Chronic exposure of Sprague-Dawley rats to 20 kHz triangular magnetic fields

Purpose:?As a continuing study of 20?kHz triangular magnetic fields (MF) [Lee et al. ], we investigated the chronic toxicity and possible health effects of exposure to 20?kHz MF at the flux density of 30?μT, which is the limit standard for the occupational population in South Korea, with the use of Sprague-Dawley rats.

Materials and methods:?Rats were exposed to 20?kHz triangular MF at 30?μT Root Mean Square for 8?h/day for 18 months. Body and organ weights were measured and urinalysis, hematological and blood biochemistry analyses were performed in individual animals. Histopathological evaluation was also performed for the brain, thymus, lung, heart, liver, kidney, intestine and reproductive organs, including tumour tissue.

Results:?The mortality patterns in male or female rats exposed to magnetic fields were compared to the mortality patterns found in sex-matched sham control animals. Significant alteration of body weight was not observed with MF exposure. No significant differences were seen in sham-exposed and MF-exposed animals based on urological factors, hematological factors and blood biochemistry. Total tumour incidence was not different between sham-exposed and MF-exposed animals.

Conclusion:?Our results suggest that chronic exposure to 20?kHz triangular MF with 30?μT flux density did not increase toxicity in rats.     

Effects of 21-kHz intermediate frequency magnetic fields on blood properties and immune systems of juvenile rats

Abstract

Purpose: Due to a lack of science-based evidence, we explored the effects of exposure to intermediate frequency magnetic fields (IF-MF) on experimental animals. We assessed several immunological parameters to determine the effect of exposure of the whole body to IF-MF.

Materials and methods: Male Sprague-Dawley rats (4–5 weeks old) were divided into three groups: Cage-control, sham, and 3.8-mT (rms) exposure groups. The animals were exposed to IF-MF at 21 kHz under fixed conditions in an acrylic holder. Exposure was performed for 1 h/day for 14 consecutive days. On the 15th day following the exposure, biochemical and hematological parameters in blood were analyzed. The effects of the exposure on immunological functions such as the cytotoxic activity of lymphocytes, chemotactic and phagocytic activity of granulocytes, and T (cluster of differentiation 4 [CD4] and cluster of differentiation 8 [CD8])-cell frequency were also examined.

Results: Hematological parameters were not affected by IF-MF exposure. Other immune functions such as the cytotoxic activity and phagocytic activity were not affected. Populations of T cells after exposure also did not show any significant differences. In blood biochemistry, there was significant difference in inorganic phosphorus level between sham and exposure group. However, this will not induce any pathophysiological status, because they were still within physiological range. Overall, no significant effect by exposure of IF-MF was observed under our experimental conditions.

Conclusions: Our results suggest that exposure to 21-kHz sinusoidal IF-MF at 3.8 mT for 1 h/day for 14 days did not affect immune function in juvenile rats.     

Altered blood chemistry and hippocampal histomorphology in adult rats following prenatal exposure to physiologically-patterned, weak (50-500 nanoTesla range) magnetic fields

PURPOSE: To discern changes in blood chemistry, cerebral sizes, and hippocampal cytomorphology in adult male and female albino Wistar rats that had been exposed during their entire prenatal development to one of two patterns of magnetic fields and one of four intensities: Very low 5 - 20 nT; low 30 - 50 nT; medium 90 - 580 nT; and high 590 nT to 1.2 microT. MATERIALS AND METHODS: A total of 48 pregnant females were exposed to either a repetitive frequency-modulated magnetic field or to a complex sequence of 50, 200-msec physiologically-patterned fields. As adults blood, cerebral, and histomorphological data were obtained from the 137 rats that had been exposed to one of these eight conditions. RESULTS: Compared to other groups, adult rats that had been exposed prenatally to the physiologically-patterned magnetic fields at the low (30 - 50 nT) and medium (90 - 580 nT) intensities exhibited peak elevations of aminotransaminase, glucose, and uric acid. Numbers of cytometric anomalies were also significantly elevated within regions of the hippocampus known for neuronal neogenesis in adults. CONCLUSIONS: The results suggest that a common factor in cellular adhesion or plasticity might be permanently altered by prenatal exposure to a narrow intensity of a series of physiologically-patterned magnetic fields.     

