The distribution of biologically effective UV spectral irradiances received on a manikin face that cause erythema and skin cancer

Journal of Photochemistry and Photobiology B: Biology 140 (2014) 205–214

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Journal of Photochemistry and Photobiology B: Biology journal homepage: www.elsevier.com/locate/jphotobiol

The distribution of biologically effective UV spectral irradiances received on a manikin face that cause erythema and skin cancer Fang Wang a, Tiantian Ge a, Qian Gao a, Liwen Hu a, Jiaming Yu b, Yang Liu a,⇑ a b

School of Public Health, China Medical University, Shenyang, Liaoning, China Ophthalmology Department, The Fourth Affiliated Hospital of China Medical University, Shenyang, Liaoning, China

a r t i c l e

i n f o

Article history: Received 7 May 2014 Received in revised form 21 July 2014 Accepted 4 August 2014 Available online 13 August 2014 Keywords: Erythemal Skin cancer Biologically effective UV Spectral Manikin

a b s t r a c t Solar ultraviolet (UV) radiation is a major cause of erythema and skin cancer in humans and the face is one of the highest risk sites. Biologically effective UV irradiation (UVBE) is wavelength-dependent, and risk assessment has been demonstrated based on the value of the received UV radiation. Therefore, this study measured the face skin exposure to UV spectral irradiance using a spectroradiometer and a head manikin, which were weighted by action spectra to calculate the UVBE that causes erythema (UVBEery), non-melanoma (UVBEnon-mel), human squamous cell cancer (UVBEh-SCC), and DNA damage (UVBEDNA-d). We determined that the biologically effective UVB and UVA irradiances on clear sky days had peak values at 65–73° SEA (8–9 UVI) and 55–68° SEA (6–7 UVI), respectively. In the 10–30° SEA range, the highly skindamaging wavelengths were all observed at 300 nm. However, in the 30–60°, 60–81°, and 10–81° SEA ranges, the highly skin damaging wavelengths were 300 nm, 304 nm and 300 nm for UVBEery, respectively; 304 nm, 306 nm and 304 nm for UVBEnon-mel, respectively; all 305 nm for UVBEh-SCC, and two small peaks at 302 nm and 312 nm for UVBEDNA-d. Ó 2014 Elsevier B.V. All rights reserved.

1. Introduction Solar ultraviolet (UV) radiation is a major cause of erythema and skin cancer in humans, which is supported by sufficient experimental and epidemiological evidence [1–11]. Recently, the reduction of stratospheric ozone has led to elevated ultraviolet radiation levels at the Earth’s surface [12]. A 10% reduction in ozone could lead to as much as a 15–20% increase in UV exposure depending on the biological process. Several studies have shown that the increase in the solar spectrum reaching the Earth’s surface through the decrease in stratospheric ozone may increase the incidence of skin damage [13–21]. According to estimates provided by the ‘‘United Nations Environment Programmer’’ (UNEP), a decrease in stratospheric ozone of 10% each year will further increase the 304,500 cases of skin cancer that occur each year worldwide [22]. People should become more aware of the risk of skin exposure to solar UV radiation. Epidemiological evidence that is relevant to the effects of UV on cancer risk in humans is derived primarily from studies of the effects of sun exposure and cancer risk. The most direct evidence of the carcinogenicity of UV radiation in humans should come, in principle, from observing the effects of personal exposure to sun.

⇑ Corresponding author. E-mail address: [email protected] (Y. Liu). http://dx.doi.org/10.1016/j.jphotobiol.2014.08.004 1011-1344/Ó 2014 Elsevier B.V. All rights reserved.

In practice, it is difficult to measure personal sun exposure accurately. Additionally, skin cancer occurs most frequently in the most highly exposed areas and correlates with the degree of outdoor exposure. The face is a high-risk area that is two to four times more sensitive than the limbs [23–25]. Accurately measuring the UV radiation that reaches the face is important for exposure assessment. A few studies have carried out using manikins to better simulate the face UV exposure for humans [26–30]. The benefit of using manikins was that it can reflect the effects of the surrounding anatomic sites to the monitored site. So we used a head manikin to accurately simulate the exposure of the face to UV radiation by the sun and assess the risk of face exposure to UV irradiance. An action spectrum is a graph of the reciprocal of the radiant exposure required to produce a given effect at each wavelength. All the data in these curves are normalized to the datum at the most efficacious wavelength(s). By summing the biologically effective irradiance over the exposure period, the biologically effective radiant exposure (J m2 effective) can be calculated. Describing the relationship of exposure (dose) to skin damage (erythema and skin cancer) requires the availability of a biological hazard function or action spectrum for skin damage. The action spectrum gives the relative biological response of damage caused by UV radiation at different wavelengths; therefore, it is specific for a certain effect. Erythema is an acute injury caused by UV radiation that appears up to 8 h after exposure to UV radiation. The relative effectiveness

