2,6-dibromo-4-cyanophenyl heptanoate

Endpoint summary

Description of key information

Oral subchronic toxicity

Key, source, RA-A, CAS 1689-84-5, M-344535-01-1; subchronic (90 d, rat, similar to OECD 408, GLP):

NOAEL (systemic): 50 ppm (corresponding to 4.4 mg/kg bw/day for males and 4.9 mg/kg bw/day for females, respectively)

LOAEL (systemic): 400 ppm (corresponding to 39.4 mg/kg bw/day for males and 41.6 mg/kg bw/day for females, respectively)

 

Key, source, RA-A, CAS 1689-84-5, M-229656-01-1; subchronic (90 d, mouse, similar to OECD 408, GLP):

NOAEL (systemic): 30 ppm (corresponding to 5.1 mg/kg bw/day for males and 6.4 mg/kg bw/day for females, respectively)

LOAEL (systemic): 100 ppm (corresponding to 18.5 mg/kg bw/day for males and 14.7 mg/kg bw/day for females, respectively)

 

Key; source, RA-A, CAS 1689-84-5, M-231742-02-1; subchronic (90 d, dog, similar to OECD 409, GLP):

NOAEL (systemic): 1 mg/kg bw/day (males and females)

LOAEL (systemic): 5 mg/kg bw/day (males and females)

 

Oral chronic toxicity

Key, source, RA-A, CAS 1689-84-5, M-240-237-03-1; chronic (52 wks, dog, similar to OECD 452, GLP):

NOAEL (systemic): 0.3 mg/kg bw/day (males and females)

LOAEL (systemic): 1.5 mg/kg bw/day (males and females)

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:

sub-chronic toxicity: oral

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

refer to the analogue justification provided in IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Key result

Dose descriptor:

NOAEL

Effect level:

50 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No adverse effects were observed at this dose level.

Remarks on result:

other: corresponding to 4.4 and 4.9 mg/kg bw/day in males and females, repectively.

Remarks:

Source: CAS 1689-84-5, 1987, rat

Key result

Dose descriptor:

LOAEL

Effect level:

400 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

clinical biochemistry

food consumption and compound intake

gross pathology

histopathology: non-neoplastic

organ weights and organ / body weight ratios

Remarks on result:

other: corresponding to 39.4 and 41.6 mg/kg bw/day in males and females, repectively.

Remarks:

Source: CAS 1689-84-5, 1987, rat

Key result

Critical effects observed:

yes

Lowest effective dose / conc.:

400 ppm

System:

hepatobiliary

Organ:

liver

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

not specified

Reference 2

Endpoint:

sub-chronic toxicity: oral

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

refer to the analogue justification provided in IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Key result

Dose descriptor:

NOAEL

Effect level:

30 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No adverse effects observed at this dose level.

Remarks on result:

other: corresponding to 5.1 and 6.4 mg/kg bw/day for males and females, respectively.

Remarks:

Source: CAS 1689-84-5, 1992, mouse

Key result

Dose descriptor:

LOAEL

Effect level:

100 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

gross pathology

histopathology: non-neoplastic

organ weights and organ / body weight ratios

Remarks on result:

other: corresponding to 18.5 and 14.7 mg/kg bw/day for males and females, respectively.

Remarks:

Source: CAS 1689-84-5, 1992, mouse

Key result

Critical effects observed:

yes

Lowest effective dose / conc.:

100 ppm

System:

hepatobiliary

Organ:

liver

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

not specified

Reference 3

Endpoint:

sub-chronic toxicity: oral

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

refer to the analogue justification provided in IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Key result

Dose descriptor:

NOAEL

Effect level:

1 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No adverse effects were observed at this dose level.

Remarks on result:

other: Source: CAS 1689-84-5, 1988, dog

Key result

Dose descriptor:

LOAEL

Effect level:

5 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

clinical signs

food consumption and compound intake

organ weights and organ / body weight ratios

Remarks on result:

other: Source: CAS 1689-84-5, 1988, dog

Key result

Critical effects observed:

yes

Lowest effective dose / conc.:

8 mg/kg bw/day (nominal)

System:

hepatobiliary

Organ:

liver

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

not specified

Reference 4

Endpoint:

chronic toxicity: oral

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

refer to the analogue justification provided in IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Key result

Dose descriptor:

NOAEL

Effect level:

0.3 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No adverse effects observed up to this dose level.

