The question of both positive and negative effects of magnetic and electromagnetic fields on biological systems has become more and more important in our world today as they have become increasingly ubiquitous in the environment, medicine, research and industry. Not only has it become an important tool for scientists to use in their research, but it has also become necessary for us to understand how safe it is and what long-term effects it could have on our environment. This article reviews biological effects of magnetic and electromagnetic fields. The review discusses intended direct effects such as neural stimulation, and unintended indirect effects from such sources as power lines, consumer electronics and mobile telephones. They address our anxicities about effects such as immune system damage and cancer, and our hopes about potential beneficial uses.

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Circlularly polarized, ellip-tically polarized, horizontal or vertical magnetic fields were exposed nearly continuously for 6 weeks on male rats. Circularly polarized field exists only very close to transmission lines and not at the ground level where humans and animals live. However, we chose the fields for the later consideration of possible mechanisms. Light: dark period was 12: 12 hours. Concentration of melatonin was assayed by RIA on both serum and pineal gland. Melatonin was reduced at 1.4μT or stronger field of cirularly polarized field exposure, and the inhibitory effect recovered within 1 week after cessation of the exposure. No inhibitory effect was observed at 1.4 μT of elliptically polarized, horizontal or vertical fields. This suggests the parameter of magnetic fields has some important implication on the biological effects.

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Human circadian clock is able to entrain to an artificial light-dark cycle and produce a phase-dependent phase shift to a single light pulse. But the threshold for the light actions is relatively high, and it is not clear that ordinary room light has these effects. On the other hand, mela tonin synthesis was suppressed by light of 500 lux which is used in ordinary houses. Bright light exposure at evening or early night may produce not only a delay phase-shift of biological clock but also an internal desynchronization. These may be the cause of sleep-wake rhythm disorders and school refusal. Artificial bright light has been used for the treatment of these rhythm disorders.

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Light could influence psychological and physiological aspects of humans in their general lives to a great extent. However, lighting plans today do not take these points enough into consideration. The purposes of this study are to investigate the influence of light on humans, focusing on the relation between the quality of light and human biological rhythms, and also to study the photoreceptor which concerns the biological rhythm, and the temporal characteristics of its sensitivity. The main results were as follows: 1) The effects of light on the behavior of core temperature and melatonin vary depending on its wavelength. 2) From the relation between the stimulus received by each photoreceptor and the inhibition of fall of core temperature and melatonin secretion, it might be concluded that the photoreceptor responsible for affecting human biological rhythm is M-cones. In addition, the influence of M-cones on human biological rhythms is strongly supported by the result that, in Deutans who lack M-cones or have their deficiency, light had no influence on the behavior of core temperature and melatonin. 3) A higher light intensity was required in the morning than in the evening to induce the inhibition of melatonin secretion. This result suggests the possibility of existence of a diurnal change of sensitivity of the photoreceptors (Mcones) . From all these results, it is proposed in the field of architecture and living engineering that light with a low color temperature should be used for low-level lighting at night, and high-level light with a high color temperature in the morning.

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The eye is known as an important photoreceptor. Development of the molecular biological studies on photoreception is most advanced among studies on senses. The eye has to receive light for vision and various physiological functions. However, light is harmfull to living organisms and induces various hazards. Here, we will review the effects of light on the eye, especially the effects of artificial light. The importance of artificial light is increasing in our every day lives. We will also introduce the results obtained in our laboratory using birds as a material. Retinal melatonin, corneal mitotic rate and basic fibroblast growth factor (bFGF) were investigated in experiments manipulating the ocular physiology by treatments with eye-lid suture, which is known to induce eye enlargement and bulgy cornea, and also in silver mutant quail which have a pigment free area in the center of the retina where the neural retinal layer is doubled. The birds were reared under LD cycles (LD 12: 12) and DD (constant darkness) . Radio immunoassay (RIA) of melatonin: Retinas were homogenized in 1 ml of phosphate buffer solultion (PBS) and centrifuged for 20 min and the supernatant was used. Retinal melatonin levels were measured directly by a double antibody RIA. Corneal mitotic rate: Corneas were stained with Meyer's hematoxylin and the number of mitotic cells per 4, 000 cells was counted in 6 different areas with a Nomarski differential interference light microscope. Immunoassay of bFGF: Retinas taken from the eye were homogenized in PBS and centrifuged for 20 min and the supernatant was used. Quantikine kits (R & D systems) were used to measure bFGF. In lid-sutured quail, (1) corneal mitotic rates were high in darkness and low in light in control eyes, but an increase in mitotic rate in the sutured eyes was induced during the light period, (2) since retinal melatonin levels of sutured eyes were similar to those of control eyes, the corneal mitotic rhythm does not seem to have a relation to retinal melatonin, (3) since retinal bFGF levels of sutured eyes were similar to those of control eyes, bFGF does not seem to have a relation to ocular enlargement. In silver mutant quail, (1) the eye weight was significantly greater than that in normal quail, (2) retinal melatonin and corneal mitotic rate were high in darkness and low in light, and therefore, the retina has the ability to perceive light, and (3) since the retinal bFGF levels were almost similar to those in normal quail, bFGF does not seem to be involved in the eye enlargement. The results were discussed in relation to eye-enlargement and myopia.

