Artificial Ultraviolet Radiation Research Articles

Potential environmental fate of elsinochrome A, a perylenequinone toxin produced in culture by bindweed biocontrol fungus Stagonospora convolvuli LA39

The photosensitizing perylenequinone toxin elsinochrome A (EA) is produced in culture by the bindweed biocontrol fungus Stagonospora convolvuli LA39 where it apparently plays a pathogenicity related role. We investigated the fate of EA with reference to its stability under different temperature and light conditions. EA remained stable when boiled in water at 100°C for 2 h. Similarly, exposing EA to 3–27°C in the dark for up to 16 weeks did not affect its stability either in dry or in aqueous form. However, results from irradiation experiments indicate that direct photolysis may be a significant degradation pathway for EA in the environment. EA either in dry form or dissolved in water was degraded by different irradiation wavelengths and intensities, with degradation plots fitting a first order rate kinetics. EA degraded faster if exposed in aqueous form, and at higher quantum flux density (μmol s−1 m−2). Sunlight was more effective in degrading EA than artificial white light and ultraviolet radiations (UV-A or UV-B). Exposing EA to natural sunlight, particularly, during the intense sunshine (1,420–1,640 μmol −1 m−2) days of 30 July to 5 August 2004 in Zurich caused the substance to degrade rapidly with half-life under such condition only 14 h. This implies that should EA gets into the environment, particularly on exposed environmental niches, such as on plant surfaces through biocontrol product spray, or released from shed diseased leaves, it may have no chance of accumulating to ‘level of concern’. Furthermore, a toxicity assay using Trichoderma atroviride P1 as biosensor showed that photo-degraded EA was not toxic, indicating that no stable toxic by-products were left.

Effect of Artificial UV Radiation on Carbon and Nitrogen Metabolism in the Macroalgae Fucus spiralis L. and Ulva olivascens Dangeard

Thalli of the intertidal Phaeophyte Fucus spiralis L. and the subtidal Chlorophyte Ulva olivascens Dangeard were exposed to artificial UV-A, UV-B and photosynthetically active radiation (PAR) by combination of PAR + UV-A + UV-B (PAB), PAR + UV-A (PA) and PAR (P) treatments. UV-A enhanced photosynthesis and stimulated carbonic anhydrase (CA) and nitrate reductase (NR) in F. spiralis whilst PAR only had an inhibitory effect in this species. U. olivascens suffered chronic photoinhibition in all the treatments as evidenced by reduced maxima photosynthesis (Pmax) and photosynthetic efficiency (α). Non stimulatory effect was observed upon CA and NR in this species. Our results showed that artificial UV radiation triggered opposite responses in both species. We suggest that differences shown by both species might be related to their location in the rocky shore and their ability to sense UV. We propose that the ratio UV:PAR acts as an environmental signal involved in the control of photosynthesis as shown by pronounced inhibition in samples exposed to only PAR. We also suggest that UV-regulated photosynthesis would be related to carbon (C) and nitrogen (N) cycles, regulating feedback processes that control C and N assimilation.

Effects of solar radiation on collagen‐based biomaterials

The effect of solar radiation on collagen and collagen/synthetic polymer blends in the form of thin films and solutions has been studied by UV‐VIS and FTIR spectroscopies. Films and solutions of collagen blended with poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) were irradiated by solar light. It was found that UV‐VIS spectra, which characterize collagen, collagen/PVA, and collagen/PVP blended films, were significantly altered by solar radiation. FTIR spectra of collagen, collagen/PVA, and collagen/PVP films showed that after solar irradiation, the positions of Amide A bands were shifted to lower wavenumbers. There was not any significant alteration in the position of Amide I and Amide II bands of collagen and its blends after solar radiation. The effect of solar UV radiation in comparison with artificial UV radiation has been discussed.

