1,5,2,4-dioxadithiane 2,2,4,4-tetraoxide

Endpoint summary

Description of key information

One key study on acute oral toxicity is available. The study was conducted using female Wistar rats and was conducted according to the Acute Toxic Class Method (OECD Guideline 423).
One key study on acute dermal toxicity is available. The study was conducted using male and female Wistar rats and was conducted according to the standard acute method (OECD Guideline 402).
One key study on acute inhalation toxicity is available. The study was conducted using male and female Wistar rats and was conducted according to the standard acute method (OECD Guideline 403).

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:

15 June 2011 to 31 July 2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was performed according to EC and OECD guidelines and according to GLP principles.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1100 (Acute Oral Toxicity)

Deviations:

no

Principles of method if other than guideline:

no additional information provided

GLP compliance:

yes (incl. QA statement)

Test type:

acute toxic class method

Limit test:

yes

Species:

rat

Strain:

Wistar

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Deutschland, Sulzfeld, Germany
- Age at study initiation: approx. 9 weeks
- Weight at study initiation:
- Fasting period before study: Animals were deprived of food overnight prior to dosing and until 3-4 hours after administration of the test substance. Water was available ad libitum
- Housing: Group housing of 3 animals per cage in labeled Macrolon cages (MIV type; height 18 cm.) containing sterilized sawdust as bedding material and paper as cage-enrichment
- Diet: Free access to pelleted rodent diet
- Water: Free access to tap water
- Acclimation period: at least 5 days before start of treatment under laboratory conditions

ENVIRONMENTAL CONDITIONS
- Temperature (°C):
- Humidity (%):
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12 hours artificial fluorescent light and 12 hours darkness per day

Route of administration:

oral: gavage

Vehicle:

corn oil

Remarks:

dewatered and specific gravity 0.92

Details on oral exposure:

VEHICLE
- Concentration in vehicle: 2000 mg/kg; 300 mg/kg
- Amount of vehicle (if gavage): 10 mL/kg b.w.
- Justification for choice of vehicle: The vehicle was selected based on trial formulations performed at NOTOX and on test substance data supplied by the sponsor

DOSAGE PREPARATION: The test substance and formulation were handled under nitrogen as much as possible, using a glove box. The test substance formulations (w/w) were prepared within 15 minutes prior to dosing. No adjustment was made for specific gravity of the vehicle. Homogeneity was obtained to visually acceptable levels.

CLASS METHOD
- Rationale for the selection of the starting dose: The toxicity of the test substance was assessed by stepwise treatment of groups of 3 females. The first group was treated at a dose level of 2000 mg/kg. The absence or presence of mortality of animals dosed at one step determined the next step, based on the test procedure defined in the guidelines. The onset, duration and severity of the signs of toxicity were taken into account for determination of the time interval between the dose groups

Doses:

2000 mg/kg (10 mL/kg) body weight.
300 mg/kg (10 mL/kg) body weight.

No. of animals per sex per dose:

3

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing:
Mortality/Viability: Twice daily. The time of death was recorded as precisely as possible.
Body weights: Days 1 (pre-administration), 8 and 15 and at death (if found dead after Day 1).
Clinical signs: At periodic intervals on the day of dosing (Day 1) and once daily thereafter, until Day 15.

- Necropsy of survivors performed: yes. The animals surviving to the end of the observation period were sacrificed by oxygen/carbon dioxide procedure. All animals assigned to the study were subjected to necropsy and descriptions of all internal macroscopic abnormalities recorded.

Statistics:

The oral LD50 value of the test substance was ranked within the following ranges: 0-5, 5-50, 50-300 or 300-2000 mg/kg b.w. or as exceeding 2000 mg/kg b.w. The LD50 cut-off value was established based on OECD guideline 423. No statistical analysis was performed (The method used is not intended to allow the calculation of a precise LD50 value).

Preliminary study:

not applicable

Sex:

female

Dose descriptor:

LD50

Effect level:

300 mg/kg bw

Based on:

test mat.

Mortality:

At 2000 mg/kg, two females were found dead on Day 1 and one female was found dead on Day 2.
At 300 mg/kg, all animals survived up to scheduled necropsy.

Clinical signs:

At 2000 mg/kg, lethargy, lateral recumbency, hunched posture, slow breathing, general blue discolouration, ptosis, dark eyes and/or piloerection were noted among all animals on Day 1.

