PCBs and Cancer: Are PCBs Carcinogenic?

Polychlorinated Biphenyls (PCBs) and Cancer

Scientific studies have found that exposure to polychlorinated biphenyls (PCBs) results in an increased risk for certain types of cancer.

Research indicates that PCBs, classified by the International Agency for Research on Cancer (IARC) as Group 1 carcinogens, are definitively linked to an increased risk of cancer in humans.

The mechanism behind PCBs’ carcinogenicity is thought to involve their ability to disrupt cellular processes, induce oxidative stress, and alter gene expression related to cell growth and differentiation.

Long-term exposure to PCBs, even at low levels, can accumulate in the body over time, leading to an elevated risk of developing cancer.

Construction materials and old fluorescent lighting fixtures in school buildings can be a consistent source of exposure to PCBs.

Occupational exposure in industries such as electrical repair, manufacturing, and waste disposal significantly increases the risk of cancer among workers.

Environmental exposure through contaminated food, air, and water also contributes to the population’s overall cancer risk associated with PCBs.

Preventative measures, including cleanup of contaminated sites and reduction of exposure in at-risk populations, are critical to mitigating the carcinogenic impact of PCBs on public health.

Mechanisms of Carcinogenesis: How PCBs Cause Cancer

The ways that PCBs induce carcinogenesis are complex and multifaceted.

Based on a publication by the International Agency for Research on Cancer (IARC), PCBs cause cancer through two mechanisms.

The first process is oxidative stress;

According to the IARC, PCBs are easily oxidized inside an organism.

Once PCBs oxidize, they become biphenyl free radicals that circulate.

These free radicals, or roaming harmful chemicals in the body, become DNA lesions that cause tissues to mutate.

The byproducts of biphenyl metabolism result in fatty acid mutations, contributing further to cancerous growth.

The other process seen by the IARC is cellular toxicity.

Whenever cells are exposed to PCBs, the PCBs accumulate in the cells until the concentrations reach toxic levels.

This is when cellular processes become affected.

With disruptions in crucial cellular processes, a body becomes an environment for uncontrolled cell growth and the formation of tumors.

The IARC discovered these among other carcinogenic mechanisms from reviewing various in vivo and in vitro animal studies.

The IARC also cited various experimental animal studies where laboratory animals were exposed to PCBs and examined for cancer growth.

The Agency for Toxic Substances and Disease Registry (ATSDR) also reported how PCBs can become carcinogenic.

According to the ATSDR, metabolized PCBs turn into phenols, which further mutate into chemicals called catechols.

Catechols then attach to essential proteins and DNA.

The attachment process damages the proteins and DNA, causing a cascade of repair processes that lead to abnormal cellular growth.

Both the IARC and ATSDR recognize the carcinogenicity of PCBs.

The Types of Cancer Linked to PCB Exposures

As cancer-causing chemicals, PCBs have led to various types of cancer in humans.

Several studies have been done to determine the prevalent forms of cancer caused by exposure to PCBs.

The following cancers are potentially linked to PCB exposure:

• Liver cancer
• Breast cancer
• Malignant melanoma
• Gastric cancer
• Intestinal cancer
• Thyroid cancer
• Non-Hodgkin’s lymphoma
• Brain cancer
• Lung cancer
• Pancreatic cancer
• Prostate cancer
• Soft tissue sarcoma
• Testicular cancer

Liver Cancer

Liver cancer may be associated with PCB exposure and has been extensively studied in relation to prolonged exposure.

PCBs — once absorbed into the body — accumulate in the liver, causing chronic inflammation and triggering the development of malignant tumors.

Studies have consistently revealed a higher incidence of liver cancer among individuals exposed to elevated levels of PCBs over extended periods.

One cohort study looked into the prevalence of liver damage and cancer among workers.

The study included 544 male and 1,556 female workers exposed to PCBs in factories making PCB capacitors.