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of the different wavelengths to induce erythema is expressed as an erythema action spectrum. The action spectrum adopted by the International Commission on Illumination (CIE) in human skin was proposed in 1987 and was based on the statistical analysis of the results of eight published studies of the determination of minimal erythema doses in groups of normal subjects. The erythema action spectrum is represented by relatively simple functions over three clearly defined spectral regions encompassing the wavelength interval from 250 to 400 nm. The most erythemogenic wavelengths are in the 250–290 nm range, and a decrease in effectiveness is observed as the wavelengths increase [31]. The erythemal (sunburn effective) action spectrum of the human skin weighted with the integral over the spectral UV irradiance on a horizontal plane in W m2 and multiplied by the constant 40 W1 m2 was used to calculate the Global Solar UV index (UVI) [31–33]. To promote solar UV protection, the UVI was developed as a tool to visualize the amount of harmful radiation and to encourage people to use sun protection [34]. Skin cancer is chronic skin damage caused by UV radiation. For UV induced skin cancer, the CIE 2006 has shown a standard which proposed the adoption of an action spectrum (weighting function) derived from experimental laboratory data [35–38] and modified to estimate the non-melanoma tumor response in human skin [39]. This action spectrum has a peak at 299 nm (at effectiveness 1) and constant value in the wavelength range 340–400 nm (at effectiveness 0.000394). In 1993, one research measured the wavelength dependency of skin cancer induced by UV in hairless mice and represented this in an action spectrum [40]. The action spectrum for humans have estimated in 1994 [37] by correcting for differences in epidermal transmission between mice and humans. The action spectra for UV-induced squamous cell cancer (SCC) have two peaks at 293 nm and 380 nm for hairless mice, and two peaks at 299 nm and 381 nm for humans. The valleys of the action spectra for UVinduced SCC were both at 352 nm for hairless mice and humans. DNA damage caused by UV radiation is an initiator and key mediator in the development of skin cancers [41–47]. One significant UVinduced DNA lesion is the cyclobutyl pyrimidine dimer, formed between adjacent pyrimidines on the same DNA strand [48]. ENVIRONMENTAL HEALTH CRITERIA 160 (EHC160) has shown an action spectra for cyclobutane pyrimidine dimer formation in epidermal DNA to shown the relative biological response of DNA damage and this action spectrum was determined by one research in 1989 [48]. The peak of this action spectrum is near 300 nm and decreases rapidly at both longer and shorter wavelengths. To accurately assess the risk of facial skin damage because of exposure to solar UV irradiance, the present study measured the facial skin exposure to UV spectral irradiance using a spectroradiometer and a head manikin, with regards to the characteristics of the facial anatomic structure. The measured UV spectral data were weighted by the erythema [31], non-melanoma [36], human-SCC [37] and pyrimidine photo-dimerization [48] action spectra to calculate the biologically effective UV irradiation (UVBE) that causes erythema (UVBEery), non-melanoma (UVBEnon-mel), human squamous cell cancer (UVBEh-SCC), and DNA damage (UVBEDNA-d), respectively. The diurnal variation of facial skin exposure to UVA and UVB waveband biologically effective irradiance at different SEAs and the biologically highly effective wavelengths for erythema, non-melanoma, human-SCC and DNA damage were determined in this study.

2. Materials and methods 2.1. Experimental materials The experimental materials consisted of a head manikin, a middle shelf, and a turntable base that rotated at a constant speed from

top to bottom. The total height of the manikin system was approximately 170 cm. The distance between the three anatomic measurement sites, including the cheek, nose, forehead and ground were approximately 155 cm, 155 cm and 165 cm, respectively. A computer and a computer-controlled fiber-optic (FO) spectrometer with two detectors were placed on the shelf to measure the UV spectral irradiance intensity (unit: lW cm2 nm1). One detector was placed at the vertex of the manikin’s head, and the other detector was placed on the anatomic measurement sites cheek (Fig. 1A), nose (Fig. 1B), forehead (Fig. 1C), where hold the plane tangent to the anatomic measurement sites at the most anterior point. For the actual anatomic measurement sites of cheek, the distance between cheek and the Lower eyelid of the head manikin is 2 cm (Fig. 1D-L5) and the distance between cheek and the Nasal septum of the head manikin is 4.5 cm (Fig. 1D-L6); For the actual anatomic measurement sites of nose was the tip of the nose; For the actual anatomic measurement sites of forehead, the distance between forehead and the vertex of the head manikin is 5 cm (Fig. 1D-L1), the distance between forehead and the connection of two eyebrow ridges is 2.5 cm (Fig. 1D-L2) and the distance between forehead and the right and left of the head manikin are 7.5 cm (Fig. 1D-L3, L4). The detectors simultaneously recorded the UV radiation levels at the corresponding horizontal ambient and anatomic measurement sites. 2.2. Spectrometer and equipment calibration The UV spectral irradiance was measured with a dual-channel miniature FO spectrometer (AvaSpec, 2048  14-2-USB2, Netherlands) with high UV sensitivity and high quantum efficiency. The design of the spectrometer is based on the AvaBench-75 symmetrical Czerny-Turner design with a 2048-pixel CCD detector array, making it particularly suitable for low-light, high-resolution applications. The full-width-at-half-maximum (FWHM) resolution of the spectrometer is 2.0 nm, and the resolution for stray light is less than 0.1%. The signal-to-noise ratio is 500 dB. The spectrometer has a slit size of 200 lm and a diffraction grating with 1200 lines per mm. The USB2 interface has ultrafast data sampling at 450 spectra s1, with data transfer at 2.24 ms. The two FO connectors can work synchronously. The detector has a cosine corrector (CC-UV/VIS) with an active area of 3.9 mm, which allows it to accept light from a 180° angle. The spectrometer was configured and radiometrically calibrated for absolute irradiance measurements over a range of 200– 400 nm. Before the experiment, the fiber optic spectrometer was calibrated by the National Physical Laboratory GB (NPL). 2.3. UV radiation measurement and experimental methods The measurements were performed in May in the town of Dou Men near Shao Xing city (30.09°N, 120.60°E, altitude 553 m), in the province of Zhejiang, China. The measurements were recorded on May 27 and 30, 2010 (summer) from 06:30 to 18:00 China Standard Time (CST) (solar noon at approximately 12:00 CST). The cheek and horizontal ambient irradiance measurements were performed on May 27, 2010. The nose, forehead and corresponding horizontal ambient irradiance measurements were performed on May 30, 2010. The mean air pollution index (API) of the measurement days in Shao Xing was approximately 62 for both days. The approximate midday maximum SEAs for the measurement days were both approximately 82°. The total column ozone amounts for May 27 and 30, 2010 were 276 Dobson Units (DU) and 326 DU, respectively (from National Aeronautics and Space Administration, NASA; http://ozoneaq.gsfc.nasa.gov/ozone_overhead_current_ v8.md). The monitoring location was on the roof of a hospital. In all cases, the roofs had unobstructed fields of view. The experimental

