Food is overwhelmingly the dominant route, accounting for roughly 90% of total PCB intake in the general population, with water contributing about 9% and air about 1%.1PubMed. Exposure sources of polychlorinated biphenyls (PCBs) and health risk assessment: a systematic review in Iran But that clean breakdown hides a more tangled reality. Although commercial PCB production was banned in the United States in 1979, these chemicals still reach people through old building materials, contaminated dust, breast milk, modern consumer products that contain inadvertently produced PCB byproducts, and workplace hazards during demolition of older structures. Some of those secondary routes matter far more than their small population-average percentages suggest, depending on where you live, what you eat, and what you do for a living.
Diet Is the Main Channel
Because PCBs are fat-soluble and resist breakdown, they accumulate in the fatty tissues of animals and move up the food chain. For most people in industrialized countries, the everyday act of eating is the primary source of exposure. A study of the American diet found that meat was the single largest contributor, responsible for about 50% of dietary PCB intake, followed by dairy products at roughly 25%, fish at about 15%, and everything else at around 10%.2PubMed Central. PCBs in Food That result surprises people who associate PCBs mainly with contaminated fish, but it reflects how much more meat and dairy the average American eats compared to seafood.
Fish still deserve special attention, though. PCBs bioaccumulate in aquatic food chains, and their concentrations rise with the fat content of the species and the degree of contamination in the water body. One risk assessment found that potential cancer risk from eating PCB-laden fish and shellfish increased exponentially with the hydrophobicity of the PCB congener, and that the risk crossed meaningful thresholds once food-chain sources of exposure were factored in.3PubMed Central. Assessment of Potential Cancer Risk from Consumption of PCBs Bioaccumulated in Fish and Shellfish In plain terms, the fattier the fish and the more polluted the water it came from, the more PCBs end up on your plate.
Drinking water, by contrast, contributes relatively little. A French comparison of exposure routes found that tap water was a minor though not entirely negligible source for a few pollutants, but concentrations stayed well below toxicity reference values in the vast majority of samples.4International Journal of Hygiene and Environmental Health. Drinking water, diet, indoor air: Comparison of the contribution to environmental micropollutants exposure For most people, what you eat matters far more than what comes out of your faucet.
The Air Inside Older Buildings
PCBs were used as plasticizers in caulks, sealants, paints, and fluorescent light ballasts throughout the middle of the twentieth century. Buildings constructed between roughly 1950 and 1980 are the likeliest to contain these materials, and as those materials age, PCBs slowly volatilize into indoor air.5PubMed Central. Review of PCBs in US schools: a brief history, an estimate of the number of impacted schools, and an approach for evaluating indoor air samples Schools are a particular concern because the peak era of school construction in the United States happened to overlap almost exactly with peak PCB production.
Measurements in one university building found indoor air PCB levels ranging from 111 to 393 nanograms per cubic meter, with dust from the ventilation system containing up to 81 parts per million.6PubMed Central. An unrecognized source of PCB contamination in schools and other buildings A study of U.S. schools confirmed that buildings from the late 1960s and early 1970s had the highest indoor air concentrations, while a school built after 1977, when production ended, had the lowest. The congener profiles pointed to legacy building materials, specifically old Aroclor formulations used in window caulking and fluorescent ballasts, as the dominant indoor source.7PubMed Central. Airborne PCBs and OH-PCBs inside and outside urban and rural U.S. Schools
Remediation helps, but the results are partial. When researchers encapsulated exposed interior caulk in one school building, indoor air PCB levels dropped by about 22%. When they also sealed caulk hidden behind heaters and built-in furniture, the total reduction reached roughly 40% from initial levels.8PubMed Central. Mitigation of building-related polychlorinated biphenyls in indoor air of a school That is meaningful but far from complete, partly because PCBs migrate into porous materials like concrete over decades and continue to off-gas even after the original source is sealed.
