2,2'-methylenebis[6-(1-methylcyclohexyl)-p-cresol]

Endpoint summary

Description of key information

Acute Oral Toxicity: LD50 >2000 (male/female Wistar rats).
Acute Dermal Toxicity: LD50 >2000 (male/female Wistar rats).

Acute inhalation toxicity: LC50> 3.18 mg/l (maximum achievable concentration) (male/female Wistar rats)

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:

July 28 - August 17, 1993

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study performed in accordance with OECD & EU test guidelines in compliance with GLP and reported with a GLP certificate.

Qualifier:

according to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Deviations:

not specified

Qualifier:

according to guideline

Guideline:

EU Method B.1 (Acute Toxicity (Oral))

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

Species: rat
Strain: Bor: WISW (SPF Cpb)
Source: Fa. Winkelmann, Versuchstierzucht GmbH & Co. KG, Gartenstr.27, 33178 Borchen
Date of receipt: July 14, 1993 (range finding); July 21, 1993 (main test)
Acclimatization period: 14 days (range finding); 13 days (main test)
Animal selection: random
Animal identification: with colored markings; cage labelled with dosage, sex, date of study initiation, project no.
Weight range at study initiation: m: 196 - 225 g, f: 158 - 187 g

Husbandry
Housing: collective housing up to a maximum of 5 animals per cage (Makrolon® type II)
Illumination: artificial lighting (120 lux) from 7.00 a.m. - 7.00 p.m.
Temperature: 22 ± 3°C
Relative humidity: 30 - 70 %
Measurement: with thermohygrometer twice daily

Route of administration:

oral: gavage

Vehicle:

polyethylene glycol

Details on oral exposure:

Solvent/vehicle: polyethylene glycol 400 (PEG 400)
Batch: 110. 297833690

The test article was administered as a 20% solution in PEG 400 in a volume of 10 ml/kg. The dissolution of the test substance was performed by stirring and mild warming.

Doses:

Single does 2000 mg/kg bw

No. of animals per sex per dose:

2 females for range finding study
10 animals in the main study (5 males & 5 females)

Control animals:

no

Details on study design:

Pre-experimental procedure
Prior to study initiation, the animals were acclimatized to laboratory conditions for 14 days (range finding) and 13 days (main test). Only healthy animals were used in the test.
The animals were fasted from 16 h before until 3 - 4 h after administration of the test article.

Administration of the test article
A single oral administration of the test article was performed by gavage using a stomach tube.

Range finding
A preliminary range finding test with a dose of 2000 mg/kg body weight was conducted using two female rats.

Main study
Clinical observations
In each animal a number of clinical-toxicological signs were evaluated according to a modified Irwin-Screening procedure (Screening Methods in Pharmacology, R. A. Turner, 1965, p. 26). Any change from the normal condition was noted (increase or decrease) and the degree of severity of any clinical symptoms was assessed. The animals were examined at the following post-treatment intervals: 10 min, 1 h, 2 h, 6 h, 24 h, and thereafter once daily up to day 14.

Body weights
Body weights were recorded immediately before treatment (day 0) and on days 7 and
14 p.a. (termination).

Necropsy
The animals were sacrificed by CO2 asphyxiation after 14 days and gross pathological examinations were subsequently performed.

Statistics:

None specified in the study report.

Preliminary study:

There were no death in the preliminary study.

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Mortality:

No animals died during the course of the main study.

Clinical signs:

No abnormal clinical signs were observed apart from a slight diarrhoea in 9 animals at 6h post administration. The situation resolved itself within 24h.

Body weight:

Weight gains were normal in all animals.

Gross pathology:

Gross pathological examinations at 14 days p. a. (terminal necropsy) revealed no test article-dependent findings. The macroscopic change that was observed was attributable to minor variations which can occur spontaneously in rats of ths strain and age.

Other findings:

No further findings reported in the study.

INDIVIDUAL DOSE AND PRE-TERMINAL DEATHS – RANGE FINDING

Test article: Mutterlaugenrückstand               Project No.: 10-04-0063/00-93

Species: Rat                                            Animal no.: 6 + 7

Sex: f

Anim. No.	Sex	Dose (mg/kg)	Volume (ml)	Pre-terminal deaths
				24h	48h	Days p.a.
						3	4	5	6	7	8	9	10	11	12	13	14
6	F	2000	1.7
7	F	2000	1.9

Open boxes: no pre-terminal deaths

 

INDIVIDUAL DOSE AND PRE-TERMINAL DEATHS – MAIN STUDY

Test article: Mutterlaugenrückstand               Project No.: 10-04-0063/00-93

Species: Rat                                           Animal no.: 1 - 10

Sex: m, f

Anim. No.	Sex	Dose (mg/kg)	Volume (ml)	Pre-terminal deaths
				24h	48h	Days p.a.
						3	4	5	6	7	8	9	10	11	12	13	14
1	M	2000	2.1
2	M	2000	2.2
3	M	2000	2.1
4	M	2000	2.0
5	M	2000	2.3
6	F	2000	1.7
7	F	2000	1.9
8	F	2000	1.8
9	F	2000	1.6
10	F	2000	1.7

Open boxes: no pre-terminal deaths

 

CLINICAL OBSERVATIONS

Test article: Mutterlaugenrückstand               Project No.: 10-04-0063/00-93

Species: Rat                                           Sex: m,f

Dose mg/kg	Observation period p.a.	Findings
2000	10 min – 2h (10/10) 6h (10/10) 24h – day 14 (10/10)	No abnormal clinical signs Slight diarrhea in 9 animals No abnormal clinical signs

Figures in parenthesis indicate number of surviving animals

 

BODY WEIGHTS – INDIVIDUAL VALUES (g)

