PCBs, which stand for polychlorinated biphenyls, were commercially produced starting in the 1920s. They were widely used in industrial and commercial applications through the 1970s due to their non-flammability, chemical stability, high boiling point, and electrical insulating properties.
PCBs were first synthesized in 1881, but commercial production began in the late 1920s by the Swann Chemical Company. Monsanto and other companies soon entered the market for PCB production due to rising industrial demand. The chemical stability and insulating properties of PCBs made them ideal for use as coolants and lubricants in transformers, capacitors, and other electrical equipment. Major uses of PCBs also included heat transfer fluids, hydraulic fluids, and additives to paints, plastics, rubber products, and more.
At their peak in the 1970s, global production of PCBs reached over 1.3 million tons annually. Concerns over their persistence in the environment and potential toxicity led many countries, including the United States, to ban PCB production in the late 1970s. Today, the use and disposal of PCBs is heavily regulated. However, PCBs remain ubiquitous environmental contaminants due to their past widespread use and extreme chemical stability.
Why PCBs are Harmful
PCBs, or polychlorinated biphenyls, have caused significant harm to human and environmental health, leading to their classification as serious toxicants and persistent pollutants. Here are some of the main reasons PCBs are considered so damaging:
PCBs bioaccumulate and persist in the environment (Learn about Polychlorinated Biphenyls | US EPA). This means they accumulate in the bodies of animals and humans and do not break down easily, allowing concentrations to build up over time through the food chain. The chemicals are stored in fatty tissue and take many years to be eliminated from the body.
PCBs have been classified by the International Agency for Research on Cancer as carcinogenic to humans (Learn about Polychlorinated Biphenyls | US EPA). Studies link exposure to increased risks of certain types of cancer like melanoma, liver, biliary tract, gall bladder, and gastrointestinal tract cancers.
PCBs have neurotoxic effects even at lower levels of exposure (PCBs | Washington State Department of Health). Neurodevelopmental impacts have been seen in children prenatally exposed to PCBs. Studies have also found neurological and behavioral effects in adults including decreased memory and learning abilities.
Developmental effects are another major concern with PCB exposure (Learn about Polychlorinated Biphenyls | US EPA). Impacts on immune function, reproductive systems, nervous system, endocrine system, and other bodily functions can occur from exposures during critical developmental periods.
How People are Exposed to PCBs
There are several ways people can be exposed to PCBs:
Contaminated Fish Consumption
Eating fish from contaminated waters is a major route of PCB exposure. PCBs accumulate in fish and other animals, reaching higher concentrations as you go up the food chain. Fish advisories are in place in many areas advising limited consumption of certain fish species due to high PCB levels (https://www7.nau.edu/itep/main/iteps/ORCA/3956_ORCA.pdf).
Contaminated Meat and Dairy
Meat and dairy products from animals that feed on contaminated soil and plants can also contain significant levels of PCBs. This is a concern around contaminated sites or areas with high environmental PCB levels (https://enveurope.springeropen.com/articles/10.1186/s12302-018-0166-9).
Inhalation of Indoor Air
Breathing indoor air in buildings containing old caulk, paint, or electrical equipment contaminated with PCBs can be a source of exposure. PCBs can volatilize out of these materials and be inhaled (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6224007/).
E-waste Exposures
Handling e-waste and working or living near e-waste recycling sites can expose people to PCBs released during dismantling and processing. PCBs are found in some plastics and equipment used in electronics (https://enveurope.springeropen.com/articles/10.1186/s12302-018-0166-9).
PCB Regulations
PCBs were banned from manufacture in the United States in 1979 under the Toxic Substances Control Act (https://www.epa.gov/pcbs). This was due to growing evidence of the toxicity of PCBs and their persistence in the environment. The Stockholm Convention, an international environmental treaty, called for the elimination of PCBs in 2001 (https://www.epa.gov/pcbs/policy-and-guidance-polychlorinated-biphenyl-pcbs).
Despite being banned decades ago, PCBs are still present in old electrical equipment, building materials, and other products. The EPA estimates that about 70% of PCBs produced are still in the environment (https://www.atsdr.cdc.gov/csem/polychlorinated-biphenyls/standards.html). Their chemical stability means they persist for many years. Cleaning up and properly disposing of PCBs remains an ongoing environmental challenge.
Where are PCBs still Found?
Old electrical equipment like transformers and capacitors still contain PCB fluids which can leak into the environment. According to a summary by Erdal (2008), spills, leaks, fires, or improper disposal of electrical equipment that contain PCBs are a significant ongoing source of PCBs entering the environment today (https://www.tandfonline.com/doi/pdf/10.3155/1047-3289.58.8.1022).
Many buildings built between 1950-1980 used PCB-containing caulk, paint, and sealants which can still be released into the environment through degradation, renovations, or demolitions. According to the USGS, landfills and hazardous waste sites containing old PCB wastes are also sources of ongoing contamination (https://pubs.usgs.gov/publication/1000794).
Health Effects of PCB Exposure
PCB exposure is linked to increased cancer risk, reproductive and neurological effects, and developmental issues in children.
