Biomedical subjects

A V Parisi

Publications and source records attributed to A V Parisi.

At least 19 recordsLinked to original sources

PubMed2006

Influence of solar UVA on erythemal irradiances.

Many materials in everyday use such as window glass in homes and offices, glass in sunrooms and greenhouses, vehicle glass and some brands of sunscreens act as a barrier to the shorter UVB wavelengths while transmitting some of the longer UVA wavelengths. This paper reports on the erythemal exposures due to the UVA waveband encountered over a 12-month period for a solar zenith angle (SZA) range of 4 degrees to 80 degrees and the resulting times required for an erythemal exposure of one standard erythemal dose (SED) due to the erythemal exposures to the UVA wavelengths. The minimum time for an exposure of one SED due to the UVA wavelengths in winter is approximately double that what it is in summer. The time period of 40 to 60 min was the most frequent length of time for an exposure of one SED with 60 to 80 min the next frequent length of time required for a one SED exposure.

Australia↗

PubMed2006

Variations in the short wavelength cut-off of the solar UV spectra.

Cloud and solar zenith angle (SZA) are two major factors that influence the magnitude of the biologically damaging UV (UVBD) irradiances for humans. However, the effect on the short wavelength cut-off due to SZA and due to clouds has not been investigated for biologically damaging UV for cataracts. This research aims to investigate the influence of cloud and SZA on the short wavelength cut-off of the spectral UVBD for cataracts. The spectral biologically damaging UV for cataracts on a horizontal plane was calculated by weighting the spectral UV measured with a spectroradiometer with the action spectrum for the induction of cataracts in a porcine lens. The UV spectra were obtained on an unshaded plane at a latitude of 29.5 degrees S. The cut-off wavelength (lambdac) was defined as the wavelength at which the biologically damaging spectral irradiance was 0.1% of the maximum biologically damaging irradiance for that scan. For the all sky conditions, the short wavelength cut-off ranged by 12 nm for the SZA range of 5 to 80 degrees and the maximum in the spectral UVBD ranged by 15 nm. Similarly, for the cloud free cases, the short wavelength cut-off ranged by 9 nm for the same SZA range. Although, cloud has a large influence on the magnitude of the biologically damaging UV for cataracts, the influence of cloud on the short wavelength cut-off for the biologically damaging UV for cataracts is less than the influence of the solar zenith angle.

Calibration↗

PubMed2005

Potential of phenothiazine as a thin film dosimeter for UVA exposures.

The research reported in this paper on the changes in absorbance and the calibration of a proposed UVA (320-400 nm) dosimeter have established the phenothiazine-mylar combination as a potential UVA dosimeter for population studies of UVA exposures. The change in optical absorbance at 370 nm was employed to quantify the UVA exposures. This change starts to saturate at a change in absorbance of approximately 0.3. This relates to solar UVA exposures at a sub-tropical site on a horizontal plane of approximately three to four hours. The shape of this calibration curve varies with the season. This can be overcome in the same manner as for polysulfone where the dosimeter is calibrated for the conditions that it will be employed to measure the UVA exposures.

Calibration↗

PubMed2005

Vitamin D effective ultraviolet wavelengths due to scattering in shade.

Solar UVB radiation (280-320 nm) is an initiator of Vitamin D3 production in the human skin. While numerous studies have been conducted in relation to the biological impact of UV exposure in full sun, less research has investigated the irradiances in shade. The purpose of this study was to determine the levels of UV radiation in relation to Vitamin D3 induction with six commonly encountered shade environments for the larger solar zenith angles observed during autumn and winter. Spectral UV irradiance measurements were made under relatively clear sky conditions at a sub-tropical Southern Hemisphere site for six specific shade environments and solar zenith angle between 35 degrees and 60 degrees to investigate the biologically effective UV irradiances for pre-Vitamin D3 production. Data from this research indicates that pre-Vitamin D3 effective UV wavelengths in the shade were most significant for tree shade and a shade umbrella. Compared to that in full sun, pre-Vitamin D3 effective UV wavelengths were at levels of approximately 52 and 55%, respectively, beneath the shade umbrella and in tree shade. UVB irradiance levels in the shade of a northern facing covered veranda and in a car with windows closed were significantly less than those beneath the shade umbrella, with levels of approximately 11 and 0%, respectively, of those in full sun. Shade is important as a UV minimisation strategy; however, it may also play an important role in providing the human body with adequate levels of UVB radiation for pre-Vitamin D3 production without experiencing the relatively higher levels of UVA irradiances present in full sun.