Effects of soman poisoning on hematology and coagulation parameters and serum biochemistry in rabbits

The effects of soman poisoning on hematological (counts of red blood cells (RBC), white blood cells (WBC), and platelets and measurement of hematocrit) and coagulation parameters (prothrombin time, activated partial thromboplastin time, thrombin time and concentrations of fibrinogen, factor V, factor VII, and factor XI) and serum biochemistry (concentration of albumin, protein, calcium, cholesterol, triglycerides, blood urea nitrogen (BUN), magnesium, and creatinine and activities of alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, cholinesterase, creatinine phosphokinase (CPK), hydroxybutyrate dehydrogenase, and amylase) were determined at 1, 2, 4, 24, and 48 hours after poisoning of rabbits. There were significant (p less than 0.05) decreases in the RBC counts in all treatment groups that were measured initially at 4 hours and were reflected by parallel decreases in the hematocrit values. These changes were probably due to an increase in the hemolysis of the RBC rather than a decrease in the production of RBC. There were minor changes in the coagulation parameters. Generally, the fibrinogen content increased. The activated partial thromboplastin time decreased significantly (p less than 0.05) 24 and 48 hours after soman (50 micrograms/kg) poisoning. Blood cholinesterase values were significantly reduced in all treatment groups at all time periods. The CPK activity was increased after 4 and 24 hours in the 20 and 50 micrograms/kg soman groups. There were minor changes in the other biochemistry values, but none that showed a dose-response relationship; thus, they were considered to be of limited significance with regard to the toxic manifestations of soman exposure.(ABSTRACT TRUNCATED AT 250 WORDS)     

静磁场辐射对大鼠外周血细胞、血清代谢酶和血浆递质的影响

目的探讨静磁场连续辐射对大鼠外周血细胞、血清代谢酶和血浆递质的影响。方法二级雄性Wistar大鼠20只,随机分为对照组和静磁场辐射组,静磁场强度为600 mT,每天辐射12 h,连续7 d,于辐射后7 d、14 d和30 d活杀取材。采用Sysmex 2100全自动血细胞分析仪进行血细胞分析;采用全自动生化分析仪检测大鼠血清天冬氨酸转氨酸（谷草转氨酶,AST,GOT）、乳酸脱氢酶（LDH）和肌酸激酶同工酶（CKMB）的改变,采用HPLC检测大鼠血浆中氨基酸和单胺类递质的改变。结果 600mT静磁场辐射后7 d,大鼠外周血淋巴细胞百分率显著降低（P〈0.05）,血小板（PLT）显著减少（P〈0.01）,辐射后14 d,红细胞（RBC）显著升高（P〈0.05）。辐射后7 d和14d,大鼠血清AST和LDH显著减少（P〈0.01）,辐射后14 d,CKMB显著减少（P〈0.01）。辐射后7 d,大鼠血浆犬尿喹啉酸（KYNA）和谷氨酸（Glu）含量显著降低（P〈0.01）,NE和5-HT含量均显著减少（P〈0.05或P〈0.01）。结论 600mT静磁场连续辐射可引起外周血淋巴细胞百分率和PLT减少、RBC增加,血清代谢酶AST、LDH和CKMB减少,血浆氨基酸和单胺类递质代谢紊乱。     

Diary of events

Purpose: To discern changes in blood chemistry, cerebral sizes, and hippocampal cytomorphology in adult male and female albino Wistar rats that had been exposed during their entire prenatal development to one of two patterns of magnetic fields and one of four intensities: Very low 5 – 20 nT; low 30 – 50 nT; medium 90 – 580 nT; and high 590 nT to 1.2 microT.

