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Toxicity Effects

CAS Registry Number: 484-20-8

Selected toxicity information from HSDB, one of the National Library of Medicine's databases. 2.

Names 1

  • 4-Methoxy-7h-Furo(3,2-Q)(1)Benzopyran-7-One (9ci)
  • 5-Methoxypsoralen
  • Bergapten

Human Toxicity Excerpts

  • ... Performed photoepicutaneous tests with psoralens isolated from the umbelliferous plant Heracleum laciniatum on normal volunteers. 5-Methoxypsoralen was the most strongly phototoxic, being active at 0.001% in ethanol. Reactions reached their max 75 hr after exposure. The action spectrum of 5-methoxypsoralen was determined, and max photosensitivity was seen at 330-335 nm. Phototoxicity could also be produced in a patient with vitiligo ... .[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 377 (1986)] **PEER REVIEWED**
  • ... Surveyed 87 employees in the bergamot oil production industry in southern Italy, 42 of whom had direct contact with bergamot essence and 45 who were involved in the cultivation, harvesting and transportation of bergamot fruit, and 31 people resident in the same area. 'Keratomas' or 'epitheliomas' of the skin were found in 15 (19%) of 79 exposed workers and in 5 (16%) of the comparison group. The bergamot-exposed group was older, on average (47 years), than the comparison group (39 years). (The Working Group noted that the possible confounding effects of age, sex and outdoor employment were not considered.)[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 338 (1986)] **PEER REVIEWED**
  • 5-METHOXYPSORALEN CAUSED CHROMOSOMAL DAMAGE IN HUMAN CELLS IN VITRO.[ASHWOOD-SMITH MJ ET AL; J NATL CANCER INST 69 (1): 189 (1982)] **PEER REVIEWED** PubMed Abstract
  • 5-Methoxypsoralen and UVA irradiation (306-428 nm; max, 345 nm) killed cultured human lymphocytes. Blast transformation stimulated by phytohemagglutinin did not alter this effect. ... In studies of phytohemagglutinin-stimulated blast transformation of cultured human lymphocytes, combined exposure to various concn of 5-methoxypsoralen and UVA irradiation (345 nm) produced no inhibition when exposure occurred 24 hr before stimulation, but there was inhibition when exposure occurred 36 hr after stimulation ... .[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 335 (1986)] **PEER REVIEWED**
  • 5-Methoxypsoralen plus UVA induced an increase in the incidence of sister chromatid exchanges, which was dependent on UVA dose ... in cultured normal human foreskin fibroblasts and in ataxia telangiectasia and xeroderma pigmentosum cells. The increase was greater in ataxia telangiectasia and xeroderma pigmentosum cells than in normal cells. ... 5-Methoxypsoralen plus UVA induced chromosomal aberrations in normal human foreskin fibroblasts and in ataxia telangiectasia and xeroderma pigmentosum cells in culture; these effects were more frequent in ataxia telangiectasia and xeroderma pigmentosum cells. ... An increase in chromosomal aberrations was also found in human lymphocytes after treatment in vitro with 5-methoxypsoralen in combination with UVA ... .[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 337 (1986)] **PEER REVIEWED**