At 300 mg/kg, one animal showed piloerection on Day 1, whilst no clinical signs were noted among the other two animals.

Body weight:

The body weight gain shown by the 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:

At 2000 mg/kg, many black(-brown) foci in the stomach were noted among all animals. One of these animals showed an advanced stage of autolysis.

At 300 mg/kg, no macroscopic abnormalities were noted.

Other findings:

no additional information provided

no additional information provided

Interpretation of results:

harmful

Remarks:

Migrated information harmful if swallowed (Category 4) for acute toxicity by the oral route Criteria used for interpretation of results: OECD GHS

Conclusions:

The oral LD50 value of MMDS in Wistar rats was established to be within the range of 300-2000 mg/kg body weight.

According to the OECD 423 test guideline, the LD50 cut-off value was considered to be 500 mg/kg body weight.

Executive summary:

Assessment of acute oral toxicity with MMDS in the rat (Acute Toxic Class Method).

 

The study was carried out based on the guidelines described in: OECD No.423 (2001) "Acute Oral Toxicity, Acute Toxic Class Method"

Commission Regulation (EC) No 440/2008, B1 tris: "Acute Oral Toxicity, Acute Toxic Class Method" EPA, OPPTS 870.1100 (2002), "Acute Oral Toxicity" JMAFF guidelines (2000) including the most recent partial revisions.

 

Initially, MMDS was administered by oral gavage to three female Wistar rats at 2000 mg/kg body weight. In a stepwise procedure additional groups of females were dosed at 300 mg/kg body weight. 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).

 

At 2000 mg/kg, two females were found dead on Day 1 and one female was found dead on Day 2.

At 300 mg/kg, all animals survived up to scheduled necropsy.

 

At 2000 mg/kg, lethargy, lateral recumbency, hunched posture, slow breathing, general blue discolouration, ptosis, dark eyes and/or piloerection were noted among all animals on Day 1.

At 300 mg/kg, one animal showed piloerection on Day 1, whilst no clinical signs were noted among the other two animals.

The body weight gain shown by the animals over the study period was considered to be normal.

 

At 2000 mg/kg, many black(-brown) foci in the stomach were noted among all animals. One of these animals showed an advanced stage of autolysis. At 300 mg/kg, no macroscopic abnormalities were noted.

 

The oral LD50value of MMDS in Wistar rats was established to be within the range of 300-2000 mg/kg body weight.

 

According to the OECD 423 test guideline, the LD50 cut-off value was considered to be 500 mg/kg body weight.

 

Based on these results:

-       according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) of the United Nations (2007), MMDS should be classified as: harmful if swallowed (Category 4) for acute toxicity by the oral route.

-      according to the Regulation (EC) No 1272/2008 on classification, labelling and packaging of substances and mixtures, MMDS should be classified as Category 4 and should be labeled as H302: Harmful if swallowed.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

300 mg/kg bw

Quality of whole database:

The study has a Klimisch score of 1.

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

23 May, 2012 - 06 December, 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study has been performed according to OECD and/or EC guidelines and according to GLP principles.

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Version / remarks:

(2009)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.2 (Acute Toxicity (Inhalation))

Version / remarks:

(2008)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1300 (Acute inhalation toxicity)

Version / remarks:

(1998)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Japanese Ministry of Agriculture, Forestry and Fisheries (JMAFF), 12 Nohsan, Notification No. 8147, April 2011; including the most recent partial revisions.

Deviations:

no

GLP compliance:

yes

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

other: Wistar strain: Crl:WI(Han)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Deutschland, Sulzfeld, Germany.
- Age at study initiation: Young adult animals were selected (approximately 9 - 13 weeks old).
- Weight at study initiation: males 311-408 g; females 185-235 g.
- Housing: Group housing of five animals per sex per cage in labelled Makrolon cages.
- Diet: Free access to pelleted rodent diet (SM R/M-Z from SSNIFF® Spezialdiäten GmbH, Soest, Germany) except during exposure to the test substance.
- Water: Free access to tap water except during exposure to the test substance.
- Acclimation period: At least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18 - 24
- Humidity (%): 40 - 70
- Air changes (per hr): approximately 15
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