Materials and methods: A total of 48 pregnant females were exposed to either a repetitive frequency-modulated magnetic field or to a complex sequence of 50, 200-msec physiologically-patterned fields. As adults blood, cerebral, and histomorphological data were obtained from the 137 rats that had been exposed to one of these eight conditions.

Results: Compared to other groups, adult rats that had been exposed prenatally to the physiologically-patterned magnetic fields at the low (30 – 50 nT) and medium (90 – 580 nT) intensities exhibited peak elevations of aminotransaminase, glucose, and uric acid. Numbers of cytometric anomalies were also significantly elevated within regions of the hippocampus known for neuronal neogenesis in adults.

Conclusions: The results suggest that a common factor in cellular adhesion or plasticity might be permanently altered by prenatal exposure to a narrow intensity of a series of physiologically-patterned magnetic fields.     

Effects in rodents of a 1-month exposure to magnetic fields (200-1200 Gauss).

Under the conditions of the present study, magnetic fields ranging from 200 to 2000 Gauss strength have no toxic or histopathological effects on rats. The in vivo study and the histopathological results show no alterations of the vascular tissues, except for a nonpathological congestion of the spleen, and no intravascular thrombosis related to the experimental conditions. An unexpected observation was that the increase in body and organ weight of young rats was significantly greater in the groups exposed to magnetic fields. Therefore, no undesirable effects should be expected when magnetic fields within the prescribed safety limits of 200 to 2000 Gauss are applied to human subjects for several hours.     

Subchronic in vivo effects of a high static magnetic field (9.4 T) in rats

The potential adverse biologic effects of sub chronic (cumulatively 10 weeks) exposure to a high magnetic field (9.4 T) were evaluated in young adult male and female Fischer rats as well as in their progeny. Biologic end points in adult rats included changes in daily clinical observations; spatial memory tests; weekly heart rates, body weights, food and water consumption, and the feed efficiency ratio; terminal hematologic, blood biochemical and urinary parameter changes; gross pathologic findings; and major organ weights. In offspring, biologic end points included the gestation period, number of live births, number of pups, ratio of male to female pups/litter; postnatal time period of eye opening; birth and weekly body weights, behavioral changes, central nervous system responses, as well as hematologic, blood biochemistry, and urinary parameter changes; and gross pathologic findings. Findings from this study showed that there were no adverse biologic effects in male and female adult rats or their progeny that could be attributed to 10-week exposure to a 9.4-T static magnetic field.     

声预处理对强噪声引起听力损伤保护作用的研究(英文)

目的 探讨低频声预处理对强噪声及中频强噪声引起听力损伤的保护作用。方法 两组声预处理组豚鼠在中心频率０．５ｋＨｚ８５ｄＢ倍频带噪声作用下,连续暴露４ｄ（６ｈ／ｄ）后,在无噪声情况下恢复３ｄ。随后分别在中心频率０．５ｋＨｚ和１ｋＨｚ１１０ｄＢ的倍频带噪声下,暴露１ｈ。两组对照组豚鼠不经声预处理,分别直接暴露在中心频率０．５ＫＨｚ和１ｋＨｚ１１０ｄＢ的倍频带噪声下,暴露１ｈ。两组对照组豚鼠不经声预处理     

One-year,simultaneous combined exposure of CDMA and WCDMA radiofrequency electromagnetic fields to rats

Purpose:?We investigated whether one-year, long-term, simultaneous exposure to code division multiple access (CDMA; 849 MHz) and wideband code division multiple access (WCDMA; 1.95 GHz) radiofrequencies (RF) would induce chronic illness in Sprague-Dawley (SD) rats.

Materials and methods:?Two groups of 40 SD rats (50% males and females in sham and exposed groups) were exposed to CDMA and WCDMA RF simultaneously at 2.0 W/kg for 45 min/day (total 4.0 W/kg), 5 days per week for a total of one year. Body and organ weight measurements, urinalysis, haematological and blood biochemical analysis, and histopathological evaluations were performed.

