Psoralen-containing sunscreen is tumorigenic in hairless mice
Sunscreens containing 5-methoxypsoralen (5-MOP) are currently being marketed to promote tanning by inducing psoralen-mediated ultraviolet (UV) A (320-400 nm) melanogenesis. The rationale is that this may prevent UVB (290-320 nm) radiation-induced skin damage. However, mouse studies have shown that 5-MOP has the same cutaneous photocarcinogenic potential as 8-methoxypsoralen. In addition, the 5-MOP--containing sunscreen Sun System III (SS III), when combined with UVA, induces epidermal ornithine decarboxylase activity, an enzyme associated with tumor promotion. Therefore, we investigated whether SS III had sufficient psoralen concentration to be tumorigenic in hairless mice exposed to chronic, intermittent UVA radiation. SS III was applied to hairless mice 5 days per week for 20 weeks. After each application the mice were exposed to 2.5 to 10 joules/cm2 UVA radiation. All test groups developed atypical squamous papillomas in direct proportion to the dosage of UVA radiation received. A shorter latency period for tumor development was seen with larger UVA doses. Test animals followed up to 1 year developed invasive squamous cell tumors. Control groups (SS III without UVA and UVA without SS III) remained free of tumors. Animals receiving SS III plus UVA developed persistent skin thickening and increased dermal cyst formation similar to that reported with chronic exposure to UVB, a known carcinogenic wavelength.
- Research Organization:
- Univ. of California, San Diego
- OSTI ID:
- 6748069
- Journal Information:
- J. Am. Acad. Dermatol.; (United States), Vol. 8:6
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
DECARBOXYLASES
CHEMICAL ACTIVATION
NEAR ULTRAVIOLET RADIATION
BIOLOGICAL EFFECTS
PSORALEN
CARCINOGENESIS
DOSE-RESPONSE RELATIONSHIPS
MICE
NEOPLASMS
SKIN
ANIMALS
ANTICOAGULANTS
BODY
CARBON-CARBON LYASES
CARBOXY-LYASES
COUMARINS
DISEASES
DRUGS
ELECTROMAGNETIC RADIATION
ENZYMES
HEMATOLOGIC AGENTS
HETEROCYCLIC COMPOUNDS
LYASES
MAMMALS
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
ORGANS
PATHOGENESIS
RADIATIONS
RODENTS
ULTRAVIOLET RADIATION
VERTEBRATES
560305* - Chemicals Metabolism & Toxicology- Vertebrates- (-1987)