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Fig. 1. The three anatomic measurement sites on head manikin (A) cheek (B) nose (C) forehead.

instrument was placed on the asphalt-covered concrete roof of the hospital, which were five-stories high. The measurements were performed between sunrise and sunset on days with a clear or slightly cloudy sky. If cloud coverage occurred during the measurements, then the experiment was paused and resumed after the sky became either clear or slightly cloudy. Before beginning the measurements on the day of the experiment, the mode of the turntable base was adjusted to ensure that the manikin rotated clockwise at a constant speed (360° min1, equivalent to 6° s1). The measurement mode of the FO spectrometer was adjusted such that the detector collected data once per second, and the duration of each measurement progression was 1 min. For each measurement progression, the manikin began facing toward the sun and then rotated 360° over 1 min. Sixty sets of monitored anatomic site and horizontal ambient UV spectral irradiance (unit lW cm2 nm1) measurements per manikin revolution were collected. The UV spectral irradiance (unit lW cm2 nm1) at 1 s intervals was calculated over a range of 300–400 nm at 1 nm intervals. The monitored anatomic site maximum at different wavelength values of each revolution was calculated to simulate the actual maximum UV exposures under clear skies. The same procedure was performed for the data obtained from the ambient detector at the same time. The time between measurements was 15 min. The UV index (UVI) at the same time point was calculated for comparison.

where UVBE is the spectral irradiance weighted with the action spectrum for a specific biological process, S (k) is the intensity of the measured UV spectral irradiance in lW cm2 nm1, A (k) is the particular action spectrum and d (k) is the wavelength increment of the spectral data, which is 1 nm here. For this study, the action spectra for erythema [31], non-melanoma [36], and human-SCC [37] ranged from 300 to 400 nm and for pyrimidine photo-dimerization in epidermal DNA damage [48], it ranged from 300 to 366 nm (Fig. 1). These ranges were used to calculate the UVBEery, UVBEnon-mel, UVBEh-SCC and UVBEDNA-d, respectively. All action spectra were linearly interpolated between the data points to 1 nm. Fig. 2 shows the difference between nonmelanoma skin cancer action spectra and human-SCC action spectra. In the wavelength range 300–340 nm, the effectiveness of these two action spectra was almost identical but different in the wavelength range 341–400 nm. In the wavelength range 341–366 nm and 391– 400 nm, the effectiveness of nonmelanoma skin cancer action spectra was higher than that of human-SCC action spectra. However, the effectiveness of human-SCC action spectra was higher than that of nonmelanoma skin cancer action spectra in the wavelength range 367–390 nm. In practice, the integral is substituted by a summation of the UV spectral irradiance within a certain wavelength range. In this study, we calculated both the integral summation of monitored UVB and UVA band intensities from 300 to 320 nm and 320 to 400 nm, respectively, and the UVBE of the wavelength increment at 1 nm.

2.4. UVBE irradiance 2.5. Exposure of UV irradiance dose The UVBE irradiance was calculated according to the following equation:

UVBE ¼

Z UV

S ðkÞA ðkÞd ðkÞ

ð1Þ

The UV irradiance dose (H) for specific time intervals was calculated according to the following equation:

H¼

Z

E dT T

ð2Þ

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Fig. 3. Diurnal variations of horizontal ambient UVB and UVA irradiances by SEA. * This figure is shown as a double ordinate. The left and right ordinates show the intensity of horizontal ambient UVA and UVB irradiances, respectively. Fig. 2. The erythema [31], non-melanoma [36], human-SCC [37] and pyrimidine photo-dimerization [48] action spectra.

where E represents spectral irradiance, both un-weighted and weighted, with the action spectrum for a specific biological process, and T is the exposure time interval. In this study, the trials were measured from 6:30 CST (corresponding to a SEA of 18°) until 18:00 CST (corresponding to a SEA of 10°). In this study, the SEA ranged from 10° to 81°, with a maximum solar elevation of 81° at 12:00 CST, and we calculated the summation dosimetry (unit: J m2) of three different SEA ranges, from 10° to 30°, 30° to 60° and 60° to 81°, according to the relationship between the local time and the corresponding SEA. However, the dosimetry of the SEA ranging from 10° to 30° was partially missing in the morning when the SEA ranged from 10° to 18°. To ensure the integrity of this measured data, the morning data were added to that of the afternoon in the SEA range of 10–18°.

