Occupationally related magnetic field exposure and male subfertility

In Vivo Cytotoxicity Induced by 60 Hz Electromagnetic Fields under a High-Voltage Substation Environment

Living beings permanently receive electromagnetic radiation, particularly from extremely low-frequency electromagnetic fields (ELF-EMFs), which may cause adverse health effects. In this work, we studied the in vivo cytotoxic effects of exposing BALB/c mice to 60 Hz and 8.8 µT EMFs during 72 h and 240 h in a switchyard area, using animals exposed to 60 Hz and 2.0 mT EMFs or treated with 5 mg/kg mitomycin C (MMC) as positive controls. Micronucleus (MN) frequency and male germ cell analyses were used as cytological endpoints. ELF-EMF exposure was observed to significantly (p < 0.05) increase MN frequency at all conditions tested, with the 2 mT/72 h treatment causing the highest response, as compared with untreated control. In addition, increased sperm counts were observed after switchyard area ELF-EMF exposure, as compared with untreated control. In contrast, low sperm counts were obtained for 72 h/2.0 mT-exposed animals and for MMC-treated mice (p < 0.05), without altering male germ cell morphological characteristics.

Extremely low-frequency electromagnetic field (EMF) generates alterations in the synthesis and secretion of oestradiol-17β (E2) in uterine tissues: An in vitro study

An electromagnetic field (EMF) of extremely low frequency may affect physiological processes in mammals. The aim of the present study was to determine the effect of an EMF on the synthesis and secretion of oestradiol-17β (E₂) in the porcine uterus. Endometrial and myometrial slices were harvested on days 12-13 of the oestrous cycle and exposed in vitro to an EMF (50 and 120 Hz, 8 mT) for 2 and 4 h in the presence or absence of progesterone (P₄). Subsequently, the incubation media were used to determine the concentration of E₂ with RIA. Tissues fragments were used to study the expression of CYP19A3 mRNA using Real-Time PCR and the abundance of P450 aromatase using Western Blotting. The 50-Hz EMF increased E₂ release from the endometrium and the myometrium at both time points of in vitro incubation. A 120-Hz EMF decreased the endometrial secretion of E₂ after 2 h of incubation and did not affect E₂ secretion after 4 h. In the myometrium, the 120-Hz EMF increased E₂ secretion after 4 h of incubation. In P₄-treated uterine fragments, no significant EMF exposition-related changes were observed. Only myometrial fragments incubated in the presence of P₄ at 120-Hz EMF (4 h) released higher amounts of E₂ due to EMF treatment. The 50-Hz EMF exposure did not change the CYP19A3 mRNA expression in endometrial fragments incubated in the presence or absence of P₄. In myometrial fragments, the highest CYP19A3 mRNA expression was observed in fragments not exposed to the 50-Hz EMF and P₄-treated tissues compared to that in fragments exposed to 50 Hz EMF and incubated with or without P₄ and control (no EMF and no P₄) fragments. The EMF at 120 Hz decreased basal endometrial CYP19A3 mRNA expression and did not change the expression in the P₄-treated endometrium. In the myometrium, the EMF at 120 Hz increased CYP19A3 mRNA expression in slices incubated without P₄ and had no effect in the presence of P₄. The EMF exposure (50 and 120 Hz) did not affect P450 aromatase abundance in either the endometrium or the myometrium. In conclusion, the EMF induces changes in the synthesis and release of E₂ in uterine tissues harvested during days 12-13 of the oestrous cycle. These changes are related to the EMF frequency used, the time of the exposition and the presence of P₄. We suspect that this observed phenomenon might lead to changes in the intrauterine milieu of oestrogen, which is crucial for the proper activity of uterine tissues during the mid-luteal phase of the oestrous cycle.

