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additional toxicological information
Type of information:
experimental study
Adequacy of study:
key study
Study period:
12-16 January 1987
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: No GLP study. There is no standardized protocol for conducting photoirritancy screening in humans. The laboratory used its own protocol.

Data source

Reference Type:
study report
Report date:

Materials and methods

Type of study / information:
Photo irritancy
Principles of method if other than guideline:
The photoirritancy was tested on 10 human volunteers. AHTN was applied to several sites on the skin. Part of the sites were irradiated and the other sites non-irradiated. The skin evaluated at different time intervals. A positive control was also employed.
GLP compliance:

Test material

Constituent 1
Chemical structure
Reference substance name:
EC Number:
EC Name:
Cas Number:
Molecular formula:
Details on test material:

Results and discussion

Any other information on results incl. tables

 There were no significant reactions to the AHTN solution but all three subjects exposed to 8-MOP (positive control) showed clear positive reactions.

Applicant's summary and conclusion

AHTN is not photo-irritant to humans.
Executive summary:

AHTN (Tonalid®; non-GLP, purity >98% - 10% dilution in ethanol/DEP (3:1)) was tested for photoirritancy on 10 female human volunteers (white Caucasian; ages 18-39). Before application of the preparation for each of the subjects, the Minimal Erythemal Dose (MED) was determined using UV light irradiation from a xenon arc solar light simulator. Subsequently, areas on the back were stripped 3 times to remove the superficial stratum corneum; followed by application of 20μL of the test solution to 3 designated test sites, each approximately 1.5 cm in diameter. One of the sites was used as the non-irradiated control site and one site was irradiated but was not treated with AHTN. In addition, three of the 10 subjects were randomly selected and treated with 20μL of a 0.2 mg/ml solution of 8-methoxypsoralen in ethanol as a positive control. After 30 min of contact, one AHTN-treated site and the site not treated with AHTN were irradiated with 10 MED of UV-A followed by 0.5 MED of UVA + UVB The sites were scored 5 min after irradiation and again at 3, 24, 48 and 73 hr after irradiation. There were no significant reactions to the AHTN solution but all three subjects exposed to 8-MOP showed clear positive reactions.

Source: EU Risk Assessment Report AHTN, ECB May 2008