3. Results

Fig. 4. Diurnal variations of cheek, nose and forehead UVB and UVA irradiances by SEA, and fitted regression curves. * This figure is shown as a double ordinate. The left and right ordinates show the UVA and UVB irradiance intensities of the cheek, nose and forehead, respectively.

3.1. Diurnal variation of UVA and UVB radiation The intensity of the ambient UVB and UVA irradiance of the two experimental days were increased by the increasing solar elevation angle (SEA). The highest intensity of ambient UVB and UVA irradiance appear in the maximum SEA of these days. At the same SEA, both the UVB band and UVA band the intensity of the ambient UV irradiance were nearly the same for the two days (Fig. 3). The diurnal variations of the UVB and UVA irradiances by SEA for the three monitored anatomic sites, the cheek, nose and forehead were different from that of the horizontal ambient UVB and UVA irradiances (Figs. 3 and 4). The peak intensities of UVB and UVA irradiance of the three monitored anatomic sites did not appear in the maximum SEA of the two days. For the UVB band irradiance, the peak of cheek exposed to UVB irradiance appeared at 73° SEA, whereas the peaks of nose and forehead exposed to UVB irradiance both appeared at 65° SEA. For the UVA band irradiance, the peak of cheek exposed to UVA irradiance was at 68° SEA, whereas the peaks of nose and forehead exposed to UVB irradiance were both at 55° SEA. At the same SEA, both the UVB band and UVA band irradiance, lowest for the cheek exposed to UV irradiance and highest for the forehead exposed to UV irradiance. Additionally, for the three monitored anatomic sites, the intensity of exposed to UVA band irradiance was significantly higher than UVB band irradiance. The fitted equations of the fitted regression curves for the three monitored anatomic site UVB and UVA

irradiances diurnal variations by SEA are shown in Table 1 and fit the function in the 10–81° SEA range. Fig. 5 shows the distribution of the cheek, nose and forehead UVB and UVA irradiances by ultraviolet Index (UVI). The maximum UVI of the two experimental days were 10. For both the UVB and UVA band irradiances, the peaks of the three monitored anatomic sites UV irradiances exposure did not appear at the maximum UVI. For the UVB band, the peak of cheek exposed to UVB irradiance was at 9 UVI, whereas the peaks of nose and forehead exposed to UVB irradiance were both at 8 UVI. For the UVA band, the peak of cheek exposed to UVA irradiance was at 7 UVI, whereas the peaks of nose and forehead exposed to UVB irradiance were both at 6 UVI. One peak of the diurnal variations of the four biologically effective UVB and UVA irradiances by SEA for the three monitored anatomic sites. The peaks of cheek exposed to the four biologically effective UVB and UVA band irradiance were 73° and 68° SEA, respectively; whereas the peaks of nose and forehead exposed to the four biologically effective UVB and UVA band irradiance were both appeared at 65° SEA, and UVA band irradiance were both 55° SEA (Fig. 6). At the same SEA, the intensity of exposure to the four biologically effective UVB band irradiances was higher than that of exposure to the four corresponding biologically effective UVA band irradiances for all three monitored anatomic sites. For the UVB band irradiances, the descending order of the intensity

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F. Wang et al. / Journal of Photochemistry and Photobiology B: Biology 140 (2014) 205–214 Table 1 Fitted equations for the UVB and UVA irradiances. Anatomic sites

Classification

UVB Fitted equations

R2

Fitted equations

R2

Cheek

Actual UV UVBEery UVBEnon-mel UVBEh-SCC UVBEDNA-d

y = 1E05x4 + 0.002x3  0.0815x2 + 1.9045x  7.9252 y = 2E06x4 + 0.0002x3  0.0102x2 + 0.222x  0.9602 y = 4E06x4 + 0.0005x3  0.0229x2 + 0.4951x  2.1168 y = 3E06x4 + 0.0004x3  0.0202x2 + 0.4367x  1.8771 y = 2E06x4 + 0.0003x3  0.0145x2 + 0.3199x  1.3877

0.95 0.91 0.92 0.91 0.93

y = 0.0002x4 + 0.0188x3  0.2126x2 + 12.186x + 186.4 y = 1E07x4 + 2E05x3  0.0004x2 + 0.0141x + 0.0577 y = 2E07x4 + 2E05x3  0.0007x2 + 0.021x + 0.0477 y = 2E07x4 + 2E05x3  0.0005x2 + 0.0161x + 0.0382 y = 3E07x4 + 4E05x3  0.0012x2 + 0.0347x  0.0094

0.92 0.93 0.93 0.94 0.94

Nose

Actual UV UVBEery UVBEnon-mel UVBEh-SCC UVBEDNA-d

y = 4E06x4  0.0017x3 + 0.1407x2  1.5898x + 9.6015 y = 1E07x4  4E05x3 + 0.0051x2  0.0354x + 0.735 y = 3E07x4  0.0001x3 + 0.0133x2  0.1204x + 1.8539 y = 3E07x4  7E05x3 + 0.0093x2  0.0633x + 1.4511 y = 4E10x4  0.0001x3 + 0.0105x2  0.0948x + 1.1696