Dose: 2000 mg/kg

Anim. No.	Sex	Day 0	Day 7 p.a.	Day 14 p.a.
1	M	205	252	274
2	M	218	270	288
3	M	206	252	287
4	M	196	232	257
5	M	225	272	304
6	F	172	191	198
7	F	187	211	217
8	F	178	200	211
9	F	158	176	189
10	F	168	192	207

 

BODY-WEIGHTS – MEAN VALUES (g)

Sex	N	Day 0	Day 7 p.a.	Day 14 p.a.
Males	5	210.0 ± 11.5	255.6 ± 16.3	282.0 ± 17.6
Females	5	172.6 ± 10.9	194.0 ± 12.9	204.4 ± 11.0

 

NECROPSY

Test article: Mutterlaugenrückstand               Project No.: 10-04-0063/00-93

Species: Rat                                           Animal no.: 1 - 10

Sex: m, f                                                Dose: 2000 mg/kg

 

Spontaneous death: ----     n = -

Killed in extremis: ----        n = -

Animal No.	Specified Findings

 

Terminal sacrifice: 14 days p.a.        n = 10

Animal No.	Specified Findings
7 1 – 6, 8 – 10	Uterus: hydrometra No specific findings

 

Interpretation of results:

not classified

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

the basis of the results obtaned after a single oral administration, the LD50 values after 24 h and 14 days were as follows:
male and female > 2000 mg/kg

Executive summary:

The aim of the test was to determine the acute median lethal dose of "Mutterlaugenrückstand". Information derived from this test serves to indicate the existence of possible hazards likely to arise from short-term exposure to the test article by the oral route.

The test was conducted according to the OECD guideline for the testing of chemicals OECD 401 (February 24, 1987) and the EEC directive 92/69ÆEC (July 31, 1992). The study was carried out as described in the corresponding protocol approved by the testing facility and the study sponsor on June 28 and July 1, 1993, respectively. The principles of Good Laboratory Practice for the testing of chemicals as specified by national (BGBL. I, no. 13, § 19 a, March 22, 1990) and international (OECD, Paris, 1982) legislation were followed during the performance of the study.

 

SUMMARY

The acute oral toxicity of "Mutterlaugenrückstand" was investigated in 5 male and 5 female Wistar rats.

On the basis of the range finding results, the animals were given a single oral administration of "Mutterlaugenrückstand" at a dose of 2000 mg/kg.

Clinical observations were conducted at regular intervals during the 14-day observation period. Body weights were measured at days 0, 7 and 14 p.a. Gross pathological examinations were performed on all animals 14 days p.a.

 

The following results were obtained:

1. No abnormal clinical signs were observed apart from a slight diarrhea in 9 animals at 6 h p.a.

2. Weight gains were normal in all animals.

3. Gross pathological examinations at 14 days p.a. (terminal necropsy) revealed no test article-dependent findings.

4. On the basis of the results obtained after a single oral administration, the LD50 values after 24 hand 14 days were as follows:

male and female > 2000 mg/kg

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Quality of whole database:

Klimish score = 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:

09 October 2017 to 05 January 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Version / remarks:

OECD Guideline for the Testing of Chemicals No. 403 “Acute Inhalation Toxicity”, adopted: 07 September 2009.

Deviations:

yes

Remarks:

See "Any other information" for details

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

EC 440/2008, Annex Part B, (2008) Method B2

Deviations:

yes

Remarks:

See "Any other information" for details

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1300 (Acute inhalation toxicity)

Version / remarks:

US Environmental Protection Agency (EPA) Health Effects Division Test Guidelines, OPPTS 870.1300, Acute Inhalation Toxicity, (August 1998)

Deviations:

yes

Remarks:

See "Any other information" for details

GLP compliance:

yes (incl. QA statement)

Test type:

traditional method

Limit test:

yes

Specific details on test material used for the study:

No further details specified in the study report.

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

Male and female Wistar Crl:WI rats (from SPF colony) were obtained from Charles River Laboratories, Research Model and Services, Germany GmbH (Sandhofer Weg 7, D-97633, Sulzfeld, Germany).
After arrival, the animals’ health was certified by the resident veterinarian.
Hygienic level at arrival: SPF
Hygienic level during the study: Standard housing conditions
Justification of strain: Recognized by international guidelines as a recommended test system
Animal room: 245/3
Number of animals: 12 (6 animals/sex)
Sex: Male and female, the females were nulliparous and non-pregnant
Age and body weight range of animals on the exposure day (Day 0) were:
Sighting exposure (Group 0.1): approximately 8 weeks old, 335 g (male) and 234 g (female)
Main study (Group 1): approximately 9 weeks old, 365-392 g (males) and 234-249 g (females).

Justification
Rats are the preferred species as they have been used historically for safety evaluation studies and they are specified by the appropriate regulatory authorities. Citoxlab Hungary Ltd. also has considerable experience with this species and historical control data in which to set the findings in context.

Husbandry
Housing: Group caging (5 animals, by sex, per cage), individual caging during the sighting study
Cage type: Polycarbonate solid floor cages (type II or III) with stainless steel mesh lids.
Light: 12 hours of continuous artificial light in each twenty-four hour period (from 6.00 a.m. to 6.00 p.m.)
Temperature: 17.0 – 26.3 °C (245/3)
Relative humidity: 37 – 54 % (245/3)
Ventilation: At least 15 air exchanges per hour.
The temperature and relative humidity were recorded twice daily during the study.

