• PCBs were linked to a statistically significant increase in lung cancer deaths
• PCBs were linked to an increase in lung cancer deaths
• PCBs may be associated with an increased incidence for all cancers combined, including lung cancer, in 5,088 men studied
• lung cancer deaths were elevated, but not considered statistically significant
• small number of deaths limits interpretation
• results support the possibility of PCBs posing a carcinogenic risk to humans
• 16 of 58 employees (27.6 percent) had lung cancer and were probably exposed to PCBs
• tumors in patients who inadvertently consumed PCBs in 1968 included lung cancer
• two workers out of 19 developed lung cancer, but the study was too small to calculate significance
• the results do not exclude the possibility of a cancer risk from PCBs
• two of 12 autopsies found lung cancer in PCB poisoning victims
• firefighters are often exposed to PCBs
• firefighters have a higher incidence of lung cancer
• abnormal serum oncogene (cancer) proteins in workers with known exposure to carcinogens (such as PCBs) may represent an early marker of neoplastic disease (cancer)
• half of PCB poisoning victims showed respiratory damage
• The incidence and severity of respiratory symptoms correlated well with the concentration of PCB in the blood and sputa
• for 5 years after PCB poisoning, respiratory symptoms persisted in most patients; in patients with high blood PCB levels, signs of chronically infected airways were observed
• pathologic changes in lungs and thymus were observed in rats, including necrosis of Clara cells, mild pulmonary edema
• respiratory problems were mainly in small airways and were due primarily to furans [PCBs are usually contaminated with furans]
• dioxins are known to cause squamous carcinomas of the oropharynx and lungs [certain PCBs are dioxin-like]
• PCBs induce enzymes which helps promote mutations caused by oil vapors
• several epidemiologic studies on the carcinogenicity of PCBs in both occupational exposure and accidental intoxication suggest that PCBs might be a potent carcinogen in the lung.
• PCBs have been reported to promote lung tumors
• certain types of PCBs associated