air

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: The chamber consisted of 3 animal sections with 8 animal ports each. The inlet of the test atmosphere was located at the top section and the outlet was located at the bottom section.
- Exposure chamber volume: not indicated
- Method of holding animals in test chamber: restraining tube
- Source and rate of air: pressurized air; at least 1 L/min
- System of generating particulates/aerosols: combination of a spiral feeder (Randcastle Extrusion Systems, Cedar Grove, NJ, USA) and an air mover (type 611210-060, Foxvalve, Dover NJ, USA). The aerosol was passed through a series of three cyclones, allowing larger particles to settle, before entering the exposure chamber. The primary aerosol was diluted with pressurized air before it entered the exposure chamber. The mean total air flow was 40 L/min.
- Method of particle size determination: gravimetrically, samples were collected with an 8 stage Marple personal cascade impactor containing fiber glass filters (SKC 225-713, fiber glass, SKC Omega Specialty Division, Chelmsford, MA, USA) and a fiber glass back-up filter (SEC-290-F1, Westech, Upper Stondon, Bedfordshire, England).
- Treatment of exhaust air: passed through a filter before it was released to the exhaust of the fume hood.
- Temperature, humidity, pressure in air chamber: Exposure to 1 mg/L: temperature 21.1 - 22.5°C and relative humidity 28 - 35%; exposure to 0.5 mg/L: temperature 21.1 - 21.6°C and relative humidity 9 - 12%; exposure to 0.05 mg/L: temperature 19.8 - 21.6°C and relative humidity 9 - 14%.

TEST ATMOSPHERE
- Brief description of analytical method used: gravimetrical analysis: Samples were drawn through a glass fiber filter (type APFC04700, Millipore, Billerica, MA, USA). The collected amount the test substance in the air sample was measured gravimetrically. Sample volumes were measured by means of a dry gas meter (type G 1.6, Actaris Meterfabriek B.V., Dordrecht, The Netherlands). Subsequently the time-weighted mean concentrations with the standard deviations were calculated.
- Samples taken from breathing zone: yes, from one of the free animal ports.

TEST ATMOSPHERE (if not tabulated)
- Particle size distribution: determined twice for each exposure level
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): Exposure to 1 mg/L: 4.2 µm/1.7 and 3.8 µm/2.1; Exposure to 0.5 mg/L: 4.3 µm/2.0 and 3.7 µm/1.7; Exposure to 0.05 mg/L: 2.4 µm/1.6 and 2.1 µm/1.9.

Analytical verification of test atmosphere concentrations:

yes

Remarks:

gravimetrically, a total of 15, 23 and 21 representative samples were taken for determination of the actual concentration during exposure at 1, 0.5 and 0.05 mg/L, respectively.

Duration of exposure:

4 h

Concentrations:

Exposure to 1 mg/L: nominal 9.42 mg/L; actual 1.12 ± 0.05 mg/L
Exposure to 0.5 mg/L: nominal 9.2 mg/L; actual 0.52 ± 0.01 mg/L
Exposure to 0.05 mg/L: nominal 3.597 mg/L; actual 0.053 ± 0.002 mg/L

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

- Duration of observation period following administration: 21 days.
- Frequency of observations and weighing: during exposure, 3 times for mortality, behavioural signs of distress and effects on respiration; twice daily for mortality/viability; on Day 1, 1 and 3 hours after exposure and once daily thereafter for clinical signs; Days 1 (pre-administration), 2, 4, 8 and Day 15 or 16 or 21 and at death (if found dead or sacrificed after Day 1) for body weights.
- Necropsy of survivors performed: yes

Statistics:

None.

Sex:

male/female

Dose descriptor:

LC50

Effect level:

0.053 - 0.52 mg/L air (analytical)

Based on:

test mat.

Exp. duration:

4 h

Mortality:

After exposure to 1 mg/L, six (of the ten) animals were found dead or sacrificed (two females were sacrificed on Day 1, two females were found dead on Day 2 and two males were found dead on Days 11 or 18).
After exposure to 0.5 mg/L, seven (of the ten) animals were found dead (one male and one female were sacrificed on Day 2, three males were found dead on Days 2, 10 or 13, two females were found dead on Days 13 and 14).
No mortality occurred following exposure to 0.05 mg/L.

