Carboxylic acids, di-, C4-6

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

No specific studies on reproduction toxicity have been conducted with the dicarboxylic acid mixture Glutaric acid tech.. Oral repeated dose studies with dicarboxylic acid mixture indicate that the toxicological profile of the dicarboxylic acid mixture is based on the acid character of the test substance, i.e. local irritation and acidification of urine. Based on the available data for dicarboxylic acid mixture there is no reason to expect specific toxicity to fertility or reproduction.

Link to relevant study records

Reference

Reference 1

Endpoint:

reproductive toxicity, other

Remarks:

13-week repeated dose toxicity study

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Reason / purpose for cross-reference:

reference to same study

Principles of method if other than guideline:

13-week repeated dose toxicity study with examination of reproductive organs

Species:

rat

Strain:

other: CD-rats

Sex:

male/female

Route of administration:

oral: gavage

Dose / conc.:

30 other: %

Dose / conc.:

10 other: %

Dose / conc.:

3 other: %

No. of animals per sex per dose:

15

Control animals:

yes, concurrent vehicle

Details on study design:

see chapter 7.5.1 of IUCLID (repeated dose toxicity)

Key result

Reproductive effects observed:

no

A sub-chronic study (Monsanto, 1985) was conducted similar to OECD TG 408 and performed under GLP. The test item AGS-Mixture (adipic acid: 3.9%; Glutaric acid: 16.43%; succinic acid 4.77% and nitric acid 3.9%) was administered daily by oral gavage to 15 male and 15 female CD rats at dose levels of 3, 10 and 30%. In this study examination of testes and ovary weight as well as histopathological examination of gonads (ovaries, testes with epididymides), mammary region (females only), prostate, seminal vesicles and uterus did not reveal substance-related adverse effects.

Executive summary:

A sub-chronic study (Monsanto, 1985) was conducted similar to OECD TG 408 and performed under GLP. The test item AGS-Mixture (adipic acid: 3.9%; Glutaric acid: 16.43%; succinic acid 4.77% and nitric acid 3.9%) was administered daily by oral gavage to 15 male and 15 female CD rats at dose levels of 3, 10 and 30%. In this study examination of testes and ovary weight as well as histopathological examination of gonads (ovaries, testes with epididymides), mammary region (females only), prostate, seminal vesicles and uterus did not reveal substance-related adverse effects.

Reference 2

Endpoint:

extended one-generation reproductive toxicity - basic test design (Cohorts 1A, and 1B without extension)

Type of information:

experimental study planned (based on read-across)

Remarks:

This EOGRTS is proposed for the assessment of adipic acid (see IUCLID for CAS No. 110-04-9). Based on read-across this EOGRTS will be used for the assessment of glutaric acid tech. as soon as the study is available.

Study period:

An OECD test guideline 443, Extended One-Generation Reproduction Toxicity Study in the rat by the oral route of exposure is proposed as per REACH Annex X, Section 8.7.3. The test period will be established once the ECHA approves this Test Plan.

Justification for type of information:

TESTING PROPOSAL ON VERTEBRATE ANIMALS
[Please provide information for all of the points below. The information should be specific to the endpoint for which testing is proposed. Note that for testing proposals addressing testing on vertebrate animals under the REACH Regulation this document will be published on the ECHA website along with the third party consultation on the testing proposal(s).]
Reproductive toxicity (extended one-generation reproductive toxicity study, EOGRTS, OECD 443) with the registered substance.

NON-CONFIDENTIAL NAME OF SUBSTANCE:
- Name of the substance on which testing is proposed to be carried out
adipic acid (CAS 124-04-9, EC 204-673-3, IUPAC name: hexanedioic acid), purity > 99% (as per IUCLID chapter 1.2, boundary composition)
- Name of the substance for which the testing proposal will be used [if different from tested substance]
Adipic acid as given above or neutralized test substance, as technically feasible (e.g. stability in diet has to be verified)

CONSIDERATIONS THAT THE GENERAL ADAPTATION POSSIBILITIES OF ANNEX XI OF THE REACH REGULATION ARE NOT ADEQUATE TO GENERATE THE NECESSARY INFORMATION [please address all points below]:
- Available GLP studies
No available GLP studies on the substances for the endpoint ‘reproductive toxicity’. All available repeated dose/developmental toxicity studies were reported before 1978 and are thus not conducted under GLP.

- Available non-GLP studies
There are 3 repeated dose toxicity studies available in which rats were fed a diet containing adipic acid (neutralized). The dosing periods comprised 3 weeks (Moody and Reddy, 1978), 33 weeks (Lang and Bartsch, 1953) and 2 years (Horn et al., 1957). Additionally, developmental toxicity studies on rats, mice and rabbits (FDA Lab, 1974) are available. Due to the time of performance the studies do not follow GLP requirements. There are no relevant repeated inhalation toxicity studies or dermal toxicity studies available.
The data base for adipic acid was assessed in 2004 in the course of the OECD/ICCA high production volume chemicals program by the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety, published under ‘OECD Existing Chemicals Database’ https://hpvchemicals.oecd.org/UI/SIDS_Details.aspx?key=e0ac34be-a634-4880-81aa-e2dd525b0c28&idx=0

OECD/ICCA summarized that ‘repeated dose studies with application via the food (…) reveal a low systemic toxicity of adipic acid’ and ‘Based on the available data there is no reason to expect specific reproductive toxicity of adipic acid’ and drew the overall conclusion that ‘The chemical is currently of low priority for further work’.
Based on this assessment and on the fact that there is no indication for a repeated dose and reproductive toxicity hazard of adipic acid, the registrant would like to point out that this EOGRTS testing proposal is prepared solely because of formal data requirements. On a scientific basis, the available toxicological information for adipic acid, showing an overall uncritical systemic toxicity profile, is considered sufficient to cover the endpoint reproductive toxicity.

The Human Health Hazard Assessment for adipic acid is based on the recent OECD/ICCA evaluation of 2004 cited above. The hazards identified and discussed in the OECD SIDS Initial Assessment Report for adipic acid in 2004 are shown below. No relevant additional information was obtained in the meantime for the endpoint repeated dose toxicity and/or reproductive toxicity.