DNA Damage Photoinduced by Cosmetic Pigments and Sunscreen Agents under Solar Exposure and Artificial UV Illumination

Nanostructured ZnO particles present in skin-care cosmetics and UVB/UVA sunscreen products generate strong oxidizing species (free radicals) when illuminated with UV radiation that can damages human skin and the horny layer. Damage to DNA by ZnO and other pigmentary ingredients in sunscreen formulations under artificial and solar UV exposure has been examined by Agarose gel electrophoresis using pUC 18 DNA plasmids (2686 base-pairs). Initial photoinduced oxidative damage done to DNA plasmids have been probed by nicking assays under in vitro conditions for ZnO. The effects of nanosize ZnO and CeO2 particles, and the newly developed CaO-doped and SiO2-coated CeO2 pigment are compared when subjected to artificial (75-W Hg-lamp) and solar UV radiation. Supercoiled DNA plasmids undergo one nick to produce the relaxed form, followed by a second nick yielding the linear form of the plasmids. The DNA constituents deoxyadenosine-5’-monophosphate (dAMP), guanosine-5’-monophosphate (GMP) and cytidine-5’-monophosphate (CMP) have been examined to assess the photooxidative damage done to these nucleotides under photocatalytic conditions using the cosmetic/sunscreen ZnO pigment. Adsorption of the nucleotide through the phosphate on the positively charged ZnO surface, followed by attack of the ribose/phosphate backbone by photogenerated · OH (and/or · OOH) radicals on the ZnO surface lead to the degradation of the dAMP’s ribose moiety and subsequently to decomposition of the adenine base residue. About 90% mineralization of the ribose/phosphate backbone occurred as evidenced by formation of H2PO4- ions after only 30 min of UV irradiation. The nitrogen atoms of the adenine base were converted to NO3- and NH4+ ions. About 45% of the organic carbons constituting the dAMP ribose backbone was mineralized to CO2 within 8 h of UV irradiation occurring through formation of carboxylic acid intermediates (succinic, acetic and formic), with 85% of the remaining nucleobase ultimately mineralized after 48 h of UV irradiation. Similar occurrences were seen for the GMP and CMP nucleotides.

Stimulation of metazooplankton by photochemically modified dissolved organic matter

We examined the response of bacteria and proto- and metazooplankton to photomodified dissolved organic matter (DOM). Sterile filtered water from a eutrophic and a humic lake, that was either exposed to artificial ultraviolet (UV) radiation or kept dark, was added to semicontinuous laboratory microcosms that lasted for 7 weeks. Bacterial production responded positively to photochemical modification of DOM regardless of lake type. Final heterotrophic biomass (bacteria1proto1metazooplankton) was 47 ± 5 and 37 ± 5 µg carbon (C) L−1 in microcosms with UVexposed and unaltered eutrophic water DOM and 15 ± 4 and 11 ± 2 µg C L−1 in microcosms with UV-exposed and unaltered humic water DOM, respectively. For the eutrophic water, there were no significant differences in proto- or metazooplankton biomasses between microcosms receiving UV-exposed or nonexposed DOM. Differences between eutrophic water microcosms were not significant when flagellates, ciliates, cladocerans, and copepods were examined separately. In microcosms with UV-exposed humic water, biomasses of heterotrophic flagellates, rotifers, nauplii, and cladocerans were higher than in those with nonexposed DOM. Higher final metazooplankton biomass following addition of UV-exposed humic water indicates that photochemically modified DOM can be effectively transferred through the microbial loop.

Age-Dependent Survival, Reproduction and Photorepair Activity in Daphnia magna (Straus, 1820) After Exposure to Artificial Ultraviolet Radiation

We examined age-related vulnerability of Daphnia magna to UV-B (ultraviolet-B radiation, 280-320 nm), the age-related relationships between UV-B dosage and reproduction, and the effects of duration of PRR (photorecovery radiation) on survival and fecundity. Animals were exposed to 0, 6, 9 or 12 h UV-B (peak emission 312 nm) at 1, 2, 3 or 4 days of age and followed to 12 days. Survival decreased with increasing exposure to UV-B, but increased with age at exposure. Duration of UV-B, but not age at exposure, decreased offspring production. Survival increased with an increase in duration of PRR for animals of all ages; however, the effect was not age related. Three-day-old animals were exposed to 6 h of UV-B followed by 0-600 min of PRR. Survival was greatest in controls, lowest in the group that received no PRR and similar for all other groups. Most mortality occurred within the first 72 h postirradiation. Offspring production was highest in light controls, lowest in the UV-B-exposed group that received no PRR and not significantly different among other groups. This study demonstrates the need to consider age when examining the effects of UV-B on zooplankton and the need to monitor responses over a sufficient length of time.

