2,4,6-triisopropyl-m-phenylene diisocyanate

Endpoint summary

Description of key information

1. Acute oral toxicity (1990), GLP, OECD 401, rats, gavage, limit test with 2000 mg/kg, LD50 >2000 mg/kg bw
2. Acute inhalation toxicity (1990), GLP, OECD 403, rats, nose/head-only, 4 h, nominal concentrations: 0 (air control), 0 (acetone control, acetone: 212 mg/m³), 300, 306, 500, 700, 1000, 625 and 1250 mg/m³ air, LC50 = 110 mg/m³ air, NOAEC = 20 mg/m³ was taken for DNEL derivation.

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:

1989-05-23 - 1989-06-06

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Version / remarks:

Limit test

Deviations:

yes

Remarks:

acclimatisation period only 4 days

Qualifier:

according to guideline

Guideline:

other: Richtlinie 84/449/EWG (Amtsblatt der Europäischen Gemeinschaften Nr. L 251 vom 19.09.1984, S.96)

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Wistar

Remarks:

Strain Bor: WISW (SPF Cpb)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Winkelmann, Borchen,
- Age at study initiation: 7 weeks (male), 10 weeks (female),
- Weight at study initiation: ca. 171 g (male), ca. 166 g (females, which were nulliparous and not pregnant),
- Fasting period before study: 16 hours before and up to 4 hours post application the animals did not receive any food (before and after this period the standard diet was given ad libitum).
- Housing: conventionally in cages equipped on low dust wood granules.
- Other: all animals in this study were housed in one room. In cases animals from other toxicological studies were housed in the same room. However appropriate organisational measures were taken to exclude confusion or any interference. The animal room was disinfected once weekly and 1 to 3 times a year a pest control was undertaken. On these occasions a contamination of the diet or any contact to the animals was excluded. The cage racks were cleaned in regular intervals and drinking bottles, lid of cages and feeding dishes were exchanged regularly. The complete cage was cleaned with hot water.
- Diet (e.g. ad libitum): "Fixed-formula"-standard diet (Altromin® 1324 Pellets (producer: Altromin GmbH und Co KG, Lage)). For feeding mangers the lids in the cage were used. The standard diet was regularly controlled and analysed for its nutritive composition and degree of contaminant with spot samples.
- Water (e.g. ad libitum): Drinking water ad libitum, the drinking bottles comprised a volume of 700 ml and were out of polycarbonate.
- Acclimation period: 4 days.

ENVIRONMENTAL CONDITIONS
- Temperature: 22 ± 2 °C,
- Humidity: ca. 50 ± 10 %,
- Air changes: ca. 10-times air change per hour,
- Photoperiod: 12-hour light dark cycle (artificial illumination from 6 to 18 o'clock MEZ).

All animals were marked with pricrinic acid (fur, chronologically numbered), the cages were marked with: substance name, type of animal, dosing, study number, application type, sex and number of animals.

Route of administration:

oral: gavage

Vehicle:

peanut oil

Remarks:

DAB0 - (Oleum Arachidis) Henry Lamotte, Charge 5917

Details on oral exposure:

VEHICLE
- Amount of vehicle (if gavage): 10 mL/kg bw

Doses:

2000 mg/kg bw.
According to the OECD - Guideline 401 (1987), it is sufficient to characterise the acute oral toxicity with doses up to 2000 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 and weighing: observations were made twice daily (on day 0 of application observations were made several times, only daily on weekends and official holidays), the bodyweights were determined weekly
- Necropsy of survivors performed: yes (All remaining animals were sacrificed at the end of the observation period after inhalation of diethylether. Every animal was submitted to a gross pathology and the findings were recorded individually.)
- Other examinations performed: clinical signs, body weight, histopathology

Statistics:

If a calculation of the mean (median) lethal dose (LD50) was possible, it was conducted via a computer assisted maximum-likelihood-method. Where the results would show 0 and 100 % mortality, the geometric mean will be used as an approximate LD50 value.
If values of 0 % and 100 % mortality appeared, the geometric mean was taken as approximate LD50.

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Remarks on result:

other: Only one female died

Mortality:

Within the 14 day observation period, only one female animal died.