Results:?The mortality patterns in male and female rats exposed to RF were compared with those found in gender-matched sham control animals. No significant alteration in body weight was observed with the simultaneous combined RF exposure. Most RF-exposed rats showed no significant alteration, based on urinalysis, haematology, blood biochemistry, or histopathology. However, some altered parameters of the complete blood count and serum chemistry were seen in RF-exposed rats. The total tumour incidence was not different between sham-exposed and RF-exposed animals.

Conclusions:?Our results suggest that one-year chronic exposure to CDMA (849 MHz) and WCDMA (1.95 GHz) RF simultaneously at 2.0 W/kg for 45-min RF exposure periods (total, 4 W/kg) did not increase chronic illness in rats, although there were some altered parameters in the complete blood count and serum chemistry.     

Impact of electromagnetic field exposure limits in Europe: is the future of interventional MRI safe?

The European Union (EU) has recently introduced a directive that aims to protect workers from adverse effects of exposure to electromagnetic fields. All countries within the EU are required to incorporate this directive into their national law by 2008. This legislation applies to all types of occupational exposure to electromagnetic fields with frequencies from 0 Hz to 300 GHz. It has dramatic implications for interventional magnetic resonance (MR) imaging, because workers who are close to the MR scanner while scanning is taking place are exposed at levels substantially above the exposure limits. This is especially the case for time-varying magnetic fields in the 110 Hz-5 kHz range, which includes the field from the imaging gradients. In this article, the scientific evidence on which the limits are based is brought into question. It is concluded that an urgent review of the directive is required and that more research, especially at MR gradient frequencies, is needed.     

Life-span exposure to sinusoidal-50 Hz magnetic field and acute low-dose γ radiation induce carcinogenic effects in Sprague-Dawley rats

Background In 2002 the International Agency for Research on Cancer classified extremely low frequency magnetic fields (ELFMF) as a possible carcinogen on the basis of epidemiological evidence. Experimental bioassays on rats and mice performed up to now on ELFMF alone or in association with known carcinogens have failed to provide conclusive confirmation.

Objectives To study the carcinogenic effects of combined exposure to sinusoidal-50?Hz (S-50Hz) magnetic fields and acute γ radiation in Sprague-Dawley rats.

Methods We studied groups of male and female Sprague-Dawley rats exposed from prenatal life until natural death to 20 or 1000?μT S-50Hz MF and also to 0.1?Gy γ radiation delivered as a single acute exposure at 6 weeks of age.

Results The results of the study showed significant carcinogenic effects for the mammary gland in males and females and a significant increased incidence of malignant schwannomas of the heart as well as increased incidence of lymphomas/leukemias in males.

Conclusions These results call for a re-evaluation of the safety of non-ionizing radiation.     

静磁场暴露对于大鼠睾丸组织电学特性的影响

目的研究静磁场暴露对于大鼠睾丸组织介电特性与导电特性的影响,从细胞水平和分子水平分析静磁场对于大鼠睾丸组织的影响。方法在10 kHz～10 MHz范围内测量被1700 Gs静磁场暴露作用大鼠的睾丸组织的电容和电阻,并进一步通过测试结果计算其介电与导电特性。结果通过静磁场暴露作用的大鼠其睾丸组织的介电常数总体上呈现降低趋势,在第7天以后开始恢复,在频率较高时恢复的时间较早,其电导率的变化趋势则是先上升,在第5天以后开始下降,具有显著差异的结果主要集中在较低频率的10 kHz～100 kHz范围内。结论静磁场对于大鼠睾丸组织电学特性的显著的影响主要集中在细胞水平,对于分子水平的影响不显著,并且这些影响在一段时间后可以自行恢复。     

