Amines, C12-18-alkyldimethyl

Endpoint summary

Description of key information

Reliable data from several guideline studies on repeated dose toxicity are available for C10-DMA, C12-14-DMA, C16-DMA and C18-DMA. These studies were performed either according to OECD TG 407 (C12-14 DMA), to OECD TG 421 (C12-14 DMA) or according to OECD TG 422 (C10-DMA, C12-14 DMA, C16-DMA and C18-DMA). Currently a OECD TG 422 study is on-going on C18-DMA. In addition, an OECD TG 408 study is planned either on C12-14 DMA or C16 DMA.

In addition, the results are supported by read-across data from several DMAOs. A two-year study with C10-16 DMAO is currently used to cover the endpoint subchronic/chronic toxicity. The toxicity patterns of all these studies are comparable to each other: The NOAEL and NOEL for systemic effects experimentally obtained is between 50 and 150 mg/kg in the available studies, no classification according to Regulation (EC) No. 1272/2008 is warranted. As key value the most conservative value for the category members is selected.

Key value for chemical safety assessment

Toxic effect type:

dose-dependent

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Reference 1

Endpoint:

repeated dose toxicity: oral, other

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Justification for type of information:

For details on endpoint-specific justification, please see read-across justification document (category approach) in the linked category of dimethylalkylamines.

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

other: Read-across from C10-DMA; value converted based on MW

Sex:

male/female

Basis for effect level:

other: No adverse effect found up to the highest dose level.

Remarks on result:

other: Original data for the source: 150 mg/kg bw

Critical effects observed:

no

Executive summary:

The study used as source investigated the repeated oral toxicity of C10-DMA. The study results of the source compound were considered applicable to the target compound. Justification and applicability of the read-across approach (category approach) is outlined in the read-across report in the linked category of dimethylalkylamines.

 

Reference 2

Endpoint:

repeated dose toxicity: oral, other

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Justification for type of information:

For details on endpoint-specific justification, please see read-across justification document (category approach) in the linked category of dimethylalkylamines.

Frequency of treatment:

Daily

Organ weight findings including organ / body weight ratios:

no effects observed

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

other: Read-across from C16-DMA; value converted based on MW

Sex:

male

Basis for effect level:

body weight and weight gain

Remarks on result:

other: Original data for the source: 100 mg/kg bw/d

Key result

Critical effects observed:

no

Executive summary:

The study used as source investigated the repeated oral toxicity of C16-DMA. The study results of the source compound were considered applicable to the target compound. Justification and applicability of the read-across approach (category approach) is outlined in the read-across report in the linked category of dimethylalkylamines.

Reference 3

Endpoint:

repeated dose toxicity: oral, other

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Justification for type of information:

For details on endpoint-specific justification, please see read-across justification document (category approach) in the linked category of dimethylalkylamines.

Key result

Dose descriptor:

NOAEL

Effect level:

>= 163 mg/kg bw/day (actual dose received)

Based on:

other: Read-across from C12-14 DMA; value converted based on MW

Sex:

male/female

Basis for effect level:

other: No adverse effect up to the highest dose

Remarks on result:

other: Original data for the source: >= 150 mg/kg bw/d

Key result

Critical effects observed:

no

Executive summary:

The study used as source investigated the repeated oral toxicity of C12-14 DMA. The study results of the source compound were considered applicable to the target compound. Justification and applicability of the read-across approach (category approach) is outlined in the read-across report in the linked category of dimethylalkylamines.

Reference 4

Endpoint:

chronic toxicity: oral

Remarks:

combined repeated dose and carcinogenicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Basic data given: comparable to guidelines/standards.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 453 (Combined Chronic Toxicity / Carcinogenicity Studies)

GLP compliance:

no

Remarks:

original study performed in 1979, prior to the adoption of GLP compliance standards. However, it was reviewed and found acceptable by the laboratory´s Quality Assurance Department in accordance with US FDA´s GLP Regulation of June 20, 1979.

Limit test:

no

Species:

rat

Strain:

other: Charles River

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding laboratories Inc., Portage, Michigan, USA
- Age at study initiation: 4 weeks
- Housing: individually
- Diet: Zeigler NIH-07diet containing test substance, ad libitum
- Water: ad libitum
- Acclimation period: 14 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22-24
- Humidity (%): 46-70
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: feed

Vehicle:

water

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:

DIET PREPARATION
- Rate of preparation of diet (frequency): weekly
- Mixing appropriate amounts with (Type of food): Zeigler NIH-07

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

not indicated

Duration of treatment / exposure:

104 weeks

Frequency of treatment:

daily with the food

Remarks:

Doses / Concentrations:
0, 0.01, 0.1 and 0.2 % of the test compound (100% (w/v) active basis)
Basis:
nominal in diet

No. of animals per sex per dose:

60

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Doses were selected based on the results from a 13 week study which showed the high dose causing about a 5 to 8 % reduction in body weight.
- Concentrations in the diet of 0, 0.01, 0.1 and 0.2 % test compound (100% (w/v) active basis) correspond to 0, 4.24, 42.3, or 87.4 mg/kg bw/day for males and 0, 5.23, 52.6, or 107 mg/kg bw/day for females according to OECD (2006).