Effect of Lepidium meyenii (maca) on testicular function of mice with chemically and physically induced subfertility

The aim of this study was to evaluate the effect of Lepidium meyenii (maca) in chemically and physically subfertile mice. After 35 days, the following groups of mice were evaluated: control, sham, chemical subfertility, chemical subfertility-maca-supplemented, physical subfertility, physical subfertility-maca-supplemented and maca-supplemented only. Motility (32.36% ± 5.34%) and sperm count (44.4 ± 5.37 × 10(6) /ml) in the chemically and physically subfertile mice (11.81% ± 4.06%, 17.34 ± 13.07 × 10(6) /ml) decreased compared to the control (75.53% ± 2.97% and 57.4 ± 19.6 10(6) /ml) and sham (53.5% ± 7.86% and 58.4 ± 14.10 10(6) /ml). Maca was able to reverse the deleterious effect of motility (76.36 ± 1.97) as well as sperm count (53.5 ± 9.18 × 10(6) /ml) on chemical subfertility. In contrast, maca did not reverse the effects of induced physical subfertility nor motility (18.78% ± 14.41%) or sperm count (20.17 ± 11.20 × 10(6) /ml). The percentage of sperm DNA fragmentation in the physically subfertile mice increased (11.1% ± 19.29%) compared to the control (0.84% ± 0.85%). However, in the physically subfertile group, maca decreased sperm DNA fragmentation (2.29% ± 2.30%) closer to the sham (1.04% ± 0.62%) and the control (0.84% ± 0.85%). The group supplemented only with maca showed 0.54% ± 0.50% of spermatozoa with DNA fragmentation. Yet, the differences observed were statistically not significant. In conclusion, it appears that maca activates the cytochrome P450 system after chemically induced subfertility. However, it does not reverse the low mitochondrial membrane potential in spermatozoa compromised in the physical subfertility group.

Effect of low-frequency electromagnetic field exposure on oocyte differentiation and follicular development

Background:

The effect of electromagnetic field (EMF) as an environmental factor on different organs including female reproductive system is of critical concern. The aim of the present study is to evaluate the effect of low-frequency (LF)-EMF on oocyte differentiation and follicular development.

Materials and Methods:

The experiment was carried out in animal lab of Faculty of Medicine Tabriz University of Medical Sciences. For this purpose, the BALB/c mice were divided into control and experimental group in animal lab. The pregnant mice in the experimental group were exposed to 3 mT EMF field, 4 h/day during the pregnancy period. The LF-EMF was produced by a system using 50 Hz alternative current, in the control group the pregnant mice were kept in a similar condition without exposure to EMF. The neonatal mice from both groups were sacrificed immediately after birth and their ovary was dissected apart and prepared for light and electron microscopy.

Result:

Microscopy revealed that in the experimental group, in comparison to control group, oocyte nests were mostly broken and irregularly arranged. The primordial follicles were less developed and nuclei of oocytes with an electron microscope appeared heterochromatic, shrunken and had vacuolated cytoplasm.

Conclusion:

It is concluded that exposure to EMF during the developmental period could affect both oocyte differentiation and folliculogenesis and may result in reduced fertility, by decreasing ovarian reservoir.

Effects of exposure to extremely low frequency magnetic fields on spermatogenesis in adult rats

The constant exposure of modern society to extremely low frequency magnetic fields (ELF-MF) has raised considerable concerns about the potential risks to male reproduction. However, the epidemiological and experimental data remain contradictory and inconclusive. In the present study, we investigated the effects of 50 Hz ELF-MF of 500 µT applied 4 h/day, 7 days/week for 4 and 8 weeks on male reproduction, focusing on changes in spermatogenesis. Several biological endpoints related to testicular function and spermatogenesis were measured, including the following: body mass, masses of testes and epididymis, sperm count and abnormal sperm ratio in the caudal epididymis, serum testosterone level, testicular histology, frequency of 14 stages of the cycle of the seminiferous epithelium and of four stages of meiosis I, germ cell apoptosis and testicular oxidative status. No significant differences were found in the biological endpoints between the sham control and the exposed rats in either the 4- or 8-week exposure period. These negative results may result from the lack of change in serum testosterone. In conclusion, our study indicates that exposure to low intensity ELF-MF may have no adverse effects on spermatogenesis.

Down-regulation of metallothionein 1 and 2 after exposure to electromagnetic field in mouse testis

BACKGROUND

It is proved that testis is sensitive to electromagnetic field (EMF) and its damage results in infertility. Exposure to EMF induces reactive oxygen species production and affects on anti-oxidants defense mechanisms. Metallothionein (MT) is a name for a group of low molecular weight (6-7 kDa), sulfhydryl rich proteins. Expression of MT1 and MT2 genes in testis tissue after EMF exposure was aimed in this study.

METHODS

Male BALB/c mice (8 weeks old) were exposed to 3 MT EMF for 8 weeks, 4 hours/day. After 8 weeks, the mice were sacrificed and the testis tissue was removed. The testis pieces were stained with hematoxylin and eosin and analyzed under an optical microscope. Assessment of MT1 and MT2 genes and also protein expression was performed by real-time PCR and Western-blot, respectively.