Remarks on result:

other: Source: CAS 1689-84-5, 1987, dog

Key result

Dose descriptor:

LOAEL

Effect level:

1.5 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

clinical biochemistry

clinical signs

haematology

organ weights and organ / body weight ratios

Remarks on result:

other: Source: CAS 1689-84-5, 1987, dog

Key result

Critical effects observed:

yes

Lowest effective dose / conc.:

1.5 mg/kg bw/day (nominal)

System:

hepatobiliary

Organ:

liver

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

not specified

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

0.3 mg/kg bw/day

Study duration:

chronic

Species:

dog

Quality of whole database:

The available information comprises adequate, reliable (Klimisch score 1-2) and consistent studies, and is thus sufficient to fulfil the standard information requirements set out in Annex VIII-IX, 8.6, of Regulation (EC) No 1907/2006. The study with the lowest dose descriptor was selected for endpoint conclusion.

System:

hepatobiliary

Organ:

liver

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

Mode of Action Analysis / Human Relevance Framework

Please refer to the information provided in the endpoint summary. 

Additional information

No data on repeated dose toxicity of the target substance (CAS 56634-95-8) is available. Therefore, a read-across approach to the analogue substance (CAS 1689-84-5) was performed. As discussed in the chapter on toxicokinetics, the target substance is converted to the source substance and hence, the read-across is based on (bio) transformation to common compound(s), which thus have the same biological target(s) and therefore cause the same type of effects. A detailed justification for read-across is provided in the technical dossier (see IUCLID section 13.2).

 

Data on repeated dose toxicity are available for the source substance to characterize the potential to induce toxicity after (sub)chronic oral exposure in rodents and non-rodents. These are three key studies addressing the subchronic toxicity of the test substance in the species rat, mouse and dog, and one 52-week study with dogs.

In the first key study (M-344535-01-1, 1987) five groups of 10 rats/sex/dose were treated for at least 13 weeks with the analogue substance (CAS 1689-84-5) by admixture in the diet at constant nominal concentrations of 0, 10, 50, 400 and 800 ppm. The study was not conducted according to any guideline and no GLP compliance was mentioned. However, it was similar to OECD guideline 408 (1981) and is considered valid. There are major deviations from the current (2018) version of the guideline. 

The stability, homogeneity and achieved concentrations of test diets were satisfactory. Mean achieved dose levels were 0, 0.9, 4.4, 39.4 and 91.6 mg/kg bw/day (males) and 0, 0.95, 4.9, 41.6 and 92.4 mg/kg bw/day (females). No premature deaths occurred during the course of the study. Clinical signs attributable to exposure to the test substance were not observed. The body weight gain was slightly reduced at the beginning of the study in the 400 ppm group (males and females) compared with control, and the body weight was similar to the control group by the end of the study period. In the 800 ppm group (males and females) the body weight gain was statistically significantly decreased compared to controls throughout the study in both sexes. The terminal body weight in the 800 ppm group was reduced by -12.4% in males and by -12.6% in females, compared with control. The food consumption was increased in the 400 and 800 ppm groups in males (up to 10.4% and 14.9%, respectively), compared with the control group. Females of the 800 ppm group also showed increased food consumption compared with the control but this finding did not reach statistical significance. The food conversion ratio was markedly lower in the 800 ppm group during the first two weeks of treatment for both sexes, compared with the control. In lower dose groups, no effect was observed on food conversion ratio. No effects on water consumption were observed at any dose level. The results of the hematological analysis showed several altered parameters in the 800 ppm group: Increased packed cell volume and hemoglobin concentration were observed in both sexes of the 800 ppm dose group compared to the control group. Mean cell erythrocyte volume was significantly increased in males of the 800 ppm dose group compared to the control group. Levels of thyroxine (T4) were statistically significantly (p < 0.001) reduced in both sexes in all treated groups compared to the control group. Triidothyronine (T3) was statistically significantly (p < 0.01) depressed for males of the 50 and 800 ppm dose, and for females at 10 and 800 ppm, compared with control. However, the effects on T3 and T4 in males and females and on alkaline phosphatase in females up to and including 50 ppm were considered minor and non-dose related as there were no concurrent gross pathological or histopathological findings, and therefore not toxicologically significant. Alkaline phosphatase levels were significantly increased in females from 50 ppm onward and in males at 800 ppm, which could be a sign of cholistics. Plasma and creatinine levels were raised in rats of both sexes in the 400 and 800 ppm dose groups and urea level was increased in males of the 800 ppm dose group, compared with control. Taken together, clinical chemistry was altered in a treatment-related manner in both sexes from the 400 ppm dose group onwards.

