In 1977, men at a pesticide plant in Lathrop, California started comparing notes. Several of them couldn't conceive. When University of California researchers tested 25 exposed workers, 14 had sperm counts at or near zero. The culprit was dibromochloropropane, a soil fumigant called DBCP. The findings, published in The Lancet that year (Whorton et al., 1977), remain one of the clearest documented links between a workplace chemical and male infertility.
Most men don't handle DBCP. But that California plant established a principle that applies far beyond agriculture. The cells that make sperm are vulnerable to workplace chemical exposure, and some jobs carry more of that risk than others. If you work around paints, solvents, pesticides, metals, or plastics, the research is worth knowing.
Chemicals Don't All Harm Sperm the Same Way
Sperm production is a continuous process. Your testicles produce millions of sperm every day, which means constantly dividing cells and a constant need for precise hormonal signals. That makes the system sensitive to chemicals that interfere with hormones, damage DNA, or create oxidative stress.
Endocrine-disrupting chemicals can mimic or block testosterone and other hormones that drive sperm production. Some bind to androgen receptors. Others disrupt signals from the pituitary gland that tell the testicles what to do. A 2021 review in Frontiers in Endocrinology covered the evidence linking endocrine-disrupting chemicals to declining male reproductive health (Rodprasert, Toppari, and Virtanen, 2021).
Other chemicals act as direct testicular toxicants. They damage the Sertoli cells that support developing sperm or the Leydig cells that produce testosterone. Still others generate reactive oxygen species, molecules that damage sperm DNA and cell membranes. The end result can be lower sperm count, abnormal morphology, reduced motility, or fragmented DNA in surviving sperm.
Heavy Metals: Lead, Cadmium, Mercury
Lead is the best-documented heavy metal threat to male fertility. Battery manufacturing, smelting, construction and renovation, shooting ranges, and radiator repair all involve lead exposure. Occupational studies have consistently found lower sperm counts, higher rates of abnormal sperm, and reduced motility in men with elevated blood lead levels. Lead also appears to disrupt the hormonal axis that drives testosterone production.
Cadmium shows up in welding fumes, battery production, and metal plating. Animal studies show testicular damage at relatively low doses. Human occupational studies link cadmium exposure to reduced testosterone and poorer sperm parameters. Cadmium accumulates in the body over years, so exposure today keeps mattering later.
Mercury is a known neurotoxicant. In occupational settings, exposure comes from mining, some electronics manufacturing, and waste handling. Research links mercury exposure to sperm abnormalities and reduced fertility in some cohorts. The reproductive effects are less extensively studied than lead.
Pesticides: The DBCP Lesson and What Followed
DBCP was banned in the United States in 1979 after the Lathrop findings. It wasn't an isolated case. Organophosphate pesticides, the class that includes chlorpyrifos and diazinon, are still widely used in agriculture and pest control. Agricultural workers exposed to organophosphates show reduced sperm concentration, abnormal morphology, and increased sperm DNA damage in occupational studies. The mechanism involves oxidative stress and disruption of the hormonal signals that regulate sperm production.
Glyphosate, the active ingredient in Roundup, has produced conflicting data. Some in vitro and animal studies suggest it can damage sperm at high doses. Human occupational studies are limited and results are mixed. Enough evidence exists to justify caution in occupational settings, not enough to make definitive fertility claims.
Solvents: Paint, Inks, and Cleaning Products
Glycol ethers, used in paints, inks, electronics manufacturing, and industrial cleaning, carry some of the strongest occupational links to reduced male fertility after DBCP. Studies of shipyard painters, semiconductor workers, and printing press operators found reduced sperm counts and altered testicular function linked to glycol ether exposure, particularly older formulations like 2-methoxyethanol and 2-ethoxyethanol. Many industrial users have moved to safer alternatives, but older products and some imported goods still contain these solvents.
Benzene, toluene, and xylene, the aromatic solvents found in petrochemicals, paints, and printing, have also been associated with sperm abnormalities in occupational cohorts. Benzene is a known hematotoxicant. Mechanics, gas station workers, and refinery staff have been studied for reproductive effects. The evidence for benzene's effect on sperm quality is consistent enough that many occupational health guidelines treat it as a reproductive hazard.
