Male Infertility Related to Stress and Job-Related Factors
The effects of STRESS on male fertility potential
Trying to have a child is often a stressful and emotional time. Many men also have significant stress associated with their job or other life situations. Stress can certainly impact sexual function in a negative manner. Studies have also shown that stress can also impact fertility in men as well (though typically to a lesser degree than the potential impact on women’s fertility/ovulation). Stress and depression in some men has been shown to decrease the responsiveness of the pituitary gland to GnRH stimulation thereby decreasing the release of LH and FSH which can lead to hypogonadism. [Schweiger U. PsychosomMed 1999]. Decreased testosterone levels have been found in men with elevated levels of stress. [Nargund VH. NatRevUrol 2015] Studies have shown that men self-perceived elevations in job-related stress were found to have lower semen parameters including counts and motility. [Bigelow PL. FertSteril 1998][Zou P. JPsychosomRes 2019][Nordkap L. Andrology 2020]
A study performed in 2010 of 950 men trying to have a child showed that 2 or more stress events of either the man or his spouse (e.g. job loss, serious illness, serious legal/financial/relationship problem, etc.) was associated with a 1.54 to 2 times increased risk of having abnormalities of sperm counts, motility, or morphology. (Gollenberg AL. FertSter 93, 2010)
The medications also used to treat job-related stress and depression have also been linked in some studies to abnormal semen parameters and ejaculatory dysfunction. [Brezina PR. JReprodInfertil 2012]
Potential strategies for dealing with stress include:
1) Exercise
2) Healthy eating/lifestyle
3) Relaxation strategies such as meditation and yoga
4) Counseling (personal or couples counseling)
JOB-RELATED FERTILITY FACTORS and their impact on sperm quality
JOBS WITH INCREASED HEAT EXPOSURE
Elevated levels of heat are known to be potentially detrimental to sperm production. Many jobs have been associated with elevated levels of scrotal temperatures, including jobs which are associated with prolonged sitting (e.g. professional drivers and computer programmers). Other jobs with increased heat exposure include chefs, bakers, and ceramic oven operators. The impact of elevated scrotal temperatures on fertility are reviewed further in the “Heat” section of this website.
OCCUPATIONAL EXPOSURE TO TOXIC CHEMICALS
According to the National Institute for Occupational Safety and Health (NIOSH), over 1000 chemicals used in the workplace have been associated with reproductive side effects in animals, though human studies are lacking for most. An additional 4 million other commercially used chemical mixtures have not been studied at all.
Men can be exposed to chemical toxins during work in several ways, including:
1) Direct exposure to heavy metals
2) Oil industry chemicals
3) Pesticide exposure in agriculture
4) Air pollution exposure
5) Other chemicals that can impact male fertility
Direct Exposure to Heavy Metals
Heavy metal exposure has been found to have a negative impact on sperm production in multiple studies. [Sharma R. ReprodBioEndocrinol 2013]. Examples include:
a) Lead- decreased fertility in men and hormone disruption
b) Mercury- disruption of spermatogenesis
c) Boron- hormonal abnormalities and lower semen parameters
d) Cadmium- testicular toxicity in mice
Exposure to these chemicals is possible in multiple industries. Lead is used in the production of batteries, while men working in fluorescent light bulb recycling can have exposure to mercury. Cadmium is often found with copper and zinc, and therefore men working in the mining industry can have exposure to this heavy metal. Boron is part of the production process of glass, soaps, and carpets.
Some particular jobs have been associated with an increased risk of chemical/heavy metal exposure. Welders are known to come into contact with heavy metals through the inspiration of solder vapors, and decreased semen parameters have been associated with men in this profession. [Younglai EV. HumReprodUpdate 2005]. Painters can also be exposed to lead through the use of lead-based paints.
Oil Industry Chemicals
Workers in the oil and natural gas extraction industry are known to come into contact with elevated levels of chemicals including benzene metabolites which can be damaging to sperm. Studies have shown that workers in conventional oil and gas extraction have about a 25% decrease in sperm counts and motility. [Balise VD. FertSteril 2016]. Though not as well studied, there are concerns that workers in the fracking industry may be at an even higher risk of fertility problems since this process involves the use of even more endocrine-disrupting chemicals.
Pesticides (including herbicides and fungicides)
There have been estimated to be over 1800 pesticides currently used in the United States, and many of these have been found to be able to cross the blood-testis barrier and have endocrine-disrupting activity as well as a direct toxic effect on spermatogenic cells. [Perry MJ. HumReprodUpdate 2008] Commonly used agents include organochlorides, organophosphates, carbamates, phenoxy acetic acids, and pyrethroids. [Sungupta P. HumExpToxicol 2013]. Exposure to pesticides can come through the manufacturing of the agents and well as agricultural work (including home gardening as well).