The indoor UV tanning industry: A review of skin cancer risk, health benefit claims, and regulation

Nearly 30 million people tan indoors in the United States annually, including 2.3 million adolescents. Despite increased evidence on the dangers of artificial UV radiation, the popularity of indoor tanning is growing. We aim to assess the following 3 entities: (1) the association of indoor tanning with skin cancer; (2) statements regarding the health benefits of indoor tanning, especially regarding the production of vitamin D; and (3) current regulation of the tanning industry in the United States. We conducted a narrative review of the literature. Indoor tanning poses great risks. Studies support the role of artificial UV radiation in cutaneous carcinogenesis. Despite claims by the tanning industry, artificial tanning is not a safe or necessary way to increase systemic vitamin D levels. The National Institutes of Health and the World Health Organization have acknowledged the risks of indoor tanning. Nonetheless, regulations limiting tanning in the United States are surprisingly sparse. Systematic review of the literature was not performed. Health care providers must increase efforts to warn and educate the public and government about the dangers of UV radiation.

Photocatalytic degradation of 3‐nitrobenzenesulfonic acid in aqueous TiO2 suspensions

AbstractThe photocatalytic degradation of 3‐nitrobenzenesulfonic acid in the presence of solar radiation and artificial UV radiation with suspended TiO2 was studied in a batch and continuous annular reactor, respectively. The effects of catalyst loading, pH, presence of anions and cations and initial concentration on the rate of photocatalytic degradation were investigated. Concentration–time data were correlated with the rate equation d[Ct=0]/dt = krK[Ct=0]/(1 + K[Ct=0]). Studies were carried out to compare the photolytic, photochemical and photocatalytic methods of degradation. Copyright © 2005 Society of Chemical Industry

Photocatalytic degradation of m‐dinitrobenzene by illuminated TiO2 in a slurry photoreactor

Abstract1,3‐dinitrobenzene (m‐DNB) is one of the compounds released to water in discharges during the manufacture of explosives. Its widespread distribution as an environmental contaminant is a potential threat to wildlife and other ecological receptors. Therefore, removal of m‐DNB from aqueous solution is very important. In this work, which is a continuation of our ongoing investigation of the effect of various functional groups in aromatic derivatives, a study of the destruction of m‐DNB in aqueous solution, was carried out using both concentrated solar radiation and artificial UV radiation. It was found that a variety of phenolic intermediates are formed via hydroxyl radicals attacking the parent compound. The effects of the various parameters such as adsorption, initial concentration, catalyst loading, pH and anions on the photocatalytic degradation of m‐DNB was studied. The kinetics of the photocatalytic reaction were also studied. The effect of the second nitro group in m‐DNB was elucidated by comparison with our earlier work on PCD of nitrobenzene. Copyright © 2005 Society of Chemical Industry

Effects of solar radiation on collagen and chitosan films

Photo-aging and photo-degradation are the deleterious effect of chronic exposure to sun light of many materials made of natural polymers. The resistance of the products on the action of solar radiation is very important for material scientists. The effect of solar radiation on two natural polymers: collagen and chitosan as well as collagen/chitosan blends in the form of thin films has been studied by UV–Vis and FTIR spectroscopy. It was found that UV–Vis spectra, which characterise collagen and collagen/chitosan films, were significantly altered by solar radiation. FTIR spectra of collagen and collagen/chitosan films showed that after solar irradiation the positions of amide A and amide I bands were shifted to lower wavenumbers. There was not any significant alteration of chitosan UV–Vis and FTIR spectra after solar radiation. In the condition of the experiment chitosan films were resistant to the action of solar radiation. The effect of solar UV radiation in comparison to artificial UV radiation has been discussed.

Effect of Humic Substance Photodegradation on Bacterial Growth and Respiration in Lake Water

This study addresses how humic substance (HS) chemical composition and photoreactivity affect bacterial growth, respiration, and growth efficiency (BGE) in lake water. Aqueous solutions of HSs from diverse aquatic environments representing different dissolved organic matter sources (autochthonous and allochthonous) were exposed to artificial solar UV radiation. These solutions were added to lake water passed through a 0.7-microm-pore-size filter (containing grazer-free lake bacteria) followed by dark incubation for 5, 43, and 65 h. For the 5-h incubation, several irradiated HSs inhibited bacterial carbon production (BCP) and this inhibition was highly correlated with H2O2 photoproduction. The H2O2 decayed in the dark, and after 43 h, nearly all irradiated HSs enhanced BCP (average 39% increase relative to nonirradiated controls, standard error = 7.5%, n = 16). UV exposure of HSs also increased bacterial respiration (by approximately 18%, standard error = 5%, n = 4), but less than BCP, resulting in an average increase in BGE of 32% (standard error = 10%, n = 4). Photoenhancement of BCP did not correlate to HS bulk properties (i.e., elemental and chemical composition). However, when the photoenhancement of BCP was normalized to absorbance, several trends with HS origin and extraction method emerged. Absorbance-normalized hydrophilic acid and humic acid samples showed greater enhancement of BCP than hydrophobic acid and fulvic acid samples. Furthermore, absorbance-normalized autochthonous samples showed approximately 10-fold greater enhancement of BCP than allochthonous-dominated samples, indicating that the former are more efficient photoproducers of biological substrates.