RESULTS

In light microscopic observation, the number of primary spermatocytes was increased significantly in EMF group (P < 0.01). In addition, in interstitial space, the number of leydig cells was increased significantly in EMF group (P < 0.01) and basement membrane thickness was increased as well. MT1 and MT2 genes were down-regulated significantly in testis tissue of mice exposed to EMF both in mRNA and protein level compared to control.

CONCLUSION

It is clear that MT is mediated in testis development and spermatogenesis. Down-regulation of MT1 and MT2 after EMF in mouse testis might be followed by some consequences that result in infertility.

The effects of electromagnetic field on the microstructure of seminal vesicles in rat: a light and transmission electron microscope study

In the industrial world, almost everyone is unavoidably exposed to ambient electromagnetic field (EMF) generated from various technical and household appliances. Controversy exists about the effects of EMF on various tissues of the living bodies. Seminal vesicles as one of these accessory glands play an important role in natural seminal fluid formation and the effects of EMF on its tissue is worthy of investigation. In order to examine this 30 rat were selected and kept for one weeks in quarantine and 15 (experimental group) were exposed to 50 Hz (non-ionizing radiation) during postnatal life for 2 months. The materials were processed and observed under a light and transmission electron microscope. In the experimental rats epithelial and basal cells showed significant destructions presented by heterochromatin and dense nuclei. Cell debris and abnormal areas was recognizable in the stromal connective tissue. Obvious vacuolization was present within the epithelial cell cytoplasm and also between the cellular organelles. The nuclei of the endothelial cells of the blood vessels were more rigid and endothelial cell cytoplasm contained a lot of vacuoles and pinoctotic vesicles. The results suggested that EMF exposure may cause profound changes in the vesicle seminal tissues. Therefore exposure to EMF may result in pathological changes that lead to sub fertility and infertility.

Evaluation of spermatogenesis and fertility in F1 male rats after in utero and neonatal exposure to extremely low frequency electromagnetic fields

AIM

To determine whether in utero and neonatal exposure to a 60 Hz extremely low frequency electromagnetic field (EMF) results in spermatotoxicity and reproductive dysfunction in the F1 offspring of rats.

METHODS

Age-matched, pregnant Sprague-Dawley rats were exposed continuously (21 h/day) to a 60 Hz EMF at field strengths of 0 (sham control), 5, 83.3 or 500 microT from day 6 of gestation through to day 21 of lactation. The experimentally generated magnetic field was monitored continuously (uninterrupted monitoring over the period of the study) throughout the study.

RESULTS

No exposure-related changes were found in exposed or sham-exposed animals with respect to the anogenital distance, preputial separation, testis weight, testicular histology, sperm count, daily sperm production, sperm motility, sperm morphology and reproductive capacity of F1 offspring.

CONCLUSION

Exposure of Sprague-Dawley rats to a 60 Hz EMF at field strengths of up to 500 microT from day 6 of gestation to day 21 of lactation did not produce any detectable alterations in offspring spermatogenesis and fertility.

Environmental and occupational factors affecting fertility and IVF success

Reproductive function has been shown to be sensitive to changes in the physical, psychosocial and chemical environments. Although reproductive effects of occupational exposure to hazardous chemicals have been well documented in the literature, the potential effects of chemical contaminants at levels representative of contemporary exposures in the general population are much less certain. Evidence for adverse effects of exposure to environmental contaminants is more conclusive among the lower animals than for humans where considerable controversy remains. In addition to potential reproductive hazards of exposure to environmental contaminants, there is also evidence for adverse reproductive effects of the physical and psychosocial environments. In this review we focus on the difficulties involved in linking exposure to putative hazardous substances in environmental and occupational settings to adverse reproductive outcomes, especially success of IVF procedures. We highlight the plausibility of adverse events through animal and cell studies and the application of these results to the interpretation of human data. We consider both the male and female partners since it is essentially their combined contributions of gametes which may be affected by chemicals, which lead to successful outcomes.