‘Hazards identified by OECD/ICCA high production volume chemicals program in 2004, Chapter 3.1.5 Repeated Dose Toxicity:

Studies in Animals

Inhalation
There is no study with histopathological examination of the nose, the probable target organ after inhalation, available. Systemic effects after repeated inhalation have not been investigated in fully valid studies. In a limited study with repeated inhalation (see 3.1.3, Gage 1970) no effects were seen, but the reliability of the study cannot be fully assigned.

Dermal
No data available

Oral
In a limited three-weeks feeding study four rats were dosed with food containing 2% adipic acid (approximately 1500 mg/kg bw/day) no differences were observed compared to control animals in general behavior, liver size, peroxisome proliferation, hepatic activities of catalase and carnitine acetyltransferase, and no hypolipidemia was seen (Moody and Reddy 1978).

Groups of 8 to 10 male rats received neutralized adipic acid (0, 50, 100, 200 and 400 mg/day, approximately 0, 833, 1666, 3333, 6666 mg/kg bw/day) in a protein deficient diet for 19 weeks. After 7 weeks and (probably) at the end of the experiment, rats were killed and examined grossly. Weight gain and general behaviour were recorded and histopathology of liver, kidneys and intestine was performed. Rats fed with 400 mg/day showed lower weight after 19 weeks. No obvious symptoms were observed. Several unexplained intercurrent deaths in control and dose groups occurred, and only 5-7 animals survived 19 weeks. Only at 400 mg/day slight effects were seen on liver and irritation of intestine. The NOAEL is 3333 mg/kg bw (Lang and Bartsch 1953). The study is very limited in its reliability because only kidneys, liver and intestine have been examined histopathologically.
Groups of 13-15 male and female rats received adipic acid (neutralized with NaOH) in a standard diet (0, 400, 800 mg/day, approximately 0, 5000, 10000 mg/kg bw/day) for 33 weeks. Weight gain and general behavior were recorded. After 8, 23 and 25 weeks, rats were killed and histopathology of liver, kidneys and intestine was performed. The administration of 400 mg/day of adipic acid had no effect on weight gain and general behavior of the animals. Ten out of 14 rats fed with 800 mg/day died during the first 4 weeks. The surviving animals showed retarded weight gain, appeared unkempt and apathetic and suffered from heavy diarrhea during the first three weeks. They recovered by the fifth week, and after 33 weeks, the weights of the high-dose rats were the same as that of the 400 mg/day group. Histopathology: slight effects were seen on liver and irritation of intestine at 400 mg/day. No NOAEL was obtained in this study (Lang and Bartsch 1953). The study bis very limited in its reliability because only kidneys, liver and intestine have been examined histopathologically.

In a two-years feeding study rats were fed with food containing different amounts of adipic acid. 20 male rats per group received food containing 0, 0.1, 1, 3 and 5 % of adipic acid (0, approximately 75, 750, 2250, and 3750 mg/kg bw/day), respectively, and 10 or 19 female rats per group received food containing 0 or 1% (0 and approx. 750 mg/kg bw/day), respectively. Body weights, food consumption and general appearance were recorded weekly throughout the experimental period. After 2 years, surviving rats were weighed, killed, and examined grossly. The brain, thyroid, lung, heart, liver, spleen, kidneys, adrenals and stomach of the animals were weighed. Microscopic examination of thyroid, lung, heart, liver, spleen, kidneys, adrenals, stomach, pancreas, bone marrow, large and small intestine uterus, ovaries, and testes on a representative number of animals (no further information) was performed. The percent survival for each test group was higher than for the control group. There were no body weight differences during the test period in female and male rats treated with 0, 0.1 and 1% adipic acid. The weight gains of the male rats receiving 3 and 5% adipic acid were significantly less than the control groups. At necropsy there was no treatment related effect observed. Results of microscopic examination of the organs revealed to be within normal limits in all groups. The NOAEL was 1% for male and female rats (approx. 750 mg/kg bw/day) (Horn et al. 1957). The study does not fully comply with the guidelines for chronic studies because microscopic examination of 15 tissues was done on a representative number of animals for each group, females received only one concentration, the MTD was reached only for males, and the purity of adipic acid is not indicated.

Conclusion (note of registrant: part repeated dose animal studies)
There is no repeated inhalation toxicity study with histopathological examination of the nose available. Systemic effects after repeated inhalation have not been investigated in fully valid studies. There are no studies on repeated dermal application available. In a limited 2-year oral study adipic acid was of low repeated dose toxicity, however it was not tested according to modern standards. The NOAEL was 1 % for male rats (approx. 750 mg/kg bw/day) and higher doses (3 and 5 %) caused body weight retardation with no indication of specific target organ toxicity. The NOAEL for female rats was 1 % (approx. 750 mg/kg bw/day), the highest dose tested in females. In one volunteer no overt toxic symptoms were seen after oral administration of 7 g adipic acid per day for 10 days.’

