Carbamic acid, (2-hydroxypropyl)-, compd. with 1-amino-2-propanol (1:1)

Endpoint summary

Description of key information

In a combined repeated dose toxicity study with the reproduction/developmental toxicity screening test (OECD TG 422) 1-amino-2-propanol was administered orally via gavage to groups of 12 male and 12 female Wistar rats at doses of 100, 300, and 1000 mg/kg body weight/day. Duration of treatment covered a 2 week premating period and a mating period in both sexes, approximately 2 weeks post-mating in males (in total 38 days exposure), and the entire gestation period and 4 days of lactation in females (in total 46 days of exposure). The NOAEL for general, systemic toxicity of the test substance is 300 mg/kg bw/day for the parental males based on some indications for a mild anemic process. 
The NOAEL for repeated dose toxicity of carbamic acid, (2-hydroxypropyl)-, compound with 1-amino-2-propanol (1:1) is considered as 300 mg/kg bw per day, based on indications for a mild anemic process in males after oral uptake of the cleavage product 1-amino-2-propanol.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: oral

Remarks:

combined repeated dose and reproduction / developmental screening

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Qualifier:

according to guideline

Guideline:

OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

Qualifier:

according to guideline

Guideline:

other: US EPA OPPTS 870.3650

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Research Models and Services, Germany
- Age at study initiation: 11-13 wks
- Weight at study initiation: Males: 267-309 g; Females: 187-218 g
- Housing: individual
- Diet and water: ad libitum (except during the fasting period and measurement of motor activity)
- Acclimation period: at least 6 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 24
- Humidity (%): 30 - 70
- Photoperiod (hrs dark / hrs light): 12 / 12

Route of administration:

oral: gavage

Vehicle:

water

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
For preparation of the administration solutions, the test substance was weighed in a graduated measuring flask, toped with tap water and dissolved by shaking. The test substance solutions were prepared at the beginning of the administration period and thereafter at intervals that took into account the stability of the test substance preparation.

VEHICLE
- vehicle: tap water
- Concentration in vehicle: test group 1 - 0; test group 2 - 1.53 g/100 ml; test group 3 - 4.59 g/100 ml; test group 4 - 15.29 g/100 ml
- Amount of vehicle including test substance solution (if gavage): 10 ml
- Purity: calculated value taking into accout the nominal active ingredient content of 65.4g/100ml

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Concentration control analyses were conducted with samples drawn from all doses at the start and at the end of the administration period. Analyses of the test substance dosing solutions in tap water confirmed the targeted concentrations. Generally, the analytical values of the samples corresponded to the expected values within the limits of the analytical method, i.e. were above 90% and below 110% of the nominal concentrations

Duration of treatment / exposure:

Total exposure period: males: 38 days; females: 46 days
Duration of test: 54 days
At least 13 days after the beginning of treatment, males and females from the same dose group were mated overnight in a ratio of 1:1 (details of pairing see chapter 'Toxicity to Reproduction'). On study day 36, a functional observational battery and motor activity measurement were carried out in the first five male animals per group. Blood from 5 F0 males per group was sampled under Isoflurane anesthesia on study day 38 followed by necropsy of all male animals under CO2 anesthesia. The females were allowed to litter and rear their pups until day 4 after parturition. On study day 43 a functional observational battery and motor activity measurement were carried out in the first five female animals per group. Blood from 5 F0 females per group was sampled under Isoflurane anesthesia on study day 45 followed by necropsy of all female animals and their pups under CO2 anesthesia.

Frequency of treatment:

once daily

Remarks:

Doses / Concentrations:
0, 100, 300, 1000 mg/kg bw per day
Basis:
other: actual ingested (as the hydrochloride salt of isopropanolamine)

No. of animals per sex per dose:

12

Control animals:

yes, concurrent vehicle

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: at least once daily for any signs of morbidity, pertinent behavioral changes and signs of overt toxicity. Abnormalities and changes were documented for each animal

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: performed in all animals prior to the administration period and thereafter at weekly intervals. The findings were ranked according to the degree of severity, if applicable.

BODY WEIGHT and BODY WEIGHT CHANGE: Yes
- Time schedule for examinations: In general, the body weight of the male and female parental animals was determined once a week at the same time of the day (in the morning). The body weight change of the animals was calculated from these results.

FOOD CONSUMPTION:
- Generally, food consumption was determined once a week (in a period of 7 days) for male and female parental animals, with the some minor exceptions. Food consumption was not determined in females without positive evidence of sperm (during the mating period of dams used in parallel) and females without litter (during the lactation period of dams used in parallel).