  • Application of 4-200 ug/2.5 sq cm 5-methoxypsoralen to human skin and irradiation with UVA induced erythema 22 min to 36 hr after irradiation, followed by marked pigmentation 7 to 15 days later ... .[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 337 (1986)] **PEER REVIEWED**
  • HUMAN MODEL TO DETECT PHOTOCONTACT ALLERGENS (EG, ESSENTIAL OILS & FRAGRANCED DYES, SCREENING AGENTS, COAL TAR HYDROCARBONS, & FUROCOUMARINS) DEVELOPED. 5-METHYOXYPSORALEN WAS A POTENT PHOTOTOXIC AGENT.[KAIDBEY KH, KLINGMAN AM; CURR CONCEPTS CUTANEOUS TOXIC (PROC CONF) 4TH: 55 (1980)] **PEER REVIEWED**
  • In a DNA repair test, 5-methoxypsoralen with UVA inhibited semiconservative DNA synthesis and induced unscheduled DNA synthesis in human embryonic skin and muscle fibroblasts ... .[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 336 (1986)] **PEER REVIEWED**
  • PHOTOSENSITIZING EFFECTS TO NEAR-UV IRRADIATION (UVA) OF 5-METHOXYPSORALEN (5-MOP) IN PRODUCING CHROMOSOME DAMAGE IN NORMAL HUMAN, ATAXIA TELANGIECTASIA (AT) & XERODERMA PIGMENTOSUM (XP) PATIENTS WERE STUDIED. 5-MOP PRODUCED SISTER-CHROMATID EXCHANGES (SCE) IN ALL. AT & XP CELLS RESPONDED WITH HIGHER FREQUENCIES OF SCE AS WELL AS CHROMOSOMAL ABERRATIONS THAN NORMAL HUMAN CELLS TO 5-MOP. 5-MOP IN SOME SUNTAN PREPARATIONS IS NOT ACCEPTABLE IN VIEW OF THE PRESENT EVIDENCE OF ITS BIOLOGICAL ACTIVITY.[NATARAJAN AT ET AL; MUTAT RES 84 (1): 113 (1981)] **PEER REVIEWED** PubMed Abstract
  • PHYTOPHOTODERMATITIS OF HERACLEUM LACINIATUM IS QUITE COMMON IN THROMOS DURING THE SUMMER MONTHS. THE INFLUENCES ON PHOTOTOXIC REACTIONS BY BERGAPTEN & UV-A BY TREATING THE SKIN WITH MEMBRANE LABILIZING AGENT, DIMETHYL SULFOXIDE & MEMBRANE STABILIZING AGENT, DESOXIMETHASONE ARE EVALUATED.[KAVLI G ET AL; BR J DERMATOL 109 (SUPPL 25): 137 (1983)] **PEER REVIEWED** PubMed Abstract
  • SUNSCREENS CONTAINING 5-METHOXYPSORALEN (5-MOP) ARE BEING PROMOTED COMMERCIALLY TO INCR SUNTANNING & SUN PROTECTION. THE SUNSCREEN, SUN SYSTEM III (SS III) WHICH CONTAINS 5-MOP PLUS 20 JOULES/SQUARE CM OF UV RADIATION (UVA) CAUSED ERYTHEMA & DELAYED PIGMENTATION IN THE SKIN. NO PHOTOXICITY WAS SEEN UNLESS THE SOLAR SIMULATOR OUTPUT WAS FILTERED THROUGH WATER TO REDUCE INFRARED RADIATION. THIS INDICATES THAT CUTANEOUS PHOTOTOXIC REACTIONS TO 5-MOP PLUS UVA ARE DIMINISHED BY HEAT. USE OF PHOTOTOXIC PSORALENS IN SUNSCREENS IS INAPPROPRIATE BECAUSE OF THE RISK OF INCR UV-INDUCED SKIN CANCER.[WALTER JF ET AL; J AM ACAD DERMATOL 6 (6): 1022 (1982)] **PEER REVIEWED** PubMed Abstract

