Elevated chromosome translocation frequencies in New Zealand nuclear test veterans.

In 1957/58 the British Government conducted a series of nuclear tests in the mid-Pacific codenamed Operation Grapple, which involved several naval vessels from Britain and New Zealand. Two New Zealand frigates with 551 personnel onboard were stationed at various distances between 20 and 150 nautical miles from ground zero. In the present study we applied the cytomolecular technique mFISH (multicolour fluorescent in situ hybridisation) to investigate a potential link between chromosome abnormalities and possible past radiation exposure in New Zealand nuclear test veterans who participated in Operation Grapple. Compared to age matched controls, the veterans showed significantly higher (P < 0.0001) frequencies of chromosomal abnormalities (275 translocations and 12 dicentrics in 9,360 cells vs. 96 translocations and 1 dicentric in 9,548 cells in the controls), in addition to a significant excess of CCRs (complex chromosomal rearrangements) in the veterans. A Kolmogorov-Smirnoff test showed that the distributions of translocations for the two groups were significantly different.

Elevated sister chromatid exchange frequencies in New Zealand Vietnam War veterans.

From July 1965 until November 1971, New Zealand Defence Force Personnel fought in the Vietnam War. During this time more than 76,500,000 litres of phenoxylic herbicides were sprayed over parts of Southern Vietnam and Laos, the most common being known as 'Agent Orange'. The current study aimed to ascertain whether or not New Zealand Vietnam War veterans show evidence of genetic disturbance arising as a consequence of their now confirmed exposure to these defoliants. A sample group of 24 New Zealand Vietnam War veterans and 23 control volunteers were compared using an SCE (sister chromatid exchange) analysis. The results from the SCE study show a highly significant difference (P < 0.001) between the mean of the experimental group (11.05) and the mean of a matched control group (8.18). The experimental group also has an exceptionally high proportion of HFCs (cells with high SCE frequencies) above the 95th percentile compared to the controls (11.0 and 0.07%, respectively). We conclude that the New Zealand Vietnam War veterans studied here were exposed to a clastogenic substance(s) which continues to exert an observable genetic effect today, and suggest that this is attributable to their service in Vietnam.

Elevated sister chromatid exchange frequencies in dividing human peripheral blood lymphocytes exposed to 50 Hz magnetic fields.

The in vitro cytomolecular technique, sister chromatid exchange (SCE), was applied to test the clastogenic potentiality of extremely low frequency (ELF) electromagnetic fields (EMFs) on human peripheral blood lymphocytes (HPBLs). SCE frequencies were scored in dividing peripheral blood lymphocytes (PBLs) from six healthy male blood donors in two rounds of experiments, R1 and R2, to determine reproducibility. Lymphocyte cultures in the eight experiments conducted in each round were exposed to 50 Hz sinusoidal (continuous or pulsed) or square (continuous or pulsed) MFs at field strengths of 1 microT or 1 mT for 72 h. A significant increase in the number of SCEs/cell in the grouped experimental conditions compared to the controls was observed in both rounds. The highest SCE frequency in R1 was 10.03 for a square continuous field, and 10.39 for a square continuous field was the second highest frequency in R2. DNA crosslinking at the replication fork is proposed as a model which could explain the mechanistic link between ELF EMF exposure and increased SCE frequency.

ELF magnetic fields increase amino acid uptake into Vicia faba L. roots and alter ion movement across the plasma membrane.

Vicia faba seedlings, subjected to a 10 microT 50 Hz square wave magnetic field for 40 min together with a radioactive pulse, showed a marked increase in amino acid uptake into intact roots. A more modest increase was observed with a 100 microT 50 Hz square wave. An increase in media conductivity at low field intensities from 10 microT 50 Hz square wave, 100 microT 50 Hz sine wave, and 100 microT 60 Hz square wave fields, indicated an alteration in the movement of ions across the plasma membrane, most likely due to an increase in net outflow of ions from the root cells. Similarly, marked elevation in media pH, indicating increased alkalinity, was observed at 10 and 100 microT for both square and sine waves at both 50 and 60 Hz. Our data would indicate that low magnetic field intensities of 10 and 100 microT at 50 or 60 Hz can alter membrane transport processes in root tips.

Determining the focus of driving fears.

Fear of driving has been recognized as a complex diagnostic entity. Studies on flying phobia have drawn similar conclusions, although increasing clarity has been gained through research that indicates that there may be subtypes of flying phobia based on the focus of fear. However, it is unclear if similar subtypes exist for fear of driving. The aim of the present study was to conduct a preliminary investigation of driving fear subtypes and to clarify further whether there were differences between driving-fearful respondents who had been in a motor vehicle accident (MVA) and those who had not. Eighty-five driving-fearful, media-recruited respondents completed a questionnaire that assessed anxiety, avoidance, and concerns related to their driving fears. The sample had high expectations of negative events while driving. There were no significant differences between those who had experienced an MVA and those who had not on various measures of fear severity. Cluster analysis revealed two main foci of fear, one characterized by danger expectancies and the other based on anxiety expectancies and unpleasant driving situations. This emphasizes the importance of assessing both internal and external foci of fear. Although this finding is consistent with the results obtained for flying phobia, more research is required to replicate and extend these results and to develop and evaluate differential treatment programs.