Cholecalciferol↗

PubMed2005

Increasing the ultraviolet protection provided by shade structures.

The side openings of a shade structure have a direct influence on where the shade is located and the level of scattered UV in the shaded area. UV exposures were assessed for the decrease in scattered UV beneath specific shade structures by the use of two types of side-on protection, namely, polycarbonate sheeting and evergreen vegetation. Dosimetric measurements conducted in the shade of a scale model shade structure during summer and winter showed significant decreases in exposure of up to 65% for summer and 57% for winter when comparing the use and non-use of polycarbonate sheeting. Measurements conducted in the shade of four shade structures with various amounts of vegetation covering different sides, showed that adequate amounts of and positioning of vegetation decreased the scattered UV in the shade by up to 87% for the larger solar zenith angles (SZA) of approximately 67 degrees and up to 30% for the smaller SZA of approximately 11 degrees when compared to the shade structure that had no surrounding vegetation.

Face↗

PubMed2005

Pre-vitamin D effective ultraviolet transmission through clothing during simulated wear.

BACKGROUND/PURPOSE: Clothing is an important protective layer used to reduce ultraviolet (UV) exposures to the skin surface. However, not all UV exposure is linked to detrimental health effects with some exposure to UVB wavelengths below 316 nm required for the synthesis of pre-vitamin D(3). The aim of the current research was to investigate the effect of fabric type, color, fit, and wetness on the transmission of pre-vitamin D(3) effective UV through garments during simulated wear, in a high UV exposure environment. METHODS: Dosimeters fabricated from polysulfone film were positioned at eight selected body sites on the skin surface and clothing surface of identically designed, loose and fitted, black and white T-shirts made up in two knitted fabric types and tested when both dry and when drying after initial wetting (n=3 replicates). The T-shirts were placed on manikins set to simulate humans in the sun between 09:30 and 12:30 Eastern Standard Time during the Southern Hemisphere summer period. The post-exposure absorbance was measured and the dosimeters were calibrated for biologically effective UV for pre-vitamin D(3) synthesis with a UV spectroradiometer. The effect of fit, fabric type, color, and wetness on pre-vitamin D(3) effective UV transmission during simulated wear was assessed. RESULTS: Irradiances varied among body sites with the highest erythemal exposures to a horizontal plane over the 3 h period reaching approximately 14.5 minimal erythema dose (MED) while the highest exposure under the garment was 0.22 MED which may not be above the threshold for pre-vitamin D(3) synthesis for the time period investigated. Fabric and fit were the main variables affecting transmission of pre-vitamin D(3) effective UV. Some interactions were identified between the fabric color and wetness and between fabric type and color; however, while significantly modifying transmission these effects were small. CONCLUSION: Transmission of pre-vitamin D(3) effective UV occurred through the high UPF knitted fabrics investigated. However, the length of exposure will influence whether the irradiances are sufficient to be above the threshold for pre-vitamin D(3) synthesis. The main effect on transmission of pre-vitamin D(3) effective UV was the fit of the T-shirt and its fabric type (probably structure) rather than color or degree of wetness.

Clothing↗

PubMed2004

Annual variation of the angular distribution of the UV beneath public shade structures.

Local governments provide many shade structures at parks and sporting ovals for public use. However, the question remains of how effective are public shade structures at reducing biologically effective UV radiation throughout the year? Broadband measurements of the angular distribution of scattered UV beneath three specific public shade structures was conducted for relatively clear skies and for a solar zenith angle (SZA) ranging from 13 degrees to 76 degrees. The ultraviolet protection factors (UPF) for the shade structures ranged from 18.3 to 1.5 for an increasing SZA. Measurements showed that the horizontal plane received the highest SUV levels from the SZA of 28 degrees to 75 degrees, 42 degrees to 76 degrees, and 50 degrees to 76 degrees for the small, medium and large structures, respectively. This was due to the angle of the sun causing the shade created by the shade structure to be outside the structure. For the small shade structure, the measurements directed to the west were the highest levels in the shade after approximately 28 degrees. For the medium and large shade structures, the measurements directed to the west and south were the highest levels in the shade after roughly 42 degrees and 50 degrees, respectively.

