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Skin irritation / corrosion

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Administrative data

skin irritation: in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
Zinc bis(dihydrogen phosphate)
EC Number:
EC Name:
Zinc bis(dihydrogen phosphate)
Cas Number:
Molecular formula:
zinc bis(dihydrogen phosphate)
Test material form:
solid: particulate/powder
migrated information: powder
Details on test material:
- Name of test material (as cited in study report): Zinc bis(dihydrogen phosphate)
- Physical state: white crystalline solid powder
- Analytical purity: ZnO(%): 25-27 P2O5(%): 43-49.5
- Composition of test material, percentage of components: Zinc bis(dihydroogen phosphate)*2H2O : phosphate (as P2O5) 44.6% ±5% rel.; Zinc: 21.5%±0.5 % rel.
- Lot/batch No.: Z 11-81
- Stability under test conditions: stable at room temperature
- Storage condition of test material: room temperature

In vitro test system

Test system:
human skin model
Source species:
Cell type:
non-transformed keratinocytes
Cell source:
skin obtained from plastic surgery from multiple donors
physiological saline
Details on test system:
- Area of exposure: after moistening the EpiDerm tissue with 25µl PBS before dosing, 25 mg of the test article was added into the Millicell atop the tissue

- Washing (if done): at the end of the exposure period, each EpiDerm tissue was rinsed with phosphate buffered saline (PBS)
- Time after start of exposure: test article remained in contact with the EpiDerm tissue for 60 minutes.

After washing EpiDerm tissue was transferred to a 24 well plate contaiing 300µl MTT solution. Afterwards the tissues were returned to the incubator for a three-hour MTT incubation period. Following MTT incubation period, each EpiDerm tissue was rinsed with PBS and then treated overnight with 2.0 ml of extractant solution (isopropanol) per well. The absorbancy of an aliquot of the extracted MTT formazan was measured at 540nm using a microplate reader.

Analysis of data:
The mean absorbance value for each time point was calculated from the optical density (OD) of the duplicate samples and expressed as percent viability for each sample using the following formula:
% viability= 100x(OD sample/OD negative control)

Quality controls: negative controls meets the acceptance criterion if the mean OD of the 2 tissues each time point is greater than or equal to 1.0 and smaller than or equal to 2.5. The positive controls meets the acceptance criterion if the mean relative tissue viability, expressed as percentage of the negative control tissues is less than or equal to 20%
the SD calculated from individual percent tissue viabilities of the three identically treated replicates is less than 18%

Amount/concentration applied:
25 mg
Duration of treatment / exposure:
60 min

Results and discussion

In vitro

Irritation / corrosion parameter:
% tissue viability
Remarks on result:
Basis: mean. Time point: 60min. Remarks: recovery period: 42h. (migrated information)

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Following exposure with Zinc bis(dihydrogen phosphate), the mean treated skin value was 92.1% and therefore non irritant. All validity criteria were within acceptable limits and therefore the study can be considered as valid.

In this in vitro skin irritation test in the EPISKIN model with Zinc bis(dihydrogen phosphate) the results indicated that the test item is Non Irritant (NI) [UN GHS: No Category].
Executive summary:

A study was conducted to predict dermal irritation potential of Zinc bis(dihydrogen phosphate) in the context of identification and classification of skin irritation hazard according to the EU classification (R38 or no label) and GHS classification system (category 2 and non-irritants) by using a three-dimensional human epidermis model (OECD 439). MatTek EpiDerm tissue samples were treated in triplicate with the test article, negative control and positive control for 60 minutes. Following treatment and subsequent incubation time, the viability of the tissues was determined using MTT uptake and conversion, and the absorbance of each sample was measured at 540nm. The viability was then expressed as a percent of control values.

In this in vitro EPIDERM model test with Zinc bis(dihydrogen phosphate), the results indicate that the test item is non irritant.