Hexanedioic acid, 1,6-bis(2-propylheptyl) ester

Endpoint summary

Description of key information

No eye irritating potential was demonstrated in an in vivo study in rabbits (Bioassay 2014) and two in vitro eye irritation studies (EpiOcular and BCOP; BASF 2013) with Dipropylheptyladipat. An in vivo study in rabbits with the structural homologue Diethylheptyladipat (CTFA 1967) showed that this substances does not have an eye irritating potential, too (for details please refer to chapter 13 of the IUCLID, Assessment reports). 
Dipropylheptyladipat caused no skin irritation in an in vivo study with rabbits (BASF 2014) and in an in vitro skin irritation study (EpiDerm, BASF 2013).  The structural homologue Diethylheptyladipat also did not show a skin irritation potential in rabbits in vivo (CTFA 1967, Smyth 1951).
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Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.4 (Acute Toxicity: Dermal Irritation / Corrosion)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2500 (Acute Dermal Irritation)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Japan/MAFF 8147

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Wiga GmbH, Germany
- Age at study initiation: Approx. 5-8 months
- Weight at study initiation: 4.22 kg – 4.91 kg
- Housing: Single housing, Stainless steel wire mesh cages with grating with shallow cage body; floor area: 4225 cm2
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20°C +/- 3°C
- Humidity (%): 30 – 70%
- Air changes (per hr): approx. 10
- Photoperiod (hrs dark / hrs light): 12 h / 12 h (6.00 a.m. – 6.00 p.m. / 6.00 p.m. – 6.00 a.m.)

IN-LIFE DATES: From: 05 May 2014 To:

Type of coverage:

semiocclusive

Preparation of test site:

clipped

Vehicle:

unchanged (no vehicle)

Controls:

other: untreated skin sites of same animals used as negative control

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.5 ml
- Concentration (if solution): undiluted

Duration of treatment / exposure:

4h

Observation period:

7d

Number of animals:

3

Details on study design:

TEST SITE
- Area of exposure: 2.5 cm x 2.5 cm
- Type of wrap if used: semi- occlusive, test patch fixed with Fixomull® stretch (adhesive fleece)

REMOVAL OF TEST SUBSTANCE
- Washing (if done): yes
- Time after start of exposure: 4h

SCORING SYSTEM: see "any other information on materials and methodes incl. tables"

Irritation parameter:

erythema score

Basis:

mean

Time point:

other: 24h - 72h

Score:

1.3

Max. score:

2

Reversibility:

fully reversible within: 7d

Irritation parameter:

edema score

Basis:

mean

Time point:

other: 24h - 72h

Score:

0.2

Max. score:

1

Reversibility:

fully reversible within: 7d

Irritation parameter:

erythema score

Basis:

animal #1

Remarks:

mean

Time point:

other: 24h - 72h

Score:

0.3

Max. score:

1

Reversibility:

fully reversible within: 48h

Irritation parameter:

erythema score

Basis:

animal #2

Remarks:

mean

Time point:

other: 24h - 72h

Score:

2

Max. score:

2

Reversibility:

fully reversible within: 7d

Irritation parameter:

erythema score

Basis:

animal #3

Remarks:

mean

Time point:

other: 24h - 72h

Score:

1.7

Max. score:

2

Reversibility:

fully reversible within: 7d

Irritation parameter:

edema score

Basis:

animal #1

Remarks:

mean

Time point:

other: 24h - 72h

Score:

0

Max. score:

0

Irritation parameter:

edema score

Basis:

animal #2

Remarks:

mean

Time point:

other: 24h - 72h

Score:

0.7

Max. score:

1

Reversibility:

fully reversible within: 7d

Irritation parameter:

edema score

Basis:

animal #3

Remarks:

mean

Time point:

other: 24h - 72h

Score:

0

Max. score:

0

readings	Animal No.	Erythema	edema
0h	1	1	0
	2	0	0
	3	0	0
1h	1	1	0
	2	0	0
	3	0	0
24h	1	1	0
	2	2	0
	3	2	0
48	1	0	0
	2	2	1
	3	2	0
72h	1	0	0
	2	2	1
	3	1	0
7d	1	-	-
	2	0	0
	3	0	0
mean 24h - 72h	1	0.3	0.0
	2	2.0	0.7
	3	1.7	0.0
mean		1.3	0.2

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.5 (Acute Toxicity: Eye Irritation / Corrosion)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2400 (Acute Eye Irritation)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Japan/MAFF 8147

GLP compliance:

yes (incl. QA statement)

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories, Netherlands
- Age at study initiation: Approx. 3 months
- Weight at study initiation: 2.27 kg – 2.51 kg
- Housing: Single housing, Stainless steel wire mesh cages with grating with shallow cage body; floor area: 4225 cm2
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 +/- 3°C
- Humidity (%): 30 - 70%
- Air changes (per hr): approx. 10
- Photoperiod (hrs dark / hrs light): 12 h / 12 h (6.00 a.m. – 6.00 p.m. / 6.00 p.m. – 6.00 a.m.)

