Phosphoric acid, mono- and di-C8-10-(even numbered)-alkyl esters

Endpoint summary

Description of key information

The test substance is corrosive to skin and eye.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From October 02, 2017 to October 06, 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 431 (In Vitro Skin Corrosion: Reconstructed Human Epidermis (RHE) Test Method)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: EU B.40 BIS "In Vitro Skin Corrosion: Human Skin Model Test

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

- Name of test material (as cited in study report): Phosphoric acid, mono-and di-C8-C10-(even numbered)-alkyl esters
- Batch: CH 205624/001
- Composition: UVCB
- Appearance: Clear colourless liquid
-Test item storage: At room temperature
-Stable under storage conditions until: 01 July 2018 (expiry date)

Test system:

human skin model

Remarks:

EpiDerm Skin Model

Source species:

human

Cell type:

non-transformed keratinocytes

Justification for test system used:

The model consists of normal, human-derived epidermal keratinocytes which have been cultured to form a multilayered, highly differentiated model of the human epidermis. It consists of organized basal, spinous and granular layers, and a multi-layered stratum corneum containing intercellular lamellar lipid layers arranged in patterns analogous to those found in vivo. The EpiDerm tissues (surface 0.6 cm²) were cultured on polycarbonate membranes of 10 mm cell culture inserts. Recommended test system in international guidelines (OECD and EC)

Vehicle:

unchanged (no vehicle)

Details on test system:

The skin tissues were kept in the refrigerator the day they were received. The next day, at least 1 h before the assay was started the tissues were transferred to 6-well plates containing 0.9 ml DMEM per well. The level of the DMEM was just beneath the tissue. The plates were incubated for approximately 3 h at 37.0 ± 1.0ºC. The medium was replaced with fresh DMEM just before the test substance was applied. The test was performed on a total of 4 tissues per test substance together with a negative control and positive control. Two tissues were used for a 3-minute exposure to the test substance and two for a 1-h exposure. 50 µL of the undiluted test substance was added into the 6-well plates on top of the skin tissues. For the negative and positive controls, 2 tissues were treated with 50 µl Milli-Q water (negative control) and 2 tissues were treated with 50 µl 8N KOH (positive control) for both the 3-minute and 1-h time point. After the exposure period, the tissues were washed with phosphate buffered saline to remove residual test substance. The skin inserts were carefully dried. Rinsed tissues were kept in 24 well plates on 300 µl DMEM until 6 tissues (= one application time) were dosed and rinsed.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

50 µL

Duration of treatment / exposure:

3 minutes and 1 h

Number of replicates:

2

Irritation / corrosion parameter:

% tissue viability

Remarks:

cytotoxicity

Run / experiment:

3 minutes treatment

Value:

86

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Irritation / corrosion parameter:

% tissue viability

Remarks:

cytotoxicity

Run / experiment:

1 h treatment

Value:

9.1

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

- The test substance was checked for colour interference in aqueous conditions and possible direct MTT reduction by adding the test substance to MTT medium. Because the solutions did not turn blue / purple nor a blue / purple precipitate was observed it was concluded that the test substance did not interfere with the MTT endpoint.

- The mean absorption at 570 nm measured after treatment with the test substance and controls were as follows:
1) Negative control 1.988 ± 0.253 (3 minute application) and 1.857 ± 0.050 (1 h application)
2) Test substance 1.710 ± 0.127 (3 minute application) and 0.170 ± 0.023 (1 h application)
3) Positive control 0.333 ± 0.247 (3 minute application) and 0.137 ± 0.028 (1 h application)

- The mean tissue viability obtained after 3 minute and 1 h treatments with the test substance compared to the negative control tissues. Skin corrosion is expressed as the remaining cell viability after exposure to the test substance. The relative mean tissue viability obtained after the 3 minute and 1 h treatments with the test substance compared to the negative control tissues was 86% and 9.1% respectively. Because the mean relative tissue viability for the test substance was below 15% after 1 hour treatment it is considered to be corrosive.

- The absolute mean OD570 (optical density at 570 nm) of the negative control tissues was within the acceptance limits of OECD 431 (lower acceptance limit ≥0.8 and upper acceptance limit ≤ 2.8) and the laboratory historical control data range. The mean relative tissue viability following the 1h exposure to the positive control was 7.4%.

- In the range of 20 - 100% viability the Coefficient of Variation between tissue replicates was ≤ 16%, indicating that the test system functioned properly.

Interpretation of results:

Category 1 (corrosive) based on GHS criteria

Conclusions:

Under the study conditions, the substance was found to be corrosive to human skin.

