2,2'-dimethyl-4,4'-methylenebis(cyclohexylamine)

Endpoint summary

Description of key information

The acute oral, dermal and inhalation toxicity was investigated in studies performed comparable to the relevant guidelines, resulting in an oral LD50 of 320-460 mg/kg bw, a dermal LD50 of 200-400 mg/kg bw and an inhalation LC50 of 420 mg/m3. Thus, the substance is harmful to health via the oral route and toxic via the dermal and inhalation route.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

12 July 1978 - 26 July 1978

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Deviations:

yes

Remarks:

The study documentation does not state whether the animals were fed or fasted, as it is often the case in pre-guideline studies. However, the described toxicity fits well into the overall toxicity profile of the test substance.

Principles of method if other than guideline:

BASF-Test

GLP compliance:

no

Remarks:

pre GLP-study

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Weight at study initiation: males: 188 g (mean), females: 165 g (mean)

Route of administration:

oral: gavage

Vehicle:

other: 0.5% aqueous CMC

Details on oral exposure:

VEHICLE
- Concentration in vehicle: 3.16, 4.64, 6.81, 10.0 %

MAXIMUM DOSE VOLUME APPLIED: 10 mL

Doses:

316, 464, 681, 1000 mg/kg bw

No. of animals per sex per dose:

5

Control animals:

not specified

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations: several times on the day of exposure and daily thereafter
- Frequency of weighing: days 0, 2, 7 and 13
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 320 - < 460 mg/kg bw

Mortality:

316 mg/kg bw: no mortality occurred;
464 mg/kg bw: 4 males and 3 females died within 24 h;
681 mg/kg bw: 5 males and 4 females died within 24 h;
1000 mg/kg bw: 5 males and 3 females died within 24 h, all animals died within 48 h.

Clinical signs:

other: dyspnoea, apathy, diarrhoea, poor health state, salivation, blood in stool at all dose groups reported

Gross pathology:

Gross pathology revealed reddening in stomach and gut, scattered occurrence of gastric ulcer, and diarrheic gut contents, acute dilatation of heart in animals that died. No changes were noted in organs of sacrificed animals.

Table 1: Mortality:

Dose (mg/kg bw)	Gender	Conc. %	1 h	24 h	48 h	day 7	day 14
1000	male	10	0/5	5/5	5/5	5/5	5/5
1000	female	10	0/5	3/5	5/5	5/5	5/5
681	male	6.81	0/5	5/5	5/5	5/5	5/5
681	female	6.81	0/5	4/5	4/5	4/5	4/5
464	male	4.64	0/5	4/5	4/5	4/5	4/5
464	female	4.64	0/5	3/5	3/5	3/5	3/5
316	male	3.16	0/5	0/5	0/5	0/5	0/5
316	female	3.16	0/5	0/5	0/5	0/5	0/5

Interpretation of results:

Category 4 based on GHS criteria

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

320 mg/kg bw

Quality of whole database:

similar to OECD TG 401

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:

22 May 1979

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

yes

Remarks:

concentration was measured, but not humidity, temperature and particle size.

Principles of method if other than guideline:

BASF-Test

GLP compliance:

no

Test type:

fixed concentration procedure

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: WIGA, Sulzfeld and MUS RATTUS, Brunnthal, Germany
- Weight at study initiation: 185±15 g (mean)
- Diet: Herilan MRH (H. EGGERSMANN KG) ad libitum
- Water: tap water ad libitum

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose/head only

Remarks:

dynamic method

Vehicle:

other: unchanged (no vehicle)

Analytical verification of test atmosphere concentrations:

yes

Remarks:

gas chromatography

Duration of exposure:

4 h

Concentrations:

0.053, 0.31, 0.41, 0.62 mg/L (analytical concentration) [0.31, 1.41, 1.83, 2.13 mg/L (nominal concentration)]

No. of animals per sex per dose:

10

Control animals:

not specified

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations: daily
- Frequency of weighing: days 0, 7 and 14
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight

Statistics:

Statistical evaluation included a probit analysis accordinmg to D.J. Finney.

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

0.42 mg/L air (analytical)

Exp. duration:

4 h

Sex:

male

Dose descriptor:

LC50

Effect level:

0.44 mg/L air (analytical)

Exp. duration:

4 h

Sex:

female

Dose descriptor:

LC50

Effect level:

0.4 mg/L air (analytical)

Exp. duration:

4 h

Mortality:

0.62 mg/L air: 9/10 (males); 10/10 (females)
0.41 mg/L air: 3/10 (males); 5/10 (females)
0.31 mg/L air: 2/10 (males); 1/10 (females)
0.053 mg/L air: 0/10 (males); 0/10 (females)

Clinical signs:

other: Animals showed apathy, staggering, squatting and abdominal position, ruffled fur and in general clinical symptoms that were indicative of a marked irritant effect on the airways and eyes such as eyelid closure, watery eye and nose discharge and corneal op

Body weight:

Some retardation in body weight gain was observed in the treated animals during the post observation. However, there was no clear dose-response and body weights were not statistically significantly different from control at the end of the postobservation period.

Gross pathology:

Animals that died:
heart: acute dilatation of the right ventricle, acute congestive hyperemia;
lungs: focal hyperemia, additional moderate edema;

Sacrificed animal: no pathologic findings noted.