Diet and Water
The animals were provided with ssniff SM R/M “Autoclavable Complete Feed for Rats and Mice – Breeding and Maintenance” (ssniff Spezialdiäten GmbH, D-59494 Soest Germany) ad libitum, and tap water from the municipal supply, as for human consumption from 500 ml bottles ad libitum.
Water quality control analysis is performed once every 3 months and microbiological assessment is performed monthly, by Veszprém County Institute of State Public Health and Medical Officer Service (ÁNTSZ, H-8201 Veszprém, József A.u.36, Hungary). The quality control results are retained in the archive of Citoxlab Hungary Ltd.
The food and drinking water were considered not to contain any contaminants that could reasonably be expected to affect the purpose or integrity of the study.

Bedding
Lignocel® Hygienic Animal Bedding produced by J. Rettenmaier & Söhne GmbH+Co. KG (Holzmühle 1, D-73494 Rosenberg, Germany), was used. The quality of the bedding material was guaranteed by the supplier. Nest building material (ARBOCEL crinklets natural (produced by J. Rettenmaier & Söhne GmbH & Co.KG, Germany)) was also added to the cages. Copies of the certificates are retained in the archives of Citoxlab Hungary Ltd.
The bedding and the nest building material were considered not to contain any contaminants that could reasonably be expected to affect the purpose or integrity of the study.

Acclimation and randomization
Animals were acclimated to laboratory conditions for 5 (sighting group) or 13 days (main study) prior to involvement in the study. Animals were also acclimatised to the test apparatus (restraint procedures) for a short period prior to testing in order to lessen the stress during exposure. Animals were randomly allocated to exposure groups before animal exposure based on the actual body weights.

Identification
Animals were individually identified with numbers written on the tail with an indelible marker. The numbers were given on the basis of Citoxlab Hungary Ltd.'s master file.
Cages were identified by cards holding information on the study code, the sex of animals, the dose group, the cage number and the individual animal number.

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

other: 50% acetone formulation of 2,2’-methylenebis[6-(1-methylcyclohexyl)-p-cresol]

Remarks:

It was not technically feasible to produce an atmosphere without the use of a vehicle; water was not a suitable vehicle.

Mass median aerodynamic diameter (MMAD):

2.89 µm

Geometric standard deviation (GSD):

1.94

Details on inhalation exposure:

Preparation
The test item was not suitable for atmosphere generation in the form supplied, therefore a trial formulation was performed in acetone as the Test Item is not soluble in water. Based on the results of the trial formulation a 50% formulation in acetone (VWR., Batch: 17B284019, Expiry: 28 February 2022) was used in both study groups.

Inhalation Exposure
Technical Trials
Prior to animal exposures, test material atmospheres were generated within the exposure chamber. Due to the physical properties of the test item, it was established that a powder atmosphere was not technically feasible. Further trials were made with formulations in acetone. During these technical trials, air-flow settings, test material input rates and test item formulation of the material were varied to achieve the required aerosol concentration of particles with a mass median aerodynamic diameter (MMAD) between 1 to 4 µm and a geometric standard deviation (GSD) in the range of 1.5 to 3.0. Measurements of aerodynamic particle size were performed from the animal’s breathing zone using a cascade impactor.

Atmosphere generation
The test item formulation was aerosolized using a stainless steel concentric jet nebulizer (TSE Systems GmbH, Bad Homburg, Germany) located at the top of the exposure chamber. The rate of test item usage was controlled by a syringe pump.
Compressed air was supplied by means of an oil-free compressor and passed through a suitable filter system prior to introduction to the nebuliser.

Animal exposure system
The animals were exposed, nose-only, to an atmosphere of the test item using a TSE Rodent Exposure System (TSE Systems GmbH, Bad Homburg, Germany). This system comprises of two concentric anodised aluminium chambers and a computer control system incorporating pressure detectors and mass flow controllers.
The exposure unit was placed in closed hood in order to avoid cross-contamination and contamination of the laboratory environment.
Fresh aerosol from the generation system was constantly supplied to the inner plenum (distribution chamber) of the exposure system from where, under positive pressure, it was distributed to the individual exposure ports. The animals were held in polycarbonate restraint tubes located around the chamber which allowed only the animal’s nostrils to enter the exposure port. After passing through the animal’s breathing zone, used aerosol entered the outer cylinder from where it was exhausted through a suitable filter system. Atmosphere generation was therefore dynamic.
Airflows and relative pressures within the system were constantly monitored and controlled by the computer system thus ensuring a uniform distribution and constant flow of fresh aerosol to each exposure port (breathing zone). The flow of air through each port was at least 0.5 L/min. This flow rate was considered adequate to minimize re-breathing of the test atmosphere as it is approximately twice the respiratory minute volume of a rat.
Homogeneity of the test atmosphere within the test chamber and amongst the exposure ports was not specifically determined during this study. However, considerably larger chambers of this design have been fully validated and have shown to produce evenly distributed atmospheres in the animals’ breathing zones.

Sighting Exposure
Sighting exposures were performed in order to estimate the item’s inhalation toxicity, identify sex differences in susceptibility and assist in selecting exposure concentration levels for the main study.

Exposure procedure
Each rat was individually held in a tapered, polycarbonate restraining tube fitted onto a single tier of the exposure chamber. Only the nose of each animal was exposed to the test atmosphere.
Following an equilibration period of at least the theoretical chamber equilibration time (T99), each group of rats was exposed to an atmosphere of the test material for a period of 4 hours.
No control animals were used in the study; the effects of the acetone vehicle are well known.

Analytical verification of test atmosphere concentrations:

not specified

Duration of exposure:

4 h

Concentrations:

Sighting exposure: 1.94 mg/L (maximum attainable)
Main Study: 3.18 mg/L (maximum attainable)

No. of animals per sex per dose:

Sighting exposure: 2 (1 male/1 female)
Mian study: 10 (5 male/5 female)

Control animals:

not specified

Details on study design:

Study design
The animals were exposed to an atmosphere of the test item for a single, continuous four-hour period, generated according to the system and flow rates determined during the technical trials.