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Non-Human Toxicity Excerpts

  • 5-Methoxypsoralen: ... induced mutations in the green algae, Chlamydomonas reinhardii, in the presence of UVA ... .[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 337 (1986)] **PEER REVIEWED**
  • 5-Methoxypsoralen alone was reported to be mutagenic to Salmonella typhimurium TA100 in the presence or absence of an exogenous metabolic system (S9) ... and to Escherichia coli lac- z (ND160) ... 5-Methoxypsoralen plus UVA reduced survival of repair-deficient mutants of Bacillus subtilis and E. coli ... addition of S9 inhibited the lethal activity ... 5-Methoxypsoralen photoinduced prophage expression in S. typhimurium TA1535 and TA1538. ... In combination with UVA, 5-methoxypsoralen induced mutations in S. typhimurium TA100 in the absence of an exogenous metabolic system. ... It was not mutagenic to B. subtilis ... but induced a UVA dose-dependent increase in mutations in E. coli WP2 try ... .[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 336 (1986)] **PEER REVIEWED**
  • 5-Methoxypsoralen formed a noncovalently-bound complex with DNA in vitro in the dark. ... It photobound covalently to DNA in vitro ... in Saccharomyces cerevisiae ... and in Chinese hamster V79 cells. ... It photoinduced interstrand cross-links in DNA in vitro ... and in Chinese hamster V79 cells ... DNA photobinding in vitro was dependent on UVA dose ... .[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 336 (1986)] **PEER REVIEWED**
  • 5-Methoxypsoralen plus UVA induced an increase in the incidence of sister chromatid exchanges, which was dependent on UVA dose, in Chinese hamster ovary cells ... .[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 337 (1986)] **PEER REVIEWED**
  • 5-Methoxypsoralen plus UVA induced revertants and forward mutations in haploid S cerevisiae ... and cytoplasmic 'petite' mutations in haploid and diploid S. cerevisiae. ... In diploid S. cerevisiae, 5-methoxypsoralen plus UVA induced nuclear mutations and mitotic recombination ... .[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 337 (1986)] **PEER REVIEWED**
  • 5-Methoxypsoralen plus UVA inhibited DNA synthesis in Chinese hamster ovary cells ... in Ehrlich ascites tumor cells ... and in the epidermis of Skh:hairless-1 mice after topical application ... .[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 335 (1986)] **PEER REVIEWED**
  • 5-Methoxypsoralen with UVA induced an increase in 6-thioguanine-resistant mutants in Chinese hamster V79 ... and cultured ovary cells. ... The response was dependent on UVA dose ... .[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 337 (1986)] **PEER REVIEWED**
  • 5-Methoxypsoralen, applied topically (2 mg/mouse) or administered orally (25 mg/kg bw) and followed by UVA irradiation (50 kJ/sq m) to Skh/hrl female hairless mice, markedly increased epidermal ornithine decarboxylase activity. ... A commercial sunscreen preparation (Sun-System III) containing unspecified amt of 5-methoxypsoralen and ethylhexyl-para-methoxycinnamate also induced ornithine decarboxylase in female albino HRS/J mice after UVA irradiation (335 nm) ... .[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 335 (1986)] **PEER REVIEWED**
  • A group of 20 male and 20 female XVIInc/Z albino mice, 12-14 weeks old, received topical applications of 40 ul of a 0.025% solution of 5-methoxypsoralen (purity, 100%; confirmed by high-performance liquid chromatography and mass spectrometry) in acetone on each ear (approx 10 ug/sq cm) on 5 days per week for 23 weeks (115 treatments). Fifteen minutes after each application, mice were immobilized and irradiated for 10 min (four Philips, HPW 125 lamps, 365 nm; wavelengths <340 nm were eliminated by running-water filter of two 6-mm Pyrex glass slides; irradiance at ear level, 28 J/sq m/sec), corresponding to a dose of 1.68x10+4 J/sq m. Eight months after the last 5-methoxypsoralen application, the 20 females received thrice-weekly promoting applications of 1 ug 12-O-tetradecanoylphorbol 13-acetate (TPA; 40 applications). Two control groups of 40 mice each received 115 applications of psoralen or methoxsalen plus UVA irradiation. Further control groups of 21 mice (sex unspecified) received applications of acetone followed by chronic radiation treatment or skin applications of psoralen without irradiation and were followed for 21 months. After 16 months, 19/20 males treated with 5-methoxypsoralen plus UVA were alive; 17/20 (85%) surviving the minimal latency developed skin carcinomas, and 25% had multiple tumors. After 15 months, 18/20 females treated with 5-methoxypsoralen plus UVA plus TPA were alive; all developed tumors, and 66% had multiple tumors. ... In the first two control groups, 37/38 (97%) mice receiving psoralen treatment