Lack of alterations on meiotic chromosomes and morphological characteristics of male germ cells in mice exposed to a 60 Hz and 2.0 mT magnetic field

The effect of in vivo exposure of mice to a 60 Hz sinusoidal magnetic field (MF) at 2.0 mT on male germ cells was studied. The cytological endpoints measured included meiotic chromosome aberrations in spermatocytes and sperm morphology. Three independent experiments were carried out: (a) animals exposed for 72 h, (b) 10 days/8 h daily, and (c) 72 h exposure to MF plus 5 mg/kg of Mitomycin-C. No statistically significant differences indicative of MF effects were observed between MF exposed and control animals. In addition, an opposite effect between MF exposure and Mitomycin-C treatment in terms of chromosomal aberrations and sperm morphology was observed.

Risk of birth defects by parental occupational exposure to 50 Hz electromagnetic fields: a population based study

OBJECTIVES

To study the risk of birth defects by parental occupational exposure to 50 Hz electromagnetic fields.

METHODS

The Medical Birth Registry of Norway was linked with census data on parental occupation. An expert panel constructed a job exposure matrix of parental occupational exposure to 50 Hz magnetic fields. Exposure to magnetic fields was estimated by combining branch and occupation into one of three exposure levels: <4 hours, 4-24 hours, and >24 hours/week above approximately 0.1 mu T. Risks of 24 categories of birth defects were compared across exposure levels. Out of all 1.6 million births in Norway in the period 1967-95, 836,475 and 1,290,298 births had information on maternal and paternal exposure, respectively. Analyses were based on tests for trend and were adjusted for parents' educational level, place of birth, maternal age, and year of birth.

RESULTS

The total risk of birth defects was not associated with parental exposure. Maternal exposure was associated with increased risks of spina bifida (p=0.04) and clubfoot (p=0.04). A negative association was found for isolated cleft palate (p=0.01). Paternal exposure was associated with increased risks of anencephaly (p=0.01) and a category of "other defects" (p=0.02).

CONCLUSION

The present study gives an indication of an association between selected disorders of the central nervous system and parental exposure to 50 Hz magnetic fields. Given the crude exposure assessment, lack of comparable studies, and the high number of outcomes considered, the results should be interpreted with caution.

Long-term exposure of male and female mice to 50 Hz magnetic field: effects on fertility

The effect of an extremely low frequency (ELF) magnetic field on the fertility of adult male and female Swiss mice was investigated. Adult male and female mice were exposed to a 50 Hz sinusoidal magnetic field at approximately 25 microT (rms) for 90 days before they were mated with unexposed counterparts. There were no exposure related effects on the fertility of male or female mice. The number of implantation sites, viable fetuses, and the total number of resorptions were not significantly affected in females impregnated by males exposed to the 50 Hz magnetic field as compared with the control group. The number of implantation sites, viable fetuses and the total number of resorptions in exposed females were also not statistically different from the control group. There were no significant effects on the weights of the testes, seminal vesicles, preputial gland or body weights of males exposed to 50 Hz magnetic field. Furthermore, body and uterine weights were not affected in females exposed to 50 Hz field; however, ovarian weight was significantly increased in females exposed to the same field. These results suggest that exposure of male and female mice to low frequency magnetic field had no adverse effects on fertility and reproduction in mice.

Effects of exposure to static magnetic fields on the morphology and morphometry of mouse epididymal sperm

Morphologic and morphometric sperm characteristics of mouse epididymal extracts from animals exposed to static magnetic fields were evaluated. For this purpose, animals were exposed for 35 days to a field of 0.7 T generated by a commercial permanent magnet for either 1 or 24 h per day. The values of morphometric parameters were obtained using the morphometric module of the Sperm Class Analyzer computerized image analysis system, and percentages of abnormalities were calculated. The size of sperm heads was unaffected by exposure to static magnetic fields. Lack of hook was a sperm head abnormality found significantly more frequently in animals exposed continually than in nonexposed animals, showing a possible alteration to the spermatogenic process after exposure to static magnetic fields. The percentage of sperm with coiled tails or of sperm with abnormal midpiece or tail was not altered by exposure.

Extremely low frequency magnetic fields and fertility: a follow up study of couples planning first pregnancies. The Danish First Pregnancy Planner Study Team

OBJECTIVES

To evaluate the impact of extremely low frequency (ELF) magnetic fields on markers of human fertility.