Exposure Monitoring
Test atmosphere concentrations
The test atmosphere was sampled at regular intervals during the exposure period. Samples were taken from an unoccupied exposure port (representing the animal’s breathing zone) by pulling a suitable volume of test atmosphere through weighed GF10 glass fibre filters (Whatman®, Whatman GmbH, Germany, Ref./Lot no.: G9768136).
The difference in the pre and post sampling (dried) weights, divided by the volume of atmosphere sampled, was equal to the actual achieved test atmosphere concentration.
Filter samples (17) were collected at the breathing zone (approximately every 10-20 minutes) during each 4-hour exposure period and measured.
The nominal concentration was calculated by dividing the mass of test material disseminated into the chamber by the total volume of air that flow through the chamber during the same period.

Particle size analysis
The particle size of the test atmosphere was determined three times during the exposure period using a 7-stage impactor of Mercer style (TSE Systems GmbH, Bad Homburg, Germany). Such devices employ an inertial separation technique to isolate particles in the discrete aerodynamic size ranges. Samples were taken from an unoccupied exposure port (representing the animal’s breathing zone).
The collection substrates and the backup filter were weighed before and after sampling and the weight of test item, collected at each stage, calculated by this difference.
The total amount collected for each stage was used to determine the cumulative amount below each cut-off point size. In this way, the proportion (%) of aerosol less than < 0.550, 0.550, 0.960, 1.550, 2.105, 3.555, 6.655 and 10.550 m was calculated.
From these data, using the software supplied with the impactor (TSE Systems GmbH, Bad Homburg, Germany), the Mass Median Aerodynamic Diameter (MMAD), and Geometric Standard Deviation (GSD) were calculated. In addition, the proportion (%) of aerosol less than 4 m (considered to be the inhalable portion) was determined.

Chamber environmental conditions
The following variables were monitored continuously and recorded at regular intervals during each exposure period by a validated monitoring system integrated into the exposure system:
-Chamber airflow rates
-Test atmosphere temperature
-Test atmosphere relative humidity
-Test atmosphere carbon dioxide concentration
-Test atmosphere oxygen concentration

Observations
Morbidity/mortality
Animals were checked hourly during exposure, 1 hour after exposure and twice daily (early and late in the working day) during the 14-day observation period for morbidity and/or mortality.

Clinical signs
All animals were observed for clinical signs at hourly intervals during exposure whilst the animals were still restrained. Following exposure, clinical observations were performed twice on the day of exposure (following removal from the restrainer and approximately one hour after completion of the exposure) and subsequently once daily for 14 days.
Observations included changes in the skin and fur, eyes and mucous membranes and also respiratory, circulatory, autonomic and central nervous system, somato-motor activity and behaviour pattern. Particular attention was directed to observation of tremors, convulsions, salivation, diarrhoea, lethargy, sleep and coma.

Body weight
Individual body weights were recorded prior to treatment on the day of exposure (on Day 0) and on Days 1, 3, 7 and 14.

Necropsy
At the end of the 14-day observation period, the surviving animals were sacrificed by exsanguination under anaesthesia (intra-peritoneal injection of pentobarbital solution – Euthanimal 40%; Lot No.: 1609291-03; Expiry: October 2019; Produced by Alfasan International B. V., Woerden, Netherlands) and gross macroscopic examination was performed.
All rats were subject to a gross necropsy which included a detailed examination of the abdominal and thoracic cavities. Special attention was given to the respiratory tract for macroscopic signs of irritancy or local toxicity.

Statistics:

Only a limit test was performed, the four-hour inhalation LC50 was not calculated.

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 3.18 mg/L air (analytical)

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

other: maximum achievable amount in air

Mortality:

There was no mortality in the study.

Clinical signs:

other: In each group, red-brown staining or fur staining, by the test item was commonly recorded on the day of the exposure and in the observation period, which were considered to be related to the restraint and exposure procedures but not to be toxicologically

Body weight:

In Group 0.1, slight body weight loss (8.5 and 10.4 %) was recorded on the day of treatment. In the observation period, normal body weight gain was recorded in both animals.
In Group 1, slight body weight loss (3.0 – 11.5 %) was recorded on the day of treatment. In the observation period, normal body weight gain was recorded in the surviving animals from Day 1 (9/10) or Day 3 (1/10).

Gross pathology:

A single four hours nose-only exposure of 2,2’-methylenebis[6-(1-methylcyclohexyl)-p-cresol] to Wistar Crl:WI rats dosed at 1.94 mg/L in Sighting exposure or 3.18 mg/L in the Main study was not associated with any test item-related gross changes.

Other findings:

No further findings reported.