According to the CDC, PCBs are considered carcinogenic to humans and can increase the risk of certain cancers such as melanoma and liver cancer. Studies have shown higher rates of liver, gall bladder, biliary tract, gastrointestinal tract, and skin melanomas in workers exposed to PCBs (CDC).
PCBs can also have adverse effects on the reproductive system and neurodevelopment. PCB exposure has been associated with menstrual cycle irregularities in women as well as lower sperm counts and motility in men. Exposure during pregnancy is linked to low birth weight and neurobehavioral effects in children including decreases in intelligence (EPA).
Studies show developmental exposure to PCBs can negatively impact cognitive function and lead to issues with memory, learning, and behavior in early childhood. Prenatal PCB exposure has been associated with poorer visual recognition memory and lower IQ scores in children (Faroon et al., 2016).
Recommendations to Reduce Exposure
The only surefire ways to prevent exposure to PCBs are proper cleanup and disposal of old equipment and avoiding consumption of high PCB fish and animal products.
Many PCB-containing items like transformers and capacitors are still in use or storage. These should be handled with care and disposed of properly as hazardous waste. Contact your local environmental or hazardous waste agency for guidance on safe handling and disposal.
Certain fish and animal products may contain high levels of PCBs. It’s recommended to limit or avoid consumption of fish known to be high in PCBs, like salmon, bluefish, striped bass, some species of tuna, and bottom feeders. Opt for fish and animal products lower in PCBs. When eating fish high in PCBs, remove the skin and fatty portions which accumulate more PCBs.
Take care when renovating or demolishing old buildings, as they may contain PCBs in caulk, paint, floor finishes, and other materials. Use safe handling procedures and have suspect materials tested prior to renovation. Follow all local regulations for containment and disposal of PCB waste from renovations.
Being informed and proactive can help minimize unnecessary exposure to lingering PCBs in older products and structures. Handle older materials carefully according to guidelines and opt for PCB-free alternatives when possible.
Remediation and Disposal
PCBs were widely used for decades before being banned, and require proper handling and disposal. There are strict guidelines in place for disposing of PCB materials.
Per the Switchgrass and Bacteria Work Together to Remove PCBs, any materials contaminated with PCBs at 50 ppm or greater must be disposed of in EPA-approved facilities designed to safely destroy or isolate PCBs.
For remediating sites contaminated with PCBs, some of the most common methods include:
- Excavation and Landfilling – Physically removing contaminated soil/sediment and disposing of it in approved landfills.
- Incineration – Burning PCBs at high temperatures to destroy them.
- Solidification/Stabilization – Mixing contaminated material with concrete, asphalt or other binders to immobilize PCBs.
- Phytoremediation – Using plants and associated microbes to extract, degrade or isolate PCBs.
Remediating PCB contamination can be very costly depending on the extent and depth of contamination. According to the Frontiers in Environmental Science report, costs can range from $50-500 per cubic yard of contaminated material. Ongoing monitoring and maintenance is also required after remediation is complete.
The Future of PCBs
While PCB production has been banned in most countries, the chemicals still linger in building materials and old equipment. Proper disposal of PCB containing products will require continued global cooperation[1].
One key area of focus will be monitoring PCB contamination in the food supply, especially in fish and animal products. Research indicates that dietary intake is a major route of exposure for the general population[2]. Reducing PCB levels in food through improved environmental regulations and consumer awareness will be important moving forward.
Within buildings, replacing old caulk, fluorescent light ballasts, cable insulation and other materials containing PCBs can lower exposure, particularly in schools and offices where people spend significant time. However, remediation can be expensive. Government programs to identify, evaluate and reduce PCBs in public buildings could have a major public health impact[1].
In summary, while PCBs are already banned in most countries, their lingering presence means continued efforts will be needed to reduce their public health impact. Key priorities are the proper disposal of old PCB-containing equipment, reducing dietary exposures, and updating buildings and schools where people are exposed regularly[2].
[1] https://anusports.com/the-evolution-of-pakistan-cricket-board-from-its-inception-to-present-day/
[2] https://anusports.com/xploring-the-strategies-and-tactics-behind-rangpur-riders-dominance-in-t20-cricket/
Conclusion
In summary, PCBs are harmful synthetic chemicals that were widely used in industrial and commercial applications due to their non-flammability, chemical stability, high boiling point, and electrical insulating properties. Although banned in the late 1970s, they persist in the environment and remain a health concern today.
The main routes of exposure are through ingestion, inhalation, or skin contact. PCBs accumulate in fatty tissue and are not easily metabolized or excreted. Even low levels of exposure can lead to a variety of health effects including cancer, neurological impairments, liver damage, skin irritation, reproductive problems, and disruption of the endocrine and immune systems.
While regulations and remediation efforts have reduced PCB contamination over time, they are still present in old electrical equipment, building materials, and waste sites. Ongoing surveillance, education, regulations, and proper containment and disposal are critical to limit exposure and protect public health. Though PCB levels have declined, their toxicity and persistence mean they will remain a health concern well into the future.
