Do Paper Mills Cause Cancer? The Evidence Explained

Working in a paper mill does appear to raise the risk of several types of cancer, though the picture is complicated and the size of the risk varies dramatically depending on the specific job, the chemical exposures involved, and how long someone worked there. Decades of occupational health research have linked pulp and paper mill employment to elevated rates of lung, intestinal, and certain rarer cancers, but the evidence is strongest for particular exposures like sulfur dioxide, mineral dusts, and asbestos rather than for the industry as a blanket hazard. The story is less about paper itself and more about what goes into making it.

Lung Cancer and the Workers Most at Risk

Lung cancer is the most studied cancer in paper mill research, and the findings paint a mixed but concerning picture. A broad review of the literature found that while an increased risk for lung cancer among pulp and paper mill workers has been reported across multiple studies, most of those studies could not pin down the specific cause. One group consistently stood out: maintenance workers, who showed higher rates of both lung cancer and malignant mesothelioma, pointing strongly toward asbestos exposure from insulation and equipment repair.¹ Workers exposed to chlorine compounds also appeared to carry a higher lung cancer risk.

Sulfur dioxide, a byproduct of the kraft and sulfite pulping processes, has drawn particular attention. A large study of workers exposed to SO₂ found that after adjusting for other workplace chemical exposures, the lung cancer risk among exposed workers was roughly 50 percent higher than among unexposed workers. There was also a dose-response pattern: the more cumulative SO₂ exposure a worker had, the higher the lung cancer mortality tended to be.² The researchers acknowledged that residual confounding from smoking or other unmeasured factors could not be fully ruled out, but the trend was statistically significant and hard to dismiss.

Dust exposure adds another layer. A case-control study nested within a pulp and paper mill workforce found that exposure to inorganic dusts like kaolin, lime, cement, and brick dust carried a fourfold increase in lung cancer risk after adjusting for smoking habits. That association showed a clear dose-response pattern. Organic dusts, including wood dust, showed a roughly doubled risk, though that result did not reach statistical significance and lacked the same dose-response relationship.³

Cancers Beyond the Lungs

The research extends well past the respiratory system. A Swedish cohort study of soft paper mill workers who had spent more than a decade in high-exposure jobs found significantly elevated rates of colon cancer, small intestine cancer, thyroid cancer, and lung cancer. The colon cancer incidence was about 66 percent higher than expected, and small intestine cancer was more than three times the expected rate.⁴ That same study found something interesting among the lower-exposed workers: they had elevated rates of connective tissue sarcomas and pleural mesothelioma, the latter being a strong marker of past asbestos exposure regardless of exposure duration.

A long-running cohort study from British Columbia told a broadly similar story from a different angle. Among workers with 15 or more years in pulp and paper mills, significantly elevated rates appeared for pleural cancer, prostate cancer, and skin melanoma across the entire cohort. When broken down by process type, workers in the sulfite process had elevated rectal cancer, while those who worked in both kraft and sulfite operations showed excess stomach cancer, prostate cancer, and leukemias.⁵ The diversity of cancer sites across these studies suggests that no single chemical agent is responsible. Instead, the mixture of exposures in different mill departments seems to create a patchwork of risks.

Bladder Cancer and the Paper Industry

One cancer that sometimes gets overlooked in discussions of occupational hazards is bladder cancer. A population-based study in Ontario found that the paper and publishing industry had a statistically significant increase in bladder cancer rates.⁶ Bladder cancer is well known to be sensitive to chemical exposures since the bladder concentrates and stores urine, giving carcinogenic metabolites prolonged contact with the bladder lining. The specific agents driving this link in paper mills have not been isolated as cleanly as, say, aromatic amines in the dye industry, but the statistical association adds to the broader picture of a workplace with multiple cancer-relevant exposures.

