Nocturnal excretion of a urinary melatonin metabolite among electric utility workers

Burch, James B.; Reif, John S.; Yost, Michael G.; Keefe, Thomas J.; Pitrat, Charles A.

doi:10.5271/sjweh.297

Cited by 100 publications

(84 citation statements)

References 54 publications

(37 reference statements)

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“…A priori, MF exposures were classified in a variety of ways, including TWA, GM, and two estimates of field stability: rate of change metric (RCM) and rate of change metric standardised (RCMS) (Burch et al, 1998). The metrics with the highest year-toyear correlation were TWA and GM.…”

Section: Data Collectionmentioning

confidence: 99%

Magnetic field exposure and long-term survival among children with leukaemia

et al. 2006

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We examined the association between magnetic field (MF) exposure and survival among children with acute lymphoblastic leukaemia (ALL) treated at 51 Pediatric Oncology Group centres between 1996 and 2001. Of 1672 potentially eligible children under treatment, 482 (29%) participated and personal 24-h MF measurements were obtained from 412 participants. A total of 386 children with ALL and 361 with B-precursor ALL were included in the analysis of event-free survival (time from diagnosis to first treatment failure, relapse, secondary malignancy, or death) and overall survival. After adjustment for risk group and socioeconomic status, the event-free survival hazard ratio (HR) for children with measurements X0.3 mT was 1.9 (95% confidence interval (CI) 0.8, 4.9), compared to o0.1 mT. For survival, elevated HRs were found for children exposed to X0.3 mT (multivariate HR ¼ 4.5, 95% CI 1.5 -13.8) but based on only four deaths among 19 children. While risk was increased among children with exposures above 0.3 mT, the small numbers limited inferences for this finding.

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Section: Data Collectionmentioning

confidence: 99%

Magnetic field exposure and long-term survival among children with leukaemia

et al. 2006

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“…Two estimates of field variability or stability, the rate of change metric (RCM), and the standardized rate of change metric (RCMS) were calculated according to Burch et al (1998) and Yost (1999). The RCM is defined as…”

Section: Exposure Metricsmentioning

confidence: 99%

“…The RCM provides an estimate of both the variability and the first-lag autocorrelation in a series of measurements (Burch et al, 1998). RCMS estimates the first lag autocorrelation, defined as RCMS ¼ RCM=SD where SD is the standard deviation of the MF over the time interval for which the RCM is calculated.…”

Section: Exposure Metricsmentioning

confidence: 99%

“…RCMS estimates the first lag autocorrelation, defined as RCMS ¼ RCM=SD where SD is the standard deviation of the MF over the time interval for which the RCM is calculated. Low RCMS values correspond to relatively small differences between successive measurements and represent MF exposures that are stable over time (Burch et al, 1998). As a measure of field stability that we call constant field metric (CFM), we calculated the total sum of the lengths of all periods of time during which the magnetic field was greater than 0.15 mT, and at least three consecutive readings were the same, which means a constant field during at least 10 s. According to Litoviz et al (1991Litoviz et al ( , 1997, biological effects can be observed if MF is stable at least for 10 s. It can also be assumed that a threshold is needed for biological effects.…”

Section: Exposure Metricsmentioning

confidence: 99%

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Use of short-term measurements for assessing temporal variability of residential ELF magnetic field exposure

Eskelinen

Niiranen

Juutilainen

2003

J Expo Sci Environ Epidemiol

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In this study, we introduced and tested a new approach to characterize residential magnetic field (MF) exposure. Short-term 20-min MF measurements were obtained by a person who carried out instantaneous spot measurements in residences. Compared to spot measurements, the 20-min measurement could potentially improve exposure assessment, because it contains information of temporal variations of MF, which have been suggested as biologically important characteristics of MF exposure. We have used this new exposure assessment method on a study of maternal MF exposure and reproductive outcomes. To validate the new method, the exposure of 30 subjects was measured with a more accurate ''gold standard'' method (24 h personal exposure measurements). The measures of validity used were the Spearman correlation coefficient (r), sensitivity, and specificity. We evaluated the validity of the 20-min measurements for estimating several different exposure metrics for the entire 24 h measurement period or for the hours spent at home: arithmetic mean, median, percentage of time above 0.15 mT, standard deviation, rate of change metric, standardized rate of change metric, constant field metric, and three metrics for the occurrence of high-peak exposures. The 20-min measurement was modestly associated with standard deviation and the rate of change metric, but gave very little information of other metrics of temporal variation. The 20-min measurement can also be used for assessing exposure metrics such as arithmetic mean and median, but it does not seem to offer any advantages compared to traditional 'spot' measurements. The 20-min measurement was not useful for assessing occurrence of high-peak exposures. We conclude that the 20-min measurement is useful for estimating some aspects of MF temporal variability.

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“…Some studies have been undertaken in real life conditions, among electric utility workers [Burch et al, 1998[Burch et al, , 1999, Swiss railway workers [Pfluger and Minder, 1996], video display unit workers [Arnetz and Berg, 1996] or among nightly electric blanket users [Wilson et al, 1990]. They indicate slight alterations in the urinary excretion of the melatonin metabolite after daytime exposure to MF; however, the perturbations were not consistent across studies, which were subjected to confounding bias like differential light exposure.…”

Section: Introductionmentioning

confidence: 99%

Daytime 50 Hz magnetic field exposure and plasma melatonin and urinary 6‐sulfatoxymelatonin concentration profiles in humans

Crasson

Beckers

Péqueux

et al. 2001

Journal of Pineal Research

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Concern about the health effects of extremely low frequency (ELF) magnetic fields (MF) has been raised by epidemiological studies indicating an association between certain cancers and living near power lines or working in high electric field environments. Alterations in pineal function have been proposed as a mechanism through which power‐frequency MFs may interact with living organisms. A double blind laboratory study was performed to evaluate daytime exposure effects of 100 μT root mean square (rms) 50 Hz MF. Three head exposure sessions of 30 min each were performed: sham, continuous, and intermittent (15 s on/off cycles) MFs were presented to each subject in early or late afternoon (13:30 or 16:30 hr). Twenty‐one healthy male volunteers (20–27 yr old) participated in these 3‐weekly experimental conditions. Blood samples were drawn for serum melatonin measurement, hourly at night (from 20:00 to 07:00 hr) under controlled environmental conditions. Urinary excretion of 6‐sulfatoxymelatonin (aMT6s), the main melatonin metabolite, was measured for a 17 hr period, by means of urine samples taken at 19:00 hr (14:00–19:00 hr “afternoon period”), 23:00 hr (19:00–23:00 hr “evening period”), and 07:00 hr, day 2 (23:00–07:00 hr day 2 “night‐time period”). There were no significant differences in either plasma melatonin or in aMT6s excretion profiles in the three experimental conditions. However, a tendency for a smaller increase of night‐time urinary aMT6s after continuous MF exposure was found (P=0.08) particularly in men with the lower excretion rate of aMT6s (“Low Group”) (P=0.07). We conclude that this study does not indicate that daytime acute MF exposure influences either melatonin secretion or aMT6s excretion. Inter‐individual differences in pineal production of melatonin, however, have to be taken into account in further studies.

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Nocturnal excretion of a urinary melatonin metabolite among electric utility workers

Cited by 100 publications

References 54 publications

Magnetic field exposure and long-term survival among children with leukaemia

Magnetic field exposure and long-term survival among children with leukaemia

Use of short-term measurements for assessing temporal variability of residential ELF magnetic field exposure

Daytime 50 Hz magnetic field exposure and plasma melatonin and urinary 6‐sulfatoxymelatonin concentration profiles in humans

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