Positive control:

none

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: weekly

BODY WEIGHT: Yes
- Time schedule for examinations: weekly for the first 14 weeks of study, biweekly for the next 12 weeks and monthly thereafter.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/week: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No data

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: yes

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: once during pretest and at 3,6,12,16,19,22 and 24 months
- Dose groups that were examined: all

HAEMATOLOGY: Yes
- Time schedule for collection of blood: all rats to be sacrificed at 52 weeks of the study and all rats at study termination
- Anaesthetic used for blood collection: No data
- Animals fasted: No data
- How many animals: all

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: all rats to be sacrificed at 52 weeks of the study and all rats at study termination
- Animals fasted: No data
- How many animals: all

URINALYSIS: Yes
- Time schedule for collection of urine: all rats to be sacrificed at 52 weeks of the study and all rats at study termination
- Metabolism cages used for collection of urine: No data
- Animals fasted: No data

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes

Statistics:

Body weights, feed consumption, efficiency of feed utilization, clinical chemistry parameters and absolute and relative organ weights were compared by analysis of variance (one way classification), Bartlett´s test for homogeneity of variances, and at least significant differences criterion. If Bartlett´s test were significant, then pairwise comparisons were made by the Mann-Whitney U test. All statistical analyses were conducted at a 5 %, two-sided risk level, and each treatment group was compared with the main control group by sex.

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

details see below

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

no effects observed

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY
There were no significant differences in survival at 104 weeks. There were no significant, compound-related differences in mean feed consumption, clinical chemistry or ophthalmology.

BODY WEIGHT AND WEIGHT GAIN
The high dose animals demonstrated >10% decreases in mean body weight. Animals in the 0.1% test substance group also showed reduced body weight, but the reduction was not as strong as in the high dose group.

HISTOLOGY
There were no compound-related effects on histopathic examination. There was no evidence of a carcinogenic response after chronic dietary administration of the test substance.

Dose descriptor:

NOAEL

Effect level:

42.3 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male

Basis for effect level:

other: based on decreased mean body weight in the highest dose group.

Dose descriptor:

NOAEL

Effect level:

52.6 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

female

Basis for effect level:

other: based on decreased mean body weight in the highest dose group.

Critical effects observed:

not specified

Conclusions:

Under the conditions of the test, no substance related effects were observed in male and female rats after oral exposure for 104 weeks. The NOAEL is 42.3 (males) or 52.6 (females) mg/kg bw/day.

Executive summary:

Male and female Charles River rats were given a diet containing 0, 0.01, 0.1 or 0.2 % test substance ad libitum for 104 weeks. No substance related effect was observed in any concentration tested. The NOAEL is 42.3 (male) or 52.6 (female) mg/kg bw/day based on decreased mean body weight in the highest dose group.

Reference 5

Endpoint:

chronic toxicity: oral

Remarks:

combined repeated dose and carcinogenicity

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

For details on endpoint specific justification please see read-across report in section 13 or find a link in cross-reference “assessment report”.

Reason / purpose for cross-reference:

assessment report

Reason / purpose for cross-reference:

read-across source

Details on study design:

-

Clinical signs:

no effects observed

Mortality:

no mortality observed

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

no effects observed

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY
There were no significant differences in survival at 104 weeks. There were no significant, compound-related differences in mean feed consumption, clinical chemistry or ophthalmology.

BODY WEIGHT AND WEIGHT GAIN
The high dose animals demonstrated >10% decreases in mean body weight. Animals in the 0.1% test substance group also showed reduced body weight, but the reduction was not as strong as in the high dose group.

HISTOLOGY
There were no compound-related effects on histopathic examination. There was no evidence of a carcinogenic response after chronic dietary administration of the test substance.

Dose descriptor:

NOAEL

Effect level:

42.3 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male

Basis for effect level:

other: based on decreased mean body weight in the highest dose group.

Dose descriptor:

NOAEL

Effect level:

52.6 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

female

Basis for effect level:

other: based on decreased mean body weight in the highest dose group.

