Hazards associated with blue light emitted during gas metal arc welding of mild steel using various shielding gases and currents.

Blue light emitted during arc welding is known to potentially cause photoretinopathy. To help prevent retinal injury, it is important to identify the hazards associated with various welding conditions. The present work conducted experiments involving gas metal arc welding of mild steel under various conditions, and measured the spectral radiance of the arcs. The effective radiance values, as used by the American Conference of Governmental Industrial Hygienists (ACGIH) to quantify exposure level of blue light, were subsequently calculated from the data. The resulting values were in the range of 5.0-118 W/cm2/sr, corresponding to hazardous levels according to ACGIH guidelines. The effective radiance was increased at higher welding currents and when pulsed currents were used rather than steady currents. The blue light hazard was also affected by the type of shielding gas employed. These data confirm that it is very hazardous to stare at arcs during gas metal arc welding of mild steel. As such, appropriate eye protection is necessary during arc welding, and directly staring at the arc should be avoided.

Threshold Ocular Exposure to Near Infrared Radiation for Causing Acute Opacification in the Rabbit Lens.

Surveys and epidemiological studies have reported an increased prevalence of cataracts in the glass and steel industries, which are associated with exposure to intense infrared radiation (IR). Indeed, animal studies have demonstrated that IR exposure can produce acute changes in the crystalline lens that are likely to lead to cataract formation. However, little is known about threshold IR exposure for causing acute cataractous changes, which is important in the prevention of IR-induced cataract, especially as a basis for short-term IR exposure limits. Previously, we exposed rabbit eyes to 808 nm wavelength IR at different irradiances for 6 min to determine the threshold irradiance to cause acute lens opacification. Presently, we similarly determined the threshold irradiance for exposure durations of 3 min, 1 min, 30 s, 10 s and 4 s. The threshold irradiance increased steadily with decreasing exposure duration, from 1.1 W cm-2 at 6 min to 4.1 W·cm-2 at 4 s. These threshold values are consistent with ICNIRP exposure limits to avoid IR-induced cataract formation in the tested range of exposure duration, but suggest that it may be necessary to lower the exposure limits for shorter exposure durations.

Structural and Functional Change in Albino Rat Retina Induced by Various Visible Light Wavelengths.

The effects of visible light, from short to long wavelengths, on the retina were investigated functionally and histologically. The left eyes of Sprague-Dawley albino rats (6-weeks old, n = 6 for each wavelength) were exposed to seven narrow-band wavelengths (central wavelengths, 421, 441, 459, 501, 541, 581, and 615 nm) with bandwidths of 16 to 29 nm (half bandwidth, ±8-14.5 nm) using a xenon lamp source with bandpass filters at the retinal radiant exposures of 340 and 680 J/cm2. The right unexposed eyes served as controls. Seven days after exposure, flash electroretinograms (ERGs) were recorded, and the outer nuclear layer (ONL) thickness was measured. Compared to the unexposed eyes, significant reductions in the a- and b-wave ERG amplitudes were seen in eyes exposed to 460-nm or shorter wavelengths of light. The ONL thickness near the optic nerve head also tended to decrease with exposure to shorter wavelengths. The decreased ERG amplitudes and ONL thicknesses were most prominent in eyes exposed to 420-nm light at both radiant exposures. When the wavelengths were the same, the higher the amount of radiant exposure and the stronger the damage. Compared to the unexposed eyes, the a- and b-waves did not decrease significantly in eyes exposed to 500-nm or longer wavelength light. The results indicate that the retinal damage induced by visible light observed in albino rats depends on the wavelength and energy level of the exposed light.

Cataract Formation by Near-infrared Radiation in Rabbits.

