reaction products of acetic anhydride and adipic acid

Carcinogenicity

Administrative data

Endpoint:

carcinogenicity: dermal

Type of information:

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

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Read-across justification: The available toxicological data for the target and source substances is outlined in the data matrix (Annex I). The toxicological properties of the target substance are related mainly to acetic acid/acetate since the anhydride components of the substance are hydrolytically unstable. When the target substance comes in contact with water or moisture a complete hydrolysis will take place to form no other hydrolysis products than acetic acid/acetate and adipic acid. Thus, the use of data from acetic acid and adipic acid is justified to evaluate toxicological properties of the target substance. Furthermore, data from acetic anhydride is used in the assessment. Experimental data obtained with the source substances indicate that the substances has low oral (LD50 > 1780 – 3310 mg/kg bw) and inhalation (LC50 1680 - 7700 mg/m3) acute toxicity. Furthermore, the acetic acid and acetic anhydride are irritating to skin at concentration < 25% and corrosive to skin at ≥ 25%. Acetic anhydride and acetic acid are not tested for sensitisation due corrosive properties; adipic acid did not show any evidence of sensitising in an animal study. The source substances did not show positive response in genetic toxicity studies available. Repeated toxicity studies via oral route conducted for acetic acid showed NOAEL values ≥ 210 mg kg bw/day and via inhalation route for acetic anhydride 4.2 mg/m3.. Reproduction toxicity studies conducted for acetic acid did not show any adverse effects on reproduction at the highest concentration tested (1600 mg/kg bw/day).

Data source

Reference

Reference Type:

publication

Title:

Acetic acid, a potent stimulator of mouse epidermal macromolecular synthesis and hyperplacia but with weak tumor-promoting ability

Author:

Slaga T, Bowden G & Boutwell R

Year:

1975

Bibliographic source:

J. Natl Cancer Inst 55:983-987

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Acetic acid was used as a promotor for tumour development in mice initiated with DMBA or β-PL and was applied dermally 1-3 times per week (at doses of 1-40 mg/animal) for 32 weeks. Control animals received acetic acid dermally once per week. The incidence of papillomas and carcinomas was recorded and they were removed at random for histological verification.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Acetic acid

EC Number:

200-580-7

EC Name:

Acetic acid

Cas Number:

64-19-7

Molecular formula:

C2H4O2

IUPAC Name:

acetic acid

Details on test material:

- Name of test material (as cited in study report): Acetic acid
- Analytical purity: Not reported
- Other: No details reported

Test animals

Species:

mouse

Strain:

CD-1

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Mouse Farms, North Wilmington, Massachusetts, USA
- Age at study initiation: 7-12 weeks old
- Weight at study initiation: not reported
- Housing: not reported
- Diet (e.g. ad libitum): not reported
- Water (e.g. ad libitum): not reported

Administration / exposure

Route of administration:

dermal

Vehicle:

acetone

Details on exposure:

TEST SITE
- Area of exposure: No details reported
- % coverage: No details reported
- Type of wrap if used: No details reported
- Time intervals for shavings or clippings: shaved 2 days before exposure

REMOVAL OF TEST SUBSTANCE
- no details reported

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.2 mL in acetone
- Concentration (if solution): 33, 167, 333, 500, 667, 833 or 1000 μmoles/animal
- Constant volume or concentration used: yes

VEHICLE
- Justification for use and choice of vehicle (if other than water): No details reported
- Amount(s) applied (volume or weight with unit): 0.2 mL

USE OF RESTRAINERS FOR PREVENTING INGESTION: no details

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

32 weeks

Frequency of treatment:

1-3 times per week.
Controls dosed once per week.

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
0, 1. 2, 10, 20, 40 mg/animal
Basis:
other: as reported in DAR

Doses / concentrations 2

Remarks:

Doses / Concentrations:
0, 17, 33, 167, 333, 667 μmoles
Basis:
nominal conc.

No. of animals per sex per dose:

20-30

Control animals:

yes, sham-exposed

Positive control:

0.25% croton oil

Examinations

Observations and examinations performed and frequency:

The animals were observed and the incidence of papillomas and carcinomas was recorded weekly.