0.99 0.98 0.99 0.98 0.99

y = 0.0003x4  0.0669x3 + 3.355x2 + 13.802x  206.97 y = 2E07x4  4E05x3 + 0.0024x2  0.0037x  0.0444 y = 2E07x4  5E05x3 + 0.003x2  0.0037x  0.0668 y = 2E07x4  4E05x3 + 0.0024x2  0.0058x  0.0309 y = 3E07x4  7E-05x3 + 0.0041x2  0.0195x + 0.0197

0.97 0.98 0.98 0.98 0.99

Forehead

Actual UV UVBEery UVBEnon-mel UVBEh-SCC UVBEDNA-d

y = 1E05x4  0.0028x3 + 0.2166x2  3.1749x + 21.428 y = 2E07x4  0.0001x3 + 0.0093x2  0.1255x + 1.5383 y = 5E07x4  0.0003x3 + 0.0232x2  0.334x + 3.7158 y = 3E07x4  0.0002x3 + 0.0172x2  0.2333x + 2.9831 y = 6E07x4  0.0002x3 + 0.0178x2  0.2506x + 2.4776

0.99 0.99 0.99 0.99 0.99

y = 0.0005x4  0.0921x3 + 4.8597x2  10.793x  35.695 y = 3E07x4  6E05x3 + 0.0035x2  0.023x + 0.0918 y = 4E07x4  8E05x3 + 0.0045x2  0.0303x + 0.1214 y = 3E07x4  6E05x3 + 0.0035x2  0.0265x + 0.1156 y = 4E07x4  1E04x3 + 0.0061x2  0.0576x + 0.2904

0.98 0.99 0.99 0.99 0.99

Fig. 5. Distribution of cheek, nose and forehead UVB and UVA irradiances by ultraviolet index (UVI). * This figure is shown as a double ordinate. The left and right ordinates show the UVA and UVB irradiance intensities of the cheek, nose and forehead, respectively.

of exposure to the four biologically effective UV irradiances at the same SEA was UVBEnon-mel, UVBEh-SCC, UVBEDNA-d, and finally was UVBEery. For the UVA band irradiances, the descending order of the intensity of exposure to the four biologically effective UV irradiances at the same SEA was UVBEDNA-d, UVBEnon-mel, finally were the UVBEh-SCC and UVBEery which were almost the same. The fitted equations of the fitted regression curves for the three monitored anatomic sites for the UVB and UVA irradiances by SEA are shown in Table 1 and fit the linear function in the 10–81° SEA range.

UVA

exposure at the same monitored anatomic site was UVBEDNA-d, UVBEnon-mel, UVBEh-SCC, and finally was UVBEery. In order to shown the diurnal distribution of the biologically effective UV irradiance exposure, Table 3 shows the dosimetry of 1 h cumulative biologically effective UVB and UVA band irradiance exposure from 08:00 to 16:00 (CST). From Table 3 we can see that for all the three monitored anatomic sites, the maximum dosimetry of biologically effective UVB and UVA band irradiance exposure during the period before midday (AM) and after midday (PM), were corresponding to the period from 10:00 to 11:00 CST (63–75° SEA) and from 13:00 to 14:00 CST (61–73° SEA), respectively. Fig. 7 shows the ratios of the UVB and UVA band irradiance exposure dosimetry to the UVR band irradiance exposure dosimetry. The ratio of the actual monitored UVB dosimetry to the UVR dosimetry was 0.03, which was significantly lower than the ratio of the UVA dosimetry to the UVR dosimetry (0.97) for the three monitored anatomic sites. For the four biologically effective UV radiations, the ratios of the UVB dosimetry to the UVR dosimetry were significantly higher than that of the UVA dosimetry to the UVR dosimetry for the three monitored anatomic sites. For the ratio of the UVB dosimetry to UVR dosimetry, the descending order of the four biologically effective UV irradiances at the same monitored anatomic site was UVBEh-SCC (0.88), UVBEnon-mel (0.87), finally were both the UVBEDNA-d and UVBEery (0.79) which were almost the same. For the ratio of UVA dosimetry to UVR dosimetry, the descending order of the four biologically effectives UV irradiance at the same monitored anatomic site: maximum were both the UVBEDNA-d and UVBEery (0.21) which were almost the same, UVBEnon-mel (0.13), UVBEh-SCC (0.12). 3.3. Dosimetry of the UV spectrum irradiances

3.2. Dosimetry of the UVB and UVA bands From Table 2, we can see that the dosimetry of the actual monitored UVA waveband irradiance was significantly higher than that of the actual monitored UVB waveband irradiance for the three monitored anatomic sites; however, the dosimetry of the biologically effective UVA waveband irradiances exposure was significantly lower than that of the biologically effective UVB waveband irradiances exposure for the three monitored anatomic sites. For the UVB band, the descending order of the dosimetry of the four biologically effective UV irradiances exposure at the same monitored anatomic site was UVBEnon-mel, UVBEh-SCC, UVBEDNA-d, and finally was UVBEery. For the UVA band, the descending order of the dosimetry of the four biologically effective UV irradiances

The dosimetry distribution by wavelength of the cheek, nose and forehead UV irradiance exposure shows that the dose increases with increasing wavelength in the three SEA ranges 10–30°, 30–60° and 60–81°, and the total SEA range from 10 to 81° (Fig. 8A). The dosimetry distribution of the cheek, nose and forehead UVBEery irradiance exposure shows that the dose decreases with increasing wavelength in the SEA ranges 10–30° and 30–60° and the total SEA range from 10 to 81°. However, in the 60–81° SEA range, the dosimetry distribution of UVBEery shows a small peak at 304 nm, and the dose increases with increasing wavelength in the range of 300–304 nm and decreases with increasing wavelength from 304 to 400 nm (Fig. 8B).