METHODS

A follow up study of time to pregnancy, semen quality, and reproductive hormones was conducted among couples planning first pregnancies (36 males were welders and 21 were non-welders). The male and the female partner were monitored for exposure to ELF magnetic field by personal exposure meters. As summary measures of exposure the median value was calculated together with the 75 percentile value and the proportion of measurements exceeding 0.2 and 1.0 microT, respectively. Each summary measure was divided in three categories: low, medium, and high.

RESULTS

Couples in which the man had a medium or a high proportion of measurements > 1.0 microT had a reduced probability of conception per menstrual cycle compared with the men with low exposure, but the result was only significant for the men with medium exposure. This finding was partly attributable to a high probability of conception per menstrual cycle among the men with low exposure compared with non-welders in the original cohort of 430 couples. Other summary measures were not related to probability of conception or other markers of fertility. A possible negative association was found between high probability of conception and female exposure measures based on the median, the 75 percentile, and the proportion of measurements > 0.2 microT, but no association was found with the proportion of measurements > 1.0 microT.

CONCLUSIONS

The findings provide no consistent support for a hypothesis of a deleterious effect of low level ELF magnetic fields on markers of human fertility. However, due to the relatively small size of the studied population only large associations would be detected.

Intrauterine effects of electromagnetic fields--(low frequency, mid-frequency RF, and microwave): review of epidemiologic studies

Electromagnetic radiations are named according to frequency or to wavelength (which is inversely proportional to frequency) and create electromagnetic fields (EMFs). Frequencies widely vary according to sources: high-voltage power lines, electrically heated beds, MRI, VDTs, microwave ovens, satellite, and radio/TV transmissions or cellular phone transmitters/receivers. Public concern has increased about the potential health effects of EMFs. There are arguments in favour of EMFs being biologically active, but no mechanism has been identified that explains the link between EMFs and bioeffects. Human data reviewed concern the potential reproductive effects (mainly spontaneous abortions, low birthweight and congenital malformations) of exposure to sources of EMFs: maternal residence, electrically heated beds, occupational exposure (mainly video display terminals), and medical exposures. The available epidemiologic studies all have limitations that prevent to draw clearcut conclusions on the effects of EMFs on human reproduction. EMFs are ubiquitous and unavoidable exposures. The matter of possible effects cannot be considered closed, but until our understanding of the biologic important parameters of EMFs exposures is stronger,design of new studies will be difficult and small epidemiologic studies are unlikely to provide definitive answers and should not be given high priority. No conclusion can be drawn for radiofrequencies and microwaves because of lack of data. There is no convincing evidence today that EMFs of the sort pregnant women or potential fathers meet in occupational or daily life exposures does any harm to the human reproductive process.

Occupationally related exposures and reduced semen quality: a case-control study

OBJECTIVE

To determine whether there is an association between abnormal semen parameters and occupational exposures to organic solvents, metals, and pesticides.

DESIGN

Case-control study using three case groups based on different cutoff values for semen parameters and one standard reference group.

SETTING

University Hospital Utrecht and University Hospital Rotterdam, the Netherlands.

PATIENT(S)

Male partners of couples having their first consultation at the two infertility clinics (n = 899).

INTERVENTION(S)

Men provided at least one semen sample. Occupational exposure was assessed with use of job-specific questionnaires, a job exposure matrix, and measurements of metals and metabolites of solvents in urine.

MAIN OUTCOME MEASURE(S)

Standard clinical semen analyses were used to define case groups and controls.

RESULT(S)

An association between aromatic solvents and reduced semen quality was demonstrated, irrespective of the exposure assessment method used. The associations were stronger if the case definition was based on stricter cutoff values for semen parameters. Risk estimates were higher if the analysis was restricted to primary infertile men. Exposure to other pollutants at the workplace was not associated with impaired semen quality.

CONCLUSION(S)

The findings indicated an association between aromatic solvent exposure and impaired semen parameters.