高压氧对一氧化碳中毒大鼠血小板CD61及多形核白细胞粘附分子CD11b/CD18表达的影响

目的 观察高压氧（HBO）对一氧化碳中毒大鼠外周血血小板CD61多形核白细胞粘附分子CD11b/CD18表达的影响。方法：健康成年Wistar大鼠共128只，动物被随机分成4组。正常对照组8只；一氧化碳中毒组（COP）40只，按观察时程，第1，5，10，15，20天各8只；高气压处理组（HPT）共40只，第1，5，10，15，20天各8只；高压氧组(HBO)40，第1，5，10，15，20天各8只。用流式细胞仪测定CO中毒大鼠在不同时间段外周血血小板CD61及多形核白细胞粘附分子CD11b/CD18的表达。结果 COP中毒后1，5，10d COP及HPT组大鼠外周血血小板CD61表达量明显高于对照组，而HBO组仅在第1天高于对照组。外周血多形核白细胞粘附分子CD11b/CD18的表达量的变化为，COP组大鼠在CO中毒后第1，5，10，15，20天及HPT组大鼠在CO中毒后第1，5，10，15天明显高于对照组，而HBO组其值在CO中毒后第1，5，10天高于对照组。结论 CO中毒后大鼠外周血血小板CD61及多形核白细胞粘附分子CD11b/CD18的表达增高并持续一段时间，HBO治疗使其增高的时间明显缩短。     

Bilirubin metabolism in the rat at high altitude

Bilirubin metabolism was studied in rats injected with unconjugated bilirubin (0, 0.5, 1.5, 3.0, or 4.5 mg X 100 g-1) after 2 and 6 weeks continuous exposure to 4,600 m (15,000 ft) simulated altitude. Exogenous loads of bilirubin were used to exceed any effect of polycythemia, thereby allowing assessment of defects in conjugation and excretion due to the exposure to high altitude. Rats given no exogenous bilirubin showed polycythemia when exposed to high altitude which may have contributed to the small but significant elevations in their serum bilirubin levels. Compared to sea-level controls, mean serum concentrations of total and unconjugated bilirubin were significantly elevated in altitude-exposed rats given exogenous bilirubin. Mean serum conjugated bilirubin levels did not rise at any dose. Thus, bilirubin uptake and/or conjugation rather than excretion are impaired in rats at high altitude. We conclude that while polycythemia may contribute to high altitude-induced bilirubinemia, an impairment in uptake and/or conjugation also exists.     

Glucose homeostasis in rats exposed to magnetic fields.

The development of diagnostic and therapeutic applications of magnetic fields, especially with regard to magnetic resonance imaging (MRI), draws attention to accompanying possible adverse effects. Recent investigations revealing an increase in insulin release in diabetic rats, increase in glycogen, and decrease in glucose level in rats exposed to magnetic fields, have provided the stimulus for the current studies. Rats were exposed to uniform constant magnetic fields of 10(-3) T and 10(-2) T, 1 hour each day, for a period of ten days. Blood glucose slightly increased, the release of insulin decreased, and the glucagon content increased when compared with controls. The efficiency of the hypophysis-hypothalamic system changed, as indicated by an increase in the level of growth hormone and thyroid-stimulating hormone. The content of the thyroid hormones, triiodothyronine and thyroxine, was higher between the third and seventh day of exposure. An increase in the cortisol level was also observed. The results might implicate a temporarily diabetic-like response in rats exposed to the magnetic field.     

Effect of a 1.5 T static magnetic field on body temperature of man

Reports in the literature concerning the effect of static magnetic fields on the body temperature of mammals have been contradictory and confusing. A significant increase in body temperature in human subjects exposed to the static magnetic fields used in magnetic resonance imaging (MRI) would have important safety implications. Therefore, in two separate studies we determined body temperature in 20 subjects exposed to a 1.5 T static magnetic field. One group of subjects (Group I, N = 9) had sublingual pocket temperature measured immediately before and after a 60 min exposure, while another group of subjects (Group II, N = 11) had esophageal temperature determined at 2 min intervals during a 20 min exposure. No statistically significant changes in body temperature were observed in either Group I or II subjects during exposure to the 1.5 T static magnetic field. We conclude that a relatively intense static magnetic field has no effect on body temperature of normal human subjects.     