Mean achieved actual and nominal aerosol concentration

Part of Study	Target Concentration (mg/L)	Mean Achieved Concentration (mg/L)	Standard Deviation of Achieved Concentration (mg/L)	Nominal Concentration (mg/L)
Sighting exposure: Group 0.1	Maximum attainable	1.94	0.22	49.73
Main study: Group 1	Maximum attainable	3.18	0.27	48.15

 

Mean achieved particle size distribution data (MMAD and GSD)

Part of Study	Target Concentration (mg/L)	Mean Mass Median Aerodynamic Diameter (MMAD) (μm)	Geometric Standard Deviation (GSD)	Inhalable Fraction (%<4μm)
Sighting exposure: Group 0.1	Maximum attainable	3.10	1.96	64.7
Main study: Group 1	Maximum attainable	2.89	1.94	68.9

 

Mortality Data

Day Number	Number of Deaths
	Group 0.1 (Sighting study) (1.94 mg/L)		Group 1 (Main study) (3.148 mg/L)
	Male	Female	Male	Female
0 (During Exposure)	0	0	0	0
0 (After Exposure)	0	0	0	0
1	0	0	0	0
2	0	0	0	0
3	0	0	0	0
4	0	0	0	0
5	0	0	0	0
6	0	0	0	0
7	0	0	0	0
8 – 14	0	0	0	0
Total Deaths	0/1	0/1	0/5	0/5
Grand Total Deaths	0/2		0/10

 

Interpretation of results:

GHS criteria not met

Conclusions:

Under the experimental conditions of the study, no death occurred in a group of 10 Wistar Crl:WI rats (main study) that were exposed to a test atmosphere concentration of 3.18 mg/L for 4 hours. The acute inhalation median lethal concentration (LC50) of 2,2’-methylenebis[6-(1-methylcyclohexyl)-p-cresol] in Wistar Crl:WI rats was therefore considered to be above 3.18 mg/L (the maximum achievable dose concentration).

Executive summary:

Wistar Crl:WI rats were exposed to a test atmosphere of 50% acetone formulation of 2,2’-methylenebis[6-(1-methylcyclohexyl)-p-cresol] at the concentration of 3.18 mg/L of test item, which was considered to be the highest attainable dose concentration. It was not technically feasible to produce an atmosphere without the use of a vehicle; water was not a suitable vehicle.

 

The study was performed in multiple steps. A sighting exposure was performed first, where a test atmosphere of 50% acetone formulation of 2,2’-methylenebis[6-(1-methylcyclohexyl)-p-cresol] at 1.94 mg/L concentration of test item was tested on single animals of both sexes (Group 0.1). As both animals survived the treatment, the main study group (Group 1) of 5 male and 5 female Crl:WI Wistar strain rats were exposed to an aerosol atmosphere of 50% acetone formulation of 2,2’-methylenebis[6-(1-methylcyclohexyl)-p-cresol] at the concentration of 3.18 mg/L.

 

In all study phases, the animals were exposed to the test atmosphere for 4 hours using a nose-only exposure system. Aerosol concentration was measured gravimetrically 17 times during each 4-hour exposure in both parts of the study and the particle size distribution of the test aerosol was determined 3 times. The day of exposure was designated as Day 0 followed by a 14-day observation period.

 

Clinical observations were performed on all animals during exposure at hourly intervals, following removal from restraint, approximately 1 hour after exposure, and daily for 14 days thereafter, as applicable. Body weight was measured on Days 0 (before the exposure), 1, 3, 7 and 14. Gross necropsy was performed on all animals sacrificed on Day 14.

 

No control group was exposed in this study.

 

Results

The quality of the test atmosphere fully complied with criteria documented in the respective guidelines: OECD 403, EPA OPPTS 870.1300 and Council Regulation (EC) No 440/2008.

 

The mean achieved atmosphere concentrations in the study were 1.94 mg/L in Group 0.1 (sighting study), and 3.18 mg/L in Group 1 (main study). The mass median aerodynamic diameters (MMAD) were 3.10 µm and 2.89 µm with geometric standard deviations (GSD) of 1.96 and 1.94 in the Sighting Group and the Main Group respectively.

 

Mortality

There was no mortality in the study.

 

Clinical observations

In each group, red-brown staining or fur staining, by the test item was commonly recorded on the day of the exposure and in the observation period, which were considered to be related to the restraint and exposure procedures but not to be toxicologically significant. In one male alopecia was observed during the observation period, this was considered non-treatment related.

 

The following observations were considered to be related to exposure to the atmospheres:

Group 0.1 (1.94 mg/L with 1 male + 1 female): Laboured respiration (slight to severe), gasping respiration, incoordination (slight) were observed on the day of the treatment. The animals were symptom free from Day 1.

 

Group 1 (3.18 mg/L with 5 males + 5 females): Laboured respiration (slight to severe), noisy respiration (slight), decreased activity (slight to severe) and prone position were recorded. The animals were symptom free from Day 2.

 

These clinical signs observed in both groups are typical of the transient effects of acetone and are not considered as clearly being effects of the test item.

 

Body weight

In Group 0.1, slight body weight loss (8.5 and 10.4 %) was recorded on the day of treatment. In the observation period, normal body weight gain was recorded in both animals.

In Group 1, slight body weight loss (3.0 – 11.5 %) was recorded on the day of treatment. In the observation period, normal body weight gain was recorded in the animals from Day 1 (9/10) or Day 3 (1/10).

 

Necropsy

A single four hours nose-only exposure of 2,2’-methylenebis[6-(1-methylcyclohexyl)-p-cresol] to Wistar Crl:WI rats dosed at 1.94 mg/L in Sighting exposure or 3.18 mg/L in the Main study was not associated with any test item-related gross changes.

 

Conclusion

Under the experimental conditions of this study, no death occurred in a group of 10 Wistar Crl:WI rats (main study) that were exposed to a test atmosphere concentration of 3.18 mg/L for 4 hours. The acute inhalation median lethal concentration (LC50) of 2,2’-methylenebis[6-(1-methylcyclohexyl)-p-cresol] in Wistar Crl:WI rats was therefore considered to be above 3.18 mg/L (the maximum achievable dose concentration).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LC50

Value:

3 180 mg/m³

Quality of whole database:

Klimish score = 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:

July 22 - August 10, 1993.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study performed in accordance with OECD & EU test guidelines in compliance with GLP and reported with a GLP certificate.