Clinical signs:

other: At 1 mg/L, no abnormalities were seen during exposure. After exposure, hunched posture, laboured respiration, rales, piloerection and/or deep respiration were seen. The surviving animals had recovered from the symptoms by Days 6 or 18 and were still prese

Body weight:

Body weight loss and reduced body weight gain was noted among the surviving animals exposed to 1 or 0.5 mg/L. At 0.05 mg/L, overall body weight gain in males and females was within the range expected for rats of this strain and age used in this type of study.

Gross pathology:

At 1 mg/L, abnormalities of the lungs (pale discoloration), thymus (isolated reddish foci) and mandibular lymph nodes (dark red discoloration both sides) were found at macroscopic post mortem examination in one male sacrificed on Day 2. Abnormalities of the lungs (pale discoloration) were seen in three of the surviving animals.
At 0.5 mg/L, abnormalities of the lungs (grey white discoloration), thymus (many dark red foci), gastro-intestinal tract (distended with gas) were at macroscopic post mortem examination in the animals found dead or sacrificed. Abnormalities of the lungs (isolated reddish foci) were noted in one surving animal.
At 0.05 mg/L, no abnormalities were found at macroscopic post mortem examination of the animals.
Incidental findings included beginning autolysis en pelvic dilation of the kidney which were considered not related to treatment.

Interpretation of results:

Toxicity Category II

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The inhalatory LC50, 4h value of MMDS in Wistar rats was established to be within the range of 0.05 - 0.5 mg/L.

Executive summary:

Rats (5/sex) were exposed for 4 hours to 1.0, 0.5 and 0.05 mg/L of the test substance by inhalation (nose-only) according to OECD 403 and GLP principles.

After exposure to 1 mg/L, six (of the ten) animals, and after exposure to 0.5 mg/L, seven (of the ten) animals were found dead or sacrificed. No mortality occurred following exposure to 0.05 mg/L.

During exposure, at 1 mg/L and 0.05 mg/L, no abnormalities were seen. At 0.5 mg/L, slow respiration was noted in females.

After exposure, at 1 mg/L and 0.5 mg/L, hunched posture, laboured respiration, rales, piloerection and/or respiration were seen. No abnormalities were seen at 0.05 mg/L.

Body weight loss and reduced body weight gain was noted among the surviving animals exposed to 1 or 0.5 mg/L. At 0.05 mg/L, overall body weight gain in the animals was within the range expected for rats of this strain and age used for this study.

At 1 mg/L and 0.5 mg/L, abnormalities of the lungs and thymus were found in the animals found dead or sacrificed. In addition, at 1 mg/L, abnormalities of the mandibular lymph nodes (dark red disoloraisation both sides) were also found, whereas at 0.5 mg/L, abnormalities of the gastro-intestinal tract (distended with gas) were also observed. Abnormalities of the lungs were seen in the surviving animals at 1 mg/L (pale discoloration) and 0.5 mg/L (isolated reddish foci).

Based on these observations, the inhalatory LC50, 4h value of MMDS in Wistar rats was established to be within the range of 0.05 - 0.5 mg/L.

Based on these results, MMDS should be classified as Toxic category 2 and should be labelled as H330: Fatal if inhaled, according to Regulation (EC) No. 1272/2008.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LC50

Value:

50 mg/m³

Quality of whole database:

The study has a Klimisch score of 1.

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

25 January - 08 February, 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study has been performed according to OECD and/or EC guidelines and according to GLP principles.

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Version / remarks:

(1987)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.3 (Acute Toxicity (Dermal))

Version / remarks:

(2008)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1200 (Acute Dermal Toxicity)

Version / remarks:

(1998)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Japanese Ministry of Agriculture, Forestry and Fisheries (JMAFF), 12 Nousan, Notification No 8147, April 2011; including the most recent partial revisions.

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

other: Wistar strain, Crl:WI (Han)

Sex:

male/female

Details on test animals or test system and environmental conditions:

- Source: Charles River Deutschland, Sulzfeld, Germany.
- Age at study initiation: Young adult animals (approx. 11 weeks old)
- Weight at study initiation: Body weight variation was within +/- 20% of the sex mean.
- Housing: Individually housed in labeled Makrolon cages (MIII type, height 18 cm.)
- Diet: Free access to pelleted rodent diet (SM R/M-Z from SSNIFF® Spezialdiäten GmbH, Soest, Germany).
- Water: Free access to tap water.
- Acclimation period: At least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21.0 ± 3.0
- Humidity (%): 40 - 70
- Air changes (per hr): approx 15
- Photoperiod (hrs dark / hrs light): 12/12

Temporary deviations from the minimum level of relative humidity occurred. Evaluation: Laboratory historical data do not indicate an effect of the deviations. The study integrity was not adversely affected by the deviation.