The study found that those exposed to PCBs in the study developed extensive liver damage as shown by high serum PCB levels.

Other workers exposed to PCBs developed liver cancer.

Breast Cancer

PCB exposure has also been associated with increased breast cancer risk.

Most researchers attribute the correlation to how PCBs remain in body fat since breasts have high body fat concentrations.

Several studies suggest a link between breast cancer risk and PCB exposure.

One of these studies was published in 2020 and highlighted how PCB exposure resulted in short-term breast cancer development and mortality.

The study included nearly 700 North Carolina women diagnosed with invasive breast cancer The researchers found that nearly all who were diagnosed were exposed to PCBs at some point.

Another study published by the Public Health Institute looked into breast cancer risk and PCB exposure, finding that women exposed to PCBs were at an increased risk of breast cancer when exposure occurred during reproductive years.

Malignant Melanoma

Emerging research has indicated a potential link between PCB exposure and malignant melanoma, a severe form of skin cancer.

PCBs can be absorbed through the skin upon direct exposure, or other routes like eating contaminated fish, breathing air or touching surfaces contaminated by PCBs within buildings, and more.

As PCBs come into contact with the skin, they can disrupt the skin’s natural defense mechanisms, making it susceptible to the development of malignant melanocytes.

Malignant melanoma is the result of several risk factors, including prolonged UV exposure.

For this reason, one case-control study examined melanoma risk in individuals with high PCB levels in the blood.

To further rule out UV exposure, the researchers ensured that the study’s cohort wasn’t exposed to the sun for long periods.

By the end of the study, the researchers found an association between melanoma risk and PCB exposure.

Due to the controls placed on other variables like sun exposure and sun sensitivity, the findings suggest PCB exposure as a major contributor to skin cancer risk.

Stomach Cancer

Research indicates that PCBs can lead to chronic inflammation of the stomach lining, which can escalate the risk of cancerous growth.

Stomach cancer occurs through various routes of exposure.

Besides eating PCB-contaminated fish or other PCB-contaminated food, the main route of exposure for stomach cancer is occupational exposure.

A longitudinal study pointed to increased stomach cancer risk and cumulative exposure.

The study followed 24,865 capacitor-manufacturing workers for 10 years.

Throughout the study’s duration, the workers were assessed for cumulative exposure to PCBs.

Most of those exposed for prolonged periods developed early-stage stomach cancer.

This finding suggests a correlation between gastric cancer and PCB exposure.

Intestinal Cancer

PCBs are known for their persistence in the human body and have been detected in intestinal tissues.

The presence of PCBs in intestinal tissue indicates a direct interaction with the gastrointestinal system.

This interaction can disrupt the normal cellular processes, potentially leading to inflammation in the intestines.

If left unchecked, the inflammation can progress to cancerous lesions in the intestines.

Several studies suggest a correlation between PCB ingestion and intestinal cancer risk.

According to the Centers for Disease Control and Prevention, PCBs can irritate the lining of the gastrointestinal tract.

With prolonged exposure via ingestion of contaminated food, cancerous growths can develop in the intestine and rectum.

Thyroid Cancer

PCBs have long been associated with thyroid damage and cancer.

PCBs can interfere with the delicate balance of thyroid hormones, leading to abnormal growth of thyroid cells and the formation of tumors.

Various animal studies and epidemiological studies provide compelling evidence linking thyroid cancer and PCBs.

A two-year animal study by the National Toxicology Program examined the carcinogenesis of two individual PCB congeners on female Harlan Sprague-Dawley rats.

In the experimental study, researchers assessed the effects of gavage-administered PCBs on rats.

By the end of the study, the researchers found rats positive for liver damage and malignant tumor growth.

Besides the study by the National Toxicology Program, another study looked into the link between PCB exposure and papillary thyroid cancer.

The nested case-control study identified 742 U.S. military service members with papillary thyroid cancer (PTC) as the study’s participants, and sought to identify whether these service members were exposed to PCBs.

