3-phenylbutyraldehyde

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

November - December 1988

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study in compliance with guidelines.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

yes

Remarks:

(20 animals per treatment group is recommended in the current guideline)

GLP compliance:

yes

Type of study:

Buehler test

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: D. Hall, Darley Oaks, Burton-on-Trent, Staffordshire, England.
- Age at study initiation: no data available. Study cited that animals are young.
- Weight at study initiation: range of 407 to 498 g (mean of 455 g)
- Housing: Animals were housed in groups of ten in stainless steel cages fitted with mesh floors and of the approximate dimensions 85 x 57 x 25cm.
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 12 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 17-23 °C
- Humidity (%): 45-68 %
- Air changes (per hr): no data available. Air conditioning was provided
- Photoperiod: 12 hrs dark / 12 hrs light

IN-LIFE DATES: experimental work was cited as taking place from 17-Nov-1988 to 23-Dec-1988.

Route:

epicutaneous, occlusive

Vehicle:

other: No vehicle was used in the induction phase. Ethanol was used as the vehicle in the challenge phase. Ethanol was also used as the vehicle in the preliminary irritation screening study.

Concentration / amount:

- Irritation screening study: 0.5 mL of the following concentrations of test material: 12.5%, 25%, 50%, 100% v/v. Solvent was ethanol. (The preliminary irritation screening assay showed no irritation effects at concentrations of 12.5%, 25%, 50% or 100% of test substance, hence the induction phase of the study used the undiluted test material).
- Main study, induction phase: 0.5 mL of undiluted test material.
- Main study, challenge phase: 0.5 mL of undiluted test material (left flank) and 0.5 mL of 50 % v/v diluted test material in ethanol (right flank).

Route:

epicutaneous, occlusive

Vehicle:

other: No vehicle was used in the induction phase. Ethanol was used as the vehicle in the challenge phase. Ethanol was also used as the vehicle in the preliminary irritation screening study.

Concentration / amount:

- Irritation screening study: 0.5 mL of the following concentrations of test material: 12.5%, 25%, 50%, 100% v/v. Solvent was ethanol. (The preliminary irritation screening assay showed no irritation effects at concentrations of 12.5%, 25%, 50% or 100% of test substance, hence the induction phase of the study used the undiluted test material).
- Main study, induction phase: 0.5 mL of undiluted test material.
- Main study, challenge phase: 0.5 mL of undiluted test material (left flank) and 0.5 mL of 50 % v/v diluted test material in ethanol (right flank).

No. of animals per dose:

- Irritation screening study: 4 animals
- Main study, induction and challenge phase:
Test group: 10 animals
Control group: 10 animals

Details on study design:

IRRITATION SCREENING STUDY:
- No. of exposures: 1
- Exposure period: 6 hrs
- Test groups: 1 group of 4 animals
- Control group: none
- Site: flank (no details on whether left or right)
- Evaluation: 24 and 48 hrs
- Concentrations: 0.5 mL of the following concentrations of test material: 12.5%, 25%, 50%, 100% v/v. Solvent was ethanol.
- Application: using a 2 cm square of gauze, occluded. Test site was clipped free of fur one day prior to application of the test material.

MAIN STUDY
A. INDUCTION PHASE
- No. of exposures: 3
- Exposure period: 6 hrs
- Test groups: 1 group of 10 animals
- Control group: 1 group of 10 animals
- Site: left shoulder area
- Frequency of applications: application at day 1, day 8 and day 15
- Duration: 28 days
- Concentrations: 0.5 mL of undiluted test material
- Application: using a 2 cm square of gauze, occluded. Test site was clipped free of fur one day prior to application of the test material.

B. CHALLENGE PHASE
- No. of exposures: 1
- Day(s) of challenge: day 29
- Exposure period: 6 hrs
- Test groups: 1 group of 10 animals
- Control group: 1 group of 10 animals
- Site: left and right flank
- Concentrations: 0.5 mL of undiluted test material (left flank) and 0.5 mL of 50 % v/v diluted test material in ethanol (right flank)
- Application: using a 2 cm square of gauze, occluded. Test site was clipped free of fur one day prior to application of the test material.
- Evaluation (hr after challenge): 24 and 48 hrs after the application.

Challenge controls:

no data

Positive control substance(s):

no

Positive control results:

not applicable

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

Undiluted and 50% test material

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

none

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: Undiluted and 50% test material . No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: none.

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

Undiluted and 50% test material

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

none

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: Undiluted and 50% test material . No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: none.

No response was exhibited by any animal of the test or control group following challenge with the undiluted test material and a 50% dilution of the test material in ethanol.

Interpretation of results:

not sensitising

Remarks:

Migrated information under CLP REGULATION (EC) No 1272/2008 Criteria used for interpretation of results: other: REGULATION (EC) No 1272/2008 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL

Conclusions:

There was no evidence to suggest that the test material acts as a sensitiser in the guinea pig.