‘Hazards identified by OECD/ICCA high production volume chemicals program in 2004, Chapter 3.1.8 Reproductive Toxicity:
Studies in Animals
Effects on Fertility
Studies on fertility are not available. In the previously described two-years feeding study in rats (see chapter 3.1.5. Repeated Dose Toxicity) histopathological examination of testes, ovaries and uterus revealed no evidence of an adverse effect on the reproductive organs up to the highest tested doses (3750 mg/kg bw/day in males, 750 mg/kg bw/day in females). Soft edematous testes were observed at least as frequent in the controls as in the adipic acid dosed animals. Two of the surviving control female animals and one of the experimental females had ovarian tumors, ovarian cysts were noted in both control and experimental rats (Horn et al. 1957).
Developmental Toxicity
The administration of up to 288 mg/kg bw/day adipic acid by gavage to groups of 20 to 24 pregnant rats from gestation days (gd) 6 – 15 (10 consecutive days) did neither result in embryo- or fetotoxicity nor in teratogenicity. No adverse effects were seen in similar experiments after administration of adipic acid to groups of 20 - 24 pregnant mice (gd 6 - 15, up to 263 mg/kg bw/day) and groups of 10 to 14 pregnant rabbits (gd 6-18, up to 250 mg/kg bw/day) (Food and Drug Res Labs, Inc. 1972 and 1974). These studies are limited to some extent by the fact that no signs of maternal toxicity have been observed and the highest doses tested were well below the limit dose of 1000 mg/kg bw which would be a precondition for a fully valid negative study.
Conclusion
No specific studies on fertility have been conducted. In a two-years feeding study in rats histopathological examination of testes, ovaries, and uterus revealed no evidence of an adverse effect on the reproductive organs up to the highest doses tested (males approx. 3750 mg/kg bw/day, females approx. 750 mg/kg bw/day). Based on the available data there is no reason to expect specific reproductive toxicity of adipic acid."
Adipic acid was not embryo- or fetotoxic and not teratogenic up to the highest tested doses of 288, 263 and 250 mg/kg bw/day via oral administration to rats, mice and rabbits, respectively. In none of these studies signs of maternal toxicity have been observed and the highest dose was well below the limit dose of 1000 mg/kg bw which would be a precondition for a valid negative study. In view of the low systemic toxicity of the compound, however, this endpoint seems to be adequately covered despite the limitations of the studies.’

- Historical human data
‘Hazards identified by OECD/ICCA high production volume chemicals program in 2004, Chapter 3.1.5 Repeated Dose Toxicity:

Studies in Humans

Inhalation

7 of 12 workers exposed (for an average of 9.2 years) to various glycols and adipic acid dust particles (concentration 0.47-0.79 mg/m3 [0.08-0.13 ppm], 8 h average value) complained of mucosal irritation (eye, nose, throat). There was no local exhaust ventilation and the workers did not wear respiratory protection. They reported that clouds of adipic acid and other materials were routinely generated during charging of reaction vessels. The investigators suggested that, since the glycol level was kept below 1 ppm, adipic acid was more likely to be the cause of these complaints (Cummings and Roseman 1985). Due to the acidic character of the substance, a local irritation potential is plausible.
Oral
Adipic acid was orally administered to 7 volunteers to investigate excretion of this compound. No symptoms were reported in subacute studies with doses of up to 7 g adipic acid per day administered for up to 10 days (Weitzel 1942 and 1947).’

- (Q)SAR
no reliable data available; there is no QSAR model available which is accepted by ECHA for the endpoint reproductive toxicity - fertility.
According to DART scheme profiler of the QSAR Toolbox 4.4 query of June 2020 adipic acid is not associated with chemical structures known to have DART, thus, adipic acid is not foreseen as developmental or reproductive toxicant. Additionally, the toxic hazard classification by Cramer (and Cramer extended) obtained in the QSAR Toolbox shows an overall low hazard for adipic acid (class I - low hazard).

- In vitro methods
no reliable data available; there are no in vitro methods available which are accepted by ECHA for the endpoint reproductive toxicity - fertility

- Weight of evidence
‘Hazards identified by OECD/ICCA high production volume chemicals program in 2004, Chapter 3.1.8 Reproductive Toxicity:
No specific studies on fertility have been conducted. In a two-years feeding study in rats histopathological examination of testes, ovaries, and uterus revealed no evidence of an adverse effect on the reproductive organs up to the highest doses tested (males approx. 3750 mg/kg bw/day, females approx. 750 mg/kg bw/day). Based on the available data there is no reason to expect specific reproductive toxicity of adipic acid.
Adipic acid was not embryo- or fetotoxic and not teratogenic up to the highest tested doses of 288, 263 and 250 mg/kg bw/day via oral administration to rats, mice and rabbits, respectively. In none of these studies signs of maternal toxicity have been observed and the highest dose was well below the limit dose of 1000 mg/kg bw which would be a precondition for a valid negative study. In view of the low systemic toxicity of the compound, however, this endpoint seems to be adequately covered despite the limitations of the studies.’
The OECD QSAR Toolbox version 4.4 does not identify any chemical structures that point to a reproductive toxicity potential (DART profiler) and furthermore classifies adipic acid into Cramer class I (low hazard).
Based on this assessment and on the fact that there is no indication for a reproductive toxicity hazard of adipic acid, the registrant would like to point out that this EOGRTS testing proposal is prepared solely because of formal data requirements. On a scientific basis, the available toxicological information for adipic acid, showing an overall uncritical systemic toxicity profile, is considered sufficient to cover the endpoint reproductive toxicity.

- Grouping and read-across
There are no read-across compounds with adequate data bases for reproductive toxicity available to cover the endpoint fertility.
Adipic acid belongs to the group of saturated dicarbonic acids. Whereas adipic acid consists of 6 C-atoms (hexane dicarbonic acid, HOOC–C4H8–COOH) the dicarbonic acid with the next lower C-number and of industrial relevance is glutaric acid, CAS 110-94-1 EC 203-817-2, (pentane dicarbonic acid, HOOC–C3H6–COOH). No EOGRTS or comparable reproductive toxicity study is available for glutaric acid, therefore, glutaric acid cannot be used as source in a read-across approach. However, the results obtained in the EOGRTS with adipic acid are intended to be included in the dossier of technical glutaric acid (CAS-No. 68603-87-2), that contains adipic acid up to about 45%. The planned EOGRTS with adipic acid will be used as source in the dossier of technical glutaric acid and will thus serve not only for the assessment of adipic acid but also as component for the assessment of technical glutaric acid.

- Substance-tailored exposure driven testing [if applicable]
not applicable.

- Approaches in addition to above [if applicable]
not applicable.

- Other reasons [if applicable]
not applicable.

CONSIDERATIONS THAT THE SPECIFIC ADAPTATION POSSIBILITIES OF ANNEXES VI TO X (AND COLUMN 2 THEREOF) OF THE REACH REGULATION ARE NOT ADEQUATE TO GENERATE THE NECESSARY INFORMATION:
- There is no EOGRTS or multi-generation study for adipic acid available and the adaptation options as defined in Annexes VI to X (and column 2 thereof) are, on a formal basis, not applicable for this substance and this endpoint.
Therefore, as none of the general and specific adaption rules in column 2 provide possibilities for omitting the testing and testing is technically feasible, there is no other option to formally fulfil the requirements than to conduct the extended one generation reproductive toxicity study with adipic acid or the analogue of the registered substance, the neutralized test substance, to fulfill the requirements.