Type of coverage:

occlusive

Vehicle:

corn oil

Details on dermal exposure:

One day before exposure (Day -1) an area of approximately 5x7 cm on the back of the animal was clipped.

The test substance formulation was applied in an area of approx. 10% of the total body surface, i.e. approx. 25 cm² for males and 18 cm² for females. The test substance formulation was held in contact with the skin with a dressing, consisting of a surgical gauze patch (Surgy 1D), successively covered with aluminum foil and Coban elastic bandage. A piece of Micropore tape was additionally used for fixation of the bandages in females only.

Frequency: Single dosage, on Day 1.

Washing: Following application, dressings were removed and the skin cleaned of residual test substance using tap water.

Duration of exposure:

24 hours.

Doses:

2000 mg/kg

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

VEHICLE
- Justification for choice of vehicle: The vehicle was selected based on trial formulations performed at NOTOX and on test substance data supplied by the sponsor.

Dose volume: 10 mL/kg body weight

DOSAGE PREPARATION: The formulation (w/w) was prepared within 4 hours prior to dosing. Homogeneity was accomplished to a visually acceptable level. Adjustment was made for specific gravity of the vehicle. No correction was made for purity of the test substance.

Duration of observation period following administration: 14 days
- Frequency of observations and weighing:
Mortality/Viability: Twice daily.
Body weights: Days 1 (pre-administration), 8 and 15.
Clinical signs: At periodic intervals on the day of dosing (Day 1) and once daily thereafter, until Day 15.
- Necropsy of survivors performed: At the end of the observation period, all animals were sacrificed by oxygen/carbon dioxide procedure and subjected to necropsy. Descriptions of all internal macroscopic abnormalities were recorded.
- Other examinations performed: none.

Statistics:

None.

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Mortality:

No mortality occurred.

Clinical signs:

Chromodacryorrhoea (snout) was observed for three males and two females on Day 1 only.
All animals showed a combination of the following findings in the treated skin-area during the observation period: general erythema, necrosis, scales, scabs and/or a yellow appearance.

Body weight:

The changes noted in body weight gain in males and females were within the range expected for rats used in this type of study and were therefore considered not indicative of toxicity.

Gross pathology:

No internal macroscopic abnormalities were found at post mortem examination of the animals.

Other findings:

None.

Interpretation of results:

not classified

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

In an acute dermal toxicity study with rats, performed according to OECD/EC test guidelines, an LD50 >2000 mg/kg bw was determined.

Executive summary:

MMDS was administered to five Wistar rats of each sex by a single dermal application at 2000 mg/kg body weight for 24 hours.

No mortality occurred. Chromodacryorrhoea (snout) was observed for three males and two females on Day 1 only. All animals showed a combination of the following findings in the treated skin-area during the observation period: general erythema, necrosis, scales, scabs and/or a yellow appearance. The mean body weight gain during the observation period was within the range expected for rats used in this type of study. No internal macroscopic abnormalities were found at post mortem examination of the animals. The dermal LD50 value of MMDS in Wistar rats was established to exceed 2000 mg/kg body weight.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Quality of whole database:

The study has a Klimisch score of 1.

Additional information

Acute oral:

MMDS, was administered to female Wistar rats by oral gavage in a single exposure to assess its ability to cause toxicity. The test was conducted according to the Acute Toxic Class Method, with doses of 300 and 2000 mg/kg bw used. Three female rats per dose group were used. All animals were subjected to daily observations, up to Day 15 of testing, and weekly determination of body weight, measured on Days 1, 8 and 15. Macroscopic examination was also performed on all animals. Two females were found dead on Day 1 and one female rat was found dead no Day 2 at 2000 mg/kg bw. All three animals at 2000 mg/kg bw found lethargy, lateral recumbency, hunched posture, slow breathing, general blue discolouration, ptosis, dark eyes and/or piloerection were noted among all animals on Day 1. One female at 300 mg/kg bw showed piloerection on Day 1, whilst no clinical signs were noted among the other two animals. The body weight gain shown by the animals over the study period was considered to be similar to that expected of normal untreated animals of the same age and strain. At 2000 mg/kg, many black(-brown) foci in the stomach were noted among all animals. One of these animals showed an advanced stage of autolysis. At 300 mg/kg, no macroscopic abnormalities were noted.