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Fig. 6. Diurnal variations of biologically effective UVB and UVA irradiances by SEA and fitted regression curves: (A) cheek, (B) nose and (C) forehead. effective UV irradiances in this figure are the UVBEery, UVBEnon-mel, UVBEh-SCC and UVBEDNA-d for the UVB and UVA bands.

For the UV irradiance band of 300–340 nm, the dosimetry distribution of the cheek, nose and forehead UVBEnon-mel irradiance exposure shows that the dose decreases with increasing wavelength in SEA range 10–30°, but in the SEA ranges 30–60° and 60–81° and the total SEA range of 10–81°, the dosimetry distribution of UVBEnon-mel shows small peaks at 304 nm, 306 nm and 304 nm, respectively. From 300 nm to the peak wavelength, the dose increases with increasing wavelength, and from the peak wavelength to 340 nm, the dose decreases with increasing wavelength. For the UV irradiance band of 340–400 nm, the dosimetry distribution of UVBEnon-mel in the SEA ranges 10–30°, 30–60° and 60–81° and the total SEA range of 10–81°, the dose slightly increases with increasing wavelength. The dose at 400 nm was significantly lower than the corresponding maximum dose for the band at 300–340 nm (Fig. 8C). For the UV irradiance band of 300–348 nm, the maximum dosimetry of the cheek, nose and forehead UVBEh-SCC at 300 nm in the SEA range of 10–30°, the dose decreases with increasing wavelength, and there is a small peak at 305 nm in SEA the ranges 30–60° and 60–81° and the total SEA range of 10–81°. From 300 nm to 305 nm, the dose increases with increasing wavelength, and from 305 nm to 348 nm, the dose decreases with increasing wavelength. For the UV irradiance band of 348–400 nm, the dosimetry distribution of UVBEh-SCC in the SEA ranges 10–30°, 30–60° and 60–81° as well as in the total SEA range of 10–81° shows a peak at 378 nm. The dose at 378 nm was significantly lower than the corresponding peak dose for the band at 300–340 nm (Fig. 8D).

*

The biologically

The dosimetry distribution of the cheek, nose and forehead UVBEDNA-d irradiances show a maximum at 300 nm, a valley at 308 nm and a small peak at 312 nm in the SEA range of 10–30°. In the SEA ranges 30–60°, 60–81° and the total SEA range of 10– 81°, the dosimetry distribution of the cheek, nose and forehead UVBEDNA-d irradiances all show a valley at 308 nm and two small peaks at 302 nm and 312 nm; additionally, the maximum dose was at 312 nm. In the SEA ranges 10–30°, 30–60°, 60–81° and the total SEA range of 10–81°, the dose decreases with increasing wavelength from 312 nm to 366 nm (Fig. 8E). 4. Discussion In this study, a head manikin was used to simultaneously measure the ambient UV spectrum irradiance data for three selected anatomic sites on the face, which were the cheek, nose and forehead. This research was performed during two days with clear skies. At the same SEA, both the UVB band and UVA band and the intensity of ambient UV irradiance were nearly the same during the two study days. Additionally, we found that the ultraviolet index (UVI) increased by the increasing the solar elevation angle (SEA) during the two study days, and the intensity of the ambient UVB and UVA irradiances of the two study days were increased by the increasing solar elevation angle (SEA). The highest UVI and maximum intensity of ambient UVB and UVA irradiances appear at the maximum SEA of the research days. However, the diurnal variations of the three monitored anatomic sites for the UVB and UVA

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F. Wang et al. / Journal of Photochemistry and Photobiology B: Biology 140 (2014) 205–214 Table 2 Dosimetry of all-day cumulative UVB and UVA irradiance (unit: J m2). Classification

UVB

Actual UV UVBEery UVBEnon-mel UVBEh-SCC UVBEDNA-d

UVA

Cheek

Nose

Forehead

Cheek

Nose

Forehead

17133.16 1165.01 2792.06 2776.56 1925.41

28184.78 1864.11 4477.62 4453.78 3109.78

33123.46 2197.66 5280.80 5252.65 3662.37

482790.78 306.59 399.01 414.90 512.65

787391.75 504.38 656.62 682.74 848.91

918771.10 589.24 767.15 797.54 992.67

Table 3 Dosimetry of 1 h cumulative UVB and UVA irradiance (unit: J m2). Sites

Cheek

Time

AM

PM

Nose

AM

PM

Forehead

AM

PM

SEA (°)

UVB

UVA

UVBEery

UVBEnon-mel

UVBEh-SCC

UVBEDNA-d

UVBEery

UVBEnon-mel

UVBEh-SCC

UVBEDNA-d

08:00–09:00 09:00–10:00 10:00–11:00 11:00–12:00 12:00–13:00 13:00–14:00 14:00–15:00 15:00–16:00