Clinical signs:

other: Day 0: After application of 2000 mg/kg bw all animals showed piloerection. Day 1: the surviving animals showed collectively increased urine production. Day 2: all surviving animals were symptom free. In the female rat which died 3 hours after applicati

Gross pathology:

The gross pathology investigation of the female rat (died on the day of application) revealed: hyperaemic lung and stomach.
All animals sacrificed at the end of the observation period were pathologically and anatomically normal.

Other findings:

No other findings were reported

Table 1: summary of clinical symptoms and death

Intensity and occurrence of symptoms and death
males
Doses (mg/kg)	2000
Application volume (mL/kg)	10
Way of application	PON
Number-dead animals	0
Number- animals with symptoms	5
Number- used animals	5
Starting time of symptoms	15'
Free of symptoms from... On	2d
Occurrence of death from	---
Occurrence of death till	---
	Number of animals / highest intensity
piloerection	5/2
polyuria	5/*
females
Doses (mg/kg)	2000
Application volume (ml/kg)	10
Way of application	PON
Number-dead animals	1
Number- animals with symptoms	5
Number- used animals	5
Starting time of symptoms	15'
Free of symptoms from... On	2d
Occurrence of death from	3h
Occurrence of death till	---
	Number of animals / highest intensity
piloerection	5/2
hypersalivation	1/2
laboured breathing	1/1
polyuria	4/*
* observation without specifying intensity

Interpretation of results:

GHS criteria not met

Remarks:

Criteria used for interpretation of results: other: EU-GHS

Conclusions:

The study was performed according to the OECD TG401 with only minor deviations and therefore considered to be of the highest quality (reliability Klimisch 1). The validity criteria of the test system are fulfilled. The test material did not induce treatment-related mortality. The clinical signs were piloerection and increased urine production. The test material was considered to be relatively non-toxic under the conditions of the test. The LD50 was identified to be >2000 mg/kg body weight.

Executive summary:

A study on the acute oral toxicity of 2,4-Triisopropylbenzoldiisocyanat for male and female Wistar rats (Bomhard, 1990) was conducted according to the OECD Guideline 401 - standard acute method with the only deviation that the acclimatisation period was only 4 days. This deviation is not judged to influence the results of the study significantly. A dose of 2000 mg/kg bw of the test substance was administered via gavage to the rats. Observations were made for a period of 14 days. No treatment-related mortalities or signs of systemic toxicity, beside piloerection during the first 24 hours following administration and an increased urine production on the following day, were observed.

One female rat died 3 hours after application, as clinical signs hypersalivation and laboured breathing were noted.

No treatment-related body weight changes were reported.

In the one female rat pathological abnormalities (hyperaemic lung and stomach) were found, in all other animals sacrificed at the end of the observation period no pathological findings were noted. The acute oral median lethal dose (LD50) of the test material in rats of both sexes observed over a period of 14 days was estimated to be greater than 2000 mg/kg bw.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

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:

1990-01-04 - 1990-11-19

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

yes

Remarks:

only 10 air changes per hour

GLP compliance:

yes

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

Wistar

Remarks:

Strain Bor: WISW (SPPVCpb)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Young adult, healthy specific-pathogen free Wistar rats (strain Bor: WISW (SPF Cpb)) from Winkelmann, Borchen, Kreis Paderborn, were used.
- Identification of animals: Individual colour codes and cages numbers.
- Randomisation: After the acclimatisation period (before beginning of the experiment) all animals were examined regarding their physical conditions. Afterwards the animals were randomly assigned to the different groups.
- Age/weight at study initiation: 170 - 210 g. Animals with these weights are usually 2 -3 months old (young adult), females were nulliparous and not pregnant
- Housing conditions: During the adaptation, as well as test time, the animals were housed conventionally in Makrolon cages type III (5 animals per cage) (according to Spiegel, A., GONNERT, R, Zschr. Laboratory Animal Science 1, 38 (196l) and MASTER , GQ, Zschr. Laboratory Animal Science 7, 144-153 (1965)). The cages (including water bottles and unused food) were changed at least once a week.
- Bedding: as bedding material low-dust wood granules type S 8 / 15 from Ssniff, D4 770 Soest, Westphalia were used. The wood pellets were randomly tested for harmful substances. The analysis results are stored. The analysis results revealed no evidence for an influence of the objective.
- Animal room: all animals of one concentration were housed in one animal room. From time to time for reasons of capacity rats from other toxicological studies were placed in the same animal room. By an adequate physical separation (different cage racks), a clear animal and cage identification and organisational measures within the work flow a mix of animals was avoided.
- Diet/water: Fixed-formula - diet ( "Altromin®1324 - Haltungsdiät für Ratten und Mäuse" (Producer: Altromin GmbH, Lage, Germany)) and tap water, ad-libitum.
- Acclimation period: 5 days