Under the condition of this study, the oral LD50 value of MMDS in Wistar rats was established to be within the range of 300-2000 mg/kg body weight. According to the OECD 423 test guideline, the LD50 cut-off value was considered to be 300 mg/kg body weight.

Under the conditions of this study, the LD50 was determined to be in the range of 300 to 2000 mg/kg bw. Based on this result, the test substance should be classified as a Category 4 toxicant and have the signal word "Warning" and the risk phrase H302: Harmful if

swallowed associated with it, in accordance with Regulation EC No. 1272/2008. According to Directive 67/548/EEC, the test substance should have the risk phrase, R22: Harmful if swallowed.

Acute dermal:

MMDS was administered to five Wistar rats of each sex by a single dermal application at 2000 mg/kg body weight for 24 hours.

No mortality occurred. Chromodacryorrhoea (snout) was observed for three males and two females on Day 1 only. All animals showed a combination of the following findings in the treated skin-area during the observation period: general erythema, necrosis, scales, scabs and/or a yellow appearance. The mean body weight gain during the observation period was within the range expected for rats used in this type of study. No internal macroscopic abnormalities were found at post mortem examination of the animals. The dermal LD50 value of MMDS in Wistar rats was established to exceed 2000 mg/kg body weight.

Acute inhalation:

Rats (5/sex) were exposed for 4 hours to 1.0, 0.5 and 0.05 mg/L of the test substance by inhalation (nose-only) according to OECD 403 and GLP principles.

After exposure to 1 mg/L, six (of the ten) animals, and after exposure to 0.5 mg/L, seven (of the ten) animals were found dead or sacrificed. No mortality occurred following exposure to 0.05 mg/L.

During exposure, at 1 mg/L and 0.05 mg/L, no abnormalities were seen. At 0.5 mg/L, slow respiration was noted in females.

After exposure, at 1 mg/L and 0.5 mg/L, hunched posture, laboured respiration, rales, piloerection and/or respiration were seen. No abnormalities were seen at 0.05 mg/L.

Body weight loss and reduced body weight gain was noted among the surviving animals exposed to 1 or 0.5 mg/L. At 0.05 mg/L, overall body weight gain in the animals was within the range expected for rats of this strain and age used for this study.

At 1 mg/L and 0.5 mg/L, abnormalities of the lungs and thymus were found in the animals found dead or sacrificed. In addition, at 1 mg/L, abnormalities of the mandibular lymph nodes (dark red disoloraisation both sides) were also found, whereas at 0.5 mg/L, abnormalities of the gastro-intestinal tract (distended with gas) were also observed. Abnormalities of the lungs were seen in the surviving animals at 1 mg/L (pale discoloration) and 0.5 mg/L (isolated reddish foci).

Based on these observations, the inhalatory LC50, 4h value of MMDS in Wistar rats was established to be within the range of 0.05 - 0.5 mg/L.

Justification for selection of acute toxicity – oral endpoint
One key study available.

Justification for selection of acute toxicity – inhalation endpoint
One key study available.

Justification for selection of acute toxicity – dermal endpoint
One key study available.

Justification for classification or non-classification

Based on the results, the test substance should be classified for acute oral toxicity as a Category 4 toxicant and have the signal word "Warning" and the risk phrase H302: Harmful if swallowed associated with it, in accordance with Regulation EC No. 1272/2008. According to Directive 67/548/EEC, the test substance should be have the risk phrase, R22: Harmful if swallowed.

Based on the observed 4h LC50 value in the range of 0.05 -0.5 mg/L, MMDS should be classified for acute inhalation toxicity as category 2 and should be labelled as H330: Fatal if inhaled, according to Regulation (EC) No. 1272/2008.

According to Directive 67/548/EEC, the test substance should be have the risk phrase, R26: Very toxic by inhalation.

MMDS does not have to be classified and has no obligatory labelling requirement for acute dermal toxicity in accordance with Regulation EC No. 1272/2008 and Directive 67/548/EEC.