Photocatalytic degradation of 4-nitroaniline using solar and artificial UV radiation

The photocatalytic degradation (PCD) of 4-nitroaniline was studied in the presence of TiO2 suspensions in a batch and continuous annular reactor. Artificial and solar radiation was employed as sources of UV radiation. The effect of catalyst loading, pH, presence of anions and initial concentration on the rate of photocatalytic degradation was investigated. p-Aminophenol, p-benzoquinone and hydroquinone were identified as the intermediates during the degradation process. A kinetic expression for PCD of 4-NA is provided.

Occupational risks for uveal melanoma results from a case-control study in nine European countries

Uveal melanoma is a rare disease with poor prognosis and largely unknown etiology. We studied potential occupational risk factors. A population based case-control study was undertaken during 1995-1997 in nine European countries using population and colon cancer controls with personal interviews. Occupational exposure to sunlight and artificial UV radiation was assessed with a job exposure matrix. In total, 320 uveal melanoma cases were eligible at pathology review, and 292 cases were interviewed, participation 91%. Out of 3357 population controls, 2062 were interviewed, 61%, and out of 1272 cancer controls 1094 were interviewed, 86%. Using population controls, occupational exposure to sunlight was not associated with an increased risk (RR=1.24, 95% CI=0.88-1.74), while an excess risk found with use of colon cancer controls was attributed to confounding factors. An excess risk in welders was restricted to the French part of the data. Cooks, RR=2.40; cleaners, RR 2.15; and laundry workers, RR=3.14, were at increased risk of uveal melanoma. Our study does overall not support an association between occupational sunlight exposure and risk of uveal melanoma. The finding of an excess risk of eye melanoma in cooks in several European countries is intriguing.

Estimate of the effects of ultraviolet radiation on the mortality of Artemia franciscana in naupliar and adult stages

The impact of different doses of artificial ultraviolet (UV) radiation on the growth stages of a marine zooplankton was investigated using laboratory microcosms. Mortality percentages of naupliar and adult samples of Artemia franciscana were recorded in relation to different UV doses (single exposure: 75, 150, 300, 600, 1,200, 2,400, 3,900, 7,800 J m(-2)) at specific observation times after exposure (24, 48, 72, 96 and 120 h). The relationship between mortality percentage and UV dose showed significant differences in relation to the zooplankton growth stage. The elevated susceptibility of the naupliar samples to UV radiation is described through a mortality model based on a logistic equation. The data analysis shows that the slope of mortality versus dose remains the same for the two growth stages while the lethal dose in the naupliar stage was 3.3 smaller than that determined for the adult stage. The slope of the UV mortality rate versus post-incubation time was found to be significantly different (P<0.05) at low UV doses for the two life stages examined, i.e. naupliar and adult. The lower value of LD(50) in naupliar stages compared to that for adults confirms that in the early growth stage this marine zooplankton is more susceptible to UV radiation.

Long-term acclimation to UV radiation: effects on growth, photosynthesis and carbonic anhydrase activity in marine diatoms

