Lack of effect of 10 kV/m 60 Hz electric field exposure on pregnant dairy heifer hormones

Burchard, J.F.; Nguyen, Duc Hai; Monardes, H.G.; Petitclerc, D.

doi:10.1002/bem.20020

Cited by 13 publications

(11 citation statements)

References 23 publications

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“…3). Results for MLT, P4, PRL, and IGF-1 are presented in Table 5 and are in agreement with those obtained elsewhere [Mäntysaari et al, 1999;Burchard et al, 2004;León et al, 2004;Muthurama- , 2006]. Serum concentrations of MLT and P4 did not differ between heifers exposed and not exposed to MF.…”

Section: Resultssupporting

confidence: 91%

Exposure of pregnant dairy heifer to magnetic fields at 60 Hz and 30 µT

Burchard

Nguyen

Monardes

2007

Bioelectromagnetics

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Thirty-two pregnant Holstein heifers weighing 499 +/- 45 kg, at 3.1 +/- .7 months of gestation and 21 +/- 2.0 months of age were confined and exposed to 30 microT magnetic fields (MFs) and a 12 h light/12 h dark light cycle. The heifers were divided into two replicates of 16 animals. Each replicate was divided into two groups of eight animals each, one group the non-exposed and the second, the exposed group. The animals were subjected to the different treatments for 4 weeks. After 4 weeks, the animals switched treatment, the exposed group becoming the non-exposed group and vice versa. Then the treatment continued for 4 more weeks. Catheters were inserted into the jugular vein, and blood samples were collected twice a week to estimate the concentration of progesterone (P4), melatonin (MLT), prolactin (PRL), and insulin-like growth factor 1 (IGF-1). Feed consumption was measured daily. The results indicated that exposure of pregnant heifers to MF similar to those encountered underneath a 735 kV high tension electrical power line for 20 h/day during a period of 4 weeks produces slight effects. This is evidenced by statistically significant higher body weight (1.2%), higher weekly body weight gain (30%), and decreases in the concentration of PRL (15%) and IGF-1 (4%) in blood serum. The absence of abnormal clinical signs and the absolute magnitude of the significant changes detected during MF exposure, make it plausible to preclude any major animal health hazard.

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Section: Resultssupporting

confidence: 91%

Exposure of pregnant dairy heifer to magnetic fields at 60 Hz and 30 µT

Burchard

Nguyen

Monardes

2007

Bioelectromagnetics

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“…Electrical fields alone did not produce any change in the body mass of pregnant lactating cows relative to unexposed controls [19], whereas magnetic fields did [2]. These results suggest that magnetic fields have an impact on body-mass gain in animals and correspond with our results.…”

Section: Discussionsupporting

confidence: 81%

“…Thyroxine is known to play key roles in growth, metabolism, reproduction, and somatic differentiation in developing and adult animals [22]. Also, in pregnant lactating dairy cows exposure to the electrical component of these fields alone (10 kV/m) did not affect production of prolactin [19]. It is possible that magnetic fields exert an effect on body size via plasma thyroxine and/or prolactin.…”

Section: Discussionmentioning

confidence: 99%

Effects of Power-Frequency Magnetic Fields on Body Mass in Rats: A Pooled Analysis

Nishimura

Tada²,

Teramukai³

et al. 2012

PIER Letters

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Abstract-There is some evidence that exposure of various animals to a power-frequency magnetic field can cause increases in body mass. However, the precise nature of the relationship is not clear, particularly for long-term exposure. To clarify the relationship between long-term power-frequency magnetic field exposure (2 years) and animal body mass, we conducted a pooled analysis of data in two studies to examine the impact of power-frequency magnetic field exposure on body mass as compared with sham-exposed rats of both sexes. Relative body mass was the response variable, and the study duration (in weeks), magnetic flux density (µT), and daily exposure time (hours/day) were the explanatory variables with adjustment for the study. We analyzed by sex. The P -value (P ) was defined as the probability of having observed our data (or more extreme data) when the null hypothesis was true. In multiple linear regression analyses of male and female rats, performed separately, we obtained estimates of the effect on relative body mass of study duration (coefficients 0.0225 and 0.0201, respectively; both P < 0.0001), magnetic flux density (coefficient 0.0002 for males, P < 0.0001; coefficient −0.0002 for females, P = 0.0015), and daily exposure time (coefficient 0.046 for

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“…Exposure to EMF also resulted in increases in prolactin (PRL) and decreases in daytime melatonin (MLT) [Rodriguez et al, 2004] but did not affect MLT nocturnal concentrations [Burchard et al, 1998b;Rodriguez et al, 2004]. Exposure to the electric component of these fields (10 kV/m) did not affect either feed consumption, MLT, P4, IGF-1, or PRL [Burchard et al, 2004].…”

Section: Introductionmentioning

confidence: 96%

Plasma concentrations of thyroxine in dairy cows exposed to 60 Hz electric and magnetic fields

Burchard

Nguyen

Rodríguez

2006

Bioelectromagnetics

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Two experiments were carried out to assess the effects of electric and magnetic fields (EMF) on blood thyroxine (T4) in dairy cattle. In experiment 1, 16 lactating pregnant Holstein cows were exposed to 10 kV/m, 30 microTesla (microT) EMF. The animals were divided into two groups of eight animals each. Each group was exposed to EMF according to one of two treatment sequences of three periods of 28 days each. Sequence 1 was EMF OFF-ON-OFF and sequence 2 was EMF ON-OFF-ON. During the last day of each treatment period, blood samples were collected every 4 h for 24 h to estimate T4 plasma concentrations. In experiment 2, 16 nonlactating, nonpregnant, multiparous Holsteins were exposed to 10 kV/m, 30 microT EMF. The animals were divided into two groups of eight animals each. Each group was exposed to EMF according to one of the two treatment sequences described above, except that each period amounted to the number of days corresponding to one estrous cycle. During treatment, blood samples were collected every other day for T4 analysis. In both experiments, the light cycle emulated a short photoperiod (8 h light/16 h dark). During the ON periods, the animals were exposed to EMF for 16 h, 8 h of the light period plus the first 8 h of during the dark period. In experiment 1, exposed animals did not have any change in T4 plasma concentrations due to treatment (P = .0968), but, the time of sample collection revealed a significant difference (P = .0012). In experiment 2, the effect of period (P = .0009) and the treatment by days interaction (P = .0003) were statistically significant. We conclude that a worst case scenario exposure of dairy cattle to 10 kV/m, 30 microT EMF influences, in a moderate fashion, the blood levels of thyroxine.

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Lack of effect of 10 kV/m 60 Hz electric field exposure on pregnant dairy heifer hormones

Cited by 13 publications

References 23 publications

Exposure of pregnant dairy heifer to magnetic fields at 60 Hz and 30 µT

Exposure of pregnant dairy heifer to magnetic fields at 60 Hz and 30 µT

Effects of Power-Frequency Magnetic Fields on Body Mass in Rats: A Pooled Analysis

Plasma concentrations of thyroxine in dairy cows exposed to 60 Hz electric and magnetic fields

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