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Deviations:

not specified

Qualifier:

according to guideline

Guideline:

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

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

Species: rat
Strain: Bor: WISW (SPF Cpb)
Source: Fa. Harlan Winkelmann, Versuchstierzucht GmbH & Co. KG, Garenstr. 27, 33178 Borchen
Date of receipt: July 14, 1993 (range finding); July 21, 1993 (main test, male); July 14, 1993 (main test, female)
Acclimatization period: at least 5 days
Animal selection: random
Animal identification: with colored markings; cage labelled with dosage, sex, date of study initiation, project no.
Weight range at study initiation: m: 188 - 198 g, f: 177 - 205 g

Husbandry
Housing: individual housing in cages (Makrolon® type II)
Illumination: artificial lighting (120 lux) from 7.00 a.m. - 7.00 p.m.
Temperature: 22 ± 3°C
Relative humidity: 30 - 70 %
Measurement: with thermohygrometer twice daily

Type of coverage:

occlusive

Vehicle:

unchanged (no vehicle)

Details on dermal exposure:

Pre-experimental procedure
Prior to study initiation, the animals were acclimatized to laboratory conditions for at least 5 days. Only healthy animals were used in the test.
24 h before treatment, the fur was removed with electric clippers from an area of roughly 5 x 10 cm on the back of each animal. The skin was subsequently examined for abrasions and animals with healthy, intact skin were then colored for individual identification.

Preparation and application of the test article
A single dermal application of the test article was performed. The substance was held in contact with the skin with a porous gauze dressing and Elastoplast® (Beiersdort).
The exposure period was 24 h. Prior to application and during the application procedure the test substance was liquified by heating up to approx. 50°C and stirring.
The test article was applied in a volume of 1.92 ml/kg.

Duration of exposure:

24 hours

Doses:

Single dose of 2000 mg/kg bw

No. of animals per sex per dose:

2 females for the dose range finding study
5 males & 5 females in the main study

Control animals:

not specified

Details on study design:

Range finding
A preliminary range finding test with a dose of 2000 mg/kg body weight was conducted on two female rats.

Main study
Clinical observations
In each animal a number of clinical-toxicological signs were evaluated according to a modified Irwin-Screening procedure (Screening Methods in Pharmacology, R. A. Turner, 1965, p. 26). The animals were examined at the following post-treatment intervals: 10 min, 1 h, 2 h, 6 h, 24 h, and thereafter once daily up to day 14.
Skin reactions
After patch removal, dermal irritation was evaluated once daily for 14 days according to a scheme based on Draize.
Body weights
Body weights were recorded immediately before treatment (day 0) and on days 7 and
14 p.a. (termination).
Necropsy
The animals were sacrificed by CO2 asphyxiation after 14 days and gross pathological examinations were subsequently performed.

Statistics:

None spceified in the study report.

Preliminary study:

There were no deaths in the preliminary study.

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Mortality:

No animals died during the course of the main study.

Clinical signs:

No abnormal clinical signs were observed.

Body weight:

Weight gains were normal in all aiumals.

Gross pathology:

Gross pathological examinations at 14 days p. a. (terminal necropsy) revealed no test article-dependent findings. Those macroscopic changes observed were attibutable to minor variations which can occur spontaneously in rats of this strain and age.

Other findings:

Very slight erytema was observed in 3 different animals at the day 3, 4 or 7 p.a. At day 6 p.a. a redness of the marginal areas was seen in 7 animals. A formation of scab was observed in some animals between the days 7 and 13 p.a.

INDIVIDUAL DOSES AND PRE-TREATMENT DEATHS – RANGE FINDING

Test article: Mutterlaugenrückstand               Project No.: 10-04-0064/00-93

Species: Rat                                           Animal No.: 6, 7

Sex: f

Animal No.	Sex	Dose (mg/kg)	Volume (mL)	Pre-terminal deaths
				24h	48h	Days p.a.
						3	4	5	6	7	8	9	10	11	12	13	14
6	F	2000	0.34
7	F	2000	0.35

Open boxes: no pre-terminal deaths

 

INDIVIDUAL DOSES AND PRE-TREATMENT DEATHS – MAIN STUDY

Test article: Mutterlaugenrückstand               Project No.: 10-04-0064/00-93

Species: Rat                                           Animal No.: 1 - 10

Sex: m + f                                              Dose: 2000 mg/kg

Animal No.	Sex	Dose (mg/kg)	Volume (mL)	Pre-terminal deaths
				24h	48h	Days p.a.
						3	4	5	6	7	8	9	10	11	12	13	14
1	M	2000	0.36
2	M	2000	0.38
3	M	2000	0.36
4	M	2000	0.36
5	M	2000	0.37
6	F	2000	0.34
7	F	2000	0.35
8	F	2000	0.39
9	F	2000	0.37
10	F	2000	0.35

Open boxes: no pre-terminal deaths

 

CLINICAL OBSERVATIONS

Test article: Mutterlaugenrückstand               Project No.: 10-04-0064/00-93

Species: Rat                                           Sex: m, f

Dose mg/kg	Observation period p.a.	Findings
2000	10 min – day 14 (10/10)	No abnormal clinical signs

Figures in parenthesis indicate number of surviving animals

 

BODY WEIGHTS – INDIVIDUAL VALUES (g)

Dose: 2000 mg/kg

Anim. No.	Sex	Day 0	Day 7 p.a.	Day 14 p.a.
1	M	188	212	240
2	M	198	224	265
3	M	190	210	245
4	M	188	199	222
5	M	194	224	250
6	F	177	192	194
7	F	182	198	201
8	F	205	206	210
9	F	191	200	202
10	F	182	179	185

 

BODY WEIGHTS – MEAN VALUES (g)