FURTHER INFORMATION ON TESTING PROPOSAL IN ADDITION TO INFORMATION PROVIDED IN THE MATERIALS AND METHODS SECTION:
- Details on study design / methodology proposed [if relevant]
An Extended One-Generation Reproductive Toxicity Study (OECD 443) - basic test design (Cohorts 1A, and 1B without extension) with oral application - is proposed by the registrant for formal reasons (no EOGRTS or multi-generation study available). On a scientific basis, the available toxicological information for adipic acid, showing an overall uncritical systemic toxicity profile, is considered sufficient to cover the endpoint reproductive toxicity.

Guideline:

OECD Guideline 443 (Extended One-Generation Reproductive Toxicity Study)

Justification for study design:

SPECIFICATION OF STUDY DESIGN FOR EXTENDED ONE-GENERATION REPRODUCTION TOXICITY STUDY WITH JUSTIFICATIONS [please address all points below]:

- Premating exposure duration for parental (P0) animals
Pre-mating exposure duration will be 10 weeks to cover the full spermatogenesis and folliculogenesis before the mating in accordance with ECHA Guidance R7a, Appendix R.7.6-3

- Basis for dose level selection
There are 3 repeated dose toxicity studies available in which rats were fed a diet containing adipic acid (neutralized). The dosing periods comprised 3 weeks (Moody and Reddy, 1978), 33 weeks (Lang and Bartsch, 1953) and 2 years (Horn et al., 1957). The NOAEL in the most relevant 2-year study was 1 % for male rats (approx. 750 mg/kg bw/day) and higher doses (3 and 5 %) caused body weight retardation with no indication of specific target organ toxicity. The NOAEL for female rats was 1 % (approx. 750 mg/kg bw/day), the highest dose tested in females. The dosing regime for the EOGRTS will be based on this information, ensuring that toxicity in both female and male animals is considered.

- Inclusion/exclusion of extension of Cohort 1B
Based on the available data an extension to include the F2 generation is not justified, since

• the substance does not display genotoxic effects in somatic cell mutagenicity tests in vivo which could lead to classifying it as Mutagen Category 2
• there are no indications that the internal dose for the substance and/or any of its metabolites will reach a steady state in the test animals only after an extended exposure. The physico-chemical properties (water solubility of 23 g/L; log Kow of 0.093) and the excretion behavior does not indicate any bioaccumulation potency.
• there are no indications of one or more relevant modes of action related to endocrine disruption from available in vivo studies or non-animal approaches.”

- Termination time for F2
Not appropriate

- Inclusion/exclusion of developmental neurotoxicity Cohorts 2A and 2B
Based on the available data an extension to include cohorts 2A/2B (developmental neurotoxicity) is not justified.

- Inclusion/exclusion of developmental immunotoxicity Cohort 3
Based on the available data an extension to include cohort 3 (developmental immunotoxicity) is not justified.

- Route of administration
Oral route, preferred via diet

- Other considerations, e.g. on choice of species, strain, vehicle and number of animals [if applicable]
Oral route, preferred via diet of adipic acid or neutralized test substance, as technically feasible (e.g. stability in diet has to be verified)

Species:

rat

Sex:

male/female

Route of administration:

other: oral, most appropriate application route

Additional information

There are no studies available for the dicarboxylic acid mixture Glutaric acid tech. that specifically investigate fertility. This endpoint is covered via read-across of a planned Extended One-Generation Reproduction Toxicity Study (EOGRTS following OECD 443) with the source adipic acid (see RAAF document). Histopathological investigations on reproductive organs investigated in sub-chronic and chronic studies with adipic acid and Glutaric acid tech. that do not show adverse effects will be taken into consideration as well. Data for glutaric acid and succinic acid published by MAK complete the uncritical picture in a weight of evidence approach. The available data do not point to reproductive or developmental toxic potential.

No specific studies on fertility or reproduction have been conducted with the dicarboxylic acid. Oral repeated dose studies with dicarboxylic acid mixture or adipic acid indicate that the toxicological profile of the dicarboxylic acid mixture is based on the acidic character of the test substance, i.e. local irritation of the gastric mucosal membrane. Based on the available data for dicarboxylic acid mixture there is no reason to expect specific toxicity to fertility or reproduction.

A sub-chronic study (Monsanto, 1985) was conducted similar to OECD TG 408 and performed under GLP. The test item AGS-Mixture (aqueour solution of adipic acid: 3.9%; Glutaric acid: 16.43%; succinic acid 4.77% and nitric acid 3.9%) was administered daily by oral gavage to 15 male and 15 female CD rats at dose levels of 3, 10 and 30%. In this study examination of testes and ovary weight as well as histopathological examination of gonads (ovaries, testes with epididymides), mammary region (females only), prostate, seminal vesicles and uterus did not reveal substance-related adverse effects.

A testing proposal for an Extended One-Generation Reproduction Toxicity Study (EOGRTS following OECD 443) with adipic acid was submitted to ECHA on December 9th, 2020. This study is planned to serve as source for read-across to Glutaric acid tech..

In the 2-year feeding study with adipic acid histopathological examination did not reveal any effects on the testes of male rats up to the high dose of 3750 mg/kg body weight and day. In the females, no effects on the ovaries or uterus were found up to the highest dose tested of 750 mg/kg body weight and day (Horn, 1957).

Data for glutaric acid and succinic acid published by MAK complete the uncritical picture in a weight of evidence approach (see RAAF document).

In conclusion, no potential for induction of adverse effects on fertility is expected for dicarboxylic acid mixture.

