Phototoxicity
Outline: Phototoxicity
Objective: To determine the phototoxicity (or photoirritation) potential of up to 4 test articles (using a modification of the provocative patch test described by Willis and Kligman, J. Invest. Derm., 51, No. 2, 116-119, 1968).
Subjects: 10 healthy men and women
Timing: 2-day test
Start test within 2 weeks of receipt of samples
Report issued within 3 weeks of study completion
Quantity: 4 oz.

Methodology:
Clinical assessment of skin response by a trained evaluator
Light Source: UV-A: A bank of four (4) 40W fluorescent bulbs (F40/350BL) with a continuous long-wave UV-A spectrum ranging between 320 and 400 nm (peak 365 nm) is used. Exposure intensity is measured at a distance of 10 cm from the lamps using a long wave UV meter (Model J-221, Ultra-Violet Products, Inc., San Gabriel, CA). Dosage of irradiation is calculated as follows: Intensity (mW/cm2) x Time (minutes) x 60 seconds x .001 = Dosage (J/cm2).

Procedures:

Approximately 0.2 mL or grams of each test article is applied occlusively to alternate (right arm/left arm) contact areas that have been cellophane tape-stripped 5 times to remove the superficial horny layers. Two hours later, the patches are removed from the forearm designated for irradiation and the sites are subjected to 10 Joules of UV-A irradiation.

Following the irradiation procedure, the control arm (non-irradiated) patches are removed. Both the test and control forearms are examined for dermal reactivity 10 minutes following the irradiation procedure and again 2 and 24 hours post-irradiation.

Skin responses are scored according to the following 6-point scale:
0 = No evidence of any effect.
+ = Minimal, faint, uniform or spotty erythema or tanning.
1 = Pink, uniform erythema or tanning covering most of the contact site.
2 = Pink-red erythema or tanning, uniform in the entire contact site.
3 = Bright red erythema or tanning with/without petechiae or papules.
4 = Deep red erythema with/without vesiculation and/or weeping or dark tanning.

Accompanying edema (swelling) at any test site is recorded with an "e" and described as mild, moderate or severe. Other possible dermal sequelae are similarly recorded.

The test subjects are instructed to report any delayed dermal reactivity that might occur following the final (24-hour) examination at the clinic. Any evidence of hyperpigmentation (tanning-like response) and/or any evidence of erythema on the irradiated test sites which differs significantly in either incidence or severity from the non-irradiated control site is considered evidence of a possible phototoxic response.