- Cleaning, disinfection, pest control:
The animal room was cleaned at least once a week and disinfected with Zephirol-10 % (1 % in water). A contamination of the food and contact with animals has been excluded. Pest controls have not been conducted in the animal room during the study.

ENVIRONMENTAL CONDITIONS

- Temperature (°C): 20 - 24 °C
- Humidity (%): ca. 50 % (relative)
- Air changes (per hr): ca. 10-times per hour
- Photoperiod (hrs dark / hrs light): 12-hour, from 6 to 18 o'clock MEZ (artificial illumination)

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose/head only

Vehicle:

other: acetone was partially used as vehicle for production of the aerosol

Details on inhalation exposure:

During the experiment rats were exposed to the aerosol in an exposure-tube (made from plexiglas). The size of those tubes was adapted to the size of the rats. The tubes (Rhema Labortechnik) were built in a way, which guaranteed, that the tail of the rat was outside of the tube. That bears the advantage that the risk of hyperthermia can be minimised. The exposure procedure was equivalent to head-nose-exposure. Any contamination of the fur can be avoided with using this type of exposure condition.
The inhalation chambers used are commercially available (Rhema Labortechnik, Am Stegskreuz 2, Hofheim).

Exposure technique
The aerosol was sprayed under dynamic conditions in a cylindrical inhalation chamber with pre-cleaner ('Baffle'). Made from PVC, the inhalation chamber had the following dimensions: diameter = 30 cm, height = 28 cm (volume: 20 litres).
In the studies, the relationship between supply and exhaust air was such that approximately < 80 % was extracted of the dynamic air supplied via an aerosolfilter (cotton-containing cylinder). The exposure system was therefore able to form an air flow towards the rats. The inhalation chambers were operated in deductions. The intake air was purified through an absolute filter.

Conditioning the air:
The compressed air was generated with two parallel Boge Compressors (type SB 270/15/350D). The compressed air was fully automatically conditioned with a downstream VIA-air dryer (type A 110), meaning to free it of water, dust and oil. The operating control pressure of the compressors is 8 to 10 bar (800 to 1000 kPa). The working pressures were set by reducers.

Aerosol generation:
With the aid of a nozzle (two-fluid nozzle, Rhema Labortechnik) and a Braun infusion pump with a 50 mL glass-cut syringe and with the aid of conditioned air (10 litres of air per minute, dispersion pressure approximately 500 kPa) the test substance atomised under dynamic conditions into a 2 L three-necked flask. For means of deposition of larger particles additionally a glass pre-cleaner (Pitt No. 1, see ASTM method) was used. The glass pre-cleaner was located between the three-necked flask, and the inhalation chamber.
The three-necked flask (baffled) and the pre-separator increase (Pitt No. 1) the efficiency of the aerosol generation and the respirable mass fraction. For aerodynamic reasons the income of the conditioned air was either before or after the pre-separator. This had an influence on the recovery rate.
The acetone test atmosphere (group 2) was generated as follows: 3 mL of acetone were placed in a tube and impinger led by a TELAB BF411 Mini-dosing pump into the air incoming to the inhalation chamber.

Air exchange:
The generation of the aerosol conditions afforded a 30-hour air changes in the inhalation chamber. Under conditions of this test arrangement, the equilibrium is ('steady state') in about 6 minutes operation achieved (. tqc-* = 3 * Chamber volume / air flow, McFarland, 1976).

Analytical verification of test atmosphere concentrations:

yes

Remarks:

Analysis of the particle distribution of the aerosol in the breathing zone of the rats showed a high inhalable mass fraction. The analytical verification revealed differences from nominal to analytical concentrations and were included in interpretation.