Effects on developmental toxicity

Description of key information

No specific studies on developmental toxicity have been conducted with the dicarboxylic acid mixture Glutaric acid tech.. Oral repeated dose studies with dicarboxylic acid mixture indicate that the toxicological profile of the dicarboxylic acid mixture is based on the acid character of the test substance, i.e. local irritation and acidification of urine. Based on the available data for dicarboxylic acid mixture there is no reason to expect specific toxicity to fertility or reproduction.
In addition, the OECD/ICCA high production volume chemicals program in 2004 evaluated adipic acid and concluded: "Adipic acid was not embryo- or fetotoxic and not teratogenic after oral administration to rats, mice, and rabbits. NOAELs for rat, mouse and rabbit are 288, 263, and 250 mg/kg bw/day, respectively, the highest doses tested. In none of these studies signs of maternal toxicity have been observed and the highest dose was well below the limit dose of 1000 mg/kg bw which would be a precondition for a valid negative study. In view of the low systemic toxicity of the compound, however, this endpoint seems to be adequately covered despite the limitations of the studies."

Link to relevant study records

Reference

Reference 1

Endpoint:

developmental toxicity

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This read-across is based on the hypothesis that source and target substance have similar toxicological properties because they share structural similarities with common functional groups, varying solely in their length. This prediction is supported by experimental data for environmental fate, ecotoxicity and human health toxicology on the multi-constituent target substance, the source substance and on further constituents of the target substance.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
The target Glutaric acid, tech. (CAS No. 68603-87-2) is a multi-constituent substance, consisting of C4-, C5- and C6- dicarboxylic acids. The source substance Adipic acid (CAS No 124-04-9, C6-dicarboxylic acid) is one of the main components of the target substance. Additionally, target and source exhibit the same core structure as they are based on linear carbon chains with same acidic moieties, varying solely in chain lengths. Adipic acid thus serves as a structural representative of glutaric acid, tech.. No relevant impurity was identified for the boundary composition of Glutaric acid tech. and adipic acid.

3. ANALOGUE APPROACH JUSTIFICATION
The prediction is supported by experimental data on the multi-constituent target substance and the source substance showing comparable properties regarding physico-chemistry, ecotoxicology and human health toxicology. Therefore, read-across from toxicity studies on the source substance is considered as an appropriate adaption to the standard information requirements for the target substance.

For detailed information see the RAAF document attached to the IUCLID:
‘Justification for a read-across approach from Adipic acid (CAS no. 124-04-9) [Source] to Glutaric acid, tech. (CAS No 68603-87-2) [Target]

Reason / purpose for cross-reference:

read-across source

Species:

mouse

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Description (incidence and severity):

no effect on nidation

Number of abortions:

no effects observed

Description (incidence and severity):

see Table 1

Description (incidence and severity):

see Table 1

Description (incidence and severity):

see Table 1

Description (incidence and severity):

see Table 1

Description (incidence and severity):

see Table 1

Changes in pregnancy duration:

no effects observed

Dose descriptor:

NOAEL

Effect level:

>= 263 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: highest dose tested

Abnormalities:

no effects observed

Fetal body weight changes:

no effects observed

Description (incidence and severity):

see Table 2

Reduction in number of live offspring:

no effects observed

Changes in sex ratio:

no effects observed

Description (incidence and severity):

see Table 2

External malformations:

no effects observed

Skeletal malformations:

no effects observed

Description (incidence and severity):

see Table 3

Visceral malformations:

no effects observed

Dose descriptor:

NOAEL

Effect level:

>= 263 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: highest dose tested

Abnormalities:

no effects observed

Developmental effects observed:

no

The administration of up to 263 mg/kg bw/day of the compound to pregnant mice for 10 consecutive days had no effect on nidation or on maternal or fetal survival. The number of abnormalities seen in either soft or skeletal tissue of the test groups did not differ from the number occurring spontaneously in the sham-treated controls. No maternal toxicity observed. The results were not evaluated statistically, but inspection of the tables shows no effects in the treated groups vs. control.

Table 1: maternal data

	vehicle control animals	positive control animals*	2.6 mg/kg bw	12 mg/kg bw	56 mg/kg bw	263 mg/kg bw
pregnants	21	21	21	23	24	20
died or aborted	0	0	0	0	0	0
corpora lutea no.	307	331	315	293	332	364
corpoa lutea/dam mated	12.3	11.4	12.6	12.7	13.3	11.7
live litters no.	21	19	20	22	24	20
implant sites no.	242	210	250	252	289	235
implant sites average/dam	11.4	10.4	11.3	10.6	11.1	11.5
resorptions no.	9	32	27	22	12	16
dams with 1 or more sites resorbed	8	10	11	8	10	6
live fetuses no.	229	178	221	229	275	214
live fetuses average/dam	10.9	8.48	10.5	9.96	11.5	10.7
dead fetuses	4	0	2	1	2	5
dams with 1 or more dead	4	0	2	1	2	5
% partial dead	19.1	0	9.52	4.35	8.33	25.0

* positive control Aspirin 150 mg/kg bw/day

Table 2: fetal data

	vehicle control animals	positive control animals*	2.6 mg/kg bw	12 mg/kg bw	56 mg/kg bw	263 mg/kg bw
live fetuses no.	229	178	221	229	275	214
average fetal body weight (g)	0.87	0.84	0.90	0.90	8.33	25.0
sex ratio (m/f)	1.04	0.91	0.55	0.68	1.23	0.98

* positive control Aspirin 150 mg/kg bw/day

Table 3: fetal skeletal findings

	vehicle control animals	positive control animals*	2.6 mg/kg bw	12 mg/kg bw	56 mg/kg bw	263 mg/kg bw
live fetuses examined (at term)/no. of litters	158/21	126/19	152/20	161/22	192/24	149/20
sternebrae incomplete oss.	95/20	47/13	71/19	91/20	129/23	116/19
sternebrae missing	20/7	24/9	18/9	23/9	18/8	36/10
ribs wavy	0	1/1	0	0	0	0
ribs more than 13	18/9	18/10	43/14	17/10	24/12	17/7
vertebrae incomplete oss.	8/3	16/8	3/2	0	2/2	14/5
skull incomplete closure	2/1	0	0	0	0	0
extremities incomplete oss.	8/3	17/8	3/3	9/5	1/1	13/5
hyoid, missing	57/16	36/14	41/15	50/14	45/16	44/14
hyoid, reduced	23/13	18/9	21/12	35/16	41/16	31/15
pelvic bones, incomplete	0	0	0	2/1	0	1/1

* positive control Aspirin 150 mg/kg bw/day

Conclusions:

The administration of up to and including 263 mg/kg bw/day adipic acid (source) by gavage to groups of 20 to 24 pregnant mice from gestation days (gd) 6 - 15 (10 consecutive days) had no effect on nidation or on maternal or fetal survival. The number of abnormalities seen in either soft or skeletal tissue of the test groups did not differ from the number occurring spontaneously in the sham-treated controls. Thus, neither embryo- or fetotoxicity nor teratogenicity was observed.