Surveys and epidemiological studies have shown an increased prevalence of cataracts in workers in the glass and steel industries. These cataracts are associated with exposure to intense infrared radiation (IR) emitted from heated materials and industrial furnaces. Thermal model calculations predicted that near and far IR would cause cataract with different mechanisms. The present study investigated cataract formation by near IR. Eyes of pigmented rabbits were exposed to IR at a wavelength of 808 nm. Morphological changes in the anterior segment of the eye were assessed by slit-lamp microscopy, and temperature distributions in the anterior chamber of the eye were observed during IR exposure using microencapsulated thermochromic liquid crystals. Cortical cataract appeared below the exposed area of the iris in eyes that had been exposed for 6 min to an irradiance of 1.27 W cm-2 or higher. The monitored temperature in the anterior chamber began to increase in the region adjacent to the exposed area of the iris with the onset of IR exposure. These results demonstrate that 808-nm IR is absorbed and converted to heat within the iris, which is then conducted to the lens and produce a cataract, as Goldmann theory states.

Zweigelt and Niagara skin extracts suppress cyclobutane pyrimidine dimer formation due to UV irradiation in NHEK cells: first attempt.

The grape skins after pressing the juice are a major problem for winery. However, because it contains a large amount of polyphenols, development of effective usages are expected to construct sustainable waste use. In this study, we examined whether grape skin extract is effective for recovery of DNA damage caused by UV irradiation. Extract from Zweigelt and Niagara skin was prepared by methanol, and UV irradiation was performed at 10 mJ/cm2 (250 nm) and 15 mJ/cm2 (290 nm) using human normal skin cells. As results, the decreased cell viability due to UV irradiation was improved by adding Niagara or Zweigelt skin extract. On the other hand, cyclobutane pyrimidine dimer production due to UV irradiation decreased significantly by Niagara or Zweigelt extract. In addition, the effects of grape skin extracts on the expression of sirtuin gene were also examined.

Comprehensive analysis of hazard of ultraviolet radiation emitted during arc welding of cast iron.

OBJECTIVES: Ultraviolet radiation (UVR) emitted during arc welding frequently causes keratoconjunctivitis and skin erythema. The extent of the hazard of UVR varies depending on the welding process and conditions. Therefore, it is important to identify the levels of UVR present under different conditions. The purpose of this study was to investigate the degree of hazard of UVR emitted by the different types of arc welding of cast iron frequently used in industry. METHODS: In this study, we experimentally measured the UVR emitted during gas tungsten arc welding (GTAW), shielded metal arc welding (SMAW), and gas metal arc welding (GMAW) of cast iron. The degree of hazard of UVR was quantitatively evaluated in accordance with the guidelines of the American Conference of Governmental Industrial Hygienists. RESULTS: Effective irradiances measured in this study were in the range 0.045-2.2 mW/cm2 at a distance of 500 mm from the welding arc. The maximum allowable exposure times corresponding to these levels were only 1.4-67 s/day. CONCLUSIONS: UVR emitted during arc welding of cast iron has the following characteristics: (a) It is more hazardous at higher welding currents. (b) The magnitude of the hazard, which depends on the welding process, increases in the order of GMAW > SMAW > GTAW. (c) It is influenced by the filler material used; that is, the components contained in the filler material affect the hazard of UVR. The effect is Fe > Ni, Cr.

Estimations of Retinal Blue-Light Irradiance Values and Melatonin Suppression Indices Through Clear and Yellow-Tinted Intraocular Lenses.

