from paper by Małgorzata Lewicka and Gabriela A. Henrykowska et all. LCD screen turned out to cause problems for health. His paper investigate correlation of electromagnetic radiation (EMR) from LCD Screen for human blood platelets.
Studies on the effect of electromagnetic radiation (EMR) already at the beginning of the 1960s, in the Soviet Union. This paper initiated by Asanowi and Rakov determined the effect of this factor on the health of workers staying close to a power transmission line and exposed to an electric field of the intensity up to 26 kV/m. They concluded that electric field can jamming autonomic and central nervous system. Another ones from effect in living organisms as well as on subjective ailments like fatigue, headache, dizziness, nausea, sleep disorder, loss of appetite, and irritation. All studies have same result of electromagnetic radiation from LCD effect not affected serious effect like die.
Malgorzata Lewica and Gabriela A investigate the effect of EMR emitted by LCD monitors with parameters of oxidative stress in human blood platelets.
read also difference of LED and LCD
Oxidative stress
oxidative Stress is imbalance of the pro-oxidant/antioxidant equilibrium, arises due to uncontrolled increase of reactive oxygen species (ROS) production and to the change of enzymatic activity of antioxidant defence proteins.
Test Approach
The aim of the study was to determine changes taking place in blood platelets under the effect of electromagnetic radiation generated by commonly used LCD monitors. This radiation is characterized by 1 kHz frequency and 150 V/m intensity at a distance of 30 cm from the monitor screen and 220 V/m at 15 cm. The tested sample was exposed to the electromagnetic field for 30 and 60 min. The following parameters of blood platelet oxygen metabolism were investigated: ROS concentration, enzymatic activity of superoxide dismutase (SOD-1), enzymatic activity of catalase, and concentration of malondialdehyde (MDA) – a marker of membrane lipid peroxidation.
Sample preparation
A suspension of human blood platelets at the concentration of 1 × 109/cm3, obtained by manual apheresis from whole blood, was the material forthe study. The preparation was obtained from the Blood Donation Centre from voluntary blood donors who underwent medical examinations (those who had contraindications for blood drawing were ex–
cluded) and laboratory tests typical for blood donors were performed. Blood donors were healthy people, not taking any medication, staying on a mixed, average-calorie diet aged 25–45. The blood was transported to the laboratory in a box shielding against
any radiation material.
Exposure condition setting and instruments
In a laboratory stand designed for reconstruction of the parameters of electromagnetic radiation generated by display screens (1 kHz, 150 V/m, 220 V/m), a flat capacitor was the source of the electromagnetic field (Figure 1). Requirements of the TCO (the Swedish Confederation of Professional Employees) and MPR (the National Board for Mea–
surement and Testing) specify strict conditions for the measurement of exposure. The authors measured the field by the measurement procedure at the location of points placed in front of the monitor.
When electromagnetic radiation of low frequency is tested, the electric and magnetic components should be investigated independently. Monitors with liquid crystal screens produce non-sinusoidal electromagnetic fields, with the dominant electric component, due to control of power semiconductor chips. Significant fields as regards their effect on the human body are fields with frequency of lower power consumption and voltage switching power supply, with superimposed oscillation dampened RLC circuits, which act as voltage ripple smoothing filters. The source of the signal simulating shape of the field generated by the LCD was the programmable generator Hameg 8010, which is amplified by the measuring amplifier W-320, and the source of the electric field was a flat capacitor arrangement. The capacitor was formed by two circular copper plates positioned over and under a plastic support in which 8 polyethylene tubes containing the tested preparation were inserted into holes made symmetrically on the circumference of the circle, the diameter of which was smaller than that of the capacitor plates so that the electrical component of the field acting on the tubes was homogeneous in nature.
The tested preparation was placed in polyethylene tubes, each containing 3 ml of the preparation. The temperature in the laboratory stand was at the same level all the time, i.e. +24/+25°C. Preserving constant conditions of the environment, the preparation was exposed to the activity of the electromagnetic field of 1 kHz frequency and 150 V/m intensity (corresponding to a distance of 30 cm from the monitor) and 220 V/m intensity
(corresponding to adistance of 15 cm from the monitor) for 30 and 60 min. The exposure of the platelets to the radiation was done on the day they were collected from the Blood Donation Centre.