All 742 service members tested positive for four different PCB congeners.

Non-Hodgkin’s Lymphoma

PCBs can compromise the immune system and create an environment that’s conducive to the growth of abnormal lymphocytes.

The disruption in immune function can lead to the development of non-Hodgkin’s lymphoma.

PCBs are environmental pollutants, meaning that inhabitants of areas like PCB plants and hazardous waste sites are the most susceptible.

According to one case-control study done in Northern Italy, there’s a potential link between PCB exposure and non-Hodgkin’s lymphoma, particularly in PCB-contaminated areas.

The study focused on an area near a PCB-producing factory.

They compared people with NHL to those without, considering their history of living in different parts of the town with varying pollution levels.

Results showed a higher non-Hodgkin’s lymphoma risk for those residing in the most PCB-polluted areas.

Individuals in these areas had a 1.8% increased risk of developing non-Hodgkin’s lymphoma.

Brain Cancer

Brain cancer has emerged as a concern in research exploring the relationship between PCB exposure and the development of malignant brain tumors.

PCBs, known for their ability to cross the blood-brain barrier, can accumulate in brain tissues, potentially leading to neurotoxic effects and tumor formation.

Epidemiological studies have indicated a possible link between PCB exposure and an increased risk of brain cancer, particularly in populations with high occupational or environmental exposure to these chemicals.

Lung Cancer

The connection between PCB exposure and lung cancer has been a topic of increasing interest in environmental health research.

Given that PCBs can be inhaled through contaminated air, especially in industrial settings or areas with high levels of environmental pollution, the risk of lung tissue exposure to these compounds is significant.

Studies have provided evidence that suggests a link between exposure to PCBs and an elevated risk of developing lung cancer.

Pancreatic Cancer

PCBs, due to their widespread environmental distribution and persistence, have been scrutinized for their potential to disrupt endocrine functions and provoke carcinogenesis in various tissues, including the pancreas.

The research into pancreatic cancer, however, presents a complex picture, with studies indicating both direct and indirect pathways through which PCBs might influence pancreatic carcinogenic processes.

Epidemiological data suggest an association between elevated PCB levels in the body and an increased risk of pancreatic cancer.

The biological plausibility of this association is supported by laboratory findings that PCBs can induce oxidative stress, inflammation, and cellular DNA damage, which are recognized pathways to cancer development.

Prostate Cancer

PCBs are potentially linked to an increased risk for prostate cancer.

A study published in “Carcinogenesis,” on non-dioxin-like PCBs analyzed their influence on prostate cancer’s grade and mortality in a Swedish cohort, complemented by cell experiment findings.

This comprehensive investigation reveals a positive correlation between dietary PCB exposure and high-grade prostate cancer, alongside a heightened risk for fatal prostate cancer, suggesting PCBs’ role in exacerbating cancer severity.

Interestingly, this association was not observed with low or intermediate-grade prostate cancers, indicating PCBs’ potential impact on cancer progression rather than initiation.

The study further explores PCB153’s effects on human prostate cancer cells and prostate stem cells, observing an increased cell invasion and upregulation of invasion-related markers, which could elucidate PCBs’ mechanism in promoting cancer aggressiveness.

This study not only strengthened the evidence linking PCB exposure to prostate cancer risk but also emphasizes the critical need for further research to unravel the underlying mechanisms and to develop targeted preventive strategies.

Testicular Cancer

PCBs may be linked to an increased risk for testicular cancer.

A comprehensive study examined blood concentrations of 37 PCB congeners in 58 testicular cancer patients, their counterparts, and both groups’ mothers.

The analysis revealed significantly elevated PCB levels in case mothers, associating certain PCB congeners with a heightened risk of developing testicular cancer.

This study further underscores the pivotal role of fetal exposure to specific PCB congeners in testicular cancer etiology, emphasizing the need for detailed understanding and preventive strategies against such environmental pollutants.