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at the end of the treatment period (males on study day 38; females on study day 45)
- Anaesthetic used for blood collection: Yes (isoflurane)
- Animals fasted: Yes
- How many animals: 5 per group and sex

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at the end of the treatment period (males on study day 38; females on study day 45)
- Animals fasted: Yes
- How many animals: 5 per group and sex

URINALYSIS: Yes
- Time schedule for collection of urine: at the end of the treatment period (males on study day 38; females on study day 45)
- Metabolism cages used for collection of urine: Yes; the individual animals were transferred to metabolism cages (withdrawal of food and water) and urine was collected overnight.
- Animals fasted: Yes
- How many animals: 5 per group and sex

Sacrifice and pathology:

The parental animals were sacrificed by decapitation under CO2 anesthesia. The exsanguinated animals were necropsied and assessed by gross pathology. After the organs were fixed, histotechnical processing and examination by light microscopy were performed.

Other examinations:

A functional observational battery was performed in the first five animals per sex and group at the end of the administration period (males on study day 36; females on study day 43) starting at about 10.00 a.m. The FOB started with passive observations without disturbing the animals, followed by removal from the home cage, open field observations in a standard arena and sensorimotor tests as well as reflex tests. The findings were ranked according to the degree of severity, if applicable. The observations were performed at random.

Motor activity was measured on the same day as FOB was performed in the first 5 animal per sex and group. The measurement was performed in the dark using the Multi-Varimex-System (Columbus Instruments Int. Corp., Ohio, USA) with 4 infrared beams per cage. During the measurement the animals were kept in Polycarbonate cages with absorbent material. The animals were put into the cages in a randomized order. The measurements started at about 1.30 p.m.. The number of beam interrupts was counted over 12 intervals, each lasting 5 minutes. Measurement did not commence at the same instant for all cages; the period of assessment for each animal started when the first beam was interrupted by pushing the cage into the rack (staggered start). Measurements ended exactly 60 minutes thereafter. Animals received no food and water during the measurements.

Statistics:

Means and standard deviations were calculated. Weight of the anesthetized animals and absolute and relative organ weights were analysed by Kruskal-Wallis and Wilcoxon test.
Further statistical methods used for clinical examination and/or clinical pathology:
DUNNETT, C.W. (1955): A multiple comparison procedure for comparing several treatments with a control. JASA, Vol. 50, 1096 – 1121
DUNNETT, C.W. (1964). New ables for multiple comparisons with a control. Biometrics, Vol. 20, 482 - 491
Siegel S. (1956): Non-parametric statistics for behavioural sciences. McGraw-Hill New York
Nijenhuis, A.; Wilf, H.S. (1978): Combinatorial Algorithms. Academic Press New York, 32-33
Hettmansperger, T.P. (1984); Statistical Inference based on Ranks. John Wiley & Sons New York, 132-142

Clinical signs:

no effects observed

Description (incidence and severity):

transient salivation and discolored urine are considered to be substance-induced but not adverse

Mortality:

no mortality observed

Description (incidence):

transient salivation and discolored urine are considered to be substance-induced but not adverse

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

slightly, but statistically significantly decreased hemoglobin and hematocrit values in the peripheral blood of high dosed males only

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

effects observed, treatment-related

Description (incidence and severity):

decreased amounts of urine with increased specific gravity; no further findings

Behaviour (functional findings):

effects observed, treatment-related

Description (incidence and severity):

measurements of motor activity and functional observation battery did not reveal test-substance related effects

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

absolute and relative liver weights increased in high dosed males and females

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

diffuse hepatocellulare hypertrophy in the liver of high dosed males

Histopathological findings: neoplastic:

no effects observed

Details on results:

Clinical observations for signs of general toxicity revealed post-dose salivation in all high dose males and most high dose females. Moreover, urine discoloration was observed for all mid and high dose rats. Both findings are considered to be without toxicological relevance and are, if seen in isolation, not assessed as being adverse. The test compound did not affect food consumption and body weight gain at dose levels as high as 1000 mg/kg body weight/day. Detailed clinical examinations in an open field, detailed observations in a functional observational battery (FOB) and measurements of motor activity did not reveal any indications of test substance-induced effects in low, mid and high dose rats.
Clinical pathology examinations revealed slightly, but statistically significantly reduced hemoglobin and hematocrit values, which are indicative of a mild anemic process, in high dose males. This is considered as an adverse substance-induced effect. No treatmentrelated effects were noted in hematology investigations of females and serum enzyme examinations of both sexes. Furthermore, reduced urine volumes with subsequently increased specific gravity were excreted by treated animals of either sex. It is likely, that this was caused by a decreased water intake. A reduction in water intake could also well account for the slightly increased urea and albumin levels of the high dose males and/or females. It is concluded that the changes in urinalysis and in blood chemistry examination are not caused by a direct toxic effect of the test compound and are not adverse in nature. This assessment is supported by the fact, that kidney weights as well as gross and histopathological evaluations of this organ did not give any indications for substance-induced alterations.
The test substance did not cause adverse effects regarding terminal body and organ weights, macroscopic evaluation or histopathologic evaluation. The statistically significantly increased liver weights in top dose males and females of the top dose group, which correlated with a minimal to mild diffuse hypertrophy of hepatocytes in several high dose males, mirror adaptive responses to the test substance administration. They are not assessed as adverse particularly, because liver enzymes in these rats remained unaffected.

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day (actual dose received)

Based on:

other: the hydrochloride salt of isopropanolamine

Sex:

female

Dose descriptor:

NOAEL

Effect level:

300 mg/kg bw/day (actual dose received)

Based on:

other: the hydrochloride salt of isopropanolamine

Sex:

male

Basis for effect level:

other: some indications for a mild anemic process

Critical effects observed:

not specified

Executive summary:

In a combined repeated dose toxicity study with the reproduction/developmental toxicity screening test (OECD TG 422) 1-amino-2-propanol was tested as hydrochloride salt to avoid damage to the gastrointestinal tract following gavage administration due to the caustic mode of action. Testing the salt also provides the ability to distinguish between symptoms caused by local effects such as irritation or corrosion and symptoms that are due to systemic toxicity.

1 -Amino-2 -propanol hydrochloride was administered orally via gavage to groups of 12 male and 12 female Wistar rats at doses of 100, 300, and 1000 mg/kg body weight/day (Schneider, 2005). The study was intended to detect possible effects of the test substance on the integrity and performance of the reproductive system of both sexes and to obtain information about the general toxicological profile after repeated oral administration. The duration of treatment covered a 2 week premating period and a mating period in both sexes, approximately 2 weeks post-mating in males (in total 38 days exposure), and the entire gestation period and 4 days of lactation in females (in total 46 days of exposure).

No clinical abnormalities were observed at doses up to 1000 mg/kg bw per day. Clinical pathology examinations revealed slightly, but statistically significantly reduced hemoglobin and hematocrit values, which are indicative of a mild anemic process, in high dose males only. The test substance did not cause adverse effects regarding terminal body and organ weights, macroscopic evaluation or histopathologic evaluation. The statistically significantly increased liver weights in top dose males and females, which correlated with a minimal to mild diffuse hypertrophy of hepatocytes in several high dose males, mirror adaptive responses to the test substance administration. They are not assessed as adverse particularly, because liver enzymes in these rats remained unaffected.

Under the conditions of this reproduction/developmental toxicity screening test the NOAEL for general, systemic toxicity of the test substance is 300 mg/kg bw/day for the parental males based on some indications for a mild anemic process. The NOAEL for parental females was found to be 1000 mg/kg body weight/day.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

300 mg/kg bw/day

Species:

rat

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

A detailed justification for read-across and classification is attached to IUCLID chapter 13 (Tegethoff, 2013b).

It was shown in a hydrolysis study performed according to OECD TG 111 that carbamic acid, (2-hydroxypropyl) -, compound with 1-amino-2-propanol (1:1) is extremely unstable in acidic aqueous media and completely disintegrates into1-amino-2-propanolunder formation of CO₂within less than 5 minutes (see IUCLID section 5.1.2). Such a rapid disintegration can also be expected in the acidic environment of the stomach of laboratory animals after oral administration and of the stomach of humans in the unlikely case of accidentally oral ingestion. Thus, according to Annex VIII and XI, column 2 of REACH Regulation (EC) 1907/2006 repeated dose toxicity studies do not need to be conducted if a substance undergoes immediate disintegration and there are sufficient data on the cleavage products. The immediate cleavage product of carbamic acid, (2-hydroxypropyl) -, compound with 1-amino-2-propanol (1:1) after oral uptake is1-amino-2-propanolunder formation ofcarbon dioxide. With regard to human health effects CO₂can be considered as of minor importance (see section 7.0 of IUCLID data set). The major and relevant cleavage product1-amino-2-propanolis toxicologically well investigated, shows a comprehensive toxicological data base (see sections 7.2 to 7.8 of IUCLID data set) and has been assessed in authority based peer review processes, either for establishment of an occupational exposure level (www. baua. de) or in the ICCA/HPV progamme. Therefore, in line with Annex XI of Regulation (EC) No 1907/2006 and taking into account animal welfare considerations, no studies with oral application were performed for the product itself but read across via1-amino-2-propanolwas chosen for the registration of carbamic acid, (2-hydroxypropyl) -, compound with 1-amino-2-propanol (1:1) for all endpoints with potential oral administration (acute oral toxicity, repeated dose toxicity and reproductive toxicity). All other relevant toxicological studies have been performed with the stabilized trade product carbamic acid, (2-hydroxypropyl) -, compound with 1-amino-2-propanol (1:1) in ethylene glycol itself.

