Some occupations and exposures can reduce male fertility. Heat is the factor most men overlook. Sperm production needs the testicles a few degrees below core body temperature. Anything that traps heat against the scrotum can push sperm count and shape in the wrong direction. Many of these effects are reversible once the exposure stops.
Heat exposure on the job
A 2013 study by Garolla and colleagues in Human Reproduction found that sauna-level heat temporarily lowered sperm count and worsened sperm morphology in healthy men. The effect reversed after the heat exposure stopped. An earlier study by Shefi and colleagues in Fertility and Sterility showed the same pattern: when men stopped the wet heat exposure, their semen parameters recovered.
That biological backdrop matters for occupations that keep the pelvic area warm for hours. Welders, foundry workers, commercial kitchen staff, firefighters, and long-haul drivers all spend long stretches in heated environments. Some of those jobs also involve extended sitting, which raises scrotal temperature on its own. Jung and colleagues measured higher scrotal temperatures during sitting compared to standing or walking in a 2005 Human Reproduction study. Mieusset and colleagues reported similar findings in the Journal of Andrology in 2007.
A laptop resting on the lap adds a direct heat source. Sheynkin and colleagues found in Human Reproduction in 2005 that laptop use raised scrotal temperature. Clothing matters too. A 2018 cohort study by Minguez-Alarcon and colleagues in Human Reproduction found that men who reported wearing looser, boxer-style underwear had higher sperm concentration and total count than men who wore tighter styles. That is an association, not a randomized trial, but it lines up with the temperature research.
Chemical exposures at work
Heat is relatively easy to understand. Chemicals are messier because some act as endocrine disruptors. They interfere with the hormone signals that drive sperm production. A 2021 review by Rodprasert, Toppari, and Virtanen in Frontiers in Endocrinology summarized research on endocrine-disrupting chemicals and male reproductive health. The strongest signals come from phthalates, bisphenols like BPA, certain pesticides, and heavy metals including lead and cadmium.
A 2024 meta-analysis in the journal Toxics reported an association between BPA exposure and poorer sperm parameters. The pooled data pointed in a consistent direction without proving that BPA caused a specific man's fertility problem. Observational research shows associations, not cause and effect.
Jobs that involve regular contact with solvents, paints, pesticides, plastics, or industrial metals tend to carry more of these exposures. Agricultural work, painting and coating, plastics manufacturing, printing, and metalworking are examples. The actual risk depends on ventilation, protective equipment, and how well a workplace follows safety protocols. A man who paints indoors with no mask and no airflow has a very different exposure than a man who paints with proper controls.
Microplastics have been found in human testicular tissue and semen. Zhao and colleagues detected them in testis and semen samples, published in Science of the Total Environment in 2023. Li and colleagues found them in every seminal fluid sample they examined in a 2024 study. Hu and colleagues detected microplastics in human and dog testes in Toxicological Sciences in 2024. A multi-site study by Zhang and colleagues in eBioMedicine in 2024 found an association between mixed microplastic exposure and poorer sperm parameters in regression models.
What those studies do not show is cause and effect. They also do not trace the particles to clothing or any single source. Microplastics are now inside the human body, including reproductive tissue, but the link to reduced fertility remains an active research area, not settled science.
How long changes take to show up
Sperm production runs on a cycle of roughly 74 days. A semen sample today reflects conditions from two to three months ago. If you remove a heat or chemical exposure, improvements may not show up on a test for several months. That is normal. Men sometimes remove an exposure, take a test two weeks later, and feel discouraged when nothing changed. The biology does not move that fast.
What men can do
You cannot quit every job because of a potential fertility risk. You can reduce the exposures that matter most while you keep working.
- In a hot job, take breaks in a cooler area when possible.
- If you sit for long stretches, stand up and walk periodically.
- Avoid resting a laptop directly on your lap for extended periods.
- Choose underwear that fits loosely enough to let air move instead of trapping heat.
- Use the gloves, respirator, and ventilation your employer provides around chemicals.
- Wash your hands before eating and change out of work clothes before leaving the job site.
If you are actively trying to conceive and concerned, a semen analysis gives you a baseline. Talk to a doctor who specializes in male fertility. Some men also choose to reduce sauna use and hot baths while trying, but that is a personal decision to discuss with a healthcare professional.
The research base supports taking heat and certain chemical exposures seriously for male reproductive health. The same research shows that many heat-related effects reverse once the exposure stops. Identify the exposures in your own day, reduce the ones you can control, and get professional guidance if you have specific concerns.
This content is for educational purposes only and is not medical advice. Oakman products are designed for physical comfort and cooling. They make no claims about fertility, sperm quality, or hormone levels. Consult a healthcare professional for personalized advice.