Another investigation explored the connection between occupational and environmental exposure to endocrine disruptors, such as PCBs and hexachlorobenzene, and testicular cancer risk.

The case-control study encompassed 125 patients and 103 controls, incorporating semen quality assessments and detailed exposure histories.

Findings highlighted reproductive tract defects, dietary patterns, and detectable organochlorine levels as significant risk factors for testicular cancer, drawing attention to the complex interplay between environmental toxins and male reproductive health.

Cancer-Causing Classification Based on Various Agencies

Agencies like the Environmental Protection Agency (EPA), the International Agency for Research on Cancer (IARC), and the World Health Organization (WHO) have deemed PCBs cancer-causing based on sufficient evidence to prove carcinogenicity.

These organizations utilize comprehensive reviews of existing research, including epidemiological studies, animal research, and mechanistic data, to inform their classifications.

The consensus among these agencies about the carcinogenic nature of PCBs plays a crucial role in guiding regulatory policies, public health recommendations, and further research priorities.

It prompts a global response towards managing PCB exposure and mitigating its health risks, especially in contexts of occupational exposure and environmental contamination.

The classifications serve as a foundation for legislative actions aimed at controlling the production, use, and disposal of PCBs.

They also stress the importance of ongoing surveillance and research to understand fully the mechanisms through which PCBs exert their carcinogenic effects.

This collective stance by the EPA, IARC, WHO, and other prominent agencies not only informs public awareness and preventive measures but also underscores the urgent need for global strategies to address the health impacts of persistent environmental pollutants like PCBs.

Probable Human Carcinogens According to the Environmental Protection Agency

The U.S. Environmental Protection Agency (EPA) classifies PCBs as probable human carcinogens.

This classification was based on a substantial body of evidence, including animal studies and epidemiological research.

The findings in existing research indicate a potential link between PCB exposure and cancer in humans.

Probable human carcinogens are substances or agents that are likely to cause cancer in humans.

Agencies like the EPA place PCBs and other chemicals under this category based on sufficient evidence showing associations between cancer-causing chemicals and cancer risk.

Besides classifying PCBs as cancer-causing, the EPA also considers PCBs to be hazardous pollutants.

PCBs are resilient chemicals that can contaminate an ecosystem’s food chain, soil, and water.

The World Health Organization’s (WHO) Classification of PCBs

The WHO classifies PCBs as dioxin-like substances.

Dioxin-like substances are carcinogens to humans.

The WHO’s classification indicates that there is sufficient evidence to establish their carcinogenicity in humans.

Besides cancer, dioxin-like substances create various health effects, including:

• Chloracne
• Immune system toxicity
• Thyroid effects
• Liver damage
• Reproductive, developmental, and neurodevelopmental effects

International Agency for Research on Cancer’s (IARC) Classification and Findings

The IARC is a specialized agency under the WHO and has also conducted extensive evaluations of PCBs.

Based on numerous scientific findings, the IARC classifies certain PCB congeners as Group 1 carcinogens.

This classification is based on extensive research that establishes a direct link between these specific PCBs and various types of cancer.

Group 1 carcinogens include a wide range of substances such as chemicals, mixtures, occupational exposures, physical agents (like ultraviolet (UV) radiation and X-rays), biological agents (like certain viruses), and lifestyle factors (like tobacco smoke).

These substances are known to cause various types of cancer in humans and are considered a significant threat to public health.

Routes of Exposure to PCBs

PCBs are ubiquitous in the environment and in numerous products.

Given their stability and resistance to degradation, PCBs persist in many settings, posing potential risks over extended periods.

This persistence facilitates multiple pathways for human exposure, encompassing a range of daily activities and occupational environments.

Efforts to mitigate these risks require understanding and addressing the myriad ways in which PCBs can enter human systems.

