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Toxicological information

Carcinogenicity

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Description of key information

The read-across substance C12-16 ADBAC was not carcinogenic following two-year chronic dietary administration up to the highest tested doses in two combined chronic toxicity and carcinogenic studies in rats. This conclusion is further supported from the available genotoxicity studies which demonstrate the absence of genotoxicity in vitro and in vivo. Toxicokinetic studies have not identified any tissues or treatment routes that might be targets for toxicity and hence carcinogenic impact. Repeated dose toxicity studies provided no evidence for concern regarding carcinogenicity (overall low toxicity together with the absence of any hyperplastic or pre-neoplastic lesions in any organs). The same behaviour is expected for C12-14 ADBAC.

Key value for chemical safety assessment

Carcinogenicity: via oral route

Link to relevant study records
Reference
Endpoint:
carcinogenicity: oral
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study was conducted according to the OECD guideline 453 and in compliance with GLP with some deviations which were not considered to have compromised the validity or integrity of the study.
Qualifier:
according to
Guideline:
OECD Guideline 453 (Combined Chronic Toxicity / Carcinogenicity Studies)
Deviations:
yes
Principles of method if other than guideline:
There were following deviations to the protocols:
- the temperature and relative humidity in the animal room were sometimes out of the target ranges
- the analysis of the dietary concentrations was performed in excess in week 104.
- for female D29585, only one sampled of mass was performed instead of two for masses 2110, 2118 and 1205
- for male D29335, because of a technical problem, macroscopic examination was performed after fixation with a pathologist
- rectum was not sampled for female D29626.
These deviations were not considered to have compromised the validity or integrity of the study.
GLP compliance:
yes
Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Route of administration:
oral: feed
Duration of treatment / exposure:
2 year
Remarks:
Doses / Concentrations:
0, 1000, 2000, 4000 ppm of test substance (i.e., equivalent to 0, 500, 1000 and 2000 ppm of ative substance)
Basis:
nominal in diet
No. of animals per sex per dose:
20 males and 20 females of each group were used for toxicological investigations and were treated for 52 weeks.
50 males and 50 females of each group were used to investigate the carcinogenic potential and were treated for 104 weeks.
A group of 60 male and 60 female rats received untreated diet under the same experimental conditions, and acted as toxicology (10 males and 10 females) and carcinogenicity (50 males and 50 females) control group.
Control animals:
yes, plain diet
Details on study design:
Post-exposure period: none
Observations and examinations performed and frequency:
Animals were checked at least twice daily for mortality and clinical signs. In addition, detailed clinical observations were made once a week. After 6 months of treatment, all animals were palpated every 2 weeks in order to record the time of onset, location, size, appearance and progression of palpable masses. Body weights were recorded once during the pre-treatment period, on Day 1 and then once a week during the first 13 weeks of the treatment period and then once every 4 weeks until the end of the study. Food consumption was recorded once a week during the first 13 weeks of the study, and then over 7-d periods once every 3 months between weeks 14 and 25, and thereafter once per month until the end of the study.
Haematological, blood biochemical investigations and urinalysis were performed on all surviving animals of the toxicology sub-groups in weeks 12, 26 and 52. During weeks 52, 78 and 104, differential white blood cell counts were determined for all surviving animals of the control and high-dose carcinogenicity sub-groups.
Sacrifice and pathology:
Surviving animals were killed at the end of the 52-week treatment period for the toxicology sub-groups and at the end of the 104-week treatment period for the carcinogenicity sub-groups. All animals were submitted for a full macroscopic post-mortem examination. Designated organs were weighed and selected tissue specimens were preserved. A microscopic examination was performed on all masses, and on designated tissues of animals from the control sub-groups and from the sub-groups treated at 4000 ppm of test substance sacrificed at the end of the 52 or 104-week treatment periods, and from all animals that died prematurely.
Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
no effects observed
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:
In the toxicology sub-groups:
-no treatment-related deaths or premature sacrifices occurred during the 52-week treatment period, no treatment-related clinical signs were observed during the 52-week treatment period.
- the mean body weight was significantly lower in the males treated at 4000 ppm than in the controls from week 2 to week 50, due to a lower body weight gain over all the study (from -15% between weeks 0 and 4, to finally -21% between weeks 0 and 50). This lower body weight gain was attributable to a slightly to moderately lower food consumption (ranging from 73.3 to 94.4% of that of controls over the toxicology study), with statistically significant differences occurring during several weeks.
-haematological, blood biochemistry and urinalysis parameters were not affected by the treatment at any dose-level.
-there were no relevant histopathological findings.
In the carcinogenicity sub-groups: -survival rate in animals treated with test substance was not statistically different from to controls. Further, mortality was comparable in terms of time of occurrence and cause. - no test substance-related clinical signs were observed in any treated group.
- the mean body weight was significantly lower in the males and females treated at 4000 ppm than in the controls from week 2 to week 13, due to a lower body weight gain (-14% and -10% for males and females, respectively). This lower body weight gain was attributable to slightly to moderately lower food consumption compared with controls, with statistically significant differences occurring during several weeks. From week 13 to termination, the body weight of the males treated at 4000 ppm was still significantly lower than that of control animals, and this was correlated to a 18% lower body weight gain over the 104 weeks when compared with controls, while the body weight and body weight gain of all other treated animals were in the range of control values.
-there were no differences in the number and localization of palpable masses in test-treated animals and controls.
-there were no significant differences in the differential white blood cell parameters of males and females treated at 4000 ppm, when compared with controls, whatever the sampling time (weeks 52, 78 and 104).
-the administration of the test substance did not induce neoplastic changes under the conditions of this study. Further, no non-neoplastic lesions were found which were considered to represent a treatment-related effect.
Dose descriptor:
NOEL
Remarks:
(systemic effects)
Effect level:
1 000 ppm
Based on:
act. ingr.
Sex:
male/female
Basis for effect level:
other: Lower body weight gain at 2000 ppm active substance (significant only in males of 52 week chronic study part; significant in males and females in 104 week carcinogenicity group).
Remarks on result:
other: Effect type: toxicity (migrated information)
Dose descriptor:
LOAEL
Remarks:
(systemic effects)
Effect level:
2 000 ppm
Based on:
act. ingr.
Sex:
male/female
Remarks on result:
other: Effect type: toxicity (migrated information)
Dose descriptor:
NOEL
Effect level:
4 000 ppm
Based on:
act. ingr.
Sex:
male/female
Basis for effect level:
other: 4000 ppm (i.e., equivalent to 97 and 119 mg a.i./kg bw/d for male and female respectively) in SD rats for two years.
Remarks on result:
other: Effect type: carcinogenicity (migrated information)
Conclusions:
The test substance is not carcinogenic following chronic dietary administration up to 4000 ppm (i.e., equivalent to 97 and 119 mg a.i./kg bw/d for male and female respectively) in SD rats for two years.
Executive summary:

A guideline study was conducted to assess the chronic toxicity and carcinogenic potential of the read-across substance C12-16 ADBAC in a combined study. The test substance was administered daily to Sprague-Dawley rats by dietary admixture at the concentrations of 1000, 2000 and 4000 ppm (i e., equivalent to 500, 1000 and 2000 ppm of active substance) for 52 weeks (toxicology sub-group) and for 104 weeks (carcinogenicity sub-group; corresponding to 24, 48 or 97 mg a.i./kg bw/day for males and 29, 58 or 119 mg a.i./kg bw/day for females). Due to absence of any treatment-related tumorigenic effect, C12-16 ADBAC was not found to be carcinogenic under the conditions of this study (Appelqvist T, 2007).

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed

Carcinogenicity: via inhalation route

Endpoint conclusion
Endpoint conclusion:
no study available

Carcinogenicity: via dermal route

Link to relevant study records
Reference
Endpoint:
carcinogenicity
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: Secondary literature.
Details on results:
Result (carcinogenicity): negative
Conclusions:
In poorly reported studies, the test substance did not reveal carcinogenic potential in studies conducted in mice, rats, rabbits or guinea pigs following dermal or oral administration.
Executive summary:

The tumorigenic potential of the test substance was evaluated in a dermal study involving 100 female Swiss mice and ten New Zealand rabbits (both males and females). Half of the mice and rabbits were treated with 8.5% test substance and the remaining half with 17% for about 80 wk. An untreated group consisting of 100 mice and 19 rabbits served as controls. The solutions were applied uncovered twice a wk (0.02 mL) on shaved dorsal skin (mice) or ear (rabbit). Complete necropsy was performed on each animal. Skin samples, grossly observed tumours, and other lesions in the lung, liver, kidneys were examined microscopically. Neither local skin tumour nor systemic tumours were induced.

 
Further, in a 2-year study in rat dosed up to 250 mg/kg bw/d via the diet, the incidence of neoplasm among the treated groups was not significantly different from that observed in the control group. Only a limited number of organs were examined. 

 

Another 1-year study in guinea pigs (10 male and 10 female/group) dose up to 25 mg/kg bw/d by stomach tube did no reveal treatment related tumours.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed

Additional information

Oral

A guideline study was conducted to assess the chronic toxicity and carcinogenic potential of the read-across substance C12-16 ADBAC in a combined study. The test substance was administered daily to Sprague-Dawley rats by dietary admixture at the concentrations of 1,000, 2,000 and 4,000 ppm (equivalent to 500, 1,000 and 2,000 ppm of active substance) for 52 weeks (toxicology sub-group) and for 104 weeks (carcinogenicity sub-group; corresponding to 24, 48 or 97 mg a.i./kg bw/day for males and 29, 58 or 119 mg a.i./kg bw/day for females). Due to absence of any treatment-related tumorigenic effect, C12-16 ADBAC was not found to be carcinogenic under the conditions of this study (Appelqvist T, 2007).

Another guideline compliant two-year oral feeding study was conducted in Sprague-Dawley CD rats to evaluate the toxicological and carcinogenic potential of C12-16 ADBAC. The test substance was orally administered to Sprague-Dawley CD rats (60/sex/group) at dose levels of 0, 300, 1,000 or 2,000 ppm (equivalent to mean intake levels of 0, 13, 44, and 88 mg/kg bw/day or 0, 11, 36 and 71 mg a.i./kg bw/day in males and 0, 17, 57 and 116 mg/kg bw/day or 14, 46 and 94 mg a.i./kg bw/day in females) in the diet daily for 104 weeks. There were two control groups of 60/sex/group each. The animals were observed twice daily, body weights and clinical findings were recorded periodically. Clinical pathology measurements (haematology, clinical chemistry and urine analysis) were made at 6, 12, 18 and 24 months. At termination, a thorough post-mortem examination was conducted on all animals. Histopathology was conducted on a full set of tissues and organs from all animals in the control and high dose groups as well as on selected organs from animals in the low and mid dose groups. Further, examinations were also performed to evaluate any treatment-related effect on tumour type or incidence in various organs. An increased incidence of loose faeces in male rats was observed which was considered to be potentially treatment-related, however, was not of biological significance. A reduction in mean absolute bodyweights and food consumption was observed in males and females in the high dose group. No treatment related effects were observed in the type or incidence of clinical signs, survival, the type or incidence of palpable masses, clinical pathology, organ weights, gross and microscopic anatomic pathology or ophthalmology. Under the test conditions, there was no evidence of carcinogenic activity of C12-16 ADBAC in rats administered at dietary dose levels up to 88 mg/kg bw/d or 71 mg a.i./kg bw/day in males and 116 mg/kg bw/d or 94 mg a.i./kg bw/day in females (Gill MW, 1991).

Dermal

The tumorigenic potential of the read-across substance C12-16 ADBAC was evaluated in a dermal study involving 100 female Swiss mice and ten New Zealand rabbits (both males and females). Half of the mice and rabbits were treated with 8.5% C12-16 ADBAC and the remaining half with 17% for about 80 weeks. An untreated group consisting of 100 mice and 19 rabbits served as controls. The solutions were applied uncovered twice a week (0.02 mL) on shaved dorsal skin (mice) or ear (rabbit). Complete necropsy was performed on each animal. Skin samples, grossly observed tumours, and other lesions in the lung, liver, kidneys were examined microscopically. Neither local skin tumours nor systemic tumours were induced (Stenbäck F, 1977).


Justification for selection of carcinogenicity via oral route endpoint:
Most recent, OECD guideline and GLP compliant study.

Justification for selection of carcinogenicity via dermal route endpoint:
The only data available is from literature.

Justification for classification or non-classification

The available oral and dermal data suggest that the read-across substance C12-16 ADBAC is not a carcinogen. The same is expected for C12-14 ADBAC. Therefore, the substance does not require classification for carcinogenicityaccording to DSD (67/548/EEC) and CLP (EC 1272/2008) criteria.