Wood Dust and Nasal Cancers

Wood dust occupies a specific and dramatic niche in the paper mill cancer story. The International Agency for Research on Cancer has long classified wood dust as carcinogenic to humans, and the evidence is particularly stark for cancers of the nasal passages and sinuses. A large epidemiological study found that workers in the wood and paper industry had nearly a 12-fold increased risk of nasal adenocarcinoma. Among furniture and cabinet makers, the odds ratio was astronomical, but even within the broader wood and paper sector, the risk was substantial and clearly tied to high-level dust exposure.⁷

In practice, most of this risk falls on workers who handle raw wood at the earliest stages of the pulping process, where sawing, chipping, and debarking generate clouds of fine particles. A study of soft paper mills attempted to investigate whether the processed paper dust further downstream also increased sinonasal cancer risk. The standardized incidence ratio was elevated, at about 1.7 to 1.9 times expected, but with only five cases total, the numbers were too small to draw firm conclusions.⁸ Sinonasal cancer is rare to begin with, so even a genuinely elevated risk produces very few cases in any single workplace study. The signal is there, but the statistical power is not.

Organochlorines and the Chlorine Bleaching Question

For decades, one of the biggest concerns about pulp mills was the use of elemental chlorine to bleach wood pulp. This process generated dioxins and other organochlorine compounds that contaminated both the workplace air and the mill’s wastewater. Given that dioxins are potent carcinogens at high doses, the worry was reasonable. But the largest study to date on this question found something that surprised many observers.

An international collaborative study pooling data from multiple countries found that workers exposed to volatile organochlorines actually had lower overall cancer mortality than the general population, with about a 7 percent deficit. No excess risk was found for most cancers of primary concern. The one exception was Hodgkin disease, which was elevated by about 76 percent among workers exposed to non-volatile organochlorines.⁹ There was also a weak but statistically significant trend of increasing overall cancer mortality with increasing cumulative volatile organochlorine exposure, which keeps the door open to a real effect at higher or longer-duration exposures.

That overall cancer deficit is a common finding in occupational studies and is usually attributed to what epidemiologists call the healthy worker effect: employed people tend to be healthier than the general population simply because seriously ill people leave the workforce. It does not mean the job is protective. It means the comparison group is less healthy on average. Still, the absence of a dramatic cancer spike from organochlorine exposure at the levels found in pulp mills was reassuring relative to the worst fears. Most of the industry has since moved to chlorine dioxide or totally chlorine-free bleaching methods, substantially reducing organochlorine formation.

Cancer Risks for Women in Paper Mills

Most paper mill cancer research has focused on male workers, partly because men historically made up the vast majority of the workforce. The studies that have looked specifically at women, though, have flagged some concerning patterns.

A cohort study from Catalonia found that female paper mill workers had an overall cancer mortality rate about 68 percent higher than expected. Large intestine cancer was elevated in both sexes, with a standardized mortality ratio roughly 2.5 times the expected rate and climbing to about 3.5 times expected after 10 or more years of employment. Breast cancer among female workers was elevated nearly threefold, though with only four deaths, the confidence interval was wide.¹⁰

A much larger Norwegian study looked at cancer incidence rather than mortality among women in pulp and paper mills and found a 50 percent excess risk of ovarian cancer. The elevated risk was highest among women under 55 and was concentrated among those working in paper departments specifically.¹¹ The specific agents driving the ovarian cancer association remain unclear, but some researchers have speculated about exposure to hormone-disrupting chemicals in the workplace environment. These findings are worth watching as the proportion of women in industrial settings continues to grow and longer follow-up data become available.

Recycled Paper Operations

Paper recycling plants are a distinct work environment from virgin pulp mills, with their own set of chemical exposures. The de-inking process that removes printed inks from recovered paper involves solvents, surfactants, and heat that can release volatile compounds. A study of cancer among paper recycling workers found a striking excess of pharyngeal cancer among men, at more than three times the expected rate. Lung cancer was slightly elevated among male production workers, and Hodgkin’s disease was roughly doubled, though the latter finding was based on only four cases and did not reach statistical significance.¹²

The pharyngeal cancer finding is particularly interesting because this cancer is uncommon enough that a threefold excess is hard to attribute to chance, and it could plausibly be linked to inhalation of de-inking chemicals or aerosolized paper particles contaminated with ink residues. This remains an understudied corner of occupational health, in part because recycling workers are a smaller and more dispersed workforce than those in large pulp and paper mills, making it harder to assemble cohorts large enough for definitive conclusions.