Executive summary:

A GLP-compliant study was conducted in guinea pigs to assess the skin sensitisation potential of the substance using the Buehler test. The study was conducted according to the OECD Testing Guideline No. 406. Following induction using the undiluted substance applied for 6 hours on each of days 1, 8, and 15 of the study, a challenge application of the undiluted (i.e., 100%) and diluted (50% in ethanol) substance was initiated on Day 28. Following scoring of the skin sites, it was observed that there were no responses in any of the animals at any of the test sites. Criteria for Buehler assay: a response of at least 15 % of the animals is considered positive and it means that at least one animal was observed to have a positive response in this study. Regarding irritation in the preliminary assay, concentrations of 12.5%, 25%, 50% and 100% of the substance did not elicit signs of irritation. Altogether, it was concluded that there was no evidence to indicate that the substance acts as a sensitiser in the guinea pig. Therefore, based on the results of this study, there is unlikely to be any risk of sensitisation occurring in man following repeated dermal exposure to the material.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Assessment of Sensitization Potential of Trifernal: Classification under CLP

The sensitization potential of the substance has been evaluated in one animal study (a guinea pig Buehler test) and in three human studies (repeated insult patch tests (RIPTs)). All of these studies were considered in a weight of evidence approach to the assessment of sensitization potential of the substance.

 

Skin sensitization studies in animals (Section 7.4.1)

A well documented GLP-compliant Guinea Pig Buehler Test conducted in accordance with the OECD Testing Guideline No. 406 is available to address the potential for sensitization by the substance (Toxicol Laboratories Limited, 1989). This study is considered to be reliable (Klimisch rating of 1). In this study, the pure test material was used in the induction phase and two concentrations (100% and 50%) were applied to the animals in the challenge phase. There was no irritating effect observed during the irritation screening study conducted at concentrations of 100%, 50%, 25% and 12.5% dilutions in ethanol. All of the dermal application sites were scored but no erythema, edema or other adverse response was observed in any treated or control group. While the main deviation of the study was a smaller treatment group size compared to current guidelines for the Buehler study (Testing Guideline No. 406), the use of the pure (i.e., undiluted) substance in the induction and challenge studies indicates that animals were exposed to maximal doses. Based on the results of this guinea pig study, there was no evidence that the substance acts as a skin sensitizer.

Skin sensitization studies in humans (Section 7.10.4)

Three reports of human RIPTs are available and summaries of the findings are presented below:

1.      In the first study (Food & Drug Human Clinical Labs [FDCHL], 1983), the RIPT was conducted to investigate the potential for the substance to cause contact sensitization. The test was conducted in 47 volunteer subjects, with an Induction Phase consisting of 10 applications of the substance diluted to 25% in anhydrous ethanol, under occluded patch test conditions. The Challenge Phase used the same test material. The results showed that 3/47 (6.3%) of subjects displayed slight to moderate erythema effects in response to the substance (25% in anhydrous ethanol) and concluded that the substance induced a low-grade allergic contact dermatitis. These results have been evaluated in light of the demonstration that 50% aqueous ethanol can induce delayed allergic skin reactivity in 6/93 (6.4%) subjects in human predictive skin sensitization tests (Stotts, 1977 and cited by McNamee in 2007). In that study, the author concluded that aqueous ethanol solutions approaching 50% concentrations should be avoided as vehicles in human predictive sensitization testing. In comparison, the vehicle in the 1983 study used a test formulation of ~75% ethanol: 25% test substance. Based on uncertainty as to the cause of the skin responses observed in 3 of 47 (6.3%) subjects (i.e., whether due to the substance or to the possible contribution of ~75% ethanol in the test formulation), the study data are considered to be unreliable and the substance cannot be concluded to be a skin sensitizer based on the results of this study. Moreover, the selection criteria for the volunteers were not given and the sample size was both small and insufficiently described in the report.

 

2.      In the second HRIPT study (TKL, 2003), the concentration of the substance in the Induction and Challenge phases was 5% in Diethyl Phthalate (DEP). This was a large study and considered to have been well conducted and reported. Following nine Induction applications and the subsequent Challenge application, none of the 100 volunteer subjects exhibited skin allergic effects. Minimal or doubtful responses were found in five cases, in which the test site was slightly different from surrounding normal skin during the Induction and Challenge phases, but these slight dermal responses were not considered to be specific sensitization effects. The author concluded that there was no evidence of sensitization of the substance at 5% in DEP.