Oyster-ponds are characterized by cyclical changes in the composition of the microalgal population, and are mainly colonized by diatoms. Species living in oyster-ponds experience higher levels of UV-R than those living in the ocean because of the low turbidity and shallow depth in ponds (where no stratification occurs). In artificial laboratory conditions, five marine Bacillariophyceae species commonly found in the oyster-ponds were acclimated to three artificial UV radiation (UV-R) treatments with differing durations (2.25 h, 5 h and 8 h) and intensities of exposure, but with the same daily UV-R dose (110 kJ m-2 d-1, unweighted) and UVB-R/UVA-R ratio (4.5%), equivalent to that observed in the natural medium. Benthic species were able to sustain active growth, in contrast to the pelagic Skeletonema costatum that failed to acclimate. Amphora coffeaeformis was the only acclimated species that did not display any significant decrease, or even change in photosynthesis-related pigments and chlorophyll a (Chl a) content when acclimated to UV-R. The other acclimated species showed different patterns of pigment content change, depending on their ability to sustain an active growth rate under UV-R exposure: Haslea ostrearia accumulated photoprotective pigments and exhibited increased diatoxanthin-diadinoxanthin content. The pigment content of Entomoneis paludosa was only slightly modified by the longest UV-R exposure, and Phaeodactylum tricornutum exhibited a marked increase in Chl a turnover, coupled with accumulation of Chl c. In all acclimated species, photosynthesis-related parameters were differently, but in general moderately, affected by UV-R treatments, with a decrease of less than 50% in the maximum photosynthetic capacity. Some species exposed to UV-R exhibited similar or higher photosynthetic capacities than the controls. Carbonic anhydrase activity was strongly enhanced in UV-R tolerant species. Correlation between carbonic anhydrase activity and UV-R tolerance (i.e., ability to sustain active growth rate) in UV-R acclimated algae was established for all the acclimated species. This original finding is concordant with other results that suggest UV-R might play a role in the shift in species composition, since in oyster ponds, Skeletonema costatum, which is usually the dominant species, was the most sensitive diatom under the UV-R conditions tested here.

The causes of skin cancer: A comprehensive review

Skin cancer is the most common type of cancer in fair-skinned populations around the world. The incidence and mortality rates of skin cancers are dramatically increasing and thus pose a threat to public health. Understanding the etiology and pathogenesis of skin cancer remains a goal for healthcare systems. A clearer understanding of causative factors is an essential step in the prevention of skin cancer. This article comprehensively reviews the causative agents which play a role in the development of skin cancer. Ultraviolet radiation (UV) from sun exposure is the most important cause of skin cancer. Sunburns and excessive exposures cause cumulative damage which induces immunosuppression and skin cancers. Ozone depletion, the level of UV light, elevation, latitude, altitude and weather conditions influence the emission of UV radiation reaching the earth's surface. Organ transplant recipients and AIDS patients have an increased incidence of skin cancers. Some treatment modalities, including radiation therapy, phototherapy and psoralen and long-wave ultraviolet radiation (PUVA) can also predispose to skin cancers. Viral infections such as the human papilloma virus can cause squamous cell carcinomas. Individuals with familial genetic syndromes are susceptible to specific types of skin cancers. Ionizing radiation, environmental pollutants, chemical carcinogens and work-related exposures have been associated with skin cancers. Exposure to artificial UV radiation (tanning beds and lamps), aging, skin color, diet and smoking are attributable risks. Skin cancers have been found in dermatoses and various types of keratoses, chronically injured or nonhealing wounds, and scars. This article provides a comprehensive and thorough overview of skin cancer, with an emphasis on understanding its epidemiology, incidence, etiology and related risk factors.

Oral Polypodium leucotomos extract decreases ultraviolet-induced damage of human skin

UV radiation induces damage to human skin. Protection of skin by an oral photoprotective agent would have substantial benefits. Objective We investigated the photoprotective effect of oral administration of an extract of the natural antioxidant Polypodium leucotomos (PL). A total of 9 healthy participants of skin types II to III were exposed to varying doses of artificial UV radiation without and after oral administration of PL (7.5 mg/kg). At 24 hours after exposure the erythema reaction was assessed and paired biopsy specimens were obtained from PL-treated and untreated skin. A significant decrease in erythema was found in PL-treated skin (P < .01). Histologically, PL-treated biopsy specimens showed less sunburn cells (P < .05), cyclobutane pyrimidine dimers (P < .001), proliferating epidermal cells (P < .001), and dermal mast cell infiltration (P < .05). A trend toward Langerhans cell preservation was seen. Oral administration of PL is an effective systemic chemophotoprotective agent leading to significant protection of skin against UV radiation.