Duration of exposure:

4 h

Concentrations:

Nominal concentrations (mg/m3 air):

Group 1: 0 (air control)
Group 2: 0 (acetone control, acetone: 212 mg/m³)
Group 3: 300
Group 4: 306
Group 5: 500
Group 6: 700
Group 7: 1000
Group 8: 625
Group 9: 1250

No. of animals per sex per dose:

5

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 4 weeks
- Frequency of observations and weighing: Records were made twice daily (mornings and evenings), bodyweights were determined manually before exposure, on day 3 and 7 post exposure, and then weekly.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight, histopathology, reflex testing, rectal temperatures

Statistics:

Analytical concentrations: From all single measures of the analytical air concentrations the mean was calculated.

Calculation of LC50: Where it was possible to calculate a mean lethal concentration (LC50), it was conducted computer-assisted after the method of A.P. Rosiella, J.M. Essigmann and G.N. Wogna (1977); modified after Pauluhn (1983) based on the Maximum-Likelihood-Method from C.I. Bliss (1938).

Body weights: arithmetic mean and standard deviation. The averages were shown graphically as a function of time - separately for male and female rats
The evaluation of the body weight differences was done with the developments described in the analysis of variance (ANOVA).
In this method, a parametric normal distribution of data by comparison of median and mean will be reviewed. The groups were compared on the level of confidence = 95 % (p = 0.05). An examination of the homogeneity of variances between groups was performed using the Box test. This test is preferred for small sample size compared to the Bartlett's test. In case, that the results in the F-test show that the variance is greater in the group than between groups, this is indicated in the notes as "no statistical difference between the groups". If a difference is found, a pairwise post hoc comparison of groups (one-and two-sided) for the Games and Howell's modification of Tukey-Kramer significance test is conducted.
The software for the analysis of variance comes from the BCTIC Computer Code Collection, modified by Pauluhn. The validation the software was done by data sets from the literature (GAD and Weil, 1982; BCTIC). The calculations are performed AG on a HP 3000 computer system, Department of Toxicology, BAYER.
Rectal temperature values were statistically analysed with ANOVA program.

Preliminary study:

No information on preliminary studies available.

Sex:

male/female

Dose descriptor:

LC50

Effect level:

110 mg/m³ air (analytical)

Based on:

test mat.

95% CL:

>= 96 - <= 126.9

Exp. duration:

4 h

Sex:

male/female

Dose descriptor:

other: NOEL

Remarks:

used as NOEC

Effect level:

10 mg/m³ air (analytical)

Based on:

test mat.

Exp. duration:

4 h

Sex:

male/female

Dose descriptor:

other: NOAEC

Effect level:

20 mg/m³ air (analytical)

Based on:

test mat.

Exp. duration:

4 h

Mortality:

The rats died in a two-phase manner, either during the first three post observation days or delayed during the 12th to 20th post observation day.

Clinical signs:

other: GROUP 1 - 3: all rats tolerated the exposure without clinical symptoms. GROUP 4: reduced motility and piloerection. After day one after application all animals were clinically without symptoms. GROUP 5: reduced and laboured breathing, hyperfrequent breath

Body weight:

In all animals dosed with concentrations higher than 61.2 mg/m³ the body weights were reduced.

Gross pathology:

Rats that were sacrificed at the end of the observation period (4-weeks):
Gross pathology revealed in animals dosed with concentrations higher than 61.2 mg/m³ signs of macroscopically recognisable lung injuries (pale and liver-like lungs, bronchial airways partly filled with highly viscous mucus).

Rats killed at the end of follow up: the pathological examinations revealed from group 5 on signs of macroscopically detectable lung damage (lung pale and liver-like appearance, bronchial tubes partially filled with highly viscous mucus).

Rats died intercurrent: hydrothorax; serous nasal discharge; airways filled with highly viscous mucus; lung inflated, reddish to liver-like (hepatisation) and oedematous; pale spleen, liver and kidneys; liver with lobular marking; gastrointestinal tract (mucosa), red, in the lumen of a yellow / bloody phlegm.

Other findings:

REFLEX TESTING
Conducted on day 0, 1 or day 2, no treatment-related observations were noted.

