group mean value was calculated for each measurement.

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 300 - < 2 000 mg/kg bw

Based on:

test mat.

Mortality:

Three out of six rats treated with 2000 mg/kg died on day 2 and 3 after the last observation. No mortality was seen after treatment with 300 mg/kg during the course of this study.

Clinical signs:

observations of tremors

other: locomotor disturbance, dyspnea and tremor

Body weight:

lower than 10% body weight loss

Remarks:

Five out of six rats treated with 2000 mg/kg showed a decrease of the body weight on day 2. The body weight development of the surviving rats treated with 2000 mg/kg after day 2 was inconspicuous until experimental day 15. The body weight development of the rats treated with 300 mg/kg was inconspicuous throughout the study.

Gross pathology:

Necropsy revealed no findings in animals dosed with 300 mg/kg. Three out of six rats (no. 4,5,6) dosed with 2000 mg/kg showed macroscopic lesions as follows. All three rats showed dark-red discolorations in the fundus mucosa of the stomach (no histology correlate). In the intestines, multifocal to diffuse red discolorations were noted (no histology correlate); a firm content was found in the cecum (no histology correlate). Animal 4 showed dark-red discolorations in the thymus (acute hemorrhages). Animal no. 5 had a smaller spleen (marked lymphoid depletion) and animal no. 6 dark-red discolored kidneys (no histology correlate) and a wet abdominal fur (reddish fluid).

Other findings:

Histopathology examination of selected organs from rats dosed with 2000 mg/kg showed lesions in the urinary bladder, the hemo-lymphoid system (bone marrow, thymus, spleen), the liver, the small intestines and the lung. In the urinary bladder of all three rats (no. 4, 5, 6) dosed with 2000 mg/kg, moderate erosions of the mucosa (urothel) or a mild cytoplasmic vacuolation of the urothelium were seen. In addition, moderate submucosal located granulocytic infiltrates and acute focal hemorrhages were found. In the bone marrow, a moderate to marked decreased cellularity was seen. In the thymus of animal no. 4, severe lymphoid necrosis and acute hemorrhages were noted. The spleen showed marked to severe lymphoid depletion and lymphoid necrosis in all three animals. In the liver, a mild cytoplasmic vacuolation of periportal hepatocytes was found in all three rats. Animal no. 5 and 6 showed multifocal mucosa ulcerations and granulocytic infiltrates in the small intestines. All three rats showed lungs with acute blood congestion (most likely an agonal change).

 

The body weight development of rats is given in the following table:

Animal No.	Sex	Dose [mg/kg]	Body weight in g on day								Body weight gain in g
			1	2	4	6	8	11	13	15	Day 1 to 15
1	Female	2000	161	155	165	176	174	190	188	199	+38
2	Female	2000	171	166	175	185	194	201	205	216	+45
3	Female	2000	171	177	178	186	194	202	204	210	+39
4*	Female	2000	157	152	-	-	-	-	-	-	-
5**	Female	2000	163	158	-	-	-	-	-	-	-
6**	Female	2000	158	151	-	-	-	-	-	-	-
7	Female	300	162	175	177	184	182	191	190	197	+35
8	Female	300	182	194	203	204	211	213	216	223	+41
9	Female	300	169	184	189	197	197	199	205	208	+39
10	Female	300	165	180	184	181	190	193	197	201	+36
11	Female	300	173	188	190	195	199	203	201	208	+35
12	Female	300	155	171	175	176	181	183	188	193	+38

* died on day 3 after last observation; body weightpost mortem: animal no. 4: 147 g

** died on day 2 after last observation; body weight post mortem: animal no. 5: 152 g, animal no. 6: 146 g

Interpretation of results:

Category 4 based on GHS criteria

Conclusions:

Under the conditions of the present study, the LD50 value for the test item is expected to be between 300 - 2000 mg/kg after single oral administration in rats

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

> 300 - < 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 study available

Justification for classification or non-classification

Based on the provided information the substance is to be classified as acute toxicity category 4 according to the EU Regulation (EC) No 1272/2008.