Measurement of reactive oxygen species and antioxidant activity of superoxide dismutase, catalase and malondialdehyde concentration
The selected parameters of oxidative stress were measured before and immediately after the exposure. The level of ROS generation, enzymatic activity of antioxidant defence proteins (superoxide dismutase and catalase) and the concentration of malondialdehyde (MDA) as a marker of lipid peroxidation were determined. Chemiluminescence (emission of light as the result of chemical reaction) was used to determine ROS concentration. After stimulation of platelet-activating factor there occurs simultaneous increase of cell metabolism associated with an elevated demand for oxygen. It results in oxidative burst generating reactive oxygen species which initiate a cascade of reactions leading to formation of different compounds which in turn lose their energy in the form of light radiation. This emission of light (chemiluminescence) accompanying oxidative burst
was measured using a Lumicom luminometer (HAMILTON) connected to an IBM PC. Simultaneously sequential measurement was performed for 6 samples for 30 min. The tested samples consisted of 200 μl of blood platelet suspension of the concentration 1 × 109/cm3, 20 μl of luminol, and 780μl of phosphate-buffered saline (PBS) (abuffer solutionof salt to pH 7.2). The obtained results were compared with the control sample of 200 μl of platelet suspension not exposed to an electromagnetic field
(EMF), 20 μl of luminol, and 780 μl of PBS. We used 36 control samples and 36 exposed samples.A CARY 100 BIO spectrophotometer (VARIAN) was used for the measurement of superoxide dismutase activity at 480 nm wavelength. Absorbance in the control and study samples was measured every minute at +25°C for 5 min. The study samples were obtained by adding 0.2cm3 of platelet suspension at the concentration of 1 × 109/cm3, 0.8 cm3 of redistilled water cooled to +4°C and 0.5 cm3 of 96% C2H5OH and 0.25 cm3 chloroform.
The obtained mixture was shaken for 2 min and then centrifuged at 4200× g at +4°C for 10 min. After centrifugation, the enzyme remained in the upper layer of the suspension. Then 0.2 cm3 of supernatant was transferred into glass tubes together with 2.6 cm3 of 0.05M carbonate buffer of pH 10.2 and 0.2 cm3 of adrenaline. The blind test did not contain supernatant; the carbonate buffer was used instead. The values were presented in U/g of platelet protein. The amount of enzyme which causes 50% inhibition at the maximal increase of absorbance by 0.025 of unit/min on a rectilinear segment of adrenochrome formation at +25°C at 480 nm is defined as aunit of SOD activity [5]. We
used 37 control and exposed samples. To determine the catalase enzymatic activity,
the suspension of blood platelets was frozen and thawed several times before the cell disintegration occurred. After centrifugation of the whole system at 4200× g at +4°C for 10 min, aclear supernatant was obtained. The measurement was performed using
aCARY 100 BIO (VARIAN) spectrophotometer at 240 nm wavelength at +25°C and absorbance was measured every minute for 5 min. The control sample contained 3 cm3 of 0.05 M phosphate buffer, whereas the study sample contained 2 cm3 of 0.05M phosphate buffer, 50 μl of supernatant and 1 cm3 of 0.1% H2O2. The obtained values were presented in Bergmeyer units per gram of platelet protein. One Bergmeyer unit (U) determines the
amount of catalase which decomposes 1 g of H2O2 per min at +25°C at pH 7.0 [6]. We used 37 control and exposed samples. The concentration of malondialdehyde was
determined by measuring the absorbance on the CARY 100 BIO spectrophotometer (VARIAN) at 532 nm wavelength vs. the control sample (1.8 cm3
PBS + 0.4 cm3 thiobarbituric acid). The study sample was prepared by adding 1 cm3 of 20% trichloroacetic acid (TCA) to 1 cm 3 of blood platelet suspension at the concentration of 1 × 109/cm3; then the mixture was shaken for 1 h at +4°C and centrifuged at 4200× g at +4°C for 15 min. To 1.8 cm3 of the obtained supernatant 0.4 cm3 of 0.12 M thio–
barbituric acid was added. The mixture was placed in a boiling water bath for 15 min. After cooling, the obtained solution was centrifuged at 3000× g for 10 min at room temperature. The obtained results were expressed in nmol/109 of platelets [7]. We used 36 control and exposed samples.
Conclution
The findings indicate that exposure to electromagnetic radiation of 1 kHz frequency and 150 V/m and 220 V/m intensity may cause adverse effects within blood platelets’ oxygen metabolism and thus may lead to physiological dysfunction of the organism.