Spectral transmittance values in the wavelength range of 300 to 800 nanometers were measured using a spectrophotometer for 18 intraocular lenses (IOLs) including clear (ZCB00) and yellow-tinted (ZCB00V, both from AMO Japan) IOLs with three different lens powers. Also measured were the blue-light irradiance (BLI) values, which might reflect retinal damage caused by sunlight, and the melatonin suppression indices (MSIs), which might reflect the nonvisual photoreception function, through these IOLs. The BLIs (in mWcm-2) calculated were 7.62, 7.50, and 7.46 for the +10-diopter (D), +20-D, and +30-D ZCB00 IOLs, respectively; 4.10, 3.92, and 4.00 for the +10-D, +20-D, and +30-D ZCB00V IOLs, respectively; 5.76 for phakic eyes; and 15.00 for aphakic eyes. The MSIs (in mWcm-2sr-1) calculated were 1.18, 1.19, and 1.18 for the +10-D, +20-D, and +30-D ZCB00 IOLs, respectively; 0.98, 0.94, and 0.95 for the +10-D, +20-D, and +30-D ZCB00V IOLs, respectively; 1.03 for phakic eyes; and 1.21 for aphakic eyes. The data from the six clear IOLs (SA60AT, Alcon Japan; VA-60BBR, Hoya; AU6 K, Kowa, N4-18B, Nidek; X-60, Santen; KS-3Ai, Staar Japan) and seven yellow-tinted IOLs (SN60AT; YA-60BBR, Hoya; AU6N, Kowa; N4-18YG, Nidek; NX-60, Santen; KS-AiN, Staar Japan; XY-1, Hoya) reported previously also were discussed. Compared to aphakic eyes, ZCB00 and ZCB00V IOLs reduce the BLI values by 49-50% and 73-74%, respectively; and currently available ultraviolet-blocking clear and yellow-tinted IOLs reduce the BLI values by 43-82%, respectively. Yellow-tinted IOLs absorb more circadian rhythm-associated light than clear IOLs. Although the data presented in this study cannot be applied directly to IOL implanted in patients, the balance between photoprotection and photoreception must be considered when using IOLs in a clinical setting.

Blue-Light Hazard From Gas Metal Arc Welding of Aluminum Alloys.

OBJECTIVES: The objective was to quantify the blue-light hazard from gas metal arc welding (GMAW) of aluminum alloys. The exposure level is expected to depend on the welding conditions. Therefore, it is important to identify the blue-light hazard under various welding conditions. METHODS: We experimentally conducted GMAW of aluminum alloys under various welding conditions and measured the spectral radiance of the arcs. The effective blue-light radiance, which the American Conference of Governmental Industrial Hygienists has defined to quantify the exposure level of blue light, was calculated from the measured spectral radiance. The maximum acceptable exposure duration per 10000 s for this effective blue-light radiance was calculated. RESULTS: The effective blue-light radiance measured in this study was in the range of 2.9-20.0 W cm-2·sr. The corresponding maximum acceptable exposure duration per 10000 s was only 5.0-34 s, so it is hazardous to view the welding arc. The effective blue-light radiance was higher at higher welding currents than at lower welding currents, when pulsed welding currents were used rather than steady welding currents, and when magnesium was included in the welding materials. CONCLUSIONS: It is very hazardous to view the arcs in GMAW of aluminum alloys. Welders and their helpers should use appropriate eye protection in arc-welding operations. They should also avoid direct light exposure when starting an arc-welding operation.

Hazard of ultraviolet radiation emitted in gas metal arc welding of mild steel.

OBJECTIVES: Ultraviolet radiation (UVR) emitted during arc welding frequently causes keratoconjunctivitis and erythema in the workplace. The degree of hazard from UVR exposure depends on the welding method and conditions. Therefore, it is important to identify the UVR levels present under various conditions. METHODS: We experimentally evaluated the UVR levels emitted in gas metal arc welding (GMAW) of mild steel. We used both a pulsed welding current and a non-pulsed welding current. The shielding gases were 80% Ar + 20% CO2 and 100% CO2. The effective irradiance defined in the American Conference of Governmental Industrial Hygienists guidelines was used to quantify the UVR hazard. RESULTS: The effective irradiance measured in this study was in the range of 0.51-12.9 mW/cm2 at a distance of 500 mm from the arc. The maximum allowable exposure times at these levels are only 0.23-5.9 s/day. CONCLUSIONS: The following conclusions were made regarding the degree of hazard from UVR exposure during the GMAW of mild steel: (1) It is more hazardous at higher welding currents than at lower welding currents. (2) At higher welding currents, it is more hazardous when 80% Ar + 20% CO2 is used as a shielding gas than when 100% CO2 is used. (3) It is more hazardous for pulsed welding currents than for non-pulsed welding currents. (4) It appears to be very hazardous when metal transfer is the spray type. This study demonstrates that unprotected exposure to UVR emitted by the GMAW of mild steel is quite hazardous.

Hazard of ultraviolet radiation emitted in gas tungsten arc welding of aluminum alloys.