Environmental endocrine modulators and human health: an assessment of the biological evidence

Recently, a great deal of attention and interest has been directed toward the hypothesis that exposure, particularly in utero exposure, to certain environmental chemicals might be capable of causing a spectrum of adverse effects as a result of endocrine modulation. In particular, the hypothesis has focused on the idea that certain organochlorine and other compounds acting as weak estrogens have the capability, either alone or in combination, to produce a variety of adverse effects, including breast, testicular and prostate cancer, adverse effects on male reproductive tract, endometriosis, fertility problems, alterations of sexual behavior, learning disability or delay, and adverse effects on immune and thyroid function. While hormones are potent modulators of biochemical and physiological function, the implication that exposure to environmental hormones (e.g., xenoestrogens) has this capability is uncertain. While it is reasonable to hypothesize that exposure to estrogen-like compounds, whatever their source, could adversely affect human health, biological plausibility alone is an insufficient basis for concluding that environmental endocrine modulators have adversely affected humans. Diethylstilbestrol (DES) is a potent, synthetic estrogen administered under a variety of dosing protocols to millions of women in the belief (now known to be mistaken) that it would prevent miscarriage. As a result of this use, substantial in utero exposure to large numbers of male and female offspring occurred. Numerous studies have been conducted on the health consequences of in utero DES exposure among the adult offspring of these women. There are also extensive animal data on the effects of DES and there is a high degree of concordance between effects observed in animals and humans. The extensive human data in DES-exposed cohorts provide a useful basis for assessing the biological plausibility that potential adverse effects might occur following in utero exposure to compounds identified as environmental estrogens. The effects observed in both animals and humans following in utero exposure to sufficient doses of DES are consistent with basic principles of dose response as well as the possibility of maternal dose levels below which potential non-cancer effects may not occur. Significant differences in estrogenic potency between DES and chemicals identified to date as environmental estrogens, as well as an even larger number of naturally occurring dietary phytoestrogens, must be taken into account when inferring potential effects from in utero exposure to any of these substances. The antiestrogenic properties of many of these same exogenous compounds might also diminish net estrogenic effects. Based on the extensive data on DES-exposed cohorts, it appears unlikely that in utero exposure to usual levels of environmental estrogenic substances, from whatever source, would be sufficient to produce many of the effects (i.e., endometriosis, adverse effects on the male reproductive tract, male and female fertility problems, alterations of sexual behavior, learning problems, immune system effects or thyroid effects) hypothesized as potentially resulting from exposure to chemicals identified to date as environmental estrogens.

Association of semen quality and occupational factors: comparison of case-control analysis and analysis of continuous variables

OBJECTIVE

To compare two statistical approaches, case-control and analysis of continuous parameters of semen, in examining the relationship between occupational exposures and male reproductive function.

DESIGN

Case-control study.

SETTING

Males providing semen samples at a university infertility clinic.

PATIENT(S)

Nonvasectomized males who provided at least one semen sample at an infertility clinic.

MAIN OUTCOME MEASURE(S)

Standard clinical semen analysis.

RESULT(S)

Analyses using a dichotomous dependent variable did not uncover significant associations between any occupational factor and infertility case status. However, linear models incorporating continuous variables identified a number of occupational factors that were associated with specific parameters of semen. A reduction in percentage of progressive sperm and an increase in percentage of coiled tail sperm defects in welders, compared with unexposed subjects, were found. Significant dose-response relationships between level of perceived job stress and percentage of progressive sperm, total motile count, morphology, abnormal heads, and coiled tail defects were found.

CONCLUSION(S)

The findings suggest that subtle changes in semen variables, possibly associated with workplace exposure, may be detected only with parametric analyses of continuous variables of semen.

Teratogen update: electromagnetic fields

Public concern is increasing about the potential health effects of extremely low frequency (ELF) electromagnetic fields (EMFs) naturally present or generated by electrical appliances and those of very low frequency (VLF) fields, like those generated by video display terminals (VDTs). There are arguments in favour of EMFs being biologically active but no mechanism has been identified that explains the link between EMFs and bioeffects. More than 50 studies on exposures of animals to EMFs have been performed within the last few years. Although there were a few statistically significant effects in the studies reviewed, no replicable results were found among laboratories. The extent of effects observed, if any, was always low, and deserves further investigation before relevance to humans can be considered. Human data reviewed concern the potential reproductive effects (mainly) spontaneous abortions, low birthweight, and congenital malformations) of exposure to various sources of EMFs: maternal residence, heated waterbeds, electric blankets, and ceiling heating coils, occupational exposure (mainly video display terminals), and magnetic resonance imaging. The totality of the evidence that is thus far available provides no convincing evidence to indicate that low frequency EMFs of the sort that might be met in occupational or daily life exposures does any harm to the human reproductive process. It is suggested that those counseling pregnant women follow the guidelines established by WHO in agreement with the International Non-ionizing Radiation Committee. This group does not consider that the results of published studies provide a basis for restricting human exposure to electromagnetic fields and radiation.