IN-LIFE DATES: From: 22 April 2014 To: 09 May 2014

Vehicle:

unchanged (no vehicle)

Controls:

other: untreated eyes of same animals used as control

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.1 ml
- Concentration (if solution): unchanged

Duration of treatment / exposure:

24h

Observation period (in vivo):

96h

Number of animals or in vitro replicates:

3

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing (if done): after 24h with warm tap water
- Time after start of exposure: 24h

SCORING SYSTEM: see "any other information on material and methods incl. tables"

TOOL USED TO ASSESS SCORE: hand-slit lamp, otoscope lamp, fluorescein

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

other: 24h - 72h

Score:

0

Max. score:

0

Irritation parameter:

iris score

Basis:

mean

Time point:

other: 24h - 72h

Score:

0

Max. score:

0

Irritation parameter:

conjunctivae score

Remarks:

redness

Basis:

mean

Time point:

other: 24h - 72h

Score:

0

Max. score:

1

Reversibility:

fully reversible within: 24h

Irritation parameter:

other: discharge

Basis:

mean

Time point:

other: 24h - 72h

Max. score:

3

Reversibility:

fully reversible within: 24h

Irritation parameter:

chemosis score

Basis:

mean

Time point:

other: 24h - 72h

Score:

0

Max. score:

1

Reversibility:

fully reversible within: 24h

No reactions on cornea or iris were observed in any animal during the observation period. Even after installation of fluorescein after 24 and 48 hours no corneal lesions were detectable. Slight conjunctival redness (grade 1) was noted in two animals at 1 hour after application. Slight conjunctival chemosis (grade 1) was noted in one animal at 1 hour after application. Severe discharge (grade 3) was noted in all animals at 1 hour after application. Additional findings like injected scleral vessels in a circumscribed area were noted at hour 1 after application only. The ocular reactions were reversible in all animals within 24 hours after application. Mean scores calculated for each animal over 24, 48 and 72 hours were 0.0, 0.0 and 0.0 for corneal opacity, 0.0, 0.0 and 0.0 for iris lesions, 0.0, 0.0 and 0.0 for redness of the conjunctiva and 0.0, 0.0 and 0.0 for chemosis.

Interpretation of results:

not irritating

Remarks:

Migrated information

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Skin irritation in vitro

The potential of Dipropylheptyladipat to cause dermal corrosion/irritation was assessed in a reconstructed three dimensional human epidermis model (EpiDerm) (BASF SE, 2013). A single topical application of 50 µL (corrosion test) or 30 µL (irritation test) of the undiluted test substance was used.De-ionized water served as negative control in the corrosion test and PBS in the irritation test. As positive control 8 -n potassium hydroxide solution was used in the corrosion test and 5% (w/v) sodium dodecyl sulfate (SDS) in the irritation test.For the corrosion test two EpiDerm tissue samples were incubated with the test substance for 3 minutes and 1 hour, respectively. The irritation test was performed with three EpiDerm tissue samples, which were incubated with the test substance for 1 hour followed by a 42-hours post incubation period. Tissue destruction was determined by measuring the metabolic activity of the tissue after exposure/post-incubation using a colorimetric test. The reduction of mitochondrial dehydrogenase activity, measured by reduced formazan production after incubation with a tetrazolium salt (MMT) was chosen as endpoint. The formazan production of the test-substance treated epidermal tissues was compared to that of negative control tissues. The quotient of the values indicates the relative tissue viability. Dipropylheptyladipat was not able to reduce MTT directly. In the corrosive test the mean viability of Dipropylheptyladipat treated tissues determined after an exposure period of 3 minutes was 97%, and it was 103% after an exposure period of 1 hour. The irritation test revealed a mean viability of Dipropylheptyladipat treated tissues of 103% after an exposure period of 1 hour with about 42 hours post-incubation. Dipropylheptyladipat did not show a skin irritation potential in the EpiDerm skin corrosion/irritation test under the test conditions chosen.

Skin irritation in vivo

Dipropylheptyladipat, was tested in a skin irritation/corrosion study in the rabbit according to OECD guideline no. 404 (Bioassay 2014). Three female rabbits were exposed to 0.5 mL of the undiluted test substance, applied onto shaved skin for 4 hours using a semi-occlusive dressing. Observations for erythema and edema were made 0 and 1h after removal of the test patches and 24, 48, 72 h after the beginning of application and were deduced according to the scoring system of Draize. Clinical observation revealed very slight to well-defined erythema (grade 1 -2) and very slight edema (grade 1) which were fully reversible within 7 days. The test item was considered to show a mild skin irritation potential.