Diffusion↗

PubMed2004

Cloud cover and horizontal plane eye damaging solar UV exposures.

The spectral UV and the cloud cover were measured at intervals of 5 min with an integrated cloud and spectral UV measurement system at a sub-tropical Southern Hemisphere site for a 6-month period and solar zenith angle (SZA) range of 4.7 degrees to approximately 80 degrees . The solar UV spectra were recorded between 280 nm and 400 nm in 0.5 nm increments and weighted with the action spectra for photokeratitis and cataracts in order to investigate the effect of cloud cover on the horizontal plane biologically damaging UV irradiances for cataracts (UVBE(cat)) and photokeratitis (UVBE(pker)). Eighty five percent of the recorded spectra produced a measured irradiance to a cloud free irradiance ratio of 0.6 and higher while 76% produced a ratio of 0.8 and higher. Empirical non-linear expressions as a function of SZA have been developed for all sky conditions to allow the evaluation of the biologically damaging UV irradiances for photokeratitis and cataracts from a knowledge of the unweighted UV irradiances.

Atmosphere↗

PubMed2003

Optical properties of poly(2,6-dimethyl-1,4-phenylene oxide) film and its potential for a long-term solar ultraviolet dosimeter.

The optical properties of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) film have been characterized in order to develop an alternative method for UV dosimetry with a focus on long-term human exposure measurements. The dynamic range of PPO film was found to extend to 2 MJ m(-2) of broadband UV exposure independently of film thickness, providing an exposure range of roughly four summer days at subtropical latitudes. The sensitivity of the film to UV exposure was positively related to film thickness in the 20-40 microm range. Films of 40 microm thickness proved to be the most suitable for long-term human UV exposure measurements. The temperature independence of the response of 40 microm PPO film was established from 1.5 degrees C to 50 degrees C within a dosimeter response uncertainty of 6.5%. Dose-rate independence was also demonstrated within 8% of the mean dosimeter response. The spectral response approximates the CIE erythemal action spectrum between 300 and 340 nm, with a peak response at 305 nm. A large deviation from this action spectrum was observed at shorter wavelengths. Investigation of the angular response in both the azimuth and altitude planes showed a cosine error of less than 6.2% between 0 degrees and 40 degrees, and did not exceed 13.3% at any angle greater than 40 degrees. These results indicate that PPO film satisfies the requirements for use as a UV dosimeter, and may be employed in long-term human exposure measurements.

Humans↗

PubMed2003

Comparison of biologically damaging spectral solar ultraviolet radiation at a southern hemisphere sub-tropical site.

The first dataset of a complete year of biologically damaging spectral UV at a sub-tropical latitude in the southern hemisphere has been presented. The new data provides a baseline dataset against which comparisons can be made in the future to establish if there have been any long term trends in the biologically damaging UV. The general shape of the variation of the daily biologically damaging exposures through the year depends on the relative response of the various action spectra at the different wavelengths. The ratio of the daily erythemal to actinic exposures drops by approximately 20 to 25% from winter to summer. The ratio of the erythemal to DNA exposures drops by approximately 50% over the same period. In contrast, the ratio of the erythemal to plant damage exposures is higher in summer compared to winter. This is due to the changes in the relative proportion of UVA to UVB wavebands and relative responses of the different action spectra. The relative changes for the different action spectra show that the erythemal action spectrum cannot be used as a proxy for other biologically damaging responses.

Animals↗

PubMed2003

Lower body anatomical distribution of solar ultraviolet radiation on the human form in standing and sitting postures.

