Reaction mass of zinc oxide and zinc peroxide

Endpoint summary

Description of key information

All available data suggests this compound does not have skin sensitisation potential.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The target substance Zinc peroxide and the source substances Zinc oxide, Zinc Chloride, Zinc sulfate, Zinc nitrate are ionic and consist of the Zinc2+ cation and the respective anion.
The read-across is based on the assumption that the zinc cation (as measure for dissolved zinc species) is the determining factor for (eco)toxicity.
For further details, see Justification for read-across attached to IUCLID chapter 13

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
See Justification for read-across attached to IUCLID chapter 13

3. ANALOGUE APPROACH JUSTIFICATION
See Justification for read-across attached to IUCLID chapter 13

4. DATA MATRIX
See Justification for read-across attached to IUCLID chapter 13

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Justification for non-LLNA method:

The metals industry has historical data to indicate that metals can induce false positives/negatives in LLNA studies; this is confirmed from experiences in test labs.

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

2%

No. with + reactions:

0

Total no. in group:

10

Remarks on result:

no indication of skin sensitisation

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

2%

No. with + reactions:

0

Total no. in group:

10

Group:

positive control

Remarks on result:

other: no information on positive control

Interpretation of results:

GHS criteria not met

Conclusions:

Zinc peroxide is not sensitising.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

No data on sensitization are available for the target substance Zinc peroxide. However, reliable data are available for Zinc compounds as well as on hydrogen peroxide. A justification for read-across is attached to IUCLID section 13.

 

Data on Zinc

Non-human data

The skin sensitising potential of zinc oxide (purity 99.69%) was investigated in female Dunkin Hartley guinea pigs in two well-performed maximisation tests, conducted according to Directive 96/54/EC B.6 and OECD guideline 406. Based on the results of a preliminary study, in the main studies experimental animals (10 in each test) were intradermally injected with a 20% concentration and epidermally exposed to a 50% concentration (i. e. the highest practically feasible concentration). Control animals (5 in each test) were similarly treated, but with vehicle (water) alone. Approximately 24 hours before the epidermal induction exposure all animals were treated with 10% SDS. Two weeks after the epidermal application all animals were challenged with a 50% test substance concentration and the vehicle. In the first study, in response to the 50% test substance concentration skin reactions of grade 1 were observed in 4/10 experimental animals 24 hours after the challenge (40% sensitisation rate), while no skin reactions were evident in the controls. In contrast, in the second study no skin reactions were evident in the experimental animals (0% sensitisation rate), while a skin reaction grade 1 was seen in one control animal. The skin reaction observed in one control animal is probably a sign of nonspecific irritation (Van Huygevoort, 1999b1, 1999b2).

In a third well-performed maximisation test, conducted according to the same guidelines and with the same experimental design, another analytical grade zinc oxide was tested (Zincweiß Pharma A; purity 99.9%). The only difference with the studies described above was the intradermal induction concentration, which was 2% as for Zincweiß Pharma A this was considered the highest concentration that could reproducibly be injected. In this test no skin reactions were evident in both experimental and control animals, hence a 0% sensitisation rate for Zincweiß Pharma A. White staining of the treated skin by the test substance was observed in some animals 24 and 48 hours after challenge (Van Huygevoort, 1999a).

Human data:

In a human patch test performed with 100 selected leg-ulcer patients, 11/100 patients gave an allergic reaction with zinc ointment (60% ZnO and 40% sesame oil). However, 14/81 patients gave a positive response when treated with sesame oil alone. This study does not give any indication for a skin sensitizing potential of zinc oxide in humans (Malten and Kuiper, 1974).

The effect of zinc oxide on contact allergy to colophony was investigated. With 14 patients with earlier history of moderate patch test reactions to colophony (a patch test) with 10% ZnO (2.3 mg Zinc/cm²) with and without colophony was performed. No positive response was observed in the 14 patients when only a 10% solution of zinc oxide was used. The addition of zinc oxide to colophony decreased the allergic reaction induced by colophony (Söderberg et al., 1990).

 

Human data

In a human patch test performed with 100 selected leg-ulcer patients, 11/100 patients gave an allergic reaction with zinc ointment (60% ZnO and 40% sesame oil). However, 14/81 patients gave a positive response when treated with sesame oil alone. This study does not provide any indication that zinc oxide has any skin sensitising potential.

 

Data on Hydrogen peroxide

Cited from theSummary Risk Assessment Report on Hydrogen peroxide (2003):

“There are two reported cases of positive patch tests to H2O2 and some uncertainty surrounds an outdated animal study with a negative result. However, when one takes into account the widespread occupational and consumer uses over many decades, it may be concluded that the potential of H2O2 to cause skin sensitisation is extremely low.”

 

Overall, the sensitizing potential of Zinc peroxide is considered to be low.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

While there is no particular study addressing respiratory sensitisation in experimental animals, there is no information suggesting zinc compounds to cause such effects in animals. Taking into account the complete absence of skin sensitization potential of zinc compounds, respiratory sensitisation is not expected to be of concern for zinc oxide.

Justification for classification or non-classification

Based on the available data, Zinc peroxide does not require classification and labelling with respect to sensitization according to the CLP Regulation (EC) No 1272/2008.