A literature review in 2008 looked at 20 studies of work-related chronic exposure to pesticides and 13 of these found the exposed workers to have significant decreases in their semen parameters. [Perry MJ. HumReprodUpdate 2008] In addition 3 of 6 studies found increases in sperm DNA fragmentation and 4 of 6 showed increased rates of sperm aneuploidy.
Air Pollution
Air pollution has multiple components which can be detrimental to both a man’s fertility and general health, including sulfur dioxide, carbon monoxide, nitrogen dioxide, and particulate matter. [Sharma R. ReprodBiolEndocrinol 2013]. A review of 17 studies on the topic showed that in addition to an increased risk of cardiovascular and respiratory problems, increased exposure to air pollution can decrease sperm density, motility, and morphology as well as an increased level of sperm DNA fragmentation. [Lafuente R. FertSteril 2016]. The use of N95 masks have been found to be effective in preventing the inhalation of a significant proportion of the particles related to air pollution. Examples of jobs with increased potential exposure to air pollution include toll booth workers as well as police officers.
Other Chemicals That Can Negatively Impact Male Fertility
1) Polychlorinated Biphenyls (PCBs)- Though their use is now banned in most countries, PBCs were utilized widely in the past for the manufacture of many products including capacitors, electric motors, and transformers. Exposure has been associated with decreased semen parameters as well as increased sperm DNA damage. [Meeker JD. SystBiolReprodMed 2010]
2) Industrial solvents (e.g. carbon disulfide)- examples: paints, varnishes, lacquers, adhesives, glues, degreasers, cleaning agents. Used in the production of dyes, polymers, plastics, textiles, printing inks, agricultural products. Exposure can lead to hormonal changes and decreases in semen quality in some men.
3) Bisphenyl-A (BPA)- Used in the production of plastics, canned food liners, and thermal receipts. Worries about BPA leaching into liquids contained in plastic bottles led the FDA to ban the use of this product the manufacture of baby bottles in 2012. BPA is a known endocrine disruptor and increased urinary levels of BPA in the urine have been shown to negatively correlated with semen parameters. [Minguez-Alarcan L. FertSteril 2016]. Also, replacement bisphenols developed after the BPA ban have similar biologic activity as BPA and may also have potentially detrimental effects on male fertility as well. [Sartain CV. FertSteril 2016]. Other endocrine-disrupting agents which have been associated with a negative impact on male fertility include phthalates, pesticides and PFAS (perfluoroalkyl an polyfluoroalkyl substances). [Minguez-Alarcon L. FertSteril 2023]
4) Parabens- Parabens are chemicals used extensively in the production of toothpaste, sunscreen, shampoo, hand soap, lotions, and some foods due to their cheap cost and low toxicity profile. They can be absorbed into the body through the skin as well as through ingestion. Studies have shown possible endocrine disruption activity and increased urinary levels have been associated with decreases in sperm motility and morphology. [Jurewicz J. JOccupEnvironMed 2017]
Management of Job-Related Fertility Factors
Work-related fertility factors can sometimes be difficult to manage, as most men cannot just take off 10 weeks of work and see if their semen parameters improve. Some factors, such as increased heat exposure, can be addressed through the wearing of looser (boxer) underwear to allow the body’s natural cooling mechanisms to work properly. Exposure to work-related chemicals can be more challenging to overcome.
The NIOSH (National Institute for Occupational Safety and Health) lists the following recommendations for limiting potential toxic exposure to workplace chemicals:
a) Store chemicals in sealed containers when not in use
b) Wash hands before eating, drinking, and smoking
c) Avoid skin contact with chemicals
d) If chemicals contact the skin, follow the directions for washing provided in the
material safety data sheet (MSDS).
e) Become familiar with the potential reproductive hazards used in your workplace.
f) To prevent home contamination:
i. Change out of contaminated clothing and wash with soap and water before
going home
ii. Store street clothes in a separate area of the workplace to prevent contamination
iii. Wash work clothing separately from other laundry (at work, if possible)
iv. Avoid bringing contaminated clothing or other objects home.
g. Participate in all safety and health education, training, and monitoring programs
offered by your employer.
h. Learn about proper work practices, engineering controls, and personal protective
equipment (i.e. gloves, respirators, and personal protective clothing) that can be
used to minimize exposures to hazardous substances.
i. Follow the safety and health work practices and procedures implemented by your
employer to prevent exposures to reproductive hazards in the workplace.