Humans undertake their daily activities in a number of different postures. This paper aims to compare the anatomical distribution of the solar erythemal UV to human legs for standing and sitting postures. The exposure ratios to the legs (ratio of the UV exposure to a particular anatomical site compared to the ambient) have been measured with UV dosimeters for standing and sitting postures of a manikin. The exposure ratios for the legs ranged from 0 to 0.75 for the different anatomical sites for the sitting posture in summer (December through February) compared to 0.14 to 0.39 for the standing posture. In winter (June through August) the exposure ratios ranged from 0.01 to 0.91 for sitting to 0.17 to 0.81 for standing. For the anterior thigh and shin, the erythemal UV exposures increased by a factor of approximately 3 for sitting compared to standing postures. The exposure ratios to specific anatomical sites have been multiplied by the ambient erythemal UV exposures for each day to calculate the annual exposures. The annual erythemal exposures to the anterior thigh and ankle were predicted to be higher than 800 MED for humans sitting outdoors each day between noon and 13:00 h Australian Eastern Standard Time (EST). For humans standing outdoors during this time, the annual erythemal UV exposure averaged over each leg site was 436 MED, whereas, the averaged annual erythemal UV exposure was 512 MED for the sitting posture. Similarly, the annual erythemal UV exposure averaged over each of the sites was 173 MED for humans standing outdoors between 09:00 h EST and noon each Saturday morning and 205 MED for humans sitting outdoors during this time. These results show that there is increased risk of non-melanoma skin cancer and malignant melanoma to the lower body if no UV preventative strategies are employed while in a sitting posture compared to a standing posture.

Environmental Exposure↗

PubMed2003

Spectral UV in public shade settings.

The protective nature of specific shade environments was investigated by measuring the spectral UV in the shade for the three planes (horizontal, 45 degrees and vertical) and comparing this to that on a horizontal plane in full sun. Spectral UV irradiance measurements were made under clear sky conditions at a sub-tropical southern hemisphere site. The solar UV in the shade of a shade umbrella, covered verandah, covered sand pit and covered walkway were measured for an increasing solar zenith angle, between March and August, for the times of 11:30 a.m.-12:30 p.m. and 2:30-3:30 p.m. The ultraviolet protection factors provided ranged from 1.4 to 10. This research shows that there is sufficient UV in the shade to cause erythema on the human body in a short period of time. For the shade umbrella placed on dry grass the time able to be spent in the shade in the middle of the day before experiencing mild erythema increased from 35 to 60 min as the solar zenith angle increased from 33 to 52 degrees. Erythemal UV levels in the shade of a northern facing covered verandah, with trees in close proximity, were approximately up to five times less than the erythemal UV beneath the shade umbrella that had no surrounding trees. Shade structures must be given careful consideration when construction occurs. Even though the UV transmission through the materials may be very low, it is the construction of the entire shade setting that determines the exposure beneath the shade structure.

Environmental Exposure↗

PubMed2003

Comparison of human facial UV exposure at high and low latitudes and the potential impact on dermal vitamin D production.

The results presented in this paper allow for the estimation of the monthly UV exposure of the human facial region at various locations across the earth. The technique allows a graphical representation of the UV exposures over the face. The erythemal UV exposures as well as the vitamin D exposures to the human facial region have been investigated. The results gained in this paper, for a clear sky and constant ozone indicate that the sun's capability to promote the development of vitamin D in the human body does not follow the erythemal UV irradiances, in particular at high latitudes. For Amsterdam (52 degrees N) in late winter, approximately 20% more UV is required to produce 215 J m(-2) of vitamin D weighted UV than erythemal UV.

Face↗

PubMed2003

Scattered UV beneath public shade structures during winters.

Broadband field measurements were conducted beneath three different-sized public shade structures, small, medium and large, during winter in the Southern Hemisphere. These measurements were compared with the diffuse UV to quantify the relationship of the UV under and around the shade structures to the diffuse UV. For the shade structures, a relationship between the diffuse UV and the UV in the shade has been provided for clear skies and solar zenith angles (SZA) of 49-76 degrees. This allows the prediction of the UV in the shade of these structures if the diffuse UV is known. The ultraviolet protection factors for the three shade structures ranged from 1.5 to 5.4 for decreasing SZA. For the greater SZA of 70-76 degrees, the erythemal UV in the shade was 65%, 59% and 51% of that in full sun for the small, medium and large structures, respectively. For the smaller SZA of 50-53 degrees the erythemal UV in the shade was 35%, 41% and 18% for the small, medium and large shade structures, respectively. From this research it can be concluded that the UV radiation levels in the shade in winter could cause erythema and other sun-related disorders.

Australia↗

PubMed2002

Comparison of the solar spectral ultraviolet irradiance in motor vehicles with windows in an open and closed position.