plus irradiation developed tumors, and 20/38 (52%) had multiple tumors; 34/37 (92%) of mice receiving methoxsalen plus irradiation developed tumors, and 16/37 (45%) had multiple tumors. Mean latent periods for tumor development were 16 months for treatment with 5-methoxypsoralen plus irradiation, 13.5 months for treatment with methoxsalen plus irradiation and 9.3 months for treatment with psoralen plus irradiation. Most of the tumors were squamous-cell carcinomas invading the dermis and cartilage. Metastases in the regional cervical lymph nodes occurred in 20% of tumor-bearing animals. At 22 months of age, 20/21 and 19/21 mice receiving treatment with acetone plus irradiation and treatment with psoralen alone, respectively, were still alive; no tumor was observed in either group ... . (The Working Group noted that a control group receiving 5-methoxypsoralen without UVA was not included in this study.)[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 332 (1986)] **PEER REVIEWED**
  • Application of 5-methoxypsoralen to guinea-pig skin (50 or 100 ug/2.5 sq cm) and exposure to UV radiation or administration of an oral dose of 8.6 mg/kg bw 5-methoxypsoralen and exposure to UV radiation induced marked erythema ... .[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 335 (1986)] **PEER REVIEWED**
  • Groups of 15 female HRS/J hairless albino mice, 8 weeks old, received skin application of 4 ul/sq cm Sun System III oil (containing 25 mg/kg 5-methoxypsoralen and ethyl hexyl-para-methoxycinnamate, a UVB screen) on their backs on 5 days per week for 20 weeks. The mice were immobilized for 60 min after each application and were irradiated (1000-watt Xenon arc solar-simulator with dichroic mirror, 335-nm long pass filter and water filter; UVAflux, 13 mW/sq cm; UVBflux, 19 uW/sq cm). Groups received 2.5x10+4, 5X10+4 or 10x10+4 J/sq m UVA radiation. One control group of 15 mice received applications of Sun System Ill oil only, and another group of six mice received UVA irradiation only (10x10+4 J/sq m). The number of tumors >1 mm in diameter per surviving mouse at 44 weeks of observation was dependent on the dose of radiation: 0.8 tumors at 2.5, 3.5 tumors at 5 and 8 tumors at 10x10+4 J/sq m; the percentages of animals with two or more tumors at that time were 13 at 2.5, 86 at 5 and 100 at 10x10+4 J/sq m. At 44 weeks, 15/15, 14/15 and 9/15 animals were still alive in the three groups, respectively. By 52 weeks, some of the tumors had developed into large invasive tumors fixed to underlying tissue, especially in the group receiving the highest dose of radiation. Histological examination showed that atypical squamous-cell papillomas had progressed to invasive squamous-cell carcinomas ... . [The Working Group noted the lack of controls given vehicle plus UVA and the inadequate number of animals in the group receiving UV radiation alone, and that the duration of the studies with 5-methoxypsoralen (Sun-System III) alone was too short to evaluate the carcinogenicity of this compound itself.][IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 333 (1986)] **PEER REVIEWED**
  • Groups of 15 pregnant female New Zealand rabbits were given 5-methoxypsoralen orally at daily doses of 0, 70 or 560 mg/kg bw on days 7-18 of gestation. With 560 mg/kg, there was maternal toxicity (decreased weight gain; only 50% of dams gave birth to living pups). There was a dose-dependent increase in fetal abnormalities: 15.4% in controls, 41.7% with 70 mg/kg and 57.1% with 560 mg/kg ... (The Working Group noted that the types, frequencies and distribution of fetal anomalies were not specified.)[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 336 (1986)] **PEER REVIEWED**
  • Groups of 20 male and 20 female hairless albino mice (an outbred strain from the Institute of Dermatology, London), eight to ten weeks old, received topical applications of 0.01% or 0.03% solutions of crystalline 5-methoxypsoralen or methoxsalen (purity, 100%; confirmed by absorption spectroscopy, thin-layer chromatography and mass spectrometry) in 70:30 (v/v) BP-grade arachis oil and isopropyl myristate on both flanks on five days per week for up to 37 weeks. After each application, the animals were immobilized for 30 min and then received simulated solar irradiation (vertically-mounted, water-cooled 6 KW Xenon arc simulating solar radiation with 2-mm Schott glass WG320 filter) for 50 min. The estimated daily dose of irradiation was 1.7x10+4 J/sq m, of which approximately 400 J/sq m were UVB radiation. Seven control groups were either left untreated or were treated with vehicle alone, arachis oil alone, simulated solar irradiation alone, vehicle plus irradiation, or applications of 0.03% 5-methoxypsoralen or 0.03% methoxsalen without irradiation. The groups treated with methoxsalen and irradiation