Consequently, the issue of PCB exposure remains a significant concern for public health authorities worldwide, necessitating ongoing vigilance and preventive measures.

Prolonged PCB Exposure in Schools (And Other Old Buildings)

PCB exposure is often prevalent in older buildings constructed or renovated before the 1970s when PCBs were widely used in construction materials such as sealants, caulks, and paints, and in old fluorescent lighting fixtures.

Individuals, particularly students and staff in schools or workers in industrial buildings, may face heightened risks due to continuous exposure through inhalation of PCB-laden air, ingestion of dust contaminated with PCBs, or direct dermal contact with aged materials.

The risk intensifies in areas with poor ventilation, such as basements, storage rooms, and attics, where stagnant air allows PCB concentrations to build over time.

Maintenance activities can disturb these materials, releasing PCBs into the environment and increasing exposure risks.

Despite regulations phasing out the production and use of PCBs, many buildings still contain these hazardous materials, underscoring the importance of ongoing monitoring, remediation efforts, and public health initiatives to mitigate exposure and safeguard occupants’ health.

Exposure to PCBs in Electrical Equipment

Exposure to PCBs through electrical equipment, particularly in PCB transformers and capacitors manufactured before their ban in 1979, poses significant health risks.

PCBs were favored for their chemical stability and insulating properties in such equipment, but as these devices age, they are prone to wear and tear, potentially causing leaks and releasing PCBs into the environment.

Workers involved in the maintenance, repair, or disposal of these aged electrical components are especially vulnerable to exposure.

The risk is heightened during the handling of these devices, where PCB vapors can be inhaled or direct contact with leaking fluids can occur, leading to skin absorption.

It is crucial to implement strict safety protocols and use protective equipment when dealing with old electrical apparatus to minimize exposure risks and protect worker health.

PCB Ingestion From Eating Contaminated Food

Eating PCB-contaminated food is a major route of exposure for the general population.

PCBs accumulate in the food chain, particularly in fish and other aquatic organisms living in contaminated waters, as well as in meat, dairy, and eggs from animals exposed to PCBs through their feed or environment.

This bioaccumulation leads to higher concentrations of PCBs in predator species, including humans, who consume these contaminated foods.

Regular consumption of such contaminated food sources can lead to significant accumulation of PCBs in the body, posing serious health risks over time.

It is essential for consumers to be aware of advisories for fish and wildlife and to follow guidelines for reducing exposure to PCBs in their diet, such as limiting intake of known contaminated foods and choosing lean cuts of meat and low-fat dairy products to minimize fat intake where PCBs may be stored.

Infant Exposure Through Breast Milk

PCBs can cross over from mother to child, specifically through breast milk.

PCBs accumulate in fatty tissues like breast tissue.

Consequently, when a mother breastfeeds her child, PCBs present in her body fat can be released into breast milk, exposing the infant to these harmful chemicals during a critical developmental stage.

Inhalation Exposure

In indoor environments like older school buildings, inhalation of airborne particles is a significant exposure route.

Dust and contaminated air particles can be inhaled, leading to direct absorption of PCBs into the bloodstream.

Occupants of contaminated buildings like schools or workers involved in renovations are at heightened risk.

Over time, exposed workers and students can develop the adverse health effects associated with prolonged PCB exposure.

Direct Exposure

Direct skin contact with PCB-contaminated surfaces or substances can result in dermal exposure.

PCBs can be absorbed through the skin, particularly if there are cuts, abrasions, or prolonged contact.

While dermal exposure might not be as significant as inhalation or ingestion, it still contributes to the overall body burden of PCBs and poses health risks, especially with prolonged or repeated contact.

TorHoerman Law: PCB Exposure Attorneys

Our law firm is currently investigating PCB exposures in St. Louis area schools.

If you were exposed to PCBs in a school setting and subsequently developed health problems such as cancer, you may be eligible to file a PCB exposure claim.

Contact TorHoerman Law for a free consultation.

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