Executive summary:

A study was conducted to determine the in vitro skin corrosion potential of the substance according to OECD Guideline 431and EU Method B.40 bis, in compliance with GLP. Duplicate tissue samples were exposed to 50 µL test substance for 3 minutes and 1 h. After the treatment period, a determination of the cytotoxic effect was performed. Cytotoxicity was expressed as the reduction of mitochondrial dehydrogenase activity measured by formazan production from MTT at the end of the treatment. Skin corrosion was expressed as the remaining cell viability after exposure to the test substance. The positive control showed a mean relative tissue viability of 7.4% after 1 h exposure. The absolute mean OD570 (optical density at 570 nm) of the negative control tissues was within the acceptance limits of OECD 431 (≥0.8 and ≤2.8) and the laboratory historical control data range. In the range of 20 - 100% viability the coefficient of variation between tissue replicates was ≤16%, indicating that the test system functioned properly. The relative mean tissue viability obtained after 3 minute and 1 h treatments with the test substance compared to the negative control tissues was 86% and 9.1%, respectively. Because the mean relative tissue viability for the test substance was below 15% after the 1 h treatment it is considered to be corrosive to the skin. Under the study conditions, the substance was found to be corrosive to human skin (Groot, 2017).

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (corrosive)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vitro / ex vivo

Remarks:

The Bovine Corneal Opacity and Permeability Assay (BCOP)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From October 03, 2017 to October 03, 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 437 (Bovine Corneal Opacity and Permeability Test Method for Identifying i) Chemicals Inducing Serious Eye Damage and ii) Chemicals Not Requiring Classification for Eye Irritation or Serious Eye Damage)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

- Name of test material (as cited in study report): Phosphoric acid, mono-and di-C8-C10-(even numbered)-alkyl esters
- Batch: CH 205624/001
- Composition: UVCB
- Appearance: Clear colourless liquid
- Test item storage: At room temperature
- Stable under storage conditions until: 01 July 2018 (expiry date)

Species:

other: Bovine

Details on test animals or tissues and environmental conditions:

Test System: Bovine eyes were used as soon as possible after slaughter.
Rationale: In the interest of sound science and animal welfare, a sequential testing strategy is recommended to minimize the need of in vivo testing (1-6). As a consequence a validated and accepted in vitro test for eye irritation should be performed before in vivo tests are conducted. One of the proposed validated in vitro eye irritation tests is the Bovine Corneal Opacity and Permeability (BCOP) test.

Source: Bovine eyes from young cattle were obtained from the slaughterhouse (Vitelco, 's Hertogenbosch, The Netherlands), where the eyes were excised by a slaughterhouse employee as soon as possible after slaughter.
Transport: Eyes were collected and transported in physiological saline in a suitable container under cooled conditions.

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

750 µL

Duration of treatment / exposure:

10 minutes

Observation period (in vivo):

-

Duration of post- treatment incubation (in vitro):

The medium in the posterior compartment was removed and both compartments were refilled with fresh cMEM. Subsequently the corneas were incubated for 120 ± 10 minutes at 32 ± 1°C.

Number of animals or in vitro replicates:

3

Details on study design:

Preparation of Corneas:
The eyes were checked for unacceptable defects, such as opacity, scratches, pigmentation and neovascularization by removing them from the physiological saline and holding them in the light. Those exhibiting defects were discarded. The isolated corneas were stored in a petri dish with cMEM (Earle’s Minimum Essential Medium containing 1% (v/v) L-glutamine and 1% (v/v) Foetal Bovine Serum. The isolated corneas were mounted in a corneal holder (one cornea per holder) of BASF (Ludwigshafen, Germany) with the endothelial side against the O-ring of the posterior half of the holder. The anterior half of the holder was positioned on top of the cornea and tightened with screws. The compartments of the corneal holder were filled with cMEM of 32 ± 1°C. The corneas were incubated for the minimum of 1 hour at 32 ± 1°C.

Cornea Selection and Opacity Reading:
After the incubation period, the medium was removed from both compartments and replaced with fresh cMEM. Opacity determinations were performed on each of the corneas using an opacitometer. The opacity of each cornea was read against a cMEM filled chamber, and the initial opacity reading thus determined was recorded. Corneas that had an initial opacity reading higher than 7 were not used. Three corneas were selected at random for each treatment group.

Treatment of Corneas and Opacity Measurements:
The medium from the anterior compartment was removed and 750 µL of either the negative control, positive control (Ethanol) or test substance was introduced onto the epithelium of the cornea. The holders were slightly rotated, with the corneas maintained in a horizontal position, to ensure uniform distribution of the control or the test substance over the entire cornea. Corneas were incubated in a horizontal position for 10 ± 1 minutes at 32 ±1°C. After the incubation the solutions were removed and the epithelium was washed with MEM with phenol red and thereafter with cMEM. Possible pH effects of the test item on the corneas were recorded. The medium in the posterior compartment was removed and both compartments were refilled with fresh cMEM. Subsequently the corneas were incubated for 120 ± 10 minutes at 32 ± 1°C. After the completion of the incubation period opacity determination was performed. Each cornea was inspected visually for dissimilar opacity patterns.