Ultraviolet radiation (UVR) emitted during arc welding frequently causes keratoconjunctivitis and erythema. The extent of the hazard of UVR varies depending on the welding method and conditions. Therefore, it is important to identify the levels of UVR that are present under various conditions. In this study, we experimentally evaluated the hazard of UVR emitted in gas tungsten arc welding (GTAW) of aluminum alloys. The degree of hazard of UVR is measured by the effective irradiance defined in the American Conference of Governmental Industrial Hygienists guidelines. The effective irradiances measured in this study are in the range 0.10-0.91 mW/cm(2) at a distance of 500 mm from the welding arc. The maximum allowable exposure times corresponding to these levels are only 3.3-33 s/day. This demonstrates that unprotected exposure to UVR emitted by GTAW of aluminum alloys is quite hazardous in practice. In addition, we found the following properties of the hazard of UVR. (1) It is more hazardous at higher welding currents than at lower welding currents. (2) It is more hazardous when magnesium is included in the welding materials than when it is not. (3) The hazard depends on the direction of emission from the arc.

Effect of Tinospora cordifolia on the reduction of ultraviolet radiation-induced cytotoxicity and DNA damage in PC12 cells.

The safety of Tinospora cordifolia and its potential to protect against ultraviolet radiation-induced cytotoxicity and DNA damage in PC12 cells were investigated. To evaluate the safety of T. cordifolia, cell viability and agarose gel electrophoresis were carried out using PC12 cells treated with 0 to 100 µg mL(-1) of methanol extract of T. cordifolia. T. cordifolia extracts did not show cytotoxicity ranging 0 to 100 µg mL(-1). In addition, T. cordifolia extracts significantly increased cell viability at 1 ng, 10 ng and 1 µg mL(-1) concentrations in serum-deprived medium compared to control. To confirm the protective role against UV-induced damage, PC12 cells alone or in the presence of 10 ng, 100 ng, or 1 µg mL(-1) of T. cordifolia extract were exposed to 250, 270 and 290 nm of UV radiation, which corresponded to doses of 120, 150 and 300 mJ cm(-2), respectively. Treatment with T. cordifolia extracts significantly increased the cell survival rate irradiated at 290 nm. In addition, T. cordifolia extracts significantly reduced cyclobutane pyrimidine dimer formation induced by UV irradiation at all wavelengths. In conclusion, T. cordifolia is not toxic and safe for cells. Our findings can support its application as phototherapy in the medical sector.

Estimation of the melatonin suppression index through clear and yellow-tinted intraocular lenses.

PURPOSE: To estimate the melatonin suppression index (MSI), which may reflect the nonvisual photoreception function, through commercially available foldable, clear and yellow-tinted intraocular lenses (IOLs). METHODS: The MSIs for 13 IOL models (6 clear IOLs, 7 yellow-tinted IOLs) with three lens powers were calculated based on previously reported data about the melatonin suppression spectrum, spectral intensity of a 20-W white fluorescent lamp and spectral transmission of IOLs in wavelengths from 300 to 800 nm. The models tested were the SA60AT and SN60AT (Alcon Japan); the VA-60BBR, YA-60BBR, and NM-1 (Hoya); the AU6K and AN6K (Kowa); the N4-18B and N4-18YG (Nidek); the X-60 and NX-60 (Santen); and the KS-3Ai and KS-AiN (Staar Japan). RESULTS: The MSIs of the clear IOLs ranged from 1.12 to 1.18 mW cm(-2) sr(-1) and those of the yellow-tinted IOLs from 0.74 to 1.01 mW cm(-2) sr(-1). All yellow-tinted IOLs had significantly lower MSIs (P < 0.0001-0.0021) than the clear IOLs; the %MSI cutoff values for yellow-tinted IOLs compared to the clear IOLs were 11.4-36.2 %. The MSIs of the six clear IOLs did not differ based on lens powers (P = 0.2159-0.6144). Except for one IOL model, all yellow-tinted IOLs had a lower MSI with higher lens powers compared to those with lower lens powers (P < 0.0001-0.0055). Compared to phakic eyes (MSI, 1.03 mW cm(-2) sr(-1)), the MSIs of the clear IOLs were higher (%MSI cutoff, -14.6 to -8.4 %), whereas those of the yellow-tinted IOLs were lower (2.6-28.1 %). Compared to aphakic eyes (MSI, 1.21 mW cm(-2) sr(-1)), the MSIs of the clear (2.1-7.4 %) and yellow-tinted (16.7-38.6 %) IOLs were lower. CONCLUSIONS: Yellow-tinted IOLs absorb more circadian rhythm-associated light than clear IOLs. The difference in the lens power is significantly related to the MSI value in some yellow-tinted IOLs. To correlate the current data with the clinical relevance of these findings, the percent loss of the MSI leading to a circadian rhythm disorder needs to be clarified.

