International Agency for Research on Cancer (IARC) - Summaries & Evaluations

(Group 2A)

For definition of Groups, see Preamble Evaluation.

Supplement 7: (1987) (p. 242)

CAS No.: 484-20-8
Chem. Abstr. Name: 4-Methoxy-7H-furo[3,2-g][1]benzopyran-7-one

A. Evidence for carcinogenicity to humans (inadequate)

In a survey of 87 persons employed in the production of bergamot oil (of which 5-methoxypsoralen is a constituent), 19% of 79 exposed workers and 16% of a comparison group of 31 people resident in the same area were observed to have 'keratomas' or 'epitheliomas' of the skin. Possible confounding effects of age, sex and outdoor employment were not considered in this analysis [ref: 1].

B. Evidence for carcinogenicity to animals (sufficient)

5-Methoxypsoralen was tested in by skin application in combination with ultraviolet A radiation or solar-simulated radiation, producing skin papillomas and carcinomas; in these studies, no or few skin tumours were observed with ultraviolet A radiation or solar-simulated radiation alone. The studies were inadequate to evaluate the local and systemic carcinogenic effects of the compound itself [ref: 1].

C. Other relevant data

No data were available on the genetic and related effects of 5-methoxypsoralen in humans.

In the presence of ultra-violet A radiation, 5-methoxypsoralen induced chromosomal aberrations, sister chromatid exchanges and unscheduled DNA synthesis in human cells in vitro; sister chromatid exchanges, mutation and DNA cross-links in rodent cells in vitro; mutation, gene conversion and DNA cross-links in yeast; and mutation and prophage in bacteria [ref: 2].

5-Methoxypsoralen, tested in the absence of ultraviolet A radiation, was reported to be weakly mutagenic to bacteria [ref: 2].

Overall evaluation

5-Methoxypsoralen is probably carcinogenic to humans (Group 2A).

For definition of the italicized terms, see Preamble Evaluation.

Also see previous evaluation: Vol. 40 (1986)


1. IARC Monographs, 40, 327-347, 1986

2. IARC Monographs, Suppl. 6, 377-379, 1987


  • Bergaptan
  • Bergapten
  • Bergaptene
  • Heraclin
  • 6-Hydroxy-4-methoxy-5-benzofuranacrylic acid, delta-latone
  • Majudin
  • 5-Methoxy-6,7-furanocoumarin
  • 5-MOP
    Last updated: 11 February 1998
        See Also:
           Toxicological Abbreviations
           Methoxypsoralen, 5- (IARC Summary & Evaluation, Volume 40, 1986)