Critical effects observed:

not specified

Executive summary:

The study used as source investigated chronic toxicity after oral exposure. The study results of the source compound were considered applicable to the target compound. Justification and applicability of the read-across approach (structural analogue) is outlined in the read-across report in section 13 or find a link in cross reference “assessment report”.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

50 mg/kg bw/day

Study duration:

chronic

Species:

rat

Quality of whole database:

good

System:

other: Body weight

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

Additional information

Toxicity after repeated oral application has been investigated with the following substances of the DMA category: C10-DMA, C12-14-DMA, C16-DMA. The studies are reliable (reliability 1 or 2) and were performed according to OECD TG 422 or 421. For one substance, C12-14-DMA, a study on subchronic toxicity according to OECD Guideline 407 is available. All available studies are gavage studies in rats with sesame or corn oil as vehicle.

Additionally, there are several studies for repeated dose toxicity after oral or dermal application available for DMAOs  in a read across procedure.

In the 28-day study (OECD TG 407, reliability 1) with C12-14-DMA no general toxicity was observed at a dose of 50 mg/kg bw/d. In the next higher dose (150 mg/kg bw/d), only marginal effects like rubbing of the snouts in the bedding material were observed. Lethality occurred at 300 mg/kg bw/d. The NOEL in this study was 50 mg/kg bw/d.

This NOEL was confirmed for the same substance with a reliable screening study for reproduction/developmental toxicity according to OECD guideline 421. Male and female rats were exposed for at least 28 days (males) or longer (females: 14 days prior to mating and during the mating period, pregnancy and lactation period). No effects were observed at 50 mg/kg bw/d, however, at 150 mg kg bw/d, the next higher dose group, lethality was already reported. Even at higher doses (up to 450 mg/kg bw/d) only lethality, but no specific toxicity effects were observed.

The newer screening study from 2022 performed with the same substance according to OECD TG 422 resulted in a NOAEL of 150 mg/kg bw/d which was the highest dose tested. No treatment related adverse effects on systemic, reproduction and fertility parameters were observed. In this study type male animals are exposed for 50 days (this includes two weeks prior to mating, during mating period and approximately, two weeks post mating). Female rats are dosed throughout the treatment period. This includes two weeks prior to mating, the variable time to conception, the duration of pregnancy and up to and including the day before scheduled sacrifice (i.e., up to LD13). No mortality was observed at any dose level. In the 14-week DRF study for the OECD-422 study adverse effects at 300 mg/kg be/d were observed including reduced food intake, reduced organ weights, changes in clinical chemistry parameters and irritation in GI tract.

The results from the OECD-422 study for C10-DMA support the findings from the screening study for C12-14 DMA. The NOAEL is 150 mg/kg bw/d (being the highest dose tested). Again, the DRF study revealed severe effects at 300 mg/kg bw (mortality, reduced food intake, irritation in GI tract).

For C16-DMA the screening study according to OECD TG 422 revealed different NOAELs for male and female animals. For females the NOAEL is 150 mg/kg bw/d (highest dose tested) whereas for males the NOAEL is 100 mg/kg bw/d (dose levels: 15, 50, 100, 150 mg/kg bw/d) based on reduced body weight and weight gain in males at 150 mg/kg bw/d. In the corresponding DRF study a LOEL of 50 mg/kg bw/d for males and females was reported, based on for example changes in body weight and  food consumption, inflammatory markers and organ weights. A NOAEL is not provided for this study.

In the 14-day DRF study for C18-DMA a NOAEL of 50 mg/kg bw/d is reported for male and female rats. THE NOAEL is based on reduced body weight gain and food consumption, changes in organ weights and irritation in the GI tract. As outlined above, one OECD 408 study is planned either on C12-14 DMA or C16-DMA. The results will be included in IUCLID and this endpoint summary when available.

As outlined above, subchronic studies according to OECD TG 408 are planned for C12-14 DMA and C16-DMA. Currently no subchronic or chronic studies with members of the DMA-category are available. To fill this data gap, read-across to DMAOs is performed. In a chronic study with C10-16 DMAO (Cardin et al., 1985, reliability 2, equivalent to OECD guideline 453) decreased body weights at the highest dose tested (87.4 mg/kg bw/d for males and 107 mg/kg bw/d for females) was reported. No other adverse effects were observed, resulting in a NOAEL of 42.3 and 52.6 mg/kg bw/d for males and females, respectively. The animals were exposed for 2 years.

Other studies with repeated exposure to DMAOs are included as supporting evidence.

For oral exposure a reliable guideline study (equivalent to OECD 422, reliability 1) is available for C12-18-DMAO. In this study, male and female rats were exposed for at least 31 days (males) or longer (females: 14 days prior to mating and during the mating period, pregnancy and at least 3 days of lactation). The NOEL in this study was 40 mg/kg bw/d based on pathological changes in the forestomach and the mesenteric lymph nodes and signs of systemic toxicity (salivation) at dose levels of 100 and/or 200 mg/kg bw/d.