The absolute and relative thyroid weight was statistically significantly reduced in females of all dose groups compared to the control group. Absolute and relative liver weight was statistically significantly increased in females of the 400 and 800 ppm group and the relative liver weight was statistically significantly increased in males of the high dose group compared to animals of the control group. Liver lesions were observed in both sexes from 50 ppm as a decrease in cytoplasmic basophilic granularity associated with an increase in cytoplasmic eosinophilic fine granular material and cell volume (incidence was 0-0-8-10-10 for males and 0-0-10-10-10 for females, corresponding to 0-10-50-400-800 ppm). The liver changes were treatment-related, but may be caused by an adaptive response to treatment, and were therefore not considered toxicologically relevant at 10 and 50 ppm. For the dose levels 400 ppm and higher, several hepatic effects were observed in both sexes (increased liver weight, increased APLH level, histopathological findings) and the combined effects are considered toxicologically relevant for the 400 and 800 pm groups. Females of the 400 (8/10) and 800 ppm (/9/10) group showed uterus atrophy as reduced stromal ground substance with closely packed stromal cells, in none of the control animals was a similar observation made. The thyroid weight and thyroid hormone levels altered at 10 ppm and above were seen as an adaptive response and therefore not considered toxicologically relevant. In the 800 ppm dose group of males, the thyroids showed an increase of follicles lined by cuboidal to columnar epithelium (8 vs 2 in the control group). In the 400 ppm group 3/10 females showed slight to moderate reduced cellularity of the bone marrow, while no treatment-related findings were found in male animals. In the 800 ppm group 9/10 females showed slight to moderate reduced cellularity, and 5/10 males showed a slight reduction in bone marrow cellularity. In the control group, 1/10 males and 0/10 females showed a slight reduction in bone marrow cellularity. The thrombocytopoenia in the 800 ppm treated females presumably reflected decreased thrombocytopoiesis in view of the depletion of bone marrow cellularity.

The body weight gain, and clinical chemistry parameters were altered after treatment with the test substance at 400 ppm and above. Treatment-related effects were observed in the liver, bone marrow, uterus and thyroid (for the thyroid, only in the 800 ppm group). Therefore, the NOAEL was set at 50 ppm, corresponding to 4.4 and 4.9 mg/kg bw/day in males and females. 

In the second key study (M-229656-01-1, 1992) groups of 10 CD-1 mice/sex/dose were treated with the source substance (CAS 1689-84-5) by admixture in the diet at constant nominal dietary concentrations of 10, 30, 100, 300, 1000 and 3000 ppm for at least 12 weeks. The study was conducted similarly to OECD guideline 408 (1981) but had major deviations from the current (2018) version of the guideline. These differences were mainly related to missing examinations, like hematology and clinical chemistry, thyroid parameters or ophthalmology.

Mean achieved dose levels were 1.8, 5.1, 18.5, 51.2 and 209.3 (males) and 2.8, 6.4, 14.7, 65.7 and 272.9 mg/kg/day (females). The control group (10 animals/sex/dose) was fed with the plain diet. In the group administered a dietary concentration of 3000 ppm of the test substance, all animals died during the first week of treatment. Chemical analysis of diets indicated adequate stability, homogeneity and achieved concentrations.

Apart from the animals of the 3000 ppm group, all animals survived to the terminal sacrifice. No treatment-related clinical signs occurred during the study in animals fed with 1000 ppm of the test substance or less. In the 1000 ppm group, males had statistically significant lower body weight gain for 11/12 weight intervals compared with control. Females of the 1000 ppm group also showed a lower body weight gain than control females, but statistically significant effects were only noted in Weeks 2 - 5. The cumulative body weight gain was statistically significantly reduced in males of the 1000 ppm group compared to the control group. Animals administered 300 ppm or less did not show any effect on body weight or body weight gain throughout the study. No difference regarding feed consumption was observed between control and treatment groups. Statistically significant higher absolute and relative liver (with gallbladder) weights were noted at or above 100 ppm in males and at or above 300 ppm in females, compared with the control group. Other treatment-related findings in the 1000 ppm group that were statistically significantly different compared to controls were higher right kidney weights (absolute and relative) and kidney-to-brain weight ratios in females and higher left kidney and brain organ-to-body weight percentages in males. In males of the 10 ppm group, the left kidney organ-to-body weight percentages were statistically significantly increased. However, since this was an isolated finding, it was considered incidental. Animals given 300 and 1000 ppm had a high incidence of diffusely dark livers (8/10 and 10/10 males, respectively, 4/10 and 9/10 females respectively, compared to none of the control animals). The same finding was observed in 1/10 males and 1/10 females fed 100 ppm. In the 1000 ppm group, increased incidences of centrolobular hepatocytic hypertrophy and hepatocellular degeneration occurred in all males and females. These changes were associated with findings of individual hepatocyte necrosis, sinusoidal cell pigmentation in all males and females. , Hepatocytic vacuolation and increased mitotic activity were observed in all males and 6/10 and 7/10 females, respectively. Males and females given 300 ppm had similar but less severe changes of centrolobular hypertrophy (10/10 males, 5/10 females) and hepatocellular degeneration (8/10 males, 5/10 females). Increased mitotic activity was seen in 1/10 females of the control group, apart from that, no control animal (male or female showed any of the observations described for animals of the higher dose groups. Males were generally more severely affected than females in the treatment groups. 2/10 males fed 100 ppm had slight multifocal hepatocytic hypertrophy but no discernible degeneration.