Executive summary:

The administration of up to 263 mg/kg bw/day adipic acid by gavage to groups of 20 to 24 pregnant mice from gestation days (gd) 6 - 15 (10 consecutive days) had no effect on developmental toxicity. As explained in the justification for type of information, the differences in molecular structure between the target and the source are unlikely to lead to differences in developmental toxicity. The acidic nature of target and source is expected to be the critical effect in toxicity studies via local toxicity. No systemic effects are expected and experimentally seen, and thus, no  differences in develomental toxicity can be expected.

Reference 2

Endpoint:

developmental toxicity

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This read-across is based on the hypothesis that source and target substance have similar toxicological properties because they share structural similarities with common functional groups, varying solely in their length. This prediction is supported by experimental data for environmental fate, ecotoxicity and human health toxicology on the multi-constituent target substance, the source substance and on further constituents of the target substance.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
The target Glutaric acid, tech. (CAS No. 68603-87-2) is a multi-constituent substance, consisting of C4-, C5- and C6- dicarboxylic acids. The source substance Adipic acid (CAS No 124-04-9, C6-dicarboxylic acid) is one of the main components of the target substance. Additionally, target and source exhibit the same core structure as they are based on linear carbon chains with same acidic moieties, varying solely in chain lengths. Adipic acid thus serves as a structural representative of glutaric acid, tech.. No relevant impurity was identified for the boundary composition of Glutaric acid tech. and adipic acid.

3. ANALOGUE APPROACH JUSTIFICATION
The prediction is supported by experimental data on the multi-constituent target substance and the source substance showing comparable properties regarding physico-chemistry, ecotoxicology and human health toxicology. Therefore, read-across from toxicity studies on the source substance is considered as an appropriate adaption to the standard information requirements for the target substance.

For detailed information see the RAAF document attached to the IUCLID:
‘Justification for a read-across approach from Adipic acid (cAS no. 124-04-9) [Source] to Glutaric acid, tech. (CAS No 68603-87-2) [Target]

Reason / purpose for cross-reference:

read-across source

Species:

rat

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Description (incidence and severity):

no effect on nidation

Number of abortions:

no effects observed

Description (incidence and severity):

only one animal aborted in the positive control group (Aspirin, 250 mg/kg bw)
see Table 1

Description (incidence and severity):

see Table 1

Total litter losses by resorption:

no effects observed

Description (incidence and severity):

only 4 dams with all sites resorbed in the positive control group (Aspirin, 250 mg/kg bw)
see Table 1

Description (incidence and severity):

see Table 1

Description (incidence and severity):

see Table 1

Changes in pregnancy duration:

no effects observed

Description (incidence and severity):

only one animal aborted in the positive control group (Aspirin, 250 mg/kg bw)

Dose descriptor:

NOAEL

Effect level:

>= 288 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: highest dose tested

Abnormalities:

no effects observed

Fetal body weight changes:

no effects observed

Description (incidence and severity):

see Table 2

Reduction in number of live offspring:

no effects observed

Changes in sex ratio:

no effects observed

Description (incidence and severity):

see Table 2

External malformations:

no effects observed

Skeletal malformations:

no effects observed

Description (incidence and severity):

see Table 3

Description (incidence and severity):

soft tissue abnormalities:
in the positive control (Aspirin 250 mg/kg bw/day) encephalomyelocele occured in 9 pups, twice in combination with umbilical hernia; 3 pups showed meningoencephalocele;
in one treatment group (13 mg/kg bw/day) one pup occued with meningoencephalocele

Dose descriptor:

NOAEL

Effect level:

>= 288 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: highest dose tested

Abnormalities:

no effects observed

Developmental effects observed:

no

The administration of up to 288 mg/kg bw/day of the compound to pregnant rats for 10 consecutive days had no effect on nidation or on maternal or fetal survival. The number of abnormalities seen in either soft or skeletal tissue of the test groups did not differ from the number occurring spontaneously in the sham-treated controls. No maternal toxicity observed. The results were not evaluated statistically, but inspection of the tables shows no effects in the treated groups vs. control.

Table 1: maternal data

	vehicle control animals	positive control animals*	2.9 mg/kg bw	13.0 mg/kg bw	62 mg/kg bw	288 mg/kg bw
pregnants	20	24	23	24	22	20
died or aborted	0	1	0	0	0	0
corpora lutea no.	292	264	314	303	279	263
corpoa lutea/dam mated	11.7	10.2	12.6	12.1	11.2	11.4
live litters no.	20	17	23	24	22	20
implant sites no.	227	238	260	254	245	230
implant sites average/dam	11.4	10.4	11.3	10.6	11.1	11.5
resorptions no.	2	81	6	3	0	7
dams with 1 or more sites resorbed	0	4	0	0	0	0
live fetuses no.	224	150	254	248	245	223
live fetuses average/dam	11.2	6.52	11.0	10.3	11.1	11.2
dead fetuses	1	7	0	3	0	0
dams with 1 or more dead	1	4	0	3	0	0

* positive control Aspirin 250 mg/kg bw/day

Table 2: fetal data

	vehicle control animals	positive control animals*	2.9 mg/kg bw	13.0 mg/kg bw	62 mg/kg bw	288 mg/kg bw
live fetuses no.	224	150	254	248	245	223
average fetal body weight (g)	3.88	2.46	3.89	3.83	4.01	3.99
sex ratio (m/f)	0.85	0.88	1.00	0.89	1.02	0.99