Living Near a Paper Mill

If the cancer risks for workers are nuanced and exposure-dependent, the question for people living near paper mills is even harder to answer clearly. Anyone who has driven past a pulp mill knows the unmistakable sulfurous smell, and it is natural to wonder whether that odor signals a cancer risk for surrounding communities.

A study that measured volatile organic compounds and sulfur compounds in ambient air near a paper mill in rural Idaho provides some reassurance on this front. The calculated cancer risk from measured carcinogens, primarily benzene, came out to roughly 2 to 11 extra cancers per million people exposed over a lifetime. That is below the national average ambient cancer risk in the United States, though still above natural background levels. The benzene exposure near the mill was comparable to levels found in nearby cities like Boise, suggesting that the mill was not the dominant source. The overall risk of non-cancer health effects was also assessed as low.¹³

One study near one mill does not settle the question for every community. Older mills with less pollution control technology, or mills using different pulping processes, might produce different results. And air quality is only one route of community exposure. Mill effluent discharged into waterways has historically been another concern, particularly when chlorine bleaching was standard practice. Modern regulatory limits on both air emissions and water discharge have substantially tightened since the era when the most alarming occupational studies were conducted.

Why the Picture Is So Messy

Anyone hoping for a clean, single-sentence answer about paper mills and cancer will be frustrated by the research. There are good reasons the evidence looks like a mosaic rather than a mural. Paper mills are not one uniform workplace. A modern tissue paper converting plant shares almost nothing, in terms of chemical exposure, with a 1970s kraft pulp mill that bleached with elemental chlorine. Even within a single mill, the woodyard, the digester room, the bleach plant, the paper machine, and the maintenance shop expose workers to completely different hazards. Studies that lump all these workers together dilute real risks for specific groups into the statistical noise of the whole workforce.

Smoking is the elephant in every room where lung cancer is discussed. Many of the older studies lacked detailed individual smoking data, leaving open the possibility that higher smoking rates among blue-collar mill workers explained part or all of the lung cancer excess. The SO₂ study mentioned earlier is notable precisely because it tried to adjust for other occupational exposures and still found an elevated risk, but even there, the researchers could not rule out residual confounding from lifestyle factors.²

The healthy worker effect compounds the confusion. Because employed people are healthier than the general population on average, studies comparing mill workers to the general public tend to underestimate occupational risks. Several of the large cohort studies showed lower-than-expected overall mortality and even lower-than-expected overall cancer mortality, even while specific cancer types were clearly elevated. Without that baseline deficit masking the signal, the true excess risks for specific cancers might be even larger than reported.

What Has Changed in Modern Mills

Much of the most alarming research draws on workers who were employed in the 1960s through the 1980s, when chemical controls and personal protective equipment were far less rigorous than they are today. Several of the most significant exposure hazards have been substantially reduced or eliminated in modern operations. Elemental chlorine bleaching, which generated the dioxins and organochlorines that fueled decades of concern, has been almost entirely replaced by chlorine dioxide or totally chlorine-free processes in developed countries. Asbestos insulation, the likely driver of the mesothelioma and excess lung cancer seen in maintenance workers, has been removed or encapsulated in most facilities.

Sulfur dioxide scrubbing and enclosed chemical recovery systems have reduced SO₂ exposure in kraft mills. Dust collection and ventilation in woodrooms and paper machine areas have improved. But “reduced” is not “eliminated,” and paper manufacturing will always involve some level of chemical exposure. Newer hazards may also be emerging as the industry adopts different raw materials, recycled feedstocks, and novel chemical additives whose long-term health effects are less well characterized. The cancer latency period for most solid tumors is 15 to 30 years, which means the full consequences of today’s exposure levels will not show up in the epidemiological literature until the 2040s or later.

For current workers, the practical takeaway is that job-specific exposure matters more than whether you work in a paper mill in some general sense. Maintenance roles with historical asbestos exposure, woodyard jobs with heavy dust, and positions involving direct contact with process chemicals carry the most documented risk. Respiratory protection, exposure monitoring, and adherence to ventilation standards are not just bureaucratic checkboxes in this industry. They are the specific tools that stand between you and the kinds of exposures that the research has linked to disease.