Sex	N	Day 0	Day 7 p.a.	Day 14 p.a.
Males	5	191.6 ± 4.3	213.8 ± 10.5	244.4 ± 15.6
Females	5	187.4 ± 11.1	195.0 ± 10.2	198.4 ± 9.4

 

INDIVIDUAL VALUES OF SKIN REACTION

Test article: Mutterlaugenrückstand               Project No.: 10-04-0064/00-93

Species: Rat                                           Dose: 2000 mg/kg

Sex: m, f

Animal No.	Sex	Days p.a.
		1		2		3		4		5		6		7
		Ery	Oed	Ery	Oed	Ery	Oed	Ery	Oed	Ery	Oed	Ery	Oed	Ery	Oed
1	M	0	0	0	0	0	0	0	0	0	0	0+	0	0*	0
2	M	0	0	0	0	1	0	0	0	0	0	0+	0	0*	0
3	M	0	0	0	0	0	0	0	0	0	0	0+	0	0*	0
4	M	0	0	0	0	0	0	0	0	0	0	0+	0	0*	0
5	M	0	0	0	0	0	0	0	0	0	0	0	0	0	0
6	F	0	0	0	0	0	0	1	0	0	0	0	0	0	0
7	F	0	0	0	0	0	0	0	0	0	0	0	0	0	0
8	F	0	0	0	0	0	0	0	0	0	0	0+	0	0*	0
9	F	0	0	0	0	0	0	0	0	0	0	0+	0	0*	0
10	F	0	0	0	0	0	0	0	0	0	0	0+	0	1*	0

Ery = Erythema

Oed = Oedema

+ = redness of the marginal area

* = formation of scab

Interpretation of results:

not classified

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

According to the requirements of the limit test, the LD50 values after 24 hand 14 days were as follows:
male and female > 2000 mg/kg

Executive summary:

The aim of the test was to determine the acute median lethal dose of "Mutterlaugenrückstand". Information derived from this test serves to indicate the existence of possible hazards likely to arise from short-term exposure to the test article by the dermal route.

The test was conducted according to the OECD guideline for the testing of chemicals OECD 402 (February 24, 1987) and to the EEC directive 92/69 EEC (December 29, 1992). The study was cairried out as described in the corresponding protocol approved by the testing facility and the study sponsor on June 28 and July 1, 1993, respectively.

The principles of Good Laboratory Practice for the testing of chemicals as specified by national (BGBI. I, no 13, § 19 a, March 22, 1990) and international (OECD, Paris, 1982) legislation were followed during the performance of the study.

 

SUMMARY

The acute dermal toxicity of "Mutterlaugenrückstand" was investigated in 5 male and 5 female Wistar rats.

On the basis of the range finding results, each animal was given a single dermal administration of "Mutterlaugenrückstand" at a dose of 2000 mg/kg body weight.

The skin was exposed to the test article for 24 h and signs of erythema and oedema were subsequently evaluated once daily for 14 days.

Clinical observations were conducted at regular intervals during the 14-day observation period. Body weights were measured at days 0, 7 and 14 p.a. Gross pathological examinations were performed on animals at termination.

 

The following results were obtained:

1. No abnormal clinical signs were observed.

2. Very slight erythema was observed in 3 different animals at the day 3, 4 or 7 p.a. Redness of the marginal areas (at day 6 p.a.) and formation of scab were seen in some animals.

3. Weight gains were normal in all animals.

4. Gross pathological examinations at 14 days p.a. (terminal necropsy) revealed no test article-dependent findings.

5. According to the requirements of the limit test, the LD50 values after 24 h and 14 days were as follows:

male and female > 2000 mg/kg

6. The above value is higher than the limit specified as harmful by the EEC directive 91/325/EEC When applied to the skin, the test article "Mutterlaugellrückstand" may therefore be classified as "non-toxic".

 

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Quality of whole database:

Klimish score = 1

Additional information

Acute Oral Toxicity:

The aim of the test was to determine the acute median lethal dose of "Mutterlaugenrückstand". Information derived from this test serves to indicate the existence of possible hazards likely to arise from short-term exposure to the test article by the oral route.

 

SUMMARY

The acute oral toxicity of "Mutterlaugenrückstand" was investigated in 5 male and 5 female Wistar rats.

On the basis of the range finding results, the animals were given a single oral administration of "Mutterlaugenrückstand" at a dose of 2000 mg/kg.

Clinical observations were conducted at regular intervals during the 14-day observation period. Body weights were measured at days 0, 7 and 14 p.a. Gross pathological examinations were performed on all animals 14 days p.a.

 

The following results were obtained:

1. No abnormal clinical signs were observed apart from a slight diarrhea in 9 animals at 6 h p.a.

2. Weight gains were normal in all animals.

3. Gross pathological examinations at 14 days p.a. (terminal necropsy) revealed no test article-dependent findings.

4. On the basis of the results obtained after a single oral administration, the LD50 values after 24 hand 14 days were as follows:

male and female > 2000 mg/kg

Acute Inhalation Toxicity

Wistar Crl:WI rats were exposed to a test atmosphere of 50% acetone formulation of 2,2’-methylenebis[6-(1-methylcyclohexyl)-p-cresol] at the concentration of 3.18 mg/L of test item, which was considered to be the highest attainable dose concentration. It was not technically feasible to produce an atmosphere without the use of a vehicle; water was not a suitable vehicle.

 

The study was performed in multiple steps. A sighting exposure was performed first, where a test atmosphere of 50% acetone formulation of 2,2’-methylenebis[6-(1-methylcyclohexyl)-p-cresol] at 1.94 mg/L concentration of test item was tested on single animals of both sexes (Group 0.1). As both animals survived the treatment, the main study group (Group 1) of 5 male and 5 female Crl:WI Wistar strain rats were exposed to an aerosol atmosphere of 50% acetone formulation of 2,2’-methylenebis[6-(1-methylcyclohexyl)-p-cresol] at the concentration of 3.18 mg/L.