The solar ultraviolet (UV) spectrum was measured by a spectroradiometer located inside two common Australian vehicles: a family wagon and a four-wheel-drive vehicle. The entrance optics of the spectroradiometer was orientated, in turn, on a horizontal plane, towards the driver and passenger windows and towards the windshield. UV spectra were recorded when the vehicles' windows were in an open and closed position. For a typical Australian family wagon, on a horizontal plane inside the vehicle, closing the windows decreased, the total UV irradiance by a factor of 3.2, whilst in a four-wheel drive the irradiance decreased by a factor of 2.1. In order to reduce the likelihood of developing of UV-related eye and skin disorders, drivers should use appropriate UV protection whilst driving a vehicle with the windows in an open position. Results gained from this research provide new findings on the exposure of humans to UV in a vehicle.

Environmental Exposure↗

PubMed2002

Understanding the UVA environment at a sub-tropical site and its consequent impact on human UVA exposure.

Daily UVA and erythemal irradiance data on a horizontal plane at a sub-tropical site were measured during a period from March 2000 to February 2001. On a relative basis, UVA radiation was shown to be a greater concern to human exposure during the winter months than summer months. In summer (December to February), the peak daily UVA exposure was 205 J cm(-2) and in winter (June to August), the minimum daily value was 19 J cm(-2). The peak daily UVery exposure was 37 MED in summer and the winter minimum was 4 MED. The occupational work day UVA exposure to the vertex of the head was estimated using the collected UV data. The outdoor workers received 89% of the available UVA radiation whilst the home workers received 18% of the available ambient UVA radiation. This result parallels the exposure patterns of these two population groups, with the outdoor workers spending most of the working week outdoors, whilst the home workers spend small, intermittent time periods outdoors in the sun.

Environmental Exposure↗

PubMed2002

Spectral ultraviolet albedo of roofing surfaces and human facial exposure.

Spectral field measurements were used to quantify the ultraviolet (UV) spectral albedos of four different metallic roofing surfaces. The effect of the albedos of two of these surfaces on erythemal exposure to human facial anatomical sites was quantified by UV dosimetry. The albedos of all roofing surfaces were greater than the albedo of grass. Little SZA dependence was observed for any of the surfaces. The albedos of the coloured metallic corrugated surfaces were strongly dependent on wavelength in the UVA, increasing from 3 to 12%. Facial erythemal measurements showed significant exposure enhancements over the galvanised corrugated surface compared to grass. The undersides of the chin and nose received exposure enhancements over the galvanised corrugated surface of about 1290 and 190%, respectively, of the exposure of these sites over grass. It is concluded that the albedo of the galvanised surfaces are higher than those of the coloured surfaces by at least 20%, and higher than grass by at least 27%. Consequently, normally shaded facial anatomical sites receive substantially higher UV exposures over these galvanised surfaces compared to grass.

Construction Materials↗

PubMed2001

Spectral shade ratios on horizontal and sun normal surfaces for single trees and relatively cloud free sky.

Spectral shade ratios, defined as the ratios of the spectral irradiances on horizontal and sun normal planes in the tree shade to those on a horizontal plane in sunlight, were calculated. These planes were in the shade of an isolated medium canopy density tree and a sparse canopy density tree at the tree shade sites of the centre, edge and trunk. The sun normal plane was employed as there are some activities that have exposures to parts of the body that are orientated in a sun normal plane. The horizontal plane shade ratios for the medium density canopy dropped by 47-56% from the ratios in the range 301 to 310 nm to the ratios in the range 391 to 400 nm. In absolute terms, the largest change in the shade ratio of 0.28 was for the centre and edge sites compared to 0.07 for the trunk. Similarly, for the sun normal plane, the ratio dropped by 40-49% with an absolute reduction of 0.19 for the edge and 0.04 for the trunk. For the sparse density canopy, the decrease in the shade ratios over the same wavelength range was a drop by 37-42% on a horizontal plane or, in absolute terms, a reduction by 0.22 for the edge and 0.13 for the trunk. Similarly, the decrease was 34-39% on the sun normal plane or, in absolute terms, a reduction by 0.19 for the edge and 0.12 for the trunk.

Spectrophotometry, Ultraviolet↗