Introduction:
Infertility and subfertility are gripping issues that are steadily rising globally. Infertility, in general, can be defined as the inability to conceive despite having unprotected sex for a year or longer. It is a grave challenge, as infertility often results in emotional and psychological distress, depression, and suffering. Despite urbanization and advancements, infertility still attracts a considerable social stigma. Studies have reported a drastic increase in the number of individuals seeking assisted reproductive treatments like in vitro fertilization and intracytoplasmic injection, thus indicating that infertility is a rising public health challenge.
What Is Infertility?
Infertility is a chronic ailment of the reproductive system. Infertility refers to a failure to attain pregnancy despite having unprotected, carefully timed sex for a year or longer. Infertility can affect males or females or both. Various factors may contribute to infertility, such as work stress, advancing age, lifestyle changes, alcohol, smoking, poor nutrition, environmental factors, and anatomical abnormalities. Infertility can be broadly categorized into two types: primary and secondary. Primary infertility is a complete inability to conceive, whereas secondary infertility is the inability to conceive after a previous pregnancy.
What is Male Infertility?
Conception is a complex process as it is governed by multifaceted factors. To achieve pregnancy, the sperm must fertilize the eggs to produce an embryo, which must be successfully implanted in the uterus. To ensure this, it is important that,
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Adequate sperms are produced.
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They are of good quality and motile so that they reach and penetrate the egg.
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The sperm produced in the testicles should be transported to the urethra for ejaculation. Hence there should be no anatomical or structural abnormalities associated with male reproductive organs.
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The egg produced must be of high quality.
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No abnormalities associated with female reproductive organs.
It is known as male infertility when the problems are associated with male factors or male reproductive organs that result in infertility. Male infertility is solely responsible for 20 % of total infertility cases and a contributing factor in another 30 %.
What Are the Factors Responsible for Male Infertility?
Male infertility can be attributed to various causes. They are as given below:
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Developmental defects of the reproductive organs.
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Medical conditions like diabetes, infections, auto-immune conditions, tumors, and cysts can result in ejaculation or sperm disorders.
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Genetic disorders could result in abnormal development of male reproductive organs.
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Varicocele (enlargement of veins in the testicles) can decrease sperm production and impair quality.
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Erectile dysfunction, painful intercourse, relationship issues, and premature ejaculation.
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Exposure to environmental toxins and chemicals could result in poor-quality sperm or decreased sperm production.
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Lifestyle factors such as smoking, alcohol, and substance abuse are very well known to reduce sperm quality and quantity.
What Is the Impact of the Environment on Male Fertility?
Environmental toxins and contaminants have been well-researched for their role in health hazards. Environmental pollution is a significant public health challenge associated with various health risks, including cardiovascular, dermatological, and respiratory illnesses. Recent studies have suggested that environmental pollution has emerged as a major cause of the increasing reproductive diseases, particularly infertility. It is proven that air pollution is a significant detrimental factor affecting sperm quality and quantity, thus majorly responsible for male infertility. Urbanization and industrial advancements have resulted in a significant rise in air pollution, which has led to roughly a 15 % rise in male infertility compared to females. Environmental pollution is largely man-made and hence modifiable, thus providing opportunities to treat infertility caused by it.
What Is Air Pollution?
Air pollution refers to the release of hazardous substances in the air that is significantly detrimental to human health and is responsible for various health hazards. Air pollution is a prime public health concern with the dramatic industrialization and urban economic development. India is considered the third most polluted country in the world.
The main sources of air pollution are:
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Factories.
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Oil refineries.
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Burning of fossils.
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Motor vehicles.
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Deforestation.
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Power plants.
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Agricultural areas.
The major air pollutants are:
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Nitrogen oxides.
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Sulfur dioxide.
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Radiation.
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Carbon monoxide.
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Polycyclic aromatic hydrocarbons (PAH).
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Volatile organic compounds.
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Particulate matter.
What Are the Effects of Air Pollution on Reproductive Health?
Air pollution has negative health effects on both the male and female reproductive systems. They can result in the following:
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Poor sperm quality.
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Reduce the motility of sperm.
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Reduce the semen quantity and quality.
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Affect sperm production.
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Affect sperm morphology.
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Decrease testosterone.
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DNA (genetic) changes in the sperm and egg.
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Poor egg quality.
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Hormonal imbalance in females.
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Reduced uterine functions.
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Disrupted egg production.
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Decreased ovulatory eggs.
The individual effects of hazardous pollutants and chemicals are as follows:
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Sulfur dioxide - Negative impact on sperm concentration and sperm motility.
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Nitrogen dioxide - Affects spermatogenesis (production of sperms), affects the semen quality, and damages sperm genetic material.
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Ozone - Reduces sperm count, alter the sperm morphology, particulate matter 2.5, alters sperm head morphology and motility, reduces sperm count, decreases semen quality, and decreases sperm concentration
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Dioxins - DNA changes, particularly during the developmental stage
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Bisphenols - Genetic sperm damage and decrease sperm motility and sperm count.
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Pesticides and herbicides - Direct spermatozoa damage, hormonal dysregulation, defective spermatogenesis, reduced sperm concentration and sperm motility, increased number of morphologically abnormal sperms and poor semen quality.
What Is the Mechanism by Which Air Pollutants Cause Male Infertility?
Though the exact mechanism is debatable, research and clinical studies have indicated certain facts that could link air pollution to male infertility. They are explained below:
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Hormonal Imbalance: The heavy metals from automobile exhaust, such as lead, copper, polyaromatic hydrocarbons, and zinc, are potent anti-estrogenic and anti-androgenic, thus impairing the homeostatic hormonal balance. Hormones are crucial in the production of sperm or ova. Hence deranged hormonal levels could result in abnormal gametogenesis, thus leading to infertility.
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Physical Obstruction: It is observed that particulate matter 2.5 can accumulate in the reproductive organs, also causing hormonal imbalance, thus resulting in infertility.
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Increased Reactive Oxygen Species: These air pollutants can cause oxidative stress in the human body, producing free radicals and reactive oxygen species, which can cause DNA fragmentation and alteration. Increased reactive oxygen species may cause genetic changes in DNA, thus leading to infertility.
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Chromosomal Abnormalities: Altered DNA synthesis could also result in changes in the genetic expression, thus causing developmental defects or defects related to spermatogenesis.
Conclusion:
To conclude, the environment is an important factor determining male fertility. Environmental pollutants can affect male reproductive health by affecting the quantity and quality of sperm. Early exposure during the developmental stage can also affect the reproductive organs. However, since the majority of these factors are modifiable and preventable, the risks can be reduced to a great extent with prompt measures. Decreasing air pollution, adopting a healthy lifestyle that will not hamper environmental wellness, and limiting or abolishing the use of environmental toxins can greatly reduce the overall incidence of male infertility.