* positive control Aspirin 250 mg/kg bw/day

Table 3: fetal skeletal findings

	vehicle control animals	positive control animals*	2.9 mg/kg bw	13.0 mg/kg bw	62 mg/kg bw	288 mg/kg bw
live fetuses examined (at term)/no. of litters	159/20	100/16 (a)	176/23	175/24	171/22	157/20
sternebrae incomplete oss.	66/19	80/16	46/18	60/13	61/17	44/15
sternebrae missing	17/8	85/16	20/9	4/3	7/2	9/5
ribs fused/split	0	10/5	0	0	0	0
ribs wavy	16/7	45/14	12/5	26/11	12/7	29/10
ribs more than 13	1/1	81/13	6/3	1/1	5/3	0
vertebrae incomplete oss.	20/10	92/16	19/8	25/9	12/7	19/8
skull incomplete closure	21/11	43/15	25/12	35/10	23/11	26/11
skull missing	0	9/3	0	0	0	0
extremities incomplete oss.	0	4/3	0	0	0	0
hyoid, missing	19/8	52/15	14/9	26/12	23/10	19/11
hyoid, reduced	3/3	7/5	18/8	24/10	18/12	24/11

* positive control Aspirin 250 mg/kg bw/day

(a) one litter lost in processing

Conclusions:

The administration of up to and including 288 mg/kg bw/day adipic acid (source) by gavage to groups of 20 to 24 pregnant rats from gestation days (gd) 6 - 15 (10 consecutive days) had no effect on nidation or on maternal or fetal survival. The number of abnormalities seen in either soft or skeletal tissue of the test groups did not differ from the number occurring spontaneously in the sham-treated controls. Thus, neither embryo- or fetotoxicity nor teratogenicity was observed.

Executive summary:

The administration of up to 288 mg/kg bw/day adipic acid by gavage to groups of 20 to 24 pregnant rats from gestation days (gd) 6 - 15 (10 consecutive days) had no effect on developmental toxicity. As explained in the justification for type of information, the differences in molecular structure between the target and the source are unlikely to lead to differences in developmental toxicity. The acidic nature of target and source is expected to be the critical effect in toxicity studies via local toxicity. No systemic effects are expected and experimentally seen, and thus, no  differences in develomental toxicity can be expected.

Reference 3

Endpoint:

developmental toxicity

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This read-across is based on the hypothesis that source and target substance have similar toxicological properties because they share structural similarities with common functional groups, varying solely in their length. This prediction is supported by experimental data for environmental fate, ecotoxicity and human health toxicology on the multi-constituent target substance, the source substance and on further constituents of the target substance.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
The target Glutaric acid, tech. (CAS No. 68603-87-2) is a multi-constituent substance, consisting of C4-, C5- and C6- dicarboxylic acids. The source substance Adipic acid (CAS No 124-04-9, C6-dicarboxylic acid) is one of the main components of the target substance. Additionally, target and source exhibit the same core structure as they are based on linear carbon chains with same acidic moieties, varying solely in chain lengths. Adipic acid thus serves as a structural representative of glutaric acid, tech.. No relevant impurity was identified for the boundary composition of Glutaric acid tech. and adipic acid.

3. ANALOGUE APPROACH JUSTIFICATION
The prediction is supported by experimental data on the multi-constituent target substance and the source substance showing comparable properties regarding physico-chemistry, ecotoxicology and human health toxicology. Therefore, read-across from toxicity studies on the source substance is considered as an appropriate adaption to the standard information requirements for the target substance.

For detailed information see the RAAF document attached to the IUCLID:
‘Justification for a read-across approach from Adipic acid (cAS no. 124-04-9) [Source] to Glutaric acid, tech. (CAS No 68603-87-2) [Target]

Reason / purpose for cross-reference:

read-across source

Species:

rabbit

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Description (incidence and severity):

no effect on nidation

Number of abortions:

no effects observed

Description (incidence and severity):

data not completely available
see Table 1

Description (incidence and severity):

see Table 1

Total litter losses by resorption:

no effects observed

Description (incidence and severity):

data not completely available
see Table 1

Description (incidence and severity):

see Table 1

Description (incidence and severity):

see Table 1

Changes in pregnancy duration:

no effects observed

Description (incidence and severity):

data not completely available

Dose descriptor:

NOAEL

Effect level:

>= 250 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: highest dose tested

Abnormalities:

no effects observed

Fetal body weight changes:

no effects observed

Description (incidence and severity):

see Table 2

Reduction in number of live offspring:

no effects observed

Changes in sex ratio:

no effects observed

Description (incidence and severity):

see Table 2

External malformations:

no effects observed

Skeletal malformations:

no effects observed

Description (incidence and severity):

see Table 3

Description (incidence and severity):

soft tissue abnormalities:
in the positive control (6 -aminonicotinamide 2.5 mg/kg bw dosed on day 9) many soft tissue abnormalities occured, as e.g. anopia (in 36 pups), cleft palate, short tail;
in one treatment group (2.5 mg/kg bw/day) one pup occued with incomplete closure of skull

Dose descriptor:

NOAEL

Effect level:

>= 250 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: highest dose tested

Abnormalities:

no effects observed

Developmental effects observed:

no

The administration of up to 250 mg/kg bw/day of the compound to pregnant rabbits for 13 consecutive days had no effect on nidation or on maternal or fetal survival. The number of abnormalities seen in either soft or skeletal tissue of the test groups did not differ from the number occurring spontaneously in theshamtreated controls. No difference between treatment and control groups were found for corpora lutea, implantations, total no. of resorptions, total no. of fetuses, total no. of live litters and fetal weights. No maternal toxicity observed. The resultes were not evaluated statistically, but inspection of tables shows no effects in the treated groups vs. control.