Based on the hepatic effects (increased liver weight in males and microscopic findings noted in the liver in males and females) at 100 ppm in male and female mice, the NOAEL of the source substance in the mouse was set at 30 ppm (5.1 mg/kg bw/day for males and 6.4 mg/kg bw/day for females).

 

In the third key study (M-231742-02-1, 1988) groups of 4 beagle dogs/sex/dose were treated orally with the source substance (CAS 1689-84-5) via gelatin capsules. The study was similar to the OECD guideline 409 (dated 1981) and was performed under GLP conditions. There are major deviations from the current (2018) version of the guideline. It was considered valid and reliable.

The initial doses chosen were 0, 5, 20, 30, 40 and 50 mg/kg bw/day. Since deaths occurred in the 30, 40 and 50 mg/kg bw/day groups during the first two days of dosing, administration of these doses was stopped. Surviving animals were allowed to recover for 11 days and were then allocated to the 3 additional dosage groups of 8, 12 and 16 mg/kg bw/day. 4 additional animals (2 m/2 f) were obtained to form the dose group of 1 mg/kg bw/day. The duration of treatment was 6 weeks for the 16 mg/kg bw/day group, after which animals were killed for humane reasons, and 13 weeks for the remaining dose groups and the control group.

Two dogs of the 16 mg/kg bw/day and all animals of the 20 mg/kg bw/day dose groups died before the final sacrifice date. Clinical signs were panting, vomiting and salivation at 30, 40 or 50 mg/kg bw/day and panting at 8, 12, 16 and 20 mg/kg/day. There was a loss in body weight at termination in all dogs given 16 or 20 mg/kg bw/day, and in 3/4 animals in the 12 mg/kg bw/day group. Dogs receiving 1, 5 or 8 mg/kg bw/day showed reduced body weight gain compared to controls. However, since the reduction in body weight gain was small (4%) in the 1 mg/kg bw/day group, the reduction at this dose level was not seen as toxicologically relevant and fell within the biological variation. In ¼ females administered 16 mg/kg bw/day and in 4/4 animals administered 20 mg/kg bw/day, the food consumption was decreased as compared to controls. The rectal temperatures were periodically elevated in animals administered 16 mg/kg bw/day or more, compared with the control group. Regarding ophthalmological examination, hematological analysis and urinalysis, no adverse effects were observed in any of the treatment group. In the clinical chemistry examinations, urea nitrogen was increased in several animals receiving 5, 8, 12 or 16 mg/kg bw/day during week 6. Only 1 dog (receiving 8 mg/kg bw/day) had increased urea nitrogen during Week 13. As no other adverse effect on the urea cycle or the kidneys was observed, this effect was not considered to be of toxicological relevance. There were no treatment-related effects on the nature and incidence of macroscopic lesions at necropsy in either sex at any dose level. At 8 mg/kg bw/day and above (and 1 animal at 5 mg/kg bw/day) there was an increase in relative liver weights of at least 30.6%. At 16 mg/kg bw/day there was an increase in relative kidney weight in several animals, which was probably an effect related to decreased body weight. The bone marrow examination revealed no abnormalities of cellularity, distribution or morphology and there were no microscopic findings during the histopathological examination that were considered to be related to treatment.

Based on the effects on body weight at 5 mg/kg bw/day, the NOAEL of the source substance was 5 mg/kg bw/day in dogs for males and females.

