Environmental Factors as the Main Hormonal Disruptors of Male Fertility

Abstract

Environmental Factors as the Main Hormonal Disruptors of Male Fertility Wdowiak N, Wójtowicz K, Wdowiak-Filip A, Pucek W, Wróbel A, Wróbel J, Wdowiak A. Environmental Factors as the Main Hormonal Disruptors of Male Fertility. J Clin Med. 2024 Mar 29;13(7):1986. doi: 10.3390/jcm13071986. Abstract Introduction and objective: Many scientific reports confirm a systematic decline in male semen parameters over the last decades. This phenomenon has been observed in all parts of the world, and its occurrence is associated, among others, with the hazardous effects of some environmental factors. The environmental factors for which the adverse effect on male fertility has been proven include water, air, and soil pollution, as well as electromagnetic fields and ionizing radiation. The aim of this article was the evaluation of the effect of selected environmental factors on male reproductive capacity based on an analysis of the current scientific reports. Review methods: A systematic literature review was carried out using three databases: PubMed, EMBASE, and Scopus. The search was limited to the period from 2015 until the end of December 2023. Brief description of the state of knowledge: Environmental factors, such as heavy metals, tobacco smoke, pesticides, dioxins, furans, phthalates, and bisphenols, are well-tested substances that exert an adverse effect on male fertility. A harmful effect of electromagnetic fields and water and air pollution on reproductive functions may be expected; however, this has not been fully proven. Summary: Results obtained by many researchers published to date should evoke great concern regarding the quality of the environment in which we live, as well as fears about the effect of environmental factors not only on male fertility, but also on all aspects of human health. The majority of environmental pollutants affect the male body by causing oxidative stress and through their effect on the endocrine system. Excerpt 12. Electromagnetic Fields Electromagnetic radiation (EMR) originating from both the natural environment and human activity constantly affects living organisms. The effect of EMR on the reproductive system may occur as a result of the thermal effect, generation of oxidative stress, changes in the structure of proteins, and causing changes in ion transport through cell membranes; however, these pathomechanisms have not yet been fully explained. Based on studies conducted to date it is known that electromagnetic fields generate oxidative stress, disrupting the function of sperm mitochondria and causing the activation of cell membrane NADH oxidase [43]. Balance in the free radical system, which is affected by the electromagnetic fields, as well as the activity of ion channels, are together responsible for the process of sperm hyperactivation. Human spermatozoa, in order to become ready to fertilize an oocyte, undergo many metabolic changes affecting the cell membrane, which leads to capacitation occurring in the woman’s reproductive tract. As a result of these transformations, sperm can interact with the structures of the corona radiata, and subsequently with the zona pellucida of the oocyte. This process is necessary for fertilization. Possible premature capacitation taking place in the seminal plasma causes energy depletion of the sperm and reduces the chance for fertilization. Balance in the free radical system is the factor responsible for the proper moment of capacitation. Ion channels are responsible for the proper course of this process, including CatSper, a pH-regulated, calcium-selective ion channel, KSper (Slo3), and the voltage-gated channel Hv1. To date, it has been considered that many other channels regulate these processes; however, this was not supported by research, and only the implementation of the patch–clamp technique shed new light on the possibilities of opportunities to learn about this process. It is known that mutations and deletions of the genes responsible for the function of these channels are responsible for the existence of certain types of male infertility. The voltage-gated channel Hv1, which is an electrical voltage sensor responsible for processes related to fertilization, seems to be the most sensitive to the effect of EMF. The results of studies concerning the effect of EMF on the immune system cells confirmed that the frequency close to 15 Hz has the greatest impact on the transport of Ca2+ ions into the cell. Therefore, it may be expected that similar relationships will also concern sperm [43,44]. It has long been known that welding arcs are a very harmful source of EMF for males. Their radiation consists of intensive thermal radiation of high-temperature welding gases, welded or cut elements, electrode, and flux material, on which the lines and bands of radiation characteristic of these materials overlap. The gas burner flame temperature usually does not exceed 