RECTAL TEMPERATURE
At the end of the observation period, from group 5 (61 mg/m³ air) and higher concentrations a toxicological relevant hypothermia was noted.

INTERCURRENT DECEASED RATS
hydrothorax, serous nasal discharge, bronchial airways filled with highly viscous mucus, distended lungs, hepatisation of the lungs, oedema of the lungs. Spleen, liver and kidneys were pale, lobular liver details, reddened GIT-mucosa, GIT filled with yellowish bloody mucus.

The results, which were obtained using the aerosol (4 hours of exposure), are depicted in the following table (group number is indicated with N)

Table 1:Toxicological results - exposure.: 1x4h

N	concentration (mg/m^3 air)		toxikol. result	duration of symptom	time of death	rel. mass < 3 - 5µm (%)
	nominal	analytical
rat (male)
1	air control		0/0/5	--	--	-
2	acetone-control		0/0/5	--	--	-
3	300	10.4	0/0/5	--	--	-**
4	306	20.0	0/5/5	4h - 6h	--	95
5	500	61.2	0/5/5	4h - 28d	--	95
6	700	79.1	1/5/5	4h - 28d	15d	79
7	1000	132.1	5/5/5	4h - 2d	1d - 2d	98
8	625	151.3	3/5/5	4h - 28d	2d	100
9	1250	249.9	5/5/5	4h - 1d	0d - 1d	96
rat (female)
1	air-control		0/0/5	--	--	-
2	acetone-control		0/0/5	--	--	-
3	300	10.4	0/0/5	--	--	-**
4	306	20.0	0/5/5	4h - 6h	--	95
5	500	61.2	0/5/5	4h - 28d	--	95
6	700	79.1	0/5/5	4h - 11d	--	79
7	1000	132.1	5/5/5	4h - 20d	1d - 20d	98
8	625	151.3	4/5/5	4h - 28d	12d - 13d	100
9	1250	249.9	5/5/5	4h - 1d	0d - 1d	96

**evaluation not possible; approximation: 1µL = 1mg

In the table in the column toxicol. result the first number indicates the number of dead animals, the second number indicates the number of animals with symptoms and the third number indicates the total number of animals.

LC50 (male./female) summarised:

LC50= 110 mg/m³ air*

confidence interval (95%)= 96.0 - 126 .9 mg/m³ air

slope = 3.01

NOEC = 10 mg/m³ air*

*These concentrations indicate the analytical concentrations in the airways of the rats.

Symptoms and mortality:

From 20 mg/m³ air on, unspecific symptoms (piloerection, reduced motility) were noted. From 61 mg/m³ air additionally typical isocyanat symptoms were noted (hypothermia, laboured breathing and in cases breathing noises, as well as cyanosis, reddened rhinarium, lethargy and reduced body weights). 10 mg/m³ air were tolerated without clinical symptoms.

The animals that died during the experiment, died biphasically (within the first 3 observation days, or after 10 to 12 days post applicationem). Death is considered to be mainly induced by the irritation potential of the test substance (free fluid in the pleural cavity, acute oedema of the lungs). The surviving rats (group 61 mg/m³ air) had highly viscous mucus in the bronchial branches.

Interpretation of results:

Category 1 based on GHS criteria

Remarks:

Criteria used for interpretation of results: other: EU-GHS

Conclusions:

The study was performed according to the OECD Guideline 403 with only negligible deviations and therefore considered to be of the highest quality (reliability Klimisch 1). The validity criteria of the test system are fulfilled. The test material did induce signs of acute inhalation toxicity. The test material was considered to have a high acute inhalation toxicity for rats under the conditions of the test, which is based on the LC50 values derived from this study (LC50 = 110 mg/m³ air (confidence interval (95 %) = 96.0 - 126 .9 mg/m³ air); NOEC = 10 mg/m³ air). Having regard to the concentration of 10 mg/m³ air, which has been tolerated without any symptoms, and the low vapour pressure at room temperature (1.1 mg/m³ air saturation concentration) exposure to the product shows no increased potential danger for people.
The concentration of 20 mg/m³ associated with unspecific symptoms (piloerection, reduced motility) without pathological changes is considered to be the NOAEC.