Occupational exposure levels of static magnetic field during routine MRI examination in 3T MR system.

Occupational exposure to the high static magnetic fields (SMFs) during magnetic resonance imaging (MRI) examinations raises concerns of adverse health effects. In this study, personal exposure monitoring of the magnetic fields during routine examinations in two 3 T MRI systems was carried out. A three-axis Hall magnetometer was attached to a subject's chest during monitoring. Data acquisition started every time the subject entered the scanner room and ended when the subject exited the room. Four radiologic technologists from two different institutes participated in this study. The maximum exposed field ranged from 0 to 1250 mT and the average peak magnetic field (B) was 428 ± 231 mT (mean ± standard deviation (SD): number of samples (N) = 103). Then, the relationship between exposure levels and work duties was analyzed. The MRI examination of the head or neck showed the highest average peak B among four work categories. These results provide information of real exposure levels for 3 T MRI system operators and can also improve the current practical training advice for preventing extra occupational field exposure.

Effects of UV wavelength on cell damages caused by UV irradiation in PC12 cells.

Ultraviolet (UV) radiations present in sunlight are a major etiologic factor for many skin diseases and induce DNA damage through formation of cyclobutane pyrimidine dimer (CPD). This study was conducted to determine the toxicological effects of different wavelengths (250, 270, 290, and 310 nm) and doses of UV radiation on cell viability, DNA structure, and DNA damage repair mechanisms in a PC12 cell system. For this, we evaluated cell viability and CPD formation. Cell survival rate was markedly decreased 24h after UV irradiation in a dose-dependent manner at all wavelengths (except at 310 nm). Cell viability increased with increasing wavelength in the following order: 250<270<290<310 nm. UV radiation at 250 nm showed the highest cell killing ability, with a median lethal dose (LD50) of 120 mJ/cm(2). The LD50 gradually increased with increase in wavelength. Among the 4 wavelengths tested, the highest LD50 (6000 mJ/cm(2)) was obtained for 310 nm. CPD formation decreased substantially with increasing wavelength. Among the 4 wavelengths, the proportion of CPD formation was highest at 250 nm and lowest at 310 nm. On the basis of LD50 values for each wavelength, PC12 cells irradiated with UV radiation of 290 nm showed maximum DNA repair ability, whereas those irradiated with the 310-nm radiation did not show any repair ability. Toxicity of UV radiation varied with wavelengths and exposure doses.

4-Hydroxyhexenal- and 4-hydroxynonenal-modified proteins in pterygia.

Oxidative stress has been suspected of contributing to the pathogenesis of pterygia. We evaluated the immunohistochemical localization of the markers of oxidative stress, that is, the proteins modified by 4-hydroxyhexenal (4-HHE) and 4-hydroxynonenal (4-HNE), which are reactive aldehydes derived from nonenzymatic oxidation of n-3 and n-6 polyunsaturated fatty acids, respectively. In the pterygial head, labeling of 4-HHE- and 4-HNE-modified proteins was prominent in the nuclei and cytosol of the epithelium. In the pterygial body, strong labeling was observed in the nuclei and cytosol of the epithelium and proliferating subepithelial connective tissue. In normal conjunctival specimens, only trace immunoreactivity of both proteins was observed in the epithelial and stromal layers. Exposures of ultraviolet (330 nm, 48.32 ± 0.55 J/cm(2)) or blue light (400 nm, 293.0 ± 2.0 J/cm(2)) to rat eyes enhanced labeling of 4-HHE- and 4-HNE-modified proteins in the nuclei of conjunctival epithelium. Protein modifications by biologically active aldehydes are a molecular event involved in the development of pterygia.