Table 1: maternal data

	vehicle control animals	positive control animals*	2.5 mg/kg bw	12 mg/kg bw	54 mg/kg bw	250 mg/kg bw
pregnants	11	13	10	11	10	14
died or aborted	0	-	-	-	0	0
corpora lutea no.	104	-	-	-	107	152
corpoa lutea/dam mated	9.45	-	-	-	11.9	10.1
live litters no.	11	-	-	-	8	12
implant sites no.	77	-	-	-	88	102
implant sites average/dam	7.0	-	-	-	8.8	7.29
resorptions no.	10	-	-	-	13	16
dams with 1 or more sites resorbed	4	-	-	-	3	6
live fetuses no.	67	46	73	67	65	78
live fetuses average/dam	6.09	-	-	-	6.50	5.57
dead fetuses	0	-	-	-	10	8
dams with 1 or more dead	0	-	-	-	1	1

* positive control 6 -aminonicotinamide 2.5 mg/kg bw dosed on day 9

- no data given for positive control, 2.5 and 12 mg/kg bw dosed animals due to incomplete duplication/copy

Table 2: fetal data

	vehicle control animals	positive control animals*	2.9 mg/kg bw	13.0 mg/kg bw	62 mg/kg bw	288 mg/kg bw
live fetuses no.	67	46	73	67	65	78
average fetal body weight (g)	42.3	-	-	-	-	41.4
sex ratio (m/f)	0.72	-	-	-	1.03	0.66

* positive control 6 -aminonicotinamide 2.5 mg/kg bw dosed on day 9

- no data given for positive control, 2.5 and 12 mg/kg bw dosed animals due to incomplete duplication/copy

Table 3: fetal skeletal findings

	vehicle control animals	positive control animals*	2.9 mg/kg bw	13.0 mg/kg bw	62 mg/kg bw	288 mg/kg bw
live fetuses examined (at term)/no. of litters	67/11	46/8	73/9	67/9	65/8	78/12
sternebrae incomplete oss.	8/6	11/5	9/5	4/3	9/3	10/5
sternebrae missing	7/4	10/6	12/5	1/1	17/5	12/4
ribs fused/split	1/1	20/5	1/1	0	0	0
vertebrae incomplete oss.	0	5/1	0	0	0	0
scoliosis	0	10/6	1/1	0	0	0
tail defects	0	39/8	0	0	0	0
skul missing	0	0	1/1	0	0	0

* positive control

6 -aminonicotinamide 2.5 mg/kg bw dosed on day 9

Conclusions:

The administration of up to and including 250 mg/kg bw/day adipic acid (source) by gavage to groups of 10 to 14 pregnant rabbits from gestation days (gd) 6 - 18 (13 consecutive days) had no effect on nidation or on maternal or fetal survival. The number of abnormalities seen in either soft or skeletal tissue of the test groups did not differ from the number occurring spontaneously in the sham-treated controls. Thus, neither embryo- or fetotoxicity nor teratogenicity was observed.

Executive summary:

The administration of up to 250 mg/kg bw/day adipic acid by gavage to groups of 10 to 14 pregnant rabbits from gestation days (gd) 6 - 18 (13 consecutive days) had no effect on developmental toxicity. As explained in the justification for type of information, the differences in molecular structure between the target and the source are unlikely to lead to differences in developmental toxicity. The acidic nature of target and source is expected to be the critical effect in toxicity studies via local toxicity. No systemic effects are expected and experimentally seen, and thus, no  differences in developmental toxicity can be expected.

Toxicity to reproduction: other studies

Additional information

For adipic acid developmental toxicity studies on rats, rabbits, and mice are available.

Groups of 20 to 24 pregnant Wistar rats were dosed orally, by gavage, with 0, 2.9, 13, 62, or 288 mg/kg bw adipic acid on days 6 to 15 of gestation. All animals were killed on day 20 of gestation. The administration of up to 288 mg/kg bw/day adipic acid had no effect on nidation or on maternal or fetal survival. The number of abnormalities seen in either soft or skeletal tissue of the test groups did not differ from the number occurring spontaneously in the sham-treated controls. Thus, neither embryo- or fetotoxicity nor teratogenicity was observed. The NOAEL for maternal and developmental toxicity was the highest dose tested of 288 mg/kg bw/day. (FDA, 1972)

Doses of 2.5, 12, 54, or 250 mg/kg bw/day adipic acid were administered by gavage to groups of 10 to 14 pregnant rabbits from gestation days 6 - 18 (13 consecutive days), followed by cesarian section on day 29 of gestation. Treatment had no clearly discernible effect on nidation or on maternal or fetal survival. The number of abnormalities seen in either soft or skeletal tissues of the test groups did not differ from the number occurring spontaneously in the sham-treated controls. Thus, neither embryo- or fetotoxicity nor teratogenicity was observed. The NOAEL for maternal and developmental toxicity was the highest dose tested of 250 mg/kg bw/day. (FDA 1972)

Groups of 20 to 24 gravid albino CD-1 mice were dosed orally, by gavage, with 0, 2.6, 12, 56, or 263 mg/kg bw adipic acid on days 6 to 15 of gestation. All animals were killed on day 17 of gestation. No effect on nidation or on maternal or fetal survival became obvious. The number of abnormalities seen in either soft or skeletal tissue of the test groups did not differ from the number occurring spontaneously in the sham-treated controls. Thus, neither embryo- or fetotoxicity nor teratogenicity was observed. The NOAEL for maternal and developmental toxicity was the highest dose tested of 263 mg/kg bw/day. (FDA, 1972)
Although all three studies are limited to some extent by the fact that no signs of maternal toxicity have been observed at the highest doses tested, they are of high validity as a whole since they clearly demonstrate the uncritical developmental toxicity profile of adipic acid.

For glutaric acid developmental toxicity studies on rats and rabbits are available that do not show adverse effects on fetal development. An OECD 422 for succinic acid also showed no effects on development of rats. (for more details see RAAF document)

Overall, no potential for induction of adverse effects on fetal development is expected for dicarboxylic acid mixture.

Justification for classification or non-classification

No classification is required according to the classification criteria 67/548/EWG and regulation no. 1272/2008 (GHS).