Executive summary:

A study on the acute inhalation toxicity of 2,4-Triisopropylbenzoldiisocyanat (aerosol) for rats was conducted according to OECD Guideline No. 403.

The exposure was conducted via head-nose-only exposure of groups of five male and five female rats to a test atmosphere containing a concentration between 10 and 250 mg (analytical) of the test item per m³ for a single 4 -hour period. The Mass Median Aerodynamic Diameter was between 1.6 and 1.88 µm. After exposure the animals were observed for 4 weeks.

From 20 mg/m³ air on, unspecific symptoms (piloerection, reduced motility) were noted. From 61 mg/m³ air additionally typical isocyanat symptoms were noted (hypothermia, laboured breathing and in cases breathing noises, as well as cyanosis, reddened rhinarium, lethargy and reduced body weights). 10 mg/m³ air were tolerated without clinical symptoms.

The animals that died during the experiment, died biphasically (within the first 3 observation days, or after 10 to 12 days post applicationem). Death is considered to be mainly induced by the irritation potential of the test substance (free fluid in the pleural cavity, acute oedema of the lungs). In the necropsies performed in the animals of group 5 (61 mg/m³ air), a highly viscous mucus was found in the bronchial branches. It was concluded that the 4-hour LC50 value was higher than 110 mg/m³ for both sexes under the present test conditions. The present data suggests the conclusion that a 2,4 Triisopropylbenzoldiisocyanat aerosol has a high impact on most of the lung periphery or the terminal / central bronchioles.
The studies thus show that the test substance has a high acute inhalation toxicity. Considering the acute symptoms tolerated concentrations of 10 mg / m³ air and the low vapour pressure at room temperature (1.1 mg / m³ air saturation concentration) can be recognized to have no increased risk for acute toxicity for people involved in using the product. The concentration of 20 mg/m³ associated with unspecific symptoms (piloerection, reduced motility) without pathological changes is considered to be the NOAEL

Results:

LC50 - Inhalation-Aerosol (Exposition: 4h)

Rat (male/female): 110 (96 - 127) mg/m³ air (analytical conc.)

NOEC = 10 mg/m³ air (analytical conc.)

NOAEC = 20 mg/m³air (analytical conc.)

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LC50

Value:

110 mg/m³ air

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Acute oral Toxicity:

A study on the acute oral toxicity of 2,4,6-triisopropyl-m-phenylene diisocyanate for male and female Wistar rats (Bomhard, 1990) was conducted according to the OECD Guideline 401 - standard acute method with the deviation that the acclimatisation period was 4 days only. This deviation is not judged to influence the results of the study significantly. As dose 2000 mg/kg bw of the test substance was administered via gavage to the rats. Observations were made for a period of 14 days. No treatment-related mortalities or signs of systemic toxicity, beside piloerection during the first 24 hours following administration and an increased urine production on the following day were observed. One female rat died 3 hours after application, where as clinical signs also hypersalivation and laboured breathing were noted. No treatment-related body weight changes were reported. In the one female rat pathological abnormalities (hyperaemic lung and stomach), in all other animals, sacrificed at the end of the observation period no pathological findings were noted. The acute oral median lethal dose (LD50) of the test material in rats of both sexes observed over a period of 14 days was estimated to be greater than 2000 mg/kg bw.

 

Acute dermal toxicity:

Even though no data is available for the substance of interest, the two available routes are sufficient to fulfil the requirements laid out in REACH Regulation (EC) No 1907/2006. Therefore this exposure route does not need to be investigated further especially since the exposure of humans via the dermal route is not likely.