Plastics Chemistry: Phthalates and Bisphenols
Phthalates are plasticizers used to make PVC flexible. They show up in vinyl flooring, cables, hoses, some industrial coatings, and certain manufacturing processes. Phthalate metabolites are measurable in the urine of almost everyone, but occupational exposure through manufacturing and handling can push levels higher. Studies link higher phthalate metabolite levels to reduced sperm concentration and motility. The 2021 Frontiers in Endocrinology review counts phthalates among the endocrine disruptors with the most consistent evidence for male reproductive effects.
Bisphenol A, or BPA, is used in epoxy resins, some plastics, and thermal receipt paper. Cashiers and workers who handle coated papers can absorb BPA through the skin. A 2024 meta-analysis in Toxics found an association between higher BPA exposure and lower sperm concentration (Lu et al., 2024). The effect sizes are modest in most studies. The consistency across different cohorts is the notable part.
PFAS: The Persistent Ones
PFAS are a family of fluorinated compounds used in firefighting foam, non-stick coatings, water-repellent treatments, and some industrial processes. People call them forever chemicals because they break down very slowly in the body and environment. Firefighters, chemical plant workers, and textile coating workers carry higher serum PFAS levels than the general population. Research associates PFAS exposure with reduced sperm quality, altered testosterone levels, and longer time to pregnancy in some cohorts. The 2021 Frontiers in Endocrinology review included PFAS among the endocrine disruptors of concern. This is emerging research. The human fertility data are still building, with more consistent evidence for some PFAS compounds than others.
PAHs: Combustion Byproducts
Polycyclic aromatic hydrocarbons form when organic material burns incompletely. Welding, asphalt paving, firefighting, coke oven work, and diesel engine maintenance all involve PAH exposure. PAHs absorb through the skin and lungs, and some metabolites have been found in seminal fluid. Occupational studies of welders and coke oven workers find higher rates of sperm DNA damage, and some find reduced sperm counts. The DNA damage matters because sperm with fragmented DNA can still fertilize an egg but may lead to failed implantation or miscarriage.
How Exposure Happens
- Inhalation is the biggest route for volatile solvents, fumes, and dusts.
- Skin absorption matters more than most people assume for solvents and pesticides. Once absorbed through skin, these compounds enter the bloodstream the same way as if inhaled.
- Ingestion happens through poor hygiene, eating with contaminated hands, or smoking a cigarette that has picked up dust.
Skin permeability varies by body site. Research from the 1970s showed that scrotal skin absorbs compounds far more readily than the forearm and sits near the top of the range across body sites (Maibach et al., 1971). That matters for men who sit on contaminated surfaces or carry residues in clothing.
Take-home exposure is a separate problem. Lead dust, pesticide residues, and metal particles ride home on work clothes, boots, and skin. Partners and children get exposed through the laundry, the car, and the house. For men trying to conceive, keeping the work environment at work is part of the picture.
What the Evidence Does and Does Not Show
None of this means that working with one of these chemicals guarantees fertility problems. Most findings come from occupational cohort studies that compare exposed workers to unexposed controls. Those studies are observational. They show associations, not proven cause and effect. Shift work, heat, stress, smoking, and other lifestyle factors cluster with certain jobs, which can muddy the picture. Dose and duration matter enormously. Short, low-level exposures produce different outcomes than years of daily contact.
The strongest evidence, where researchers see consistent effects across multiple studies and a dose-response relationship, sits with DBCP, glycol ethers, lead, and some phthalates. The evidence for glyphosate, PFAS, and BPA is real but younger, with more mixed results.
What You Can Do
- Know what you handle. Request Safety Data Sheets from your employer and look for reproductive hazard warnings. The European hazard code H360 signals reproductive toxicity. Many US manufacturers use similar wording on SDS documents.
- Use the controls that already exist. Local exhaust ventilation, enclosed processes, and respirators reduce inhaled dose. The right gloves reduce skin absorption, but glove material matters: some chemicals pass through nitrile or latex quickly. Match the glove to the chemical.
- Change out of work clothes before leaving the site when possible. Wash work clothes separately. Keep work boots out of living areas. Shower at work if you can.
- Wash your hands before eating, drinking, or smoking. A surprising amount of exposure happens through the hand-to-mouth route.
- If you and a partner are trying to conceive and you work in a higher-exposure role, an occupational health physician can discuss whether a semen analysis makes sense for you. Many exposed men produce normal results. Knowing your baseline gives you information.
Consult a doctor for any personal concerns about fertility or hormone levels. This post is educational context, not individual medical advice.
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.