served as controls (because of the photocarcinogenic potential of this chemical. ... A random sample of tumors was examined histologically, and 83% of the skin tumors in the group treated with 5-methoxypsoralen and irradiation were found to be papillomas. Trend tests using life-table methods indicated a positive dose-related trend in incidence for treatment with either 5-methoxypsoralen (p < 0.01) or methoxsalen (p < 0.01) in combination with simulated solar radiation. A dose adjusted life-table test comparing the relative tumor incidences in these two groups showed no statistically significant difference at the 5% level ... . (The Working Group noted that the duration of the studies with 5-methoxypsoralen was too short to evaluate the carcinogenicity of this chemical alone.)[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 332 (1986)] **PEER REVIEWED**
  • Groups of 26 pregnant female Sprague-Dawley rats were given 5-methoxypsoralen orally at daily doses of 0, 70 or 560 mg/kg bw on day 6-15 of gestation. With 560 mg/kg, there was maternal toxicity (decreased weight gain, fewer litters), but no significant increase in anomalies in surviving fetuses ... .[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 336 (1986)] **PEER REVIEWED**
  • LETHAL PHOTOSENSITIZATION OF ESCHERICHIA COLI & MUTAGENIC ACTIVITY IN E COLI WP2 TRY- IN NEAR UV LIGHT BY 5-METHOXYPSORALEN WAS STUDIED. 5-METHOXYPSORALEN IN CONJUCTION WITH NEAR UV RADIATION POSSESSES MUTAGENIC, CLASTOGENIC, & CARCINOGENIC PROPERTIES.[ASHWOOD-SMITH MJ ET AL; NATURE (LONDON) 285 (5764): 407 (1980)] **PEER REVIEWED**
  • PHOTOSENSITIZING EFFECTS TO NEAR-UV IRRADIATION OF 5-METHOXYPSORALEN (5-MOP) IN PRODUCING CHROMOSOME DAMAGE IN VITRO IN CHINESE HAMSTER STUDIED. 5-MOP PRODUCED SISTER-CHROMATID EXCHANGES.[NATARAJAN AT ET AL; MUTAT RES 84 (1): 113 (1981)] **PEER REVIEWED** PubMed Abstract
  • SERUM & EPIDERMAL CONCN OF 5-METHOXYPSORALEN 2 HR AFTER ORAL AMIN TO GUINEA PIG WERE DETERMINED. A RELATION WAS FOUND BETWEEN SERUM CONCN & APPEARANCE OF PHOTOTOXICITY. LOWER PHOTOTOXICITY OF ORALLY ADMIN 5-METHOXYPSORALEN COMPARED TO 8-METHOXYPSORALEN IN GUINEA PIG APPEARS TO BE DUE TO ITS REDUCED CONCN IN THE EPIDERMIS.[KORNHAUSER A ET AL; SCIENCE 217 (4561): 733 (1982)] **PEER REVIEWED** PubMed Abstract
  • SUNSCREENS CONTAINING 5-METHOXYPSORALEN (5-MOP) PROMOTE TANNING BY INDUCING PSORALEN-MEDIATED ULTRAVIOLET (UVA) MELANOGENESIS. MOUSE STUDIES HAVE SHOWN THAT 5-MOP HAS SAME CUTANEOUS PHOTOCARCINOGENIC POTENTIAL AS 8-MOP. IN ADDN, 5-MOP CONTAINING SUNSCREEN SUN SYSTEM III (SS III) WHEN COMBINED WITH UVA, INDUCES EPIDERMAL ORNITHINE DECARBOXYLASE ACTIVITY, AN ENZYME ASSOCIATED WITH TUMOR PROMOTION. SS III WAS APPLIED TO HAIRLESS MICE 5 DAYS/WK FOR 20 WK & AFTER EACH APPLICATION MICE WERE EXPOSED TO 2.5-10 J/SQ CM UVA RADIATION. MICE DEVELOPED ATYPICAL SQUAMOUS PAPILLOMAS DIRECTLY PROPORTIONAL TO DOSAGE OF UVA RADIATION RECEIVED. MICE FOLLOWED UP TO 1 YR DEVELOPED INVASIVE SQUAMOUS CELL TUMORS. CONTROLS REMAINED TUMOR FREE. OVER-THE-COUNTER SUNSCREENS CONTAINING 5-MOP DO CONTAIN SUFFICIENT PSORALEN CONCN TO CAUSE CUTANEOUS PHOTOTOXICITY & PHOTOCARCINOGENICITY IN MICE.[CARTWRIGHT LE, WALTER JF; J AM ACAD DERMATOL 8 (6): 830 (1983)] **PEER REVIEWED** PubMed Abstract
  • When 5-methoxypsoralen was given orally to beagle dogs at daily doses of 100 or 400 mg/kg (8 days), 60 mg/kg (28 days) or 48 mg/kg (26 wk) (bw presumed), at the highest doses tested there were delayed signs of behavioral toxicity, bullous dermatitis, bilateral keratitis, decreased food consumption and decreased weight gain. The cutaneous lesions were reversible, whereas the ocular lesions were not. Hepatomegaly, necrosis and hepatic inflammation occurred in the 48-mg/kg dose group. In the group receiving 60 mg/kg per day, polycythemia was present 24 hr after administration of the last dose. At doses lower than those specified there was no marked change ... (The Working Group noted the inadequate reporting of the data.)[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 335 (1986)] **PEER REVIEWED**
  • When daily doses of 70, 280 or 560 mg/kg 5-methoxypsoralen were given orally to Wistar AF rats for 1 yr, several slight changes were observed at the highest dose, such as increased water consumption, decreased weight gain, reduced blood urea and increased liver weight. Thyroid hypofunction occurred early and persisted. Epidermoid cysts of the thyroid (in males) were present in approx 1/3 of slides examined from all three treated groups (the numbers for controls were not give). A dose-dependent perimedullary connective tissue proliferation of the adrenals was observed in females ... . (The Working Group noted the inadequate reporting of the data.)[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 335 (1986)] **PEER REVIEWED**