On the durability of low-density polyethylene nanocomposites

Abstract Low-density polyethylene (PE) containing nano-particulate clay was prepared after functionalization with maleic anhydride (MA) by reactive grafting in the presence of peroxide followed by blending of maleated PE with neat polymer in different concentrations. Four classes of composites were obtained: (i) exfoliated, (ii) intercalated, (iii) microcomposites, and (iv) intermediate of intercalated and microcomposites, as evidenced by wide-angle X-ray diffraction. All samples were kept for artificial UV irradiation (λ ≥ 290 nm) and for composting to study their photo- and bio-durability. Fourier-transform IR spectroscopy (FT-IR) and scanning electron microscopy were used to monitor the functional group and morphological changes, respectively, whereas biodurability was evaluated by measuring the weight loss. MA functionalization and nature of composites have detrimental effects on the overall durability of composites. Nanocomposites showed higher resistance than microcomposites during initial weathering and composting with a long induction period. The stability of nanocomposites decreases with time and overall durability was worse than of pristine polymer in both environments. It was concluded that the initial protection is due to the filler-generated long diffusion path, which decreases the oxygen diffusion through the matrix. The bio-durability of composites decreased with oxo-degradation. Biodegradation of PE nanocomposites during composting follows the mechanism described by Albertsson et al. as evidenced by FT-IR spectroscopy.

Availability of ammonium influences photosynthesis and the accumulation of mycosporine-like amino acids in two Porphyra species (Bangiales, Rhodophyta)

The effect of ammonium concentration on photosynthetic activity estimated as in vivo chlorophyll fluorescence, i.e. maximal quantum yield (Fv/Fm) and electron transport rate (ETR) and on the accumulation of mycosporine-like amino acids (MAAs), chlorophyll a (chl a), biliproteins (BP) and soluble proteins (SP) in the red algae Porphyra leucosticta Thuret in Le Jolis collected from Lagos (Malaga, Spain) and Porphyra umbilicalis (Linnaeus) J. Agardh from Helgoland (Germany) was evaluated. Discs of both species were incubated with three ammonium concentrations (0, 100 and 300 µM) under artificial PAR and UV radiation for 7 days. Photosynthetic activity decreased under the culture conditions due to UV radiation and ammonium availability. The decrease of both Fv/Fm and maximal ETR was related to ammonium supply, i.e. the lowest decrease occurred in algae growing with the highest concentration of ammonium. In both species, after 7 days of culture, the content of chl a, BP and SP was higher under 300 µM than that under 0 and 100 µM ammonium. In both species, the content of MAAs was increased under 300 µM ammonium compared to the initial value, whereas a decrease under 0 and 100 µM ammonium was observed only in P. leucosticta. The content of MAAs in P. umbilicalis did not present significant differences compared to the initial value, probably because of the high initial content of MAAs. In both Porphyra species, four MAAs were identified: shinorine, porphyra-334, palythine and asterina-330. However, P. leucosticta modified its MAA pattern during the incubation time, reaching the same percentages found for P. umbilicalis, which did not show any change during the experimental period. P. leucosticta exhibited a decrease in BP/SP and BP/chl a ratios through the incubation time and an increase in MAAs/BP. The ratio MAAs/chl a did not show any variation with time or treatment, as was also true for all ratios in P. umbilicalis. In summary, ammonium supply diminished the decrease of Fv/Fm, increased the content of photosynthetic pigments (chlorophyll and biliprotein) and soluble protein, and stimulated of the accumulation of MAAs in the red algae P. leucosticta and P. umbilicalis.

Artificial ultraviolet radiation and ocular melanoma in Australia.

We examined risk of ocular melanoma with exposure to artificial sources of exposure to ultraviolet radiation (UVR) in a population-based epidemiologic study of 290 cases of ocular melanoma and 893 controls aged 18-79 years in Australia in 1996-1998. Cases were identified through a prospective survey of all ophthalmologists and cancer registries in Australia; 91.8% participated. Controls were sourced from electoral rolls; 67.4% of those who were eligible and contactable participated, while 27.3% could not be contacted. Exposure to welding and use of sunlamps, including sunbeds and tanning booths, was measured by telephone interview. Analyses used unconditional logistic regression and included age, sex, region of birth, eye color, ocular and cutaneous sun sensitivity and personal sun exposure as covariates. Risk of choroid and ciliary body melanoma in 246 cases increased significantly with longer duration of use of sunlamps, first use before 21 years of age and first use after 1980. These effects were independent of personal sun exposure. Risk of these melanomas also increased with increasing duration of welding exposure, although the trend was not significant overall. There was no evidence that these exposures increased the risk of iris (n = 25) or conjunctival (n = 19) melanomas. Personal exposure to sunlamps and welding predicts risk of choroid and ciliary body melanoma in Australia.