37–50 50–63 63–75 75–81 73–81 61–73 48–61 35–48

108.24 155.94 193.12 147.99 149.27 161.73 120.24 58.49

255.08 372.26 468.47 370.92 367.96 390.41 289.85 140.72

209.21 302.25 375.29 287.02 289.86 314.15 232.14 111.75

175.61 255.55 321.40 259.13 254.55 267.34 201.72 100.77

29.36 38.68 45.46 40.39 38.17 40.04 33.41 19.85

37.95 50.39 59.71 53.28 50.15 52.11 43.41 25.73

29.13 38.91 46.31 41.44 38.90 40.20 33.44 19.77

47.31 64.91 79.27 72.08 66.82 66.94 55.22 32.39

08:00–09:00 09:00–10:00 10:00–11:00 11:00–12:00 12:00–13:00 13:00–14:00 14:00–15:00 15:00–16:00

37–50 50–63 63–75 75–81 73–81 61–73 48–61 35–48

177.99 226.70 262.95 171.45 203.75 237.09 189.77 177.74

426.16 550.33 642.75 424.47 502.85 576.68 456.62 421.86

342.18 437.98 510.04 332.33 394.77 459.31 366.54 341.56

299.63 383.13 444.14 295.41 349.51 398.93 317.24 296.03

52.81 59.81 63.41 42.23 49.66 58.32 52.14 54.98

68.61 78.22 83.41 55.70 65.55 76.42 67.61 70.88

52.91 60.64 64.90 43.53 51.19 59.45 52.27 54.53

87.78 103.09 112.39 76.73 90.02 102.18 86.88 88.43

08:00–09:00 09:00–10:00 10:00–11:00 11:00–12:00 12:00–13:00 13:00–14:00 14:00–15:00 15:00–16:00

37–50 50–63 63–75 75–81 73–81 61–73 48–61 35–48

211.19 273.32 334.35 231.23 259.44 273.77 192.63 198.61

506.33 663.00 816.96 569.62 638.62 664.69 463.35 471.69

406.19 528.33 649.01 448.73 503.23 530.73 371.93 381.69

355.80 461.20 563.51 394.30 442.27 458.77 322.15 331.14

61.93 71.81 79.97 55.41 62.89 69.20 53.43 61.28

80.53 93.94 105.20 73.00 82.85 90.30 69.26 79.06

62.13 72.80 81.82 56.97 64.60 70.03 53.51 60.83

103.36 123.70 141.62 99.78 112.78 118.82 88.81 98.91

irradiances by SEA were different from the ambient UVB and UVA irradiances. For the UVB band, the peak of the three monitored anatomic sites were at 65° to 73° SEA with 8 to 9 UVI. For the UVA band, the peak of the three monitored anatomic sites were at 55° to 68° SEA with 6 to 7 UVI. Additionally, the maximum dosimetry of biologically effective UVB and UVA irradiance exposure were not appear at midday but at 10:00–11:00 CST (63–75° SEA) and 13:00–14:00 CST (61–73° SEA) during the period before midday (AM) and after midday (PM), respectively. This study suggests that the high-risk time for skin damage of the three monitored anatomic sites is not at midday. This is in contrast to the WHO, which showed that noon was the high-risk time for skin damage caused by UV radiation [12]. UVI is a simple measure of UV radiation level at the surface of Earth. This study was different from other studies that suggest that the UV index report always represents the daily maximum value according to the appropriate protection measures that are recommended. Particularly in countries with a higher intensity of ultraviolet radiation, it is considered important for the public to be aware of and avoid over-exposure to UV radiation [49,50]. For areas where the highest solar elevation was above the most dangerous value, sun protection measures should be observed at noon and also at other times when ambient ultraviolet radiation exposure is lower. The biologically damaging effective of UV irradiances on human bodies is dependent on the UVBE irradiance intensity. In this study, we found that the diurnal distribution of skin UVBEery, UVBEnon-mel, UVBEh-SCC, and UVBEDNA-d irradiance exposures for both the UVA and UVB bands at different SEAs were different. This study

Fig. 7. Ratios of UVB and UVA dosimetry to UVR dosimetry. * This figure shows the ratio of biologically effective and monitored UV irradiances. The biologically effective UV radiations in this table are the UVBEery, UVBEnon-mel, UVBEh-SCC, and UVBEDNA-d for the UVB and UVA bands for the cheek, nose and forehead.

calculated the dosimetry of the UVB and UVA irradiances for entire days, and calculated the multiples of four biologically effective UV dosimetries for erythema dosimetry in UVB and UVA bands. These calculations confirmed that the UVBEnon-mel, UVBEh-SCC, and

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Fig. 8. The dosimetry of UV spectrum irradiance: (A) monitored UV, (B) UVBEery, (C) UVBEnon-mel, (D) UVBEh-SCC, and (E) UVBEDNA-d.