 

3.      In the third HRIPT study (Harrison Research Laboratories [HRL], 2009), the substance was tested at a concentration of 5% in a vehicle of 3:1 (DEP: ethanol (EtOH)). This was a large study and considered to have been well conducted and reported. No positive responses were observed. The substance (5% in a vehicle of 3:1 DEP: EtOH) caused low-level reactions in twelve subjects during the Induction Phase and in five subjects during the Challenge Phase. The results showed that the vehicle control 3:1 DEP:EtOH caused low-level reactions in six subjects during the Induction Phase and in three subjects during the Challenge. Similarly, the negative control, saline, caused low-level reactions in ten subjects during the Induction Phase and in five subjects during the Challenge Phase. While not classified as an irritant, it was noted that the substance caused slight effects in the eye/skin irritation tests in rabbits (Gibraltar Biological Laboratories, 1981a, 1981b; see Section 7.3.1 and 7.3.2 of the IUCLID dossier, respectively) and therefore the low-level reactions may be background responses to repeated patch testing with the substance or, based on results with the saline control, may represent background responses to patch testing. It was concluded that the substance did not induce dermal sensitization in 102 human subjects in this HRIPT study.

 

The concentration of 5% employed in the negative HRIPT studies (TKL, 2003; HRL, 2009) is expected to be the highest concentration found in consumer products that contain the substance (IFRA, 2011). Due to the small number of study participants in the equivocal HRIPT (n = 47, FDHCL, 1983), the positive response observed in this study may not be supported by a substantial statistical power relative to the negative responses observed in the other two HRIPTs (n = 100 for TKL, 2000; n= 102 for HRL, 2009). Furthermore, the potential contribution of ethanol, which has been acknowledged to have potential as a weak sensitizer, to the observed positive response in the 1983 study could not be excluded. Taking into account these factors, it can be seen that the data from the 1983 study are of questionable reliability. For perspective, it is noted that for the classification of a substance as a skin sensitizer, positive data from patch tests in volunteers would normally be found in data from more than one dermatology clinical site (ECHA, 2012). In the case of the present substance, the "positive" results as seen in the 1983 study were from a single clinical test site, with two other independent test sites producing negative results. Therefore, the human data for skin sensitization for the substance is not considered to fulfil the criteria addressed in Annex 1: 3.4.2.2.2 in the CLP guidance (ECHA, 2012).

Conclusions

Overall, taking into consideration the negative results in the well-documented guinea pig Buehler test, and that two well-conducted human RIPT studies (HRL, 2009; TKL, 2003) were negative [with the exception of the study in which the test formulation included high levels of ethanol (Food & Drugh Human Clinical Labs, 1983), which is known to cause irritation in this test (Stotts, 1977 and cited by McNamee in 2007)], the substance is not expected to cause a skin sensitization (allergic) reaction on the basis of an assessment of the weight of evidence.

Based on the available data the substance is not classified as a skin sensitizer under Directives 67/548/EEC, Regulation No. 1272/2008 and Regulation (EC) No. 286/2011.

References

European Chemicals Agency (ECHA). 2012. Guidance on the application of the CLP criteria. Guidance to Regulation (EC) No 1272/2008 on classification, labelling and packaging (CLP) of substances and mixtures. November 2012 (Version 3.0).

International Fragrance Accociation (IFRA). 2011. IFRA RIFM QRA Information Booklet ver. 6.0 (available at: http://www.ifraorg.org/Upload/Docs/22182_GC_2008_02_15_IFRA_RIFM_QRA_Information_booklet_V6.0_(46th_IFRA_Amendment).pdf).

McNamee PM, 2007. A review of critical factors in the conduct and interpretation of the human repeat insult patch test. Regul Toxicol Pharmacol 52:24-34.

Stotts J, Ely WJ, 1977. Induction of human skin sensitization to ethanol. J Invest Dermatol. 1977 Aug;69(2):219-22.

Migrated from Short description of key information:
Studies in animals:
Skin sensitisation (Guinea Pig, OECD 406): negative

Studies in humans:
Skin sensitisation (HRIPT, 25% trifernal in Ethanol): Ambiguous
Skin sensitisation (HRIPT, 5% trifernal in diethyl phthalate (DEP)): Negative
Skin sensitisation (HRIPT, 5% trifernal in 3:1 DEP: ethanol): Negative

Justification for selection of skin sensitisation endpoint:
Klimisch 1 study similar to guideline study

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information:

The substance is not considered as a skin sensitization toxicant.

Justification for classification or non-classification

Skin sensitization: the substance is not expected to cause a skin sensitization (allergic) reaction on the basis of weight of evidence. As a result, the substance does not meet the criteria for classification according to Regulation (EC) No 1272/2008, Annex I section 3.4, as amended by Regulation (EC) No 286/2011.

 

Respiratory sensitization: The substance is not considered as a skin sensitization toxicant and there is no data indicating that the substance has respiratory sensitization potential. As a result, the substance does not meet the criteria for classification according to Regulation (EC) No 1272/2008, Annex I section 3.4, as amended by Regulation (EC) No 286/2011.