 

The second study in dogs was performed under GLP conditions and similar to OECD guideline 452 (M-240237-03-1, 1988). Groups of 6 male and 6 female Beagle dogs received the test substance via gelatin capsules for 52 weeks at doses of 0.1, 0.3, 1.5 and 7.5 mg/kg bw/day, diluted 1:25 in lactose. Animals of the control group received lactose only. All animals were checked daily for signs of ill health. The body weight, feed consumption and water consumption were measured weekly. Before beginning of treatment and in Week 52, ophthalmoscopic examinations were performed. Blood was withdrawn before the study and in weeks 13, 26 and 52 to assess hematology and clinical chemistry parameters. At the same intervals, urine was collected for urinalysis. At sacrifice, animals were subjected to gross necropsy, several organs were weighed and histopathology was performed.

No treatment-related mortality occurred during the study. One male of the control group was sacrificed in Week 38 of the study due to repeated seizures. The animal showed signs of ill-health two days before sacrifice. Clinical signs were restricted mainly to panting, salivation, liquid feces and pale gums. Salivation, liquid feces were seen throughout all control and treated groups but were predominantly observed for dogs receiving 1.5 and 7.5 mg/kg bw/day and was considered to be of toxicological relevance in this dose groups. The group mean body weight gain for males receiving 1.5 and 7.5 mg/kg bw/day and for females receiving 7.5 mg/kg bw/day was statistically significantly lower than that seen for controls. The majority of dogs on study consumed almost all the offered feed. Female animals in the control group and those receiving 0.1 or 0.3 mg/kg bw/day showed a tendency towards lower food consumption throughout the dosing period than that seen for females from other treated group. Food consumption was considered to be affected in a toxicological relevant matter at 7.5 mg/kg bw/day (both sexes). Group mean hematocrit, hemoglobin and red blood cells values were statistically significantly decreased in the group receiving 7.5 mg/kg bw/day during Weeks 13, 26 and 52. In the 1.5 mg/kg bw/day group, these values were also decreased throughout the study but the difference to the control group did not reach statistical significance and the finding was therefore not considered relevant. A significant increase in urea level was seen in males and females receiving 7.5 mg/kg bw/day during Week 13, 26 and 52. Significantly decreased alkaline phosphatase levels were seen in males and females receiving 7.5 mg/kg bw/day during Week 13 and 26 and males only during Week 52. In the treatment groups receiving lower doses, no relevant findings were observed regarding clinical chemistry. Ophthalmoscopic and bone marrow investigations did not show any differences between control and treatment groups, no changes were seen in the urinalysis and there was no macroscopic finding which could be attributed to treatment. Weights of specific organs were altered at 1.5 and 7.5 mg/kg bw/day in both sexes: Increased liver weights were recorded in males and females receiving 1.5 or 7.5 mg/kg bw/day. A significantly lower spleen weights was also noted in males receiving 7.5 mg/kg bw/day. In addition, prostate weights in males receiving 1.5 or 7.5 mg/kg bw/day were greater than control values although the differences did not attain statistical significance. There were no histopathological changes considered to be directly related to the administration of the test substance.

Taken together, the test substance induced reduced body weight or body weight gain in treated animals compared to controls at 1.5 mg/kg bw/day and higher. The liver weight was increased in the 1.5 and 7.5 mg/kg bw/day group. Clinical signs (panting) were observed at 1.5 mg/kg bw/day. Hematology and clinical chemistry was altered at 7.5 mg/kg bw/day and above.

 Based on decreased body weight gain, panting and increased liver weights at 1.5 mg/kg bw/day, the NOAEL of the test substance was 0.3 mg/kg bw/day for dietary administration of the test substance to the male and female Beagle dog over 52 weeks.

 

Conclusion:

In summary, the repeated dose toxicity studies in rodents and dogs were performed with the source substance (CAS 1689-84-5). The test material caused weight increase and/or microscopic alterations of the liver in all species, however, to a lesser extend in dogs. Some hematological and clinical parameters were altered and the bone marrow and uterus was affected by treatment with the test substance in rats, but not in dogs and mice. The body weight was affected in all studies and was the most sensitive parameter in the chronic dog study. The lowest relevant NOAEL for repeated oral exposure was 0.3 mg/kg bw/day in the 52-week study in dogs. Since the effect on the liver in all studies is seen as an adaptive response to treatment and – especially in dogs – showed no functional disturbance or morphological changes which were toxicologically relevant, no classification is needed.

References not included in IUC:

Detailed information on references not included in IUC are available in the CSR and in chapter 13.

Justification for classification or non-classification

An extensive data base exists to assess repeated dose toxicity following the oral route. Based on the available data on subchronic exposure, the source substance does not meet the classification criteria in regard to STOT-RE according to the CLP regulation (EC) No. 1272/2008 which is in line with the harmonized classification of the source substance according to Annex VI of the CLP Regulation (EC) No. 1272/2008 (Index no. 607-427-00-7).