Test concentrations and mortality:

Dose (mg/L)	male	female
0.62	9/10	10/10
0.41	3/10	5/10
0.31	2/10	1/10
0.053	0/10	0/10

Body weight:

Mean body weight (in g)	male			female
	0 days	7 days	14 days	0 days	7 days	14 days
0.62 mg/L	189 (10)	196 (1)	233 (1)	178 (10)	-	-
0.41 mg/L	180 (10)	166 (7)	233 (7)	177 (10)	188 (5)	209 (5)
0.31 mg/L	181 (10)	189 (8)	234 (8)	184 (10)	185 (9)	198 (9)
0.053 mg/L	190 (10)	202 (10)	240 (10)	184 (10)	189 (10)	203 (10)
control	182 (10)	220 (10)	253 (10)	175 (10)	182 (10)	194 (10)

(): number of animals;

"-": all animals dead.

Interpretation of results:

Category 2 based on GHS criteria

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LC50

Value:

420 mg/m³ air

Quality of whole database:

similar to OECD TG 403

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:

7 September 1978 - 16 November 1978

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Deviations:

yes

Remarks:

two dose levels; scarce study report omitts details of test conditions which are, however, contained in raw data.

Principles of method if other than guideline:

BASF-Test

GLP compliance:

no

Test type:

standard acute method

Limit test:

yes

Species:

rabbit

Strain:

Vienna White

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Weight at study initiation: males: 2.95 kg; females: 3.1 kg
- Diet: SNIFF, ad libitum

Type of coverage:

occlusive

Vehicle:

unchanged (no vehicle)

Details on dermal exposure:

TEST SITE
- Area of exposure: 50 cm² (200 mg/kg bw) and 45 - 102 cm² (400 mg/kg bw)

REMOVAL OF TEST SUBSTANCE
- Washing: After the application time the skin was washed with water/Lutrol (1:1)
- Time after start of exposure: 24 h

Duration of exposure:

24 h

Doses:

200, 400 mg/kg bw

No. of animals per sex per dose:

5

Control animals:

not specified

Details on study design:

- Duration of observation period following administration: 8 days
- Frequency of observations: daily
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 200 - < 400 mg/kg bw

Mortality:

400 mg/kg bw: After day 7 4/5 males and 5/5 female rabbits died and mortality ocurred mainly within the first 24 hours.
200 mg/kg bw: None of the 5 male rabbits died and 3/5 females died within 24 hours.

Clinical signs:

other: Systemic toxicity: cyanosis, apathy, dyspnea, accelerated breathing, abdominal position with flaccid extremities, lateral position, trembling. Local irritations: All animals showed formation of soft necrosis after removal of dressing. The surviving animal

Gross pathology:

Animals that died:
Heart: acutely dilated, right; acute congestion;
Lungs: notable congestion, in some animals edematized;
Liver: gray-white lobular periphery broader.

Table 1: Mortality

Dose (mg/kg bw)	Gender	1 h	24 h	48 h	7 days	14 days
200	male	0/5	0/5	0/5	0/5	0/5
200	female	0/5	3/5	3/5	3/5	3/5
400	male	0/5	3/5	3/5	4/5	4/5
400	female	0/5	5/5	5/5	5/5	5/5

Interpretation of results:

Category 3 based on GHS criteria

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

200 mg/kg bw

Quality of whole database:

similar to OECD TG 402

Additional information

oral

In a study comparable to OECD TG 401, 5 male and 5 female rats per group were dosed with 316; 464; 681 or 1000 mg/kg bw in 0.5 % aqueous carboxymethylcellulose preparation. While complete mortality was observed at the highest dose level, mortality rates in the mid dose groups were 90 respectively 70 % and no rats died when treated with 316 mg/kg bw. Clinical symptoms were unspecific (BASF AG 1979a). The LD50 rat was 320-460 mg/kg bw.

inhalation

In a study similar OECD TG 403, 10 rats per sex and dose group were exposed to analytical aerosol concentrations of 53; 310; 410 or 620 mg/m³. While 9 males and 10 females died at the highest concentration, mortality rates in the mid dose groups were 40 resp. 15%. No rats died at the lowest concentration. The LC50 rat (inhalation, liquid aerosol) was 420 mg/m³/4h (BASF AG 1979b).

A supporting report stated that as a result of exposure of rats to saturated test item atmosphere (concentration not given) at 20°C for 4 or 8 hours, 1/6 animals died after 8 h exposure (BASF AG, 1957).

dermal

In a study similar to OECD TG 402 necrotic skin changes at the application site were reported when 5 animals per sex and per dose group treated with the undiluted test substance were examined. While 4 males and 5 females died when treated with 400 mg/kg bw, none of the males and 3 females died when treated with 200 mg/kg bw. The LD50 rabbit was 200-400 mg/kg bw (BASF AG 1979c).

Furthermore, there a several other acute oral, dermal as well as inhalative toxicity studies on different species available, which were not considered for hazard assessment due to their weak reliability (reliability 3, not reliable).

Justification for classification or non-classification

Classification, Labeling, and Packaging Regulation (EC) No 1272/2008

2,2'-dimethyl-4,4'-methylenebis(cyclohexylamine) is listed in Annex VI of Regulation (EC) No 1272/2008 with cat. 3 for acute dermal and inahaltion (H311 and H 331) and cat. 4 (H302) for acute oral expsoure as a minimum classification. However, the available data for acute toxicity are reliable and suitable for classification purposes under Annex I of Regulation (EC) No 1272/2008. Based on these data, 2,2'-dimethyl-4,4'-methylenebis(cyclohexylamine) is considered to be classified for acute oral toxicity cat. 4 (H302), acute inhalation toxicity cat. 2 (H330) and for acute dermal toxicity cat. 3 (H311) under Regulation (EC) No 1272/2008, as amended for the twelfth time in Regulation (EU) 2019/521.