Oral route

As described above it was shown that under acidic environmental conditions carbamic acid, (2-hydroxypropyl)-, compound with 1-amino-2-propanol (1:1) immediately disintegrates into1-amino-2-propanol and carbon dioxide. Such a rapid disintegration can also be expected in the acidic environment of the stomach of laboratory animals after oral administration and of the stomach of humans in the unlikely case of accidentally oral ingestion. Thus, for evaluation of oral repeated dose toxicity of carbamic acid, (2-hydroxypropyl)-, compound with 1-amino-2-propanol (1:1) read-across of data for 1-amino-2-propanol was considered appropriate.

In a combined repeated dose toxicity study with the reproduction/developmental toxicity screening test (OECD TG 422) 1-amino-2-propanol was tested as hydrochloride salt to avoid damage to the gastrointestinal tract following gavage administration due to the caustic mode of action. Testing the salt also provides the ability to distinguish between symptoms caused by local effects such as irritation or corrosion and symptoms that are due to systemic toxicity.

1 -Amino-2 -propanol hydrochloride was administered orally via gavage to groups of 12 male and 12 female Wistar rats at doses

of 100, 300, and 1000 mg/kg body weight/day (Schneider, 2005). The study was intended to detect possible effects of the test substance on the integrity and performance of the reproductive system of both sexes and to obtain information about the general toxicological profile after repeated oral administration. The duration of treatment covered a 2 week premating period and a mating period in both sexes, approximately 2 weeks post-mating in males (in total 38 days exposure), and the entire gestation period and 4 days of lactation in females (in total 46 days of exposure).

No clinical abnormalities were observed at doses up to 1000 mg/kg bw per day. Clinical pathology examinations revealed slightly, but statistically significantly reduced hemoglobin and hematocrit values, which are indicative of a mild anemic process, in high dose males only. The test substance did not cause adverse effects regarding terminal body and organ weights, macroscopic evaluation or histopathologic evaluation. The statistically significantly increased liver weights in top dose males and females, which correlated with a minimal to mild diffuse hypertrophy of hepatocytes in several high dose males, mirror adaptive responses to the test substance administration. They are not assessed as adverse particularly, because liver enzymes in these rats remained unaffected.

Under the conditions of this reproduction/developmental toxicity screening test the NOAEL for general, systemic toxicity of the test substance is 300 mg/kg bw/day for the parental males based on some indications for a mild anemic process. The NOAEL for parental females was found to be 1000 mg/kg body weight/day.

 

Thus, the NOAEL for repeated dose toxicity of carbamic acid, (2-hydroxypropyl)-, compound with 1-amino-2-propanol (1:1) is considered as 300 mg/kg bw per day, based on indications for a mild anemic process in males after oral uptake of the cleavage product 1-amino-2-propanol.

Inhalation route

Repeated inhalation toxicity studies are not available for carbamic acid, (2-hydroxypropyl)-, compound with 1-amino-2-propanol (1:1).

 

Dermal route

Repeated dermal toxicity studies are not available for carbamic acid, (2-hydroxypropyl)-, compound with 1-amino-2-propanol (1:1).

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
only one study available

Justification for classification or non-classification

A detailed justification for read-across and classification is attached to IUCLID chapter 13 (Tegethoff, 2013b).

No classification is required for repeated oral dose toxicity based on the NOAEL of 300 mg/kg bw per day obtained in a combined oral repeated dose toxicity study with the reproduction/developmental toxicity screening test (OECD TG 422) for the immediate cleavage product 1-amino-2-propanol. No data are available for repeated inhalation and dermal toxicity.