2000 K. Thus, this radiation consists mainly of infrared and light, and only hydrogen and acetylene burners are characterized by a higher combustion temperature and emit near-ultraviolet light. Scientific reports concerning the effect of welding on male fertility confirm that in males performing this profession, deterioration of the main sperm parameters occurs, and their partners are at an increased risk of miscarriage. The type of harmful effect on the male reproductive system depends on the type of materials to be welded and applies primarily to mild steel [43,44]. Exposure to strong EMF also concerns employees operating radar stations. Currently, various types of radars operate on frequencies from 3 MHz (HF band) to 110 GHz (W band). In the lower part of this range operate radars which measure the height of the ionosphere, and those using the phenomenon of reflection of electromagnetic waves from the ionosphere for detecting objects hidden beyond the horizon, often over a distance of thousands of kilometers. Most radars operate at frequencies ranging from several hundred megahertz to 100 GHz, including speed cameras known to drivers, which are used to take photos of cars and are based on the 34.3 ± 0.1 GHz band. The reports concerning their effect on male fertility are contradictory. Some researchers describe an increase in the percentage of abnormal sperm and reduction in sperm motility, with a simultaneous absence of effect on its density in employees of radar stations. In turn, other researchers describe a decreased sperm density in people exposed to radar waves. There are also reports that do not indicate any differences in the quality of sperm between males exposed to a radar, and those not exposed to its effect. Due to the development of telecommunication technologies, at present, almost every person is exposed to EMF related to GSM. Our own study conducted at the beginning of the ‘era of mobile phones’ demonstrated an increase in the percentage of abnormal sperm and a decrease in the percentage of sperm in progressive movement, together with an increase in exposure to GSM. Studies concerning the effect of mobile phone technology on sperm have been continued by many researchers. They demonstrated that the waves emitted by mobile phones cause an increased production of the reactive oxygen species (ROS), leading to oxidative stress in sperm, and intensification of sperm DNA fragmentation. Similar relationships were confirmed on animal models. In a study in which mice were exposed to radiation of 900 mW/kg for 12 h daily for 7 days an adverse effect of EMR was observed on mitochondrial genome integrity. It was also proven that long-lasting telephone calls lead to an increase in temperature in the brain, which may affect the activity of the hypothalamic–pituitary–gonadal axis [43,44]. A significant exposure to electromagnetic fields also concerns males working on high-voltage electrical installations. It was found that among employees exposed for many years to contact with voltage of 400 kV, fewer children were born compared to the control group. Among children exposed to high voltage, the male gender prevailed. It was also observed that among offspring of males exposed to high voltage, congenital defects occurred more frequently. There are also other scientific reports that confirm a beneficial effect of electromagnetic fields with lower frequency ranges on both sperm parameters and the function of tissues responsible for human reproduction. Some scientific studies confirmed that exposure of sperm to magnetic fields within the range from 10–50 Hz contributes to the improvement of the motility of human sperm, whereas others presented opposite results. In animal models, while investigating the exposure of fish reproductive cells to magnetic fields, an improvement was observed in sperm motility parameters, and an increase in the percentage of fertilizations. Electromagnetic fields have found application in the treatment of prostate disorders in animals. A group of researchers confirmed that in dogs, the exposure of the prostate to frequencies of 4–12 Hz has a healing effect on prostate enlargement, not causing changes in sperm parameters of the animals. The results of studies confirming a beneficial effect of electromagnetic fields provide hope for their use in the treatment of human infertility; however, a long-term impact of this type of energy will require meticulous research, especially regarding possible epigenetic effects diagnosed only in future generations. Own studies of sperm exposed in vitro to weak EMF, close to that used at security checkpoints, showed an effect on DNA methylation [43,44]. At present, we are unable to specify what amount of energy related to EMF is harmful, neutral, or beneficial for human reproductive capacity. It may be expected that there are amounts of energy with neutral or beneficial effect, and only exceeding them may cause harmful effects. Open access paper: mdpi.com