Assessment of genetic damage in peripheral blood of human volunteers exposed (whole-body) to a 200 μT, 60 Hz magnetic field

Aim:?To investigate the extent of damage in nucleated cells in peripheral blood of healthy human volunteers exposed to a whole-body 60 Hz, 200 μT magnetic field.

Materials and methods:?In this study, 10 male and 10 female healthy human volunteers received a 4 h whole-body exposure to a 200 μT, 60 Hz magnetic field. In addition, five males and five females were treated in a similar fashion, but were exposed to sham conditions. For each subject, a blood sample was obtained prior to the exposure period and aliquots were used as negative- (pre-exposure) and positive- [1.5 Gray (Gy) ⁶⁰Cobalt (⁶⁰Co) γ-irradiation] controls. At the end of the 4 h exposure period, a second blood sample was obtained. The extent of DNA damage was assessed in peripheral human blood leukocytes from all samples using the alkaline comet assay. To detect possible clastogenic effects, the incidence of micronuclei was assessed in phytohemagglutinin (PHA)-stimulated lymphocytes using the cytokinesis-block micronucleus assay.

Results:?There was no evidence of either increased DNA damage, as indicated by the alkaline comet assay, or increased incidence of micronuclei (MN) in the magnetic field exposed group. However, an in vitro exposure of 1.5 Gy γ-irradiation caused a significant increase in both DNA damage and MN induction.

Conclusions: This study found no evidence that an acute, whole-body exposure to a 200 μT, 60 Hz magnetic field for 4 hours could cause DNA damage in human blood.     

Eryptosis and hemorheological responses to maximal exercise in athletes: Comparison between running and cycling

We compared the effects of cycling and running exercise on hemorheological and hematological properties, as well as eryptosis markers. Seven endurance‐trained subjects randomly performed a progressive and maximal exercise test on a cycle ergometer and a treadmill. Blood was sampled at rest and at the end of the exercise to analyze hematological and blood rheological parameters including hematocrit (Hct), red blood cell (RBC ) deformability, aggregation, and blood viscosity. Hemoglobin saturation (SpO2), blood lactate, and glucose levels were also monitored. Red blood cell oxidative stress, calcium content, and phosphatidylserine exposure were determined by flow cytometry to assess eryptosis level. Cycling exercise increased blood viscosity and RBC aggregation whereas it had no significant effect on RBC deformability. In contrast, blood viscosity remained unchanged and RBC deformability increased with running. The increase in Hct, lactate, and glucose concentrations and the loss of weight at the end of exercise were not different between running and cycling. Eryptosis markers were not affected by exercise. A significant drop in SpO2 was noted during running but not during cycling. Our study showed that a progressive and maximal exercise test conducted on a cycle ergometer increased blood viscosity while the same test conducted on a treadmill did not change this parameter because of different RBC rheological behavior between the 2 tests. We also demonstrated that a short maximal exercise does not alter RBC physiology in trained athletes. We suspect that exercise‐induced hypoxemia occurring during running could be at the origin of the RBC rheological behavior differences with cycling.     

104名战士5km负重越野训练前后相关生化与外周血指标对比分析

目的　探讨 5km负重越野训练前后机体的相关生化与外周血指标变化规律。方法　对某部步兵连队 104名战士 5km负重越野训练前后的静脉血进行 17项生化与外周血指标检测。结果　检测的 17项指标中,运动后与运动前相比,除ALT,LDH,Hb,BUN,IgA,IgM无显著差异 (P>0. 05 )外;AST,AMM,IgG差异显著 (P<0. 05 );GL,RBC,WBC,PAP,UA,CRP差异非常显著 (P<0. 01 )。结论　5km负重越野训练后可以引起机体多项检验指标的变化。通过对这些指标的观察,对科学合理的完成军体训练有指导意义。