[Blue light hazards associated with crystal glassware production].

OBJECTIVES: In factories for glassware production, workers are exposed to intense visible light emitted from hot objects such as furnaces and molten glass. High exposure to short-wavelength visible light, called blue light, can cause photoretinopathy. The objective of this study was to quantify the blue-light hazards associated with glassware production. METHODS: Spectral radiances of walls and heating elements inside furnaces were measured, as well as those of molten glass placed inside furnaces in a factory producing crystal glass crafts. The factory had two reheating furnaces, three melting furnaces, and a furnace for preheating blowpipes. The effective radiances of the inner furnace walls, the heating elements, and the molten glass were calculated from the measured spectral radiances and compared with the threshold limit value (TLV) in accordance with ACGIH guidelines. The temperature of each light source was determined by comparing the measured spectral radiance with that of a black body. RESULTS: The measured effective radiances were in the range of 0.00498-0.708 mW/cm(2)sr and increased steeply with increasing light source temperatures in the range of 1,075-1,516 °C. The effective radiance of each light source was nearly equal to the effective radiance of the black body at the same temperature. CONCLUSIONS: The effective radiances of walls, heating elements, and molten glass inside the furnaces are lower than one tenth of the TLV for exposure durations longer than 10(4) s per day. Thus, it is not hazardous to view these light sources. However, the effective radiance at a higher light source temperature of approximately 1,800 °C will exceed the TLV. In this case, hot objects in a workplace for glassware production may present blue light hazards.

Ultraviolet action spectrum for cell killing of primary porcine lens epithelial cells.

OBJECTIVES: The aim of this study was to determine ultraviolet (UV) action spectra for cell killing of primary porcine lens epithelial cells (LECs) that can be used to establish guidelines for evaluation of the hazard of cataract due to UV exposure in the workplace. METHODS: Primary porcine LECs were exposed to different doses (radiant exposure) of UV at 17 different wavelengths from 235 nm to 311 nm. At 2 days after exposure, cell viability was assessed by measuring crystal violet staining of the cells and lactate dehydrogenase release into the culture medium. The exposure dose required to kill 50% of cells (LD(50)) was determined from the dose-effect relationship obtained at each wavelength and was used to construct action spectra. RESULTS: The action spectra had a broad minimum in the approximate range of 250-280 nm, indicating that UV is most hazardous to porcine LECs within this wavelength range. The spectra rose steeply at both longer and shorter wavelengths. These action spectra are consistent with the in vivo action spectra for opacities in the rabbit lens and for light scattering in the rat lens, taking the transmittance of the ocular media into account. CONCLUSIONS: These results will help to determine a UV hazard function for cataract formation, which can be used to draft guidelines for evaluation of the hazard of cataract due to UV exposure in the workplace.

Measurements of transmission spectrums and estimation of retinal blue-light irradiance values of currently available clear and yellow-tinted intraocular lenses.