AI evidence extraction

Main findings

This systematic review summarizes evidence that multiple environmental pollutants adversely affect male fertility, while stating that harmful effects of electromagnetic fields (EMF) on reproductive functions may be expected but are not fully proven. The EMF section describes proposed mechanisms (including oxidative stress and ion transport changes) and reports mixed findings across contexts: welding exposure is described as associated with deterioration of sperm parameters and increased miscarriage risk, radar exposure reports are described as contradictory, and mobile phone/GSM studies are described as reporting increased ROS/oxidative stress and sperm DNA fragmentation. The authors also note reports of potentially beneficial effects of low-frequency magnetic fields on sperm motility and some animal reproductive outcomes, and conclude that harmful/neutral/beneficial EMF energy thresholds cannot currently be specified.

Outcomes measured

• Semen parameters (e.g., motility, morphology, density)
• Male fertility/reproductive capacity
• Oxidative stress / reactive oxygen species (ROS)
• Sperm mitochondrial function
• Sperm DNA fragmentation
• Mitochondrial genome integrity (animal study)
• Hypothalamic–pituitary–gonadal axis activity (temperature-related mechanism discussed)
• Miscarriage risk in partners (occupational welding reports)
• Offspring outcomes (number of children, sex ratio, congenital defects)
• DNA methylation changes (in vitro sperm exposure)

Limitations

• The abstract indicates EMF-related harm is not fully proven despite expectations of harm.
• Findings described for some EMF sources (e.g., radar) are explicitly contradictory across reports.
• No quantitative synthesis, effect sizes, or study counts are provided in the supplied abstract/excerpt.
• Exposure metrics (e.g., SAR, field strength) and standardized exposure characterization are not specified in the provided text.

Suggested hubs

• occupational-exposure (0.86)
  Discusses occupational EMF exposures including welding, radar stations, and high-voltage electrical installations.
• cell-phones (0.78)
  Includes discussion of GSM/mobile phone exposure and reported sperm-related outcomes.

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    "exposure": {
        "band": null,
        "source": "Environmental factors including electromagnetic fields (general; includes occupational sources such as welding, radar, high-voltage installations, and consumer sources such as GSM/mobile phones)",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": "Search limited to 2015 through end of December 2023 (review period); individual exposure durations vary by cited studies"
    },
    "population": "Males / male fertility (human and animal evidence discussed)",
    "sample_size": null,
    "outcomes": [
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        "The abstract indicates EMF-related harm is not fully proven despite expectations of harm.",
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    "summary": "This paper reports a systematic literature review (2015–Dec 2023) on environmental factors affecting male reproductive capacity, including electromagnetic fields (EMF). It states that several pollutants are well-established as harmful to male fertility, while EMF-related harm may be expected but is not fully proven. The EMF evidence summarized is mixed, with occupational and consumer exposures described as sometimes associated with worsened sperm parameters and oxidative stress, but with contradictory or null findings also reported and some low-frequency exposures described as potentially beneficial in certain studies.",
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        "Proposed EMF mechanisms discussed include thermal effects, oxidative stress, protein structure changes, and altered ion transport.",
        "Occupational welding exposure is described as associated with deterioration of sperm parameters and increased miscarriage risk in partners.",
        "Radar-station exposure reports are described as contradictory, including both adverse and no-difference findings for sperm quality.",
        "Mobile phone/GSM-related studies are described as reporting increased ROS/oxidative stress and sperm DNA fragmentation, with animal findings also mentioned.",
        "Some studies are described as reporting beneficial effects of low-frequency magnetic fields on sperm motility and certain animal reproductive outcomes.",
        "The authors conclude that harmful, neutral, or beneficial EMF energy levels cannot currently be specified."
    ],
    "categories": [
        "Male Fertility",
        "Reproductive Health",
        "Oxidative Stress",
        "Occupational Exposure",
        "Radiofrequency (RF)",
        "Extremely Low Frequency (ELF)"
    ],
    "tags": [
        "Male Fertility",
        "Semen Parameters",
        "Sperm Motility",
        "Sperm Morphology",
        "Sperm DNA Fragmentation",
        "Oxidative Stress",
        "Reactive Oxygen Species",
        "Electromagnetic Fields",
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        "Radar Exposure",
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        "High-Voltage Installations",
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        "Systematic Review"
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    "social": {
        "tweet": "Systematic review (2015–2023) on environmental factors and male fertility reports mixed evidence for EMF: mechanisms like oxidative stress are discussed, welding exposure is linked to poorer sperm parameters, radar findings are contradictory, and mobile phone/GSM studies report ROS and DNA fragmentation—overall thresholds for harm vs neutrality remain unclear.",
        "facebook": "A systematic review of studies from 2015–2023 examines environmental factors affecting male fertility. For electromagnetic fields (EMF), the authors describe proposed mechanisms (including oxidative stress) and summarize mixed findings across sources such as welding, radar, and mobile phones, concluding that harmful vs neutral exposure levels cannot yet be clearly defined.",
        "linkedin": "This systematic review (2015–Dec 2023) evaluates environmental factors influencing male reproductive capacity. Regarding EMF, it summarizes proposed biological pathways (e.g., oxidative stress/ion transport) and reports mixed evidence across occupational (welding, radar, high-voltage work) and consumer (GSM/mobile phone) exposures, highlighting uncertainty about exposure thresholds for harm or benefit."
    }
}

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