 

Acute inhalation Toxicity:

A study on the acute inhalation toxicity of 2,4,6-triisopropyl-m-phenylene diisocyanate (aerosol) for rats (Pauluhn, 1990) was conducted according to OECD Guideline No. 403. The exposure was conducted via head-nose-only exposure of one group of five male and five female rats to a test atmosphere containing a concentration between 10 and 250 mg (analytical) of the test item per m³ for a single 4 -hour period. The Mass Median Aerodynamic Diameter was between 1.6 and 1.88 µm. After exposure the animals were observed for 4 weeks. From 20 mg/m³ air on, unspecific symptoms (piloerection, reduced motility) were noted. From 61 mg/m³ air additionally typical isocyanate symptoms were noted (hypothermia, laboured breathing and in cases breathing noises, as well as cyanosis, reddened rhinarium, lethargy and reduced body weights). 10 mg/m³ air were tolerated without clinical symptoms. 20 mg/m³ air were tolerated with unspecific symptoms and no pathological changes. The animals, which died during the experiment, died biphasically (within the first 3 observation days, or after 10 to 12 days post applicationem). Death is considered to be mainly induced by the irritation potential of the test substance (free fluid in the pleural cavity, acute oedema of the lungs). In the necropsies performed in the animals of group 5 (61 mg/m³ air), a highly viscous mucus was found in the bronchial branches. It was concluded that the 4-hour LC50 value was higher than 110 mg/m³ for both sexes under the present test conditions. The present data suggests the conclusion that a 2,4,6-triisopropyl-m-phenylene diisocyanate aerosol has a high impact on most of the lung periphery or the terminal / central bronchioles.
The studies thus show that the test substance has a high acute inhalation toxicity. Considering the acute symptoms tolerated concentrations of 10 mg / m³ air and the low vapour pressure at room temperature (1.1 mg / m³ air saturation concentration) can be recognized to have no increased risk for acute toxicity for people involved in using the product.

The concentration of 20 mg/m³ associated with unspecific symptoms (piloerection, reduced motility) without pathological changes is considered to be the NOAEC.

Additionally the substance was subject to an investigation of the influence of the concentration and the particle size on the acute inhalation toxicity by Pauluhn et al. (2004). This publication reports the substance TRIDI to cause lesions at the alveolar and the airway level. In general the main information given by the author includes that the methodologies used in inhalation toxicity studies for the generation of respirable aerosols may not be translated directly into the hazards likely to occur during normal handling and use, and without specific considerations of the measures actually taken to generate airborne particulates of both sufficiently high concentration and respirability. Additionally they state that a state-of-the-art hazard characterisation needs to include aspects of the specific conditions employed in an inhalation test along with those likely to occur during common handling and use of the product. An extensive micronisation of organic particles not only increases the active surface area, it may also increase their rate of decomposition and dissolution. This means rate-dependent decomposition processes may be dependent on the pre-treatment of dust.

The comparison of data suggests that lethality is most likely related to both the relative irritant potency of respirable particles as well as the lung region predominantly involved.

Thus, the experimental evidence suggests that for solid and non-volatile aerosols the irritant mode of action causing the critical lesion within the respiratory tract is apparently more dependent on the specific site receiving the highest fraction of dose rather than the total airborne concentration. Upon deposition, the rate of dissolution and chemical reactivity towards nucleophilic agents contained in the lining fluids might be decisive for the outcome of study. Highly reactive substances may readily overcome the ‘neutralizing’ capacity of this barrier, leading then to damage of cell membranes and cytotoxicity. For agents likely to be decomposed in the lining fluids of the lung, the rate of formation of reactive intermediates, which is contingent upon particle size, their surface (re)activity and associated kinetics of dissolution, might be dependent on the specific measures taken to optimize particle size. In summary, this analysis demonstrates that for irritant particulates the concentration and particle size are equally important for the outcome of test, independent of whether a lethal or non-lethal endpoint is chosen. For a meaningful risk characterisation, test results from inhalation studies using specifically optimised particle size ranges of irritant aerosols need to be compared with the actual properties of the substance as it is marketed and handled.

 

 

Justification for classification or non-classification

Acute oral toxicity:

The test material does not meet the criteria for classification and will not require labelling for oral toxicity in accordance with Regulation (EC) No 1272/2008.

Acute dermal toxicity:

The test material does not meet the criteria for classification and will not require labelling for dermal toxicity in accordance with Regulation (EC) No 1272/2008.

Acute inhalation toxicity:

The test material meets the criteria for classification (category 1) and will require labelling for inhalation toxicity in accordance with Regulation (EC) No 1272/2008. It falls into acute toxicity inhalation Cat 1, H330. In addition the substance is classified as STOT SE Cat 3., H 335. The signal word danger and the label GHS06 and GHS08 will have to be added.