Lijinsky et al. (1984, reliability 3) reported a chronic study in rats. The animals were exposed for 93 weeks to ca. 250 mg C12-DMAO/kg bw/d. There was no effect on life span, no other data are available.

There are three additional studies with DMAOs. However, they were only available from a secondary source (OECD SIDS, 2006) which gives them a reliability of 4:

A 90-day toxicity study with C10-16-DMAO in rats determined a NOAEL of 80 mg/kg bw/d (females) and 63 mg/kg bw/d (males) (The Procter & Gamble, 1980). The NOAEL for females was based on decreases in mean body weight at 150 and 301 mg/kg bw/d (no other effects observed). Opthalmoscopic examination revealed lenticular opacities pertaining to the posterior cortex of the lens in males at 112 and 236 mg/kg bw/d. The body weight of the males was reduced in the highest dose group (236 mg/kg bw/d).

In a 32-week feeding study with C10-16-DMAO in rabbits, a NOAEL of 40 mg/kg bw/d (males) is established (The Procter & Gamble, 1977A). Decreased alkaline phosphatase levels and an increased liver/body weight ratio were noted in males at 196 mg/kg bw/d.

These NOAEL values were confirmed by the results of a two-generation study in rats (Lion Corporation, 1978B) which reported a NOAEL > 40 mg/kg bw/d (see section 5.9).

The toxicity patterns of all these studies are comparable to each other: The NOAEL and NOEL for systemic effects experimentally obtained is between 50 and 150 mg/kg in the available studies.  

 

For the chronic toxicity assessment of DMAs the use of 50 mg/kg as systemic NOAEL is considered to be sufficiently conservative, since there was no systemic effect present at this dose level. This approach is also in line with the approach taken by EFSA (2007), in which NOAEL of 50 mg/kg for DMAOs (based on Cardin et al, 1985) is used for the derivation of a TDI for DMAs in food contact materials.

 

Repeated-dose toxicity of DMAOs was also tested after dermal exposure. A reliable guideline study (Cardin et al, 1985, reliability 2, equivalent to OECD guideline 453) is available for C10-16-DMAO. In this study, mice were exposed for 2 years. The highest concentration tested (0.26%, corresponding to 5.6 mg/kg bw/d) did not result in any effects except for skin irritation (diffuse acanthosis and hyperkeratosis), which was observed microscopically in the high dose group of mice. Therefore, a NOAEL of ≥ 0.26% (5.6 mg/kg bw/d, highest dose tested) was established for systemic toxicity.

This result is supported by four non-reliable studies with DMAOs on rabbit skin (Petersen, 1988 a, b, c and Pang, 1994). Petersen exposed rabbits for 28 or 91 days against to 0, 0.3, 0.6 and 1.5 mg/kg bw/d or 0, 0.5, 1.0 and 2.5 mg/kg bw/d, administered as C12-14-DMAO. There were no signs of systemic toxicity or compound-related microscopic or macroscopic lesions in any dosage group. Therefore, the NOAEL values were 1.5 mg/kg bw/d and 2.5 mg/kg bw/d, the highest dosages tested. Pang exposed rabbits for 28 days to 0 or 6 mg/kg bw/d. Only slight irritation was observed, no significant changes in mean body weight, clinical observations, mean absolute organ weights or organ-to-body weight ratios were observed. Therefore, the NOEL for systemic effects was 6 mg/kg bw/d, the highest dose tested.

All in all, it can be stated that studies using DMAO as test substances are indicative of absence of systemic effects at skin irritation dose levels.

 

The overall NOAEL for repeated-dose toxicity after oral administration is 50 mg/kg bw/d. This is in agreement with the evaluation by EFSA (2007), which also identified a NOAEL of 50 mg/kg from the same study (Cardin et al, 1985) for the derivation of a TDI for DMAs in food contact materials. Unspecific toxic effects like effects on body weight or health conditions were observed at doses ≥ 100 mg/kg bw/day.

Data on dermal application indicate NOAEL values for DMAOs between 2 and 6 mg/kg bw/d, i.e. the highest doses tested. No specific systemic effects were observed at doses already causing local skin effects. Therefore, the members of the DMA category do not have to be classified for specific target organ toxicity – repeated exposure or repeated dose toxicity according to Regulation (EC) No 1272/2008

Justification for classification or non-classification

The NOAEL and NOEL for systemic effects experimentally obtained after oral exposure is between 50 and 150 mg/kg in the available studies. After dermal application of DMAOs no systemic toxicity was observed up to doses causing local effects on the skin (about 6 mg/kg bw/d).

Based on the category approach and the available data for repeated oral exposure, members of the DMA category do not have to be classified for specific target organ toxicity – repeated exposure or repeated dose toxicity according to Regulation (EC) No 1272/2008.