Irritation parameter:

in vitro irritation score

Run / experiment:

10 minutes exposure

Value:

112

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

The individual in vitro irritancy scores for the negative controls ranged from 0.2 to 0.7. The individual in vitro irritancy scores for the positive control ranged from 55 to 59. The corneas treated with the positive control item were turbid after the 10 minutes of treatment. The corneas treated with the test substance showed opacity values ranging from 54 to 63 and permeability values ranging from 3.384 to 3.918. The corneas were turbid after the 10 minutes of treatment with the test substance. A pH effect of the test item was observed on the rinsing medium, the corneas were rinsed until no color change of the medium was observed. Hence, the in vitro irritancy scores ranged from 107 to 115 after 10 minutes of treatment with the test substance.

In Vitro Irritancy Score:

Treatment	Final Opacity^2	Final OD490^2	In vitroIrritancy Score^1
Negative control	0.7	0.000	0.7
	0.3	0.003	0.4
	0.2	0.002	0.2
Positive control	21	2.478	59
	23	2.098	55
	22	2.322	56
The test item	63	3.460	115
	56	3.384	107
	54	3.918	113

¹  In vitro irritancy score (IVIS) = opacity value + (15 x OD₄₉₀value).

²  Positive control and test item are corrected for the negative control.

Summary of Opacity, Permeability and In Vitro Scores:

Treatment	Mean Opacity^1	Mean Permeability^1	MeanIn vitroIrritation Score^1, 2
Negative control	0.4	0.002	0.4
Positive control (Ethanol)	22	2.299	57
The test item	58	3.587	112

¹  Calculated using the negative control mean opacity and mean permeability values for the positive control and test item.

²  In vitro irritancy score (IVIS) = mean opacity value + (15 x mean OD₄₉₀value).

Interpretation of results:

Category 1 (irreversible effects on the eye) based on GHS criteria

Conclusions:

Under the study conditions, the substance was found to be causing serious eye damage in bovine corneal opacity and permeability test.

Executive summary:

A study was conducted to determine the in vitro eye damage potential of the substance according to OECD Guideline 437, in compliance with GLP. The eye damage potential of the test substance was tested through topical application for 10 minutes. The test substance was applied as is (750 µL) directly on top of the freshly isolated bovine cornea sample. The negative control responses for opacity and permeability was less than the upper limits of the laboratory historical control range indicating that the negative control did not induce irritancy on the corneas. The mean in vitro irritancy score of the positive control (Ethanol) was 57 and was within two standard deviations of the current historical positive control mean. It was therefore concluded that the test conditions were adequate and that the test system functioned properly. The test substance induced serious eye damage through both endpoints, resulting in a mean in vitro irritancy score of 112 after 10 minutes of treatment. Under the study conditions, the substance was found to be causing serious eye damage in bovine corneal opacity and permeability test (Groot, 2017).

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irreversible damage)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

In vitro skin irritation:

A study was conducted to determine the in vitro skin corrosion potential of the substance according to OECD Guideline 431and EU Method B.40 bis, in compliance with GLP. Duplicate tissue samples were exposed to 50 µL test substance for 3 minutes and 1 h. After the treatment period, a determination of the cytotoxic effect was performed. Cytotoxicity was expressed as the reduction of mitochondrial dehydrogenase activity measured by formazan production from MTT at the end of the treatment. Skin corrosion was expressed as the remaining cell viability after exposure to the test substance. The positive control showed a mean relative tissue viability of 7.4% after 1 h exposure. The absolute mean OD570 (optical density at 570 nm) of the negative control tissues was within the acceptance limits of OECD 431 (≥0.8 and ≤2.8) and the laboratory historical control data range. In the range of 20 - 100% viability the coefficient of variation between tissue replicates was ≤16%, indicating that the test system functioned properly. The relative mean tissue viability obtained after 3 minute and 1 h treatments with the test substance compared to the negative control tissues was 86% and 9.1%, respectively. Because the mean relative tissue viability for the test substance was below 15% after the 1 h treatment it is considered to be corrosive to the skin. Under the study conditions, the substance was found to be corrosive to human skin (Groot, 2017).

In vitro eye irritation:

A study was conducted to determine the in vitro eye damage potential of the substance according to OECD Guideline 437, in compliance with GLP. The eye damage potential of the test substance was tested through topical application for 10 minutes. The test substance was applied as is (750 µL) directly on top of the freshly isolated bovine cornea sample. The negative control responses for opacity and permeability was less than the upper limits of the laboratory historical control range indicating that the negative control did not induce irritancy on the corneas. The mean in vitro irritancy score of the positive control (Ethanol) was 57 and was within two standard deviations of the current historical positive control mean. It was therefore concluded that the test conditions were adequate and that the test system functioned properly. The test substance induced serious eye damage through both endpoints, resulting in a mean in vitro irritancy score of 112 after 10 minutes of treatment. Under the study conditions, the substance was found to be causing serious eye damage in bovine corneal opacity and permeability test (Groot, 2017).

Justification for classification or non-classification

Based on in vitro skin and eye irritation studies, the substance warrants classification as Skin Corr. 1 (H314: Causes severe skin burns and eye damage) and Eye Damage 1 (H318: Causes serious eye damage) according to EU CLP (1272/2008) criteria.