PURPOSE: To compare the spectral transmission characteristics of currently available, foldable, clear and yellow-tinted intraocular lenses (IOLs), and evaluate the protective effects they provide against retinal damage by sunlight. METHODS: We measured the spectral transmittance in the wavelength range of 300-800 nm using a spectrophotometer for 63 IOLs including three clear IOLs (N4-18B, Nidek; X-60, Santen; KS-3Ai, Staar Japan) and four yellow-tinted IOLs (N4-18YG, Nidek; NX-60, Santen; KS-AiN, Staar Japan; NM-1, Hoya) with three different lens powers. The blue-light irradiance (BLI) values through the IOLs were calculated as the retinal hazard index for sungazing. The data from three clear IOLs (SA60AT, Alcon Japan; VA-60BBR, Hoya; AU6K, Kowa) and three yellow-tinted IOLs (SN60AT, Alcon Japan; YA-60BBR, Hoya; AU6N, Kowa) reported previously were also discussed. RESULTS: Except for the X-60, the clear IOLs completely absorbed ultraviolet (UV) light and nearly completely transmitted visible light at wavelengths longer than 440 nm. Yellow-tinted IOLs absorbed more in the blue-light range (400-500 nm) than clear IOLs. All IOLs had lower BLI values than aphakic eyes, and all yellow-tinted IOLs had lower BLI values than phakic eyes. The BLI values of the NX-60, KS-AiN, NM-1, SN60AT and YA-60BBR IOLs decreased with the increase in lens power. CONCLUSIONS: Compared to aphakic eyes, currently available UV-blocking clear and yellow-tinted IOLs reduce the BLI values by 43-82%. However, the data presented in this study are not directly applicable to humans implanted with IOLs or for the use of IOLs in a clinical situation, since in those cases the balance between photoprotection and photoreception must be taken into account.

Measuring exposed magnetic fields of welders in working time.

The assessment of the occupational electromagnetic field exposure of welders is of great importance, especially in shielded-arc welding, which uses relatively high electric currents of up to several hundred amperes. In the present study, we measured the magnetic field exposure level of welders in the course of working. A 3-axis Hall magnetometer was attached to a subject's wrist in order to place the sensor probe at the closest position to the magnetic source (a cable from the current source). Data was acquired every 5 s from the beginning of the work time. The maximum exposed field was 0.35-3.35 mT (Mean ± SD: 1.55 ± 0.93 mT, N=17) and the average value per day was 0.04-0.12 mT (Mean ± SD: 0.07 ± 0.02 mT, N=17). We also conducted a finite element method-based analysis of human hand tissue for the electromagnetic field dosimetry. In addition, the magnetic field associated with grinders, an air hammer, and a drill using electromagnetic anchorage were measured; however, the magnetic fields were much lower than those generated in the welding process. These results agreed well with the results of the electromagnetic field dosimetry (1.49 mT at the wrist position), and the calculated eddy current (4.28 mA/m(2)) was much lower than the well-known guideline thresholds for electrical nerve or muscular stimulation.

Transmission spectrums and retinal blue-light irradiance values of untinted and yellow-tinted intraocular lenses.

PURPOSE: To record and compare the spectral transmission characteristics of foldable untinted and yellow-tinted intraocular lenses (IOLs) and evaluate the protective effects against retinal damage by sunlight. SETTING: Shimane University Faculty of Medicine, Izumo, Japan. METHODS: The study evaluated 3 untinted IOLs (SA60AT, VA-60BBR, AU6 K) and 3 yellow-tinted IOLs (SN60AT, YA-60BBR, AU6 N) of 3 lens powers (+10.0 diopters [D], +20.0 D, and +30.0 D). Spectral transmittance in the wavelength range of 300 to 800 nm was measured using a spectrophotometer through 2.5 mm and 4.5 mm diameter apertures. Retinal hazard indices, including blue-light irradiance and maximum permissible exposure duration per day (t(max)) for viewing sunlight, were calculated. RESULTS: The untinted IOLs completely absorbed ultraviolet (UV) light and nearly completely absorbed transmitted visible light at wavelengths longer than 440 nm. Yellow-tinted IOLs absorbed more in the blue-light range (400 to 500 nm) than untinted IOLs. The blue-light irradiance was 34.2% to 56.0% lower with the SN60AT IOL than with the SA60AT IOL, 35.2% to 48.4% lower with the YA-60BBR IOL than with the VA-60BBR IOL, and 16.8% to 22.9% lower with the AU6 N IOL than with the AU6 K IOL. Blue-light irradiance values of SN60AT and YA-60BBR IOLs decreased as the lens power increased. CONCLUSIONS: Compared with aphakic eyes, UV-blocking untinted IOLs reduced the blue-light irradiance value by 60%; yellow-tinted IOLs conferred an additional 17% to 56% reduction. The difference in lens power was significantly related to the blue-light irradiance value of some yellow-tinted IOLs. .