Registration Dossier

Administrative data

Description of key information

Acute toxicity oral: The oral LD50 of OS1600 was determined to be ca. 1234 mg/kg bw in rats. The LD50 of MPKO, the hydrolysis product of OS1600, was determined to be ca 1133 mg/kg bw in rats.

Acute toxicity dermal: Based on the read-across approach from the analogue substance OS1200, the acute lethal dermal dose to rats of OS1600 was determined to be > 1782 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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 425 (Acute Oral Toxicity: Up-and-Down Procedure)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 870.1100 (Acute Oral Toxicity)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Test type:
up-and-down procedure
Limit test:
no
Species:
rat
Strain:
Wistar
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Deutschland, Sulzfeld, Germany
- Age at study initiation: Approximately 9-12 weeks old
- Weight at study initiation: Body weight variation did not exceed +/- 20% of the sex mean
- Fasting period before study: Food was withheld overnight (for a maximum of 20 hours) prior to dosing until 3-4 hours after administration of the
test substance.
- Housing: Individually housed in labeled Macrolon cages (Mill type, height 18 cm.) containing sterilized sawdust as bedding material (Litalabo , S.P.P.S., Argenteuil, France) and paper as cage-enrichment 9Enviro-dri, Wm. Lillico & Son (Wonham Mill Ltd), Surrey, United Kingdom).
- Diet (e.g. ad libitum): Free access to pelleted rodent diet (SM R/M-Z from SSNIFF(R) Spezialdiatem GmbH, Soest, Germany)
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: The acclimatization period was at least 5 days before the start of treatment under laboratory conditions. Accommodation was as described above except that the animals were group housed in labeled Macrolon cages (MIV type; height 18 cm)

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21.0 +/- 3.0°C ( actual range: 19.5-21.6°C)
- Humidity (%): 30-70% (actual range: 31-81%)
- Air changes (per hr): 15 per hr
- Photoperiod (hrs dark / hrs light): 12 hrs dark/ 12 hrs light

Route of administration:
oral: gavage
Vehicle:
unchanged (no vehicle)
Details on oral exposure:
VEHICLE:
The test substance was dosed undiluted as delivered by the sponsor.

MAXIMUM DOSE VOLUME APPLIED:
2000 mg/kg (2.07 ml/kg) body weight
Doses:
Frequency: Single dosage on Day 1
2000 mg/kg (2.07 mL/kg) body weight
550 mg/kg (0.569 mL/kg) body weight
175 mg/kg (0.181 mL/kg) body wieght
Dose volume calculated as dose level (g/kg)/ density (g/mL)
No. of animals per sex per dose:
Test substance was administered by oral gavage to a female Wistar rat at 2000 mg/kg body weight. In a stepwise procedure twelve additional females were dosed at 175, 550 or 2000 mg/kg body weight. The animals were dosed sequentially one at a time.
Control animals:
no
Details on study design:
- Frequency of observations and weighing: Observations: Twice daily. Weighing: Days 1 (pre-administration), 8 and 15.
- Necropsy of survivors performed: Yes
- Other examinations performed:
- Clinical Signs: At periodic intervals on the day of dosing (Day 1) and once daily thereafter, until Day 15. The symptoms were graded according to fixed scales and the time of onset, degree and duration were recorded: Maximum grade 3: grading slight (1) to severe (3). Maximum grade 1: presence is scored (1)
- Necropsy: The animals surviving to the end of the observation period were sacrificed by oxygen/carbondioxide procedure. All animals assigned to the study were subjected to necropsy and descriptions of all internal macroscopic abnormalities recorded.
- Organ Weights: The weight from the liver, kidneys and spleen were recorded from all animals that were necropsied after 21st of April 2008. These organs were also fixed in 10% buffered formalin (neutral phosphate buffered 4% formaldehyde solution) for posible further pathological investigations.
- Blood Sampling: As requested by sponsor, a blood sample was collected from aminal 13 (550 mg/kg) under iso-flurane 24 hrs post treatment. The sample was drawn from the retro-orbital sinus and collected into a tube prepared with EDTA for haematological parameters (0.5 mL)
Statistics:
The LD50 was estimated based on maximum likelihood by means of the AOT425StatPGM
Key result
Sex:
female
Dose descriptor:
LD50
Effect level:
ca. 1 234 mg/kg bw
Based on:
test mat.
Mortality:
2000 mg/kg bw; Number of animals: 7; Number of deaths: 5
550 mg/kg bw; Number of animals: 5; Number of deaths: 0
175 mg/kg bw; Number of animals: 1; Number of deaths: 0
Clinical signs:
Signs of toxicity related to dose levels: The decedents and moribund animal were found on the day of treatment (Day 1).
Clinical signs observed during the study period were as follows:
175 mg/kg: Hunched posture.
550 mg/kg: Lethargy, hunched posture, uncoordinated movements, flat posture, slow breathing, shallow respiration, piloerection, hypothermia.
2000 mg/kg: Lethargy, hunched posture, uncoordinated movements, flat posture, slow breathing, shallow and laboured respiration, piloerection, watery discharge eye, ptosis, salivation.
The surviving animals had recovered from the symptoms between Days 2 and 5.
Body weight:
The mean body weight gain shown by the surviving animals over the study period was considered to be similar to that expected of normal untreated
animals of the same age and strain.
Gross pathology:
Effects on organs: The weights of the liver and kidneys animal 13 (550 mg/kg) and the liver, kidneys and spleen of animals 14 (2000 mg/kg) were within the normal range. The weight of the spleen of animal 13 (550 mg/kg) was 0.306 and just below the normal range (0.40 - 0.69 grams). No abnormalities were found at macroscopic post mortem examination of the animals.
Other findings:
Haematology was perfomred on animal 13 (550 mg/Kg) and showed a slight increase in red blood cells, haemoglobin and haematocrit.
Interpretation of results:
Category 4 based on GHS criteria
Conclusions:
The Oral LD50 value of the test substance was estimated to be approximately 1234 mg/kg bw, within the range of 300-2000 mg/kg bw.
Executive summary:

An acute oral toxicity study was performed with OS1600 in the rat in accordance with OECD Guideline 425 using the Up and Down procedure. Test item was initially administered by oral gavage to a female rat at 2000 mg/kg bw. In a stepwise procedure 12 additional females were dosed at 175, 550 and 2000 mg/kg bw. The animals were dosed sequentially one at a time. All animals were subjected to daily observations and weekly determination of body weight. Macroscopic examination was performed on the day of death or after terminal sacrifice (Day 15). Animals at 2000 mg/kg bw were found dead. Clinical signes were observed at all doses, from hunched posture at 175 mg/ kg bw to lethargy, uncoordinated movements, slow breathing, shallow and laboured respiration, piloerection, discharge eye, ptosis and salivation at 2000 mg/kg bw. The surviving animals had recovered from this symptons. No effects were observed on the body weight gain. The liver and kidney weights of the two animals observed were within the historical data. Instead, the spleen weight was within the historical data in one of them and in the other one was lower. Slight increase in red blood cells, haemoglobi and haematocrit was observed in the analysed animal. No macroscopic abnormalities were observed. Based on these results, the LD50 of OS1600 in rats was determined to be ca. 1234 mg/kg bw and within the range of 300 -2000 mg/kg bw.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
LD50
1 234 mg/kg bw
Quality of whole database:
The study is a GLP compliant and has a Klimisch score 1.

Acute toxicity: via inhalation route

Endpoint conclusion
Endpoint conclusion:
no study available

Acute toxicity: via dermal route

Link to relevant study records
Reference
Endpoint:
acute toxicity: dermal
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Read-across from an analogue substance for which a guideline study (Klimish =1) is available.
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
See attached reporting format.
Reason / purpose:
read-across source
Key result
Sex:
male/female
Dose descriptor:
LD50
Effect level:
> 1 782 mg/kg bw
Based on:
other: Read-across from an analogue substance.
Remarks on result:
other: (read-across from an analogue for which LD50 > 2000 mg/kg bw)

The data matrix is included in the reporting format attached.

The results from the read-across approach are expressed (calculated) on the basis of the molecular weight of OS1600 and OS1200 since the basic structures of the target and source substances are the same. No other adaptation is necessary.

Interpretation of results:
other: Not classified according to CLP criteria.
Conclusions:
Based on the read-across approach from the analogue substance OS1200, the LD50 of OS1600 to rats was determined to be greater than 1782 mg/kg bw.
Executive summary:

An acute dermal toxicity study was performed on the analogue substance OS-1200 according to EU Method B.3. Based on these results, the read-across approach was applied and the acute lethal dermal dose of OS1600 to rats was determined to be greater than 1782 mg/kg bw.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
LD50
1 782 mg/kg bw
Quality of whole database:
The study is a GLP compliant and has a Klimisch score 1 (since read-across, the Klimisch score is 2).

Additional information

Acute toxicity oral:

Key study: An acute oral toxicity study was performed with OS1600 in the rat in accordance with OECD Guideline 425 using the Up and Down procedure (GLP study). The LD50 of OS1600 in rats was determined to be ca. 1234 mg/kg bw and within the range of 300 -2000 mg/kg bw.

Supporting study: An acute oral toxicity study was performed with MPKO, the hydrolysis product of OS1600, in the rat in accordance with OECD Guideline 425 using the Up and Down procedure (GLP study). The LD50 in rats was determined to be ca. 1133 mg/kg bw and within the range of 300 -2000 mg/kg bw.

Acute toxicity dermal:

Key study: Read-across approach from experimental data on the analogue substance OS1200: An acute dermal toxicity study was performed on the analogue substance OS-1200 according to EU Method B.3 (GLP study). Based on the experimental results obtained with the analogue substance OS1200 (LD50 > 2000 mg/kg bw, with no signs of systemic reaction to treatment and no abnormalities at the macroscopic examination), the acute lethal dermal dose (LD50) to rats for OS1600 was determined to be > 1782 mg/kg bw.

Justification for selection of acute toxicity – oral endpoint

One study available on the test item.

Justification for selection of acute toxicity – inhalation endpoint

According to REACH Annex VIII, column 2: In addition to the oral route, for substances other than gases, the information mentioned under 8.5.2 to 8.5.3 shall be provided for at least one other route. The choice for the second route will depend on the nature of the substance and the likely route of human exposure. If there is only one route of exposure, information for only that route need be provided. The information is provided for dermal route.

Justification for classification or non-classification

Based on the available data, the substance is classified as Acute Toxicity Category 4, H302 in accordance with CLP Regulation (EC) no. 1272/2008 since the acute toxicity value expressed as LD50 is between 300 and 2000 mg/kg bw.