In all study phases, the animals were exposed to the test atmosphere for 4 hours using a nose-only exposure system. Aerosol concentration was measured gravimetrically 17 times during each 4-hour exposure in both parts of the study and the particle size distribution of the test aerosol was determined 3 times. The day of exposure was designated as Day 0 followed by a 14-day observation period.

Clinical observations were performed on all animals during exposure at hourly intervals, following removal from restraint, approximately 1 hour after exposure, and daily for 14 days thereafter, as applicable. Body weight was measured on Days 0 (before the exposure), 1, 3, 7 and 14. Gross necropsy was performed on all animals sacrificed on Day 14.

No control group was exposed in this study.

 

Results

The quality of the test atmosphere fully complied with criteria documented in the respective guidelines: OECD 403, EPA OPPTS 870.1300 and Council Regulation (EC) No 440/2008.

The mean achieved atmosphere concentrations in the study were 1.94 mg/L in Group 0.1 (sighting study), and 3.18 mg/L in Group 1 (main study). The mass median aerodynamic diameters (MMAD) were 3.10 µm and 2.89 µm with geometric standard deviations (GSD) of 1.96 and 1.94 in the Sighting Group and the Main Group respectively.

 

Mortality

There was no mortality in the study.

Clinical observations

In each group, red-brown staining or fur staining, by the test item was commonly recorded on the day of the exposure and in the observation period, which were considered to be related to the restraint and exposure procedures but not to be toxicologically significant. In one male alopecia was observed during the observation period, this was considered non-treatment related.

The following observations were considered to be related to exposure to the atmospheres:

Group 0.1 (1.94 mg/L with 1 male + 1 female): Laboured respiration (slight to severe), gasping respiration, incoordination (slight) were observed on the day of the treatment. The animals were symptom free from Day 1.

Group 1 (3.18 mg/L with 5 males + 5 females): Laboured respiration (slight to severe), noisy respiration (slight), decreased activity (slight to severe) and prone position were recorded. The animals were symptom free from Day 2.

These clinical signs observed in both groups are typical of the transient effects of acetone and are not considered as clearly being effects of the test item.

Body weight

In Group 0.1, slight body weight loss (8.5 and 10.4 %) was recorded on the day of treatment. In the observation period, normal body weight gain was recorded in both animals.

In Group 1, slight body weight loss (3.0 – 11.5 %) was recorded on the day of treatment. In the observation period, normal body weight gain was recorded in the animals from Day 1 (9/10) or Day 3 (1/10).

Necropsy

A single four hours nose-only exposure of 2,2’-methylenebis[6-(1-methylcyclohexyl)-p-cresol] to Wistar Crl:WI rats dosed at 1.94 mg/L in Sighting exposure or 3.18 mg/L in the Main study was not associated with any test item-related gross changes.

 

Conclusion

Under the experimental conditions of this study, no death occurred in a group of 10 Wistar Crl:WI rats (main study) that were exposed to a test atmosphere concentration of 3.18 mg/L for 4 hours. The acute inhalation median lethal concentration (LC50) of 2,2’-methylenebis[6-(1-methylcyclohexyl)-p-cresol] in Wistar Crl:WI rats was therefore considered to be above 3.18 mg/L (the maximum achievable dose concentration).

Acute Dermal Toxicity:

The aim of the test was to determine the acute median lethal dose of "Mutterlaugenrückstand". Information derived from this test serves to indicate the existence of possible hazards likely to arise from short-term exposure to the test article by the dermal route.

 

SUMMARY

The acute dermal toxicity of "Mutterlaugenrückstand" was investigated in 5 male and 5 female Wistar rats.

On the basis of the range finding results, each animal was given a single dermal administration of "Mutterlaugenrückstand" at a dose of 2000 mg/kg body weight.

The skin was exposed to the test article for 24 h and signs of erythema and oedema were subsequently evaluated once daily for 14 days.

Clinical observations were conducted at regular intervals during the 14-day observation period. Body weights were measured at days 0, 7 and 14 p.a. Gross pathological examinations were performed on animals at termination.

 

The following results were obtained:

1. No abnormal clinical signs were observed.

2. Very slight erythema was observed in 3 different animals at the day 3, 4 or 7 p.a. Redness of the marginal areas (at day 6 p.a.) and formation of scab were seen in some animals.

3. Weight gains were normal in all animals.

4. Gross pathological examinations at 14 days p.a. (terminal necropsy) revealed no test article-dependent findings.

5. According to the requirements of the limit test, the LD50 values after 24 h and 14 days were as follows:

male and female > 2000 mg/kg

 

Justification for selection of acute toxicity – oral endpoint
Study performed in a GLP accredited laboratory in accordance with OECD Guideline 401 and EU Method B.1.

Justification for selection of acute toxicity – dermal endpoint
Study performed in a GLP accredited laboratory in accordance with OECD Guideline 402 and EU Method B.3.

Justification for selection of acute toxicity – inhalation endpoint
Study performed in a GLP accredited laboratory in accordance with OECD Guideline 403 .

Justification for classification or non-classification

Acute Oral Toxicity:

The LD50 value is higher than the limit specified and the test article may therefore be classified as "non-toxic".

Acute Dermal Toxicity:

The LD50 value is higher than the limit specified and the test article may therefore be classified as "non-toxic".

Acute Inhalation Toxicity:

The LC50 value is higher than the achievable concentration in air and the test article may therefore be classified as "non-toxic".