House Dust and Skin Contact
PCBs that volatilize from building materials or drift indoors from the outside settle into household dust, where they concentrate and persist. This matters because people, especially young children, regularly ingest dust (by putting hands in their mouths) and absorb it through their skin. In-vitro testing of contaminated house dust found that about 60% of the PCB content was bioaccessible through simulated digestion and roughly 70% was available for dermal penetration.9Journal of Exposure Science & Environmental Epidemiology. Bioaccessibility of pesticides and polychlorinated biphenyls from house dust: in-vitro methods and human exposure assessment
The skin route turned out to be far more important than either inhalation or ingestion in that analysis. Even at average dust contamination levels of about 0.5 parts per million, children’s estimated dermal PCB dose reached up to 300% of the tolerable daily intake. Adults hit about 60%. At higher dust contamination levels, the absorbed dose through skin climbed to as much as 5,000% of recommended limits.9Journal of Exposure Science & Environmental Epidemiology. Bioaccessibility of pesticides and polychlorinated biphenyls from house dust: in-vitro methods and human exposure assessment Children are more vulnerable because they spend more time on floors, touch more surfaces, and have a higher skin-surface-to-body-weight ratio than adults. A health risk assessment of indoor dust in Lahore, Pakistan, found that toddlers faced roughly ten times higher cancer risk than adults from the combined routes of inhalation, ingestion, and skin contact.10PubMed. Polychlorinated biphenyls in indoor dust from urban dwellings of Lahore, Pakistan: Congener profile, toxicity equivalency, and human health implications
Occupational Exposure During Demolition and Remediation
Workers who tear apart or renovate older buildings face some of the highest PCB exposures of anyone. Their risks are concentrated and task-specific: personnel who physically cut PCB-containing sealants experience the highest levels across air samples, dust, and blood measurements.11Environment International. PCB exposure during remediation and demolition of contaminated buildings: Full congener analysis and effects of hygiene measures A longitudinal study tracked demolition workers on a PCB-contaminated site for a year and found that even with safety measures in place, their blood levels of lower-chlorinated PCBs rose more than fourfold compared to office workers’ baseline levels. The increases were most dramatic for certain specific congeners.12Environment International. Lower chlorinated PCBs accumulate in demolition workers while working on a contaminated worksite
The finding about lower-chlorinated versus higher-chlorinated congeners is worth pausing on. Higher-chlorinated PCBs are the ones most people think of when they hear “persistent.” They accumulate in body fat and remain for years. But the demolition workers’ primary new burden was lower-chlorinated PCBs, which are more volatile, more easily inhaled, and more readily absorbed through the skin on the job. The fact that these levels continued to climb despite safety gear being used suggests that standard protective measures are insufficient for this type of work.
PCBs Still Being Made by Accident
One of the most underappreciated facts about PCBs is that they are still being produced. Not intentionally, and not in the same industrial quantities as before the ban, but new PCBs form as unwanted byproducts during the manufacture of certain pigments and other chemical processes. Testing of 33 commercial paint pigments found more than 50 PCB congeners, including several dioxin-like varieties, across the samples. The contaminated pigment types, azo and phthalocyanine, show up not just in paint but in inks, textiles, paper, cosmetics, leather, plastics, and food packaging.13PubMed Central. Inadvertent polychlorinated biphenyls in commercial paint pigments
PCB-11, a congener rarely found in the old commercial Aroclor mixtures, has become the signature marker of this inadvertent production. It was the most common congener detected in a screening of 39 consumer products bought from local and online stores, with concentrations in some products exceeding 800 nanograms per gram.14PubMed Central. Inadvertently Generated PCBs in Consumer Products: Concentrations, Fate and Transport, and Preliminary Exposure Assessment Other congeners, including PCB-28, PCB-52, PCB-77, and even some heavily chlorinated forms, have also been found in pigments and the products they go into.15Science of The Total Environment. An overlooked environmental issue? A review of the inadvertent formation of PCB-11 and other PCB congeners and their occurrence in consumer products and in the environment The school air study mentioned earlier confirmed the presence of PCB-11 in indoor air and suggested that modern PCB-contaminated pigments are contributing alongside legacy building materials.7PubMed Central. Airborne PCBs and OH-PCBs inside and outside urban and rural U.S. Schools
This means that even in brand-new buildings with no legacy PCB materials, exposure can still occur through painted surfaces, printed materials, and colored consumer goods. The doses are far lower than what you would get from crumbling 1970s caulk, but they represent a continuous, low-level source that regulators are only beginning to address.
Transfer from Mother to Child
Because PCBs accumulate in body fat, they mobilize into breast milk along with the fat that milk contains. The transfer is efficient enough that an infant’s blood PCB levels are strongly influenced by how long they are breastfed. One early study found that children’s PCB levels were closely tied to the duration of breastfeeding but showed little relationship to the PCB levels in the mother’s blood itself.16PubMed. Postnatal transfer of PCBs from exposed mothers to their babies: influence of breast-feeding In other words, even mothers with modest blood levels can deliver a meaningful dose to their infants through sustained nursing.
This puts parents in an uncomfortable position. The Pregnancy, Infection and Nutrition Babies Study measured PCBs in breast milk at three months postpartum and tracked infant growth to 12 months, specifically among infants breastfed for six months or longer.17PubMed Central. Lactational exposure to polychlorinated biphenyls, dichlorodiphenyltrichloroethane, and dichlorodiphenyldichloroethylene and infant growth: an analysis of the Pregnancy, Infection, and Nutrition Babies Study The research framing acknowledged the tension directly: breastfeeding delivers documented health benefits alongside chemical contaminants, and disentangling the two is tricky. Public health guidance consistently favors continued breastfeeding, but the exposure pathway is real and documented.
Why Geography and Diet Create Unequal Burdens
PCB exposure varies enormously across populations, and diet is the main reason. One of the starkest examples comes from Greenland, where traditional Inuit diets rely heavily on fish and marine mammals. These foods sit at the top of marine food chains where PCBs concentrate most intensely. Median blood levels of PCB-153, one of the most commonly measured congeners, were 17 times higher in Greenlandic Inuit who ate traditional foods most frequently compared to those who ate mainly imported food.18PLOS ONE. The influence of persistent organic pollutants in the traditional Inuit diet on markers of inflammation The gap was not a few percentage points. It was an order of magnitude.