In a second skin irritation study (CFTA, 1967) with Diethylhexyladipat, a structural analogue to Dipropylheptyladipat, six rabbits were topically exposed for 24 hours followed by a 72 hours observation period. Scoring was performed according to Draize. The skin of the animals was abraded as well as intact. Slight erythema was observed when the patch was removed. The mean value for 24 and 72 hours was maximum 1.5 in one animal of the abraded skin group and one animal in the intact skin group. There was no apparent difference between abraded and intact skin. The severity of the observed erythema decreased in all animals by 72 hours. Based on the results of this study Diethylhexyladipat was considered as non-irritating to the skin.

In addition, Smyth et al. (1951) reported that the structural analogue Diethylhexyladipat was not irritating to the rabbit skin.

 

Conclusion skin irritation

The in vitro skin irritation study (EpiDerm, BASF 2013) and the in vivo study with rabbits (Bioassay 2014) indicated that Dipropylheptyladipat is not or mildly skin irritating. This is in line with the results achieved in the in vivo skin irritation studies (CFTA 1967, Smyth 1951) where the structural analogue to Dipropylheptyladipat, Diethylhexyladipat, induced no signs of skin irritation in rabbits.

Eye irritation in vitro

The eye irritation properties of Dipropylheptyladipat were examined in vitro by means of the BCOP assay using fresh bovine cornea (BASE SE, 2013; 63V0814/12A528). Each treatment group (undiluted liquid test substance, de-ionized water as negative control and 1% (w/v) solution of sodium hydroxide as positive control) consisted of 3 corneas. 750 µL test solution was applied into the anterior chamber of a specially designed cornea holders and the corneas were incubated in a horizontal position at about 32°C for approximately 10 minutes followed by a 2 hours post-incubation period. Corneal opacity was measured quantitatively as the amount of light transmission through the cornea. The control groups were treated in the same manner. Permeability was measured quantitatively as the amount of sodium fluorescein dye that passes across the full thickness of the cornea. Both measurements were used to calculate an In Vitro Irritancy Score (IVIS) of the test substance relative to the control corneas. The positive control showed clear opacity effects corresponding to a classification as corrosive / severe irritant to the eye (IVIS: 177.5). Relative to the negative control, the test item Dipropylheptyladipat did not cause any increase of the corneal opacity or permeability. The calculated mean iVIS was 1.5 and thus the test substance did not cause ocular or severe irritation in the BCOP Test under the test conditions chosen.

In a second in vitro test the eye irritation potential of Dipropylheptyladipat was tested using the EpiOcular assay (BASF SE, 2013; 62V0814/12A527

). Two EpiOcular tissue samples were incubated with the test substance, the negative control (de-ionized water) and the positive control (Methylacetate) for 30 minutes followed by a 2-hours post-incubation period. Tissue destruction was determined by measuring the metabolic activity of the tissue after exposure/post-incubation using a colorimetric test. The reduction of mitochondrial dehydrogenase activity, measured by reduced formazan production after incubation with a tetrazolium salt (MTT) was chosen as endpoint. The formazan production of the test substance treated epidermal tissues is compared to that of negative control tissues. The quotient of the values indicates the relative tissue viability. The mean tissue viability of the positive control was 33% indicating the appropriate sensitivity of the test system. The test substance was not able to reduce MTT directly. The mean viability of the test-substance treated tissues was 100%. Based on the observed results it was concluded that Dipropylheptyladipat does not show an eye irritation potential in vitro.

 

 

Eye irritation in vivo

An in vivo eye irritation study (OECD 405, Bioassay 2014) was conducted with Dipropylheptyladipat using three female rabbits. A volume of 0.1 mL of the undiluted test substance was applied in the conjuctival sac of one eyelid of each rabbit. The test substance was washed out and the untreated eye served as control. After 1, 24, 48, 72 and 96 hours the rabbit eyes were examined and the effects were scored according to the scoring system of Draize. The cornea, iris, conjunctiva and chemosis score (mean of 24, 48 and 72 h) did not show an effects in any test animal and the test item was demonstrated to be not an eye irritant. 

In addition, a structural analogue to Dipropylheptyladipt, Diethylhexyladipat, was examined for its potential to exert eye irritation using six albino rabbits (CFTA, 1967). A volume of 0.1 mL of undiluted test item was instilled in one eye of the rabbits. The other eye remained untreated. The eyes were examined at 24, 48 and 72 hours after treatment. As a result, no irritation was observed at any time point. 

 

Conclusion eye irritation

Both in vitro eye irritation studies (EpiOcular and BCOP, BASF 2013) and the in vivo study (Bioassay 2014) with Dipropylheptyladipat demonstrated negative results. This is in line with the results obtained in the in vivo eye irritation study (CFTA 1967) with the structural analogue to Dipropylheptyladipat, Diethylhexyladipat, that revealed no eye irritation in rabbits.

Justification for classification or non-classification

Based on the available data, Dipropylheptyladipat does not have to be classified for skin or eye irritation according to Directive 67/548/EEC (DSD) and Regulation (EC) No 1272/2008 (CLP/GHS).