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This study was conducted to investigate the influence of posture on sensible temperature. The contacted surface areas between the floor and the human body were measured to quantitatively determine the heat conduction from the floor to subjects. Six postures were used for the measurements: standing, sedentary, sitting upright, sitting with legs crossed, sitting with knees drawn up, and lateral decubitus. Under the sitting upright posture, the contacted surface area was smaller than under the sitting with legs crossed, sitting with knees drawn up, and lateral decubitus postures, and it was almost the same as the contacted areas under the standing and sedentary postures. The contacted surface area of the sitting upright posture was almost negligible compared with the total surface area. The effective radiation area and configuration factors between the human body and rectangular planes were measured to make a quantitative thermal radiation. The sitting upright posture was used to measure the effective radiation area between the human body and numerous rectangular planes and thereby determine a quantitative thermal radiation value. The effective radiation area factor was found to be 0.66 for a sitting upright nude subject and 0.70 for a sitting upright clothed subject. Diagrams of the configuration factors between the human body and the rectangular planes were represented. Configuration factors between sitting upright subjects and the floor were found to be significantly larger than those for standing or sedentary subjects. The indoor climate of a house was used, and the thermal environmental index calculated on each posture from the result of measurements. The modified effective temperature (ETV) was used for calculating the thermal environmental index. A clear, qualitative correlation was evident between posture and sensible temperature.

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The effects of the human menstrual cycle on thermoregulatory responses were examined on eight healthy women in a climatic chamber controlled at 28°C and 50% r.h. The physiological and psychological responses of each subject were measured in the three stages of her menstrual cycle: luteal phase (L), menstrual phase (M) and follicular phase (F) . Rectal and oral temperatures were higher in L than in M and F (p<0.01) . There was no significant difference in the metabolic rate, but the mean value was slightly higher in L than in the other two phases.Weight loss due to perspiration in L was the lowest of all (p<0.01) . Mean skin temperature was higher in L than in M (p<0.05), but not significantly different between L and F. This is because skin temperature of the trunk regions was higher in L than in F, whereas skin temperature of the peripheral regions was lower in L than in F. As for thermal sensation, most subjects felt cooler in L than in F and M, dispite no change in the environment. These results show that the menstrual cycle affects both thermoregulation and thermal sensation in women.

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The water balance in daily living in summer and winter was studied in 14 aged females (mean age, 74.4 years) living at home to obtain basic data for evaluation of prevention of dehydration in the elderly. The following results were obtained. 1) The total water intake was 2.81 in summer and 2.21 in winter, and the water intake from drinking water and meals was greater in summer than in winter. 2) Drinking water was taken primarily as Japanese tea in winter and as Japanese tea and barley tea in sum-mer. 3) Although no difference was observed in the urine volume between summer and winter (1.2 1 in winter and 1.51 in summer), the volume of perspiration was greater in summer (1.51) than in win-ter (0.61) . 4) The total water intake showed negative correlation with the age (r=-0.57 in summer, r=-0.61 in winter) but positive correlation with the water intake from meals (r=0.62 in summer, r=0.61 in winter) and water intake from drinking water (r=0.97 in summer, r=0.89 in winter) . The total water intake was found to depend upon the body surface area, the frequency of water intake and age, both in summer (r²=0.86) and winter (r²=0.92) according to the multiple regression analysis. These findings suggest that there is a clear seasonal difference in the water balance of the elderly and that more conscious drinking of water and intake of meals with greater water contents are effective for prevention of dehydration.

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