Proximity to contaminated industrial sites, on the other hand, matters less than people tend to assume. A study near a Superfund site found that living closer to the site did not predict higher cord blood PCB levels. What did predict them was consumption of organ meat and local dairy products, along with the timing of site dredging activities. Age, previous breastfeeding, and smoking also influenced levels.19PubMed Central. Does living near a Superfund site contribute to higher polychlorinated biphenyl (PCB) exposure? The takeaway is counterintuitive: your diet is a more reliable predictor of your PCB burden than your zip code, even when your zip code includes a known contaminated site.
What Blood Tests Reveal About Cumulative Exposure
Biomonitoring studies confirm that nearly everyone in the U.S. carries a detectable load of persistent organic pollutants, including PCBs. An analysis of nearly 4,700 participants found that more than two-thirds had at least one of the 37 most common persistent organic pollutants at concentrations in the top 10% of the distribution. Among people carrying multiple pollutants at high concentrations, PCBs dominated the mix, making up more than 40% of the elevated compounds once someone had three or more pollutants in the top decile.20PLOS ONE. Number of Persistent Organic Pollutants Detected at High Concentrations in Blood Samples of the United States Population
PCBs also accumulate in the brain. Postmortem analysis of human brain tissue found 14 higher-chlorinated PCB congeners at detection frequencies above 50%. Adults carried higher levels than younger donors, and the congener profiles in adult brains were more uniform across different brain regions and individuals. That uniformity suggests a steady-state buildup over decades of exposure rather than a single acute event.21PubMed Central. Assessment of Polychlorinated Biphenyls and Their Hydroxylated Metabolites in Postmortem Human Brain Samples: Age and Brain Region Differences
Can You Reduce PCBs in Food Through Preparation?
For fish, the answer is a qualified yes. Because PCBs concentrate in fat, trimming visible fatty tissue before cooking removes a substantial share. One study on bluefish fillets found that trimming alone reduced PCB residues by an average of about 59%, with an additional 7% or so removed by cooking (whether baking, broiling, frying, or poaching). The cooking method itself did not make a significant difference; it was the trimming that mattered.22Journal of Food Safety. Effects of Trimming and Cooking by Several Methods on Polychlorinated Biphenyls (PCB) Residues in Bluefish
A Korean study of various seafood told a more complicated story. For high-fat fish, cooking showed a slight trend toward lower PCB concentrations, consistent with fat rendering out during heat treatment. But for seafood that started with very low PCB levels (under 1 nanogram per gram), cooking actually appeared to increase the concentration, probably because water loss concentrated the remaining contaminants in a smaller mass of food.23Chemosphere. Dietary exposure to PCBs by seafood cooking method: A Korean study The practical lesson: if you eat sport-caught fish from waters with known PCB advisories, trim the belly fat, the skin, and the dark lateral-line meat before cooking. If you eat commercially farmed low-fat seafood, cooking preparation is less consequential.
Microplastics as an Emerging Carrier
A newer dimension of PCB exposure involves microplastics. These tiny plastic fragments, now found in drinking water, food, and air, can adsorb persistent organic pollutants like PCBs on their surfaces and carry them into the body. Research has established that microplastics interact with a range of environmental contaminants and may act as vehicles that facilitate the transfer of hazardous chemicals through food chains.24PubMed. Microplastics as carriers of environmental contaminants: Implications for human exposure, toxicokinetics, and health risk How much this “Trojan horse” effect contributes to total human PCB intake remains an open question. The concern is not that microplastics are currently a major PCB source compared to food, but that they represent an additional, poorly characterized route that may grow in importance as microplastic contamination increases.
Why the Same Exposure Hits People Differently
Not everyone processes PCBs at the same rate. Your body metabolizes PCBs through a family of liver enzymes, and genetic variation in those enzymes changes how quickly you convert PCBs into their hydroxylated metabolites. A study of 129 Japanese individuals found that people carrying a deletion variant in the CYP2A6 gene appeared to have reduced metabolic activity for certain PCB congeners, meaning they may retain those specific PCBs in their blood longer than someone without the variant.25Journal of Hazardous Materials. Association between CYP2A6 genetic variants and serum concentrations of highly persistent OH-PCBs and their parent PCBs in humans The practical implications of these genetic differences are still being worked out, but they help explain why two people with similar diets and environments can end up with meaningfully different PCB burdens. They also complicate the already-difficult task of setting universal safe exposure thresholds, since the same dose effectively lingers at different concentrations in different people’s tissues.
Age compounds the problem. Because the body eliminates higher-chlorinated PCBs extremely slowly, older adults carry decades of accumulated exposure even if their current diet is clean. The brain tissue data showing higher levels and more uniform congener profiles in adults compared to younger donors reflects this slow, relentless buildup. A person born in the 1950s who ate an ordinary Western diet has had a lifetime of low-level intake with minimal clearance, and their body burden reflects that entire history, not just last year’s meals.