Stability of driving fear acquisition pathways over one year.

The present study was conducted in response to increasing concerns about the potential unreliability of retrospective accounts in assessing the origins of fears and phobias. Some investigators [e.g. Menzies, R.G., & Clarke, J.C. (1993). The etiology of fear of heights and its relationship to severity and individual response patterns. Behaviour Research and Therapy, 31, 355-365; Kirkby, K.C., Menzies, R.G., Daniels, B.A., & Smith, K.L. (1995). Aetiology of spider phobia: Classificatory differences between two origins instruments. Behaviour Research and Therapy, 33, 955-958; King, N.J., Gullone, E., & Ollendick, T.H. (1998). Etiology of childhood phobias: current status of Rachman's three pathways theory. Behaviour Research and Therapy, 36, 297-309.] have questioned the reliability of retrospective reports at a single assessment point, although the test-retest reliability of such accounts has yet to be examined. The aim of the present study was to conduct a one-year follow-up of the subclinical driving-fearful sample studied by Taylor and Deane [Taylor, J. E., & Deane, F. P. (1999). Acquisition and severity of driving-related fears. Behaviour Research and Therapy, 37, 435-449.] to primarily investigate, the stability of fear onset ascriptions and fear severity over time. 85 respondents completed a questionnaire which assessed fear origins, anxiety response patterns, and additional fear-relevant events occurring over the year. The results suggest that retrospective accounts of fear onset may be quite unstable over time, although this instability does not clearly appear to be related to intervening events, and limitations of the study make these results inconclusive. Fear-relevant negative thinking worsened over time, while physiological reactions and general anxiety remained relatively stable. The theoretical, methodological and clinical implications of the findings are discussed, along with suggestions for future research.

Influence of extremely low frequency magnetic fields on chromosomes and the mitotic cycle in Vicia faba L., the broad bean.

Vicia faba seedlings were subjected to one of the following magnetic fields continuously for 3 days: 0 Hz (DC) at 5 mT, 50 Hz at 1.5 mT, 60 Hz at 1.5 mT, and 75 Hz at 1.5 mT. The lengths of all the phases of mitosis differed from the controls in all treatments using alternating magnetic fields and for prophase and metaphase in the DC condition. In particular, all treatments increased the length of prophase significantly in meristematic root-tip cells compared with the controls. The implications of these results for chromosome coiling are discussed. The length of prophase, however, did not vary significantly between any of the treatments. Furthermore, none of the exposed seedlings had a greater frequency of chromosome breakages above that of the control plants.

Acute effects of 50 Hz magnetic field exposure on human visual task and cardiovascular performance.

One hundred subjects, males and females with ages ranging between 18 and 48 years, were studied under both field-exposed and sham-exposed conditions. A 50 Hz, 100 mu T magnetic field (MF) was used. To examine the effect of field exposure on performance, a two-alternative, forced-choice, duration-discrimination task with three levels of difficulty was used. The subject's task was to decide which of two sequentially presented light flashes had the longer duration. The standard duration was 50 ms, and the alternative durations were 65, 100, or 125 ms. Both reaction time and percentage of correct responses were recorded for each subject. MF and sham exposure were for 9 min each. Blood pressure and heart rate were also measured before and following MF exposure and sham-exposure trials. The study was performed double blind, with the exposure order counterbalanced. Compared to sham exposure, MF exposure significantly decreased reaction time on the hardest level of the performance task. MF exposure did not reliably affect percentage correct or cardiovascular performance. It was demonstrated that a relatively high level of statistical power was the basis for the observed MF effect, and the need to pay closer attention to power levels in future research is discussed.

Human performance and physiology: a statistical power analysis of ELF electromagnetic field research.

Research examining the effects of electromagnetic fields (EMFs) on human performance and physiology has produced inconsistent results; this might be attributable to low statistical power. Statistical power refers to the probability of obtaining a statistically significant result, given the fact that a real effect exists. The results of a survey of published investigations of the effects of EMFs on human performance and physiology show that statistical power levels are very low, ranging from a mean of .08 for small effect sizes to .46 for large effect sizes. Implications of these findings for the interpretation of results are discussed along with suggestions for increasing statistical power.

Do ELF magnetic fields affect human reaction time?

Two double-blind studies were run in an attempt to confirm the finding that a 0.2 Hz magnetic field affects simple reaction time (RT) in humans, whereas a 0.1 Hz field does not. In the first experiment, 12 volunteer subjects were exposed to a continuous 0.2 Hz, 0.1 Hz, or sham field in a fully counterbalanced, within-subjects design. Subjects were run singly for one condition each day over 3 consecutive days with a field strength of 1.1 mT and a daily exposure duration of 5 min. Neither magnetic field had any effect on RT at any time during the exposure. One condition of a second study, using a new group of 24 volunteer subjects, also failed to find any field effects at 0.2 Hz. Additionally, the second study failed to show any effects when the frequency, flux density, and field orientation were set according to parametric resonance theory. It is suggested that, although ELF magnetic field effects on human behaviour may be elusive, future research can improve detection rates by paying greater attention to reducing error variance and increasing statistical power.