UVBEDNA-d irradiance exposures for both the UVA and UVB bands were different from UVBEery. In this study, we found that the dosimetry distribution of the cheek, nose and forehead UV irradiances for UVBEery, UVBEnon-mel, UVBEh-SCC, UVBEDNA-d irradiance exposures for different wavelengths at different SEAs were different from the cheek, nose and forehead exposure for UV irradiances, which increases with longer wavelengths at the same SEA. For the UVBEery irradiance, in the 60–81° SEA range, the dosimetry distribution shows a small peak at 304 nm. For the UVBEnon-mel irradiance, in the SEA ranges 30–60°, 60–81° and the total 10–81° SEA range, the dosimetry distribution shows small peaks at 304 nm, 306 nm and 304 nm,

respectively. For the UVBEh-SCC irradiance, in SEA ranges 30–60°, 60–81° and the total 10–81° SEA range, the dosimetry distribution shows a small peak for all at 305 nm. For the UVBEDNA-d irradiance, in the SEA ranges 30–60°, 60–81° and the total 10–81° SEA range, the dosimetry distribution shows a valley for all at 308 nm and two small peaks at 302 nm and 312 nm. For the other SEA bands of UVBEery, UVBEnon-mel, UVBEh-SCC, and UVBEDNA-d, there was a small peak at 300 nm for all bands. In this study, the solar UV radiation was measured on a roof surface covered with asphalt. The measured UV irradiance is influenced by ground reflectance factors [51]. This research did not obtain the reflectance of the surface, so the influence of

F. Wang et al. / Journal of Photochemistry and Photobiology B: Biology 140 (2014) 205–214

reflectance on the UV exposure measurements cannot be estimated. However, according to Tanskanen and Manninen [52] demonstrated that at ultraviolet wavelengths, the albedo of most surfaces is small, with the exception of snow and ice, and Blumthaler [53], the surface albedo for the total solar radiation over grassland was approximately 20.7%, over worn asphalt it was approximately 10.6%, over a field it was approximately 11.5%, and over new dry snow it was approximately 87.0%. However, for UVB radiation, the albedo at these types of surfaces was 1.3%, 5.5%, 2.2% and 94.4%, respectively [53]. Therefore, the conclusion of the current study is not appropriate for all ground conditions, particularly for high albedo surfaces. Measurements should be recorded on other high albedo surfaces. Furthermore, because the UVBE irradiance was calculated with the UV spectrum irradiance weighted by the relative action spectrum, the above data are dependent on the intensity of the UV spectrum irradiance and the action spectra. As long as the measured data of the facial skin exposure influences the UV spectrum irradiances at different wavelengths, the skin exposure UVBE irradiances will also change. This study was performed on a sunny day. The influence of cloud-layer and air pollution on UV radiances is wavelength-dependent [54,55]. Accordingly, further studies should be performed under different weather conditions, particularly when there are black clouds or significant air pollution, because the results will most likely be different. This study demonstrates the diurnal distribution at SEAs ranging from 10° to 81° and their contribution to skin damage at different wavelengths with normal maximum UV exposure under clear sky conditions. This study demonstrates that the UVBEery, UVBEnon-mel, UVBEh-SCC, and UVBEDNA-d irradiances are wavelength-dependent. The risk assessment for skin damage from the UVBEery, UVBEnon-mel, UVBEh-SCC, and UVBEDNA-d irradiances requires comprehensive evaluation with regard to the SEA range and the intensity of UV irradiance of different wavelengths. Acknowledgment This research was supported by the National Natural Science Foundation of China (NSFC81273034). We were thank you for everyone who helped me during writing this thesis. References [1] IARC, Solar and Ultraviolet Radiation, International Agency for Research on Cancer (Monographs on the Evaluation of Carcinogenic Risks to Humans), Lyon, vol. 55, 1992. [2] H.F. Blum, E.G. Butler, T.H. Dailey, J.R. Daube, R.C. Mawe, G.A. Soffen, Irradiation of mouse skin with single doses of ultraviolet light, J. Natl. Cancer Inst. 22 (1959) 979–993. [3] F. Urbach, J.H. Epstein, P.D. Forbes, Ultraviolet carcinogenesis: experimental, global and genetic aspects, in: M.A. Pathak, L.C. Harber, M. Seiji, A. Kukita (Eds.), Sunlight and Man – Normal and Abnormal Photobiological Responses, University of Tokyo Press, Tokyo, 1974, pp. 259–283. [4] WHO/UNEP/IRPA, Ultraviolet Radiation, Environmental Health Criteria 14, World Health Organization, United Nations Environment Programme, WHO, Geneva, 1979. [5] J.H. Epstein, Animal models for studying photocarcinogenesis, in: H. Maibach, N. Lowe (Eds.), Models in Dermatology, vol. 2, Karger, Basel, 1985, pp. 303– 312. [6] F.R. de Gruijl, J.B. van der Meer, J.C. van der Leun, Dose-time dependency of tumor formation by chronic UV exposure, Photochem. Photobiol. 37 (1983) 53–62. [7] P.T. Strickland, B.C. Vitasa, S.K. West, F.S. Rosenthal, E.A. Emmett, H.R. Taylor, Quantitative carcinogenesis in man: solar ultraviolet B dose dependence of skin cancer in Maryland watermen, J. Natl. Cancer Inst. 81 (1989) 1910–1913. [8] D.S. Berger, F. Urbach, A climatology of sunburning ultraviolet radiation, Photochem. Photobiol. 35 (1982) 187–192. [9] J. Scotto, T.R. Fears, J.F. Fraumeni, Incidence of Nonmelanoma Skin Cancer in the United States, National Cancer Institute (NIH Publication No. 83-2433), Bethesda, Maryland, 1983. [10] J. Scotto, T.R. Fears, The association of solar ultraviolet and skin melanoma incidence among Caucasians in the United States, Cancer Invest. 5 (1987) 275– 283.

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