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Human Toxicity Values

  • None found

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Non-Human Toxicity Values

  • The oral LD50 for 5-methoxypsoralen has been reported to be 8100 mg/kg bw in NMRI Hanover mice, >30,000 mg/kg bw in Wistar AF rats and 9000 mg/kg bw in Hartley guinea-pigs ... .[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 335 (1986)] **PEER REVIEWED**

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Absorption, Distribution And Excretion

  • 5-METHOXYPSORALEN SHOWED A HIGH BINDING AFFINITY TO SERUM PROTEINS & 98-99% WAS PROTEIN BOUND. ITS HIGH BINDING AFFINITY RESULTED IN HIGHER TISSUE CONCN. IN THE EPIDERMIS, IT APPEARED TO BE BOUND TO INDEPENDENT & NONINTERACTING SITES.[ARTUC M ET AL; BR J DERMATOL 101 (6): 669 (1979)] **PEER REVIEWED** PubMed Abstract
  • 5-Methoxypsoralen binds to human serum proteins, principally albumin. ... Data on 5-methoxypsoralen binding to low-density lipoproteins suggest that these are the primary vehicle for intracellular transport of 5-methoxypsoralen ... .[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 338 (1986)] **PEER REVIEWED**
  • ENRICHMENT IN EPIDERMIS OF 5-METHOXYPSORALEN WAS MEASURED. IT WAS CONCENTRATED BY HUMAN EPIDERMIS & CONCN REACHED WITHIN THE TISSUE WAS 10-500 TIMES HIGHER THAN CONCN OF SUBSTANCE IN SURROUNDING BUFFER. THE PARTITIONING DISTRIBUTION AMONG TISSUE COMPONENTS COULD ACCOUNT FOR ITS BEHAVIOR.[ARTUC M ET AL; ARCH DERMATOL RES 268 (2): 129 (1980)] **PEER REVIEWED** PubMed Abstract
  • Following oral administration of 40 mg 5-methoxypsoralen to healthy male volunteers, absorption was documented by measurement of plasma levels. The plasma concn peaked 2-4 hr after administration and declined to low levels by 8 hr. Distribution to the skin after topical application of 0.15 and 0.0015% 5-methoxypsoralen was evident from photosensitization, persisting up to 8 hr, to 366 nm UV light with an irradiance of 22 mW/sq cm 2 hr after administration. Minute amt of 5-methoxypsoralen were excreted in urine and bile ... .[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 338 (1986)] **PEER REVIEWED**
  • In young adult Hartley guinea-pigs, a linear relation was found between serum and epidermal concn of 5-methoxypsoralen, and the observed skin phototoxicity correlated with the serum 5-methoxypsoralen concn ... .[IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/ENG/Classification/index.php, p. V40 336 (1986)] **PEER REVIEWED**
  • MICRONIZED BERGAPTEN IN CAPSULES WAS ABSORBED SLOWLY BY VOLUNTEERS (TIME TO MAX SERUM CONCN 3.2 HR; ELIM HALF-TIME ABOUT 1 HR). WHEN INJECTED IV INTO RABBITS, ELIM HALF-TIME 1-2 MIN (ALPHA-PHASE) & 15 MIN (BETA-PHASE).[STOLK LM L; PHARM WEEKBL 117 (28): 609 (1982)] **PEER REVIEWED**

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Metabolism/Metabolites

  • None found

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Tsca Test Submissions

  • None found

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Footnotes

1 Source: the NTP's CEBS database.

2 Source: the National Library of Medicine's Hazardous Substance Database, 02/28/2017.

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