Sacrifice and pathology:

GROSS PATHOLOGY: No data
HISTOPATHOLOGY: Yes - during the 32 week study, papillomas and carcinomas were removed for histological verification at random

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Details on results:

Tumour Promotion:
- Acetic acid alone at a dose of 30 mg/animal given once per week for 32 weeks did not induce the formation of skin tumours (Table 1). However acetic acid did act as a promotor in animals treated with with ß-PL or DMBA, especially when exposed to a single dose per week.

Mortality:
- A single dermal application of acetic acid at doses of up to 40 mg/animal, in mice initiated with ß-PL or DMBA did not induce excessive mortality. However, more than one weekly application of 10-40 mg acetic acid caused excessive mortality. 33% of mice died when 10 mg acetic acid/animal was applied dermally 3 times per week and approximately 50% of mice died when 20 mg was applied twice a week.

Relevance of carcinogenic effects / potential:

Concentrated acetic acid when applied dermally to mice for 32 weeks at a dose level of 30 mg/animal did not show any carcinogenic potential. However, with a dosing regimen that did not lead to excessive toxicity, acetic acid exhibited weak promotor activity in mice initiated with ß-PL or DMBA .

Effect levels

1

Dose descriptor:

NOAEL

Effect level:

30 other: mg/animal

Sex:

female

Basis for effect level:

other: No deaths and no skin tumours when applied dermally once per week for 32 weeks

Remarks on result:

other: Effect type: carcinogenicity (migrated information)

2

Dose descriptor:

LOAEL

Effect level:

10 other: mg/animal

Sex:

female

Basis for effect level:

other: Mortality (33%) when applied dermally 3 times per week.

Remarks on result:

other: Effect type: toxicity (migrated information)

3

Dose descriptor:

dose level:

Effect level:

40 other: mg/animal

Sex:

female

Basis for effect level:

other: 41% of mice with papillomas after 32 weekly dermal exposures in mice initiated with ß-PL or DMBA.

Remarks on result:

other: Effect type: carcinogenicity (migrated information)

Any other information on results incl. tables

TABLE1. Skin tumour formation in female Charles River CD-1 mice as a result of initiation by ß-PL or DMBA and promotion by applications of 0.2 mL of acetic acid or 0.25% croton oil

Initiator	Acetic acid		Mice		% with papillomas	Papillomas / mouse
	mg	Times/week	N	Survivors
None	30	1	30	27	0	0
β-PL (480 μmoles)	0	-	20	nd	0	0
	10	1	20	18	11	0.11
	20	1	20	19	21	0.26
	40	1	20	17	41	0.41
DMBA (0.2 μmole)	0	0	nd	nd	0	0
	1	3	30	29	4	0.03
	2	1	20	19	42	0.63
	2	2	30	28	4	0.1
	2	3	30	25	4	0.03
	10	2	30	25	0	0
	10	3	30	20	0	0
	20	2	30	16	6	0.06
	40	1	20	17	41	0.73
Initiator	Croton oil		Mice		% with papiillomas	Papillomas / mouse
	mg	Times/week	N	Survivors
β-PL	30	2	30	26	71	4.50
DMBA	30	2	30	28	100	10.20

Mice that were only initiated with DMBA orβ-PL did not develop any tumours after 32 weeks. Also, mice promoted once a week for 32 weeks with acetic acid developed no tumours.

 

Applicant's summary and conclusion

Conclusions:

Application of acetic acid to the skin of mice was reported to stimulate the occurrence of epidermal hyperplasia, suggesting that it was a very weak tumour promotor.

Executive summary:

Acetic acid was used as a promotor for tumour development in mice initiated with DMBA or β-PL and was applied dermally 1-3 times per week (at doses of 1-40 mg/animal) for 32 weeks. Control animals received acetic acid dermally once per week. The incidence of papillomas and carcinomas was recorded and they were removed at random for histological verification.

A single dermal application of acetic acid at doses of up to 40 mg/animal, in mice initiated with ß-PL or DMBA did not induce excessive mortality. However, more than one weekly application of 10-40 mg acetic acid caused excessive mortality. 33% of mice died when 10 mg acetic acid/animal was applied dermally 3 times per week and approximately 50% of mice died when 20 mg was applied twice a week.

Mice that were only initiated with DMBA or β-PL did not develop any tumours after 32 weeks. Also, mice promoted once a week for 32 weeks with acetic acid developed no tumours. However, with a dosing regimen that did not lead to excessive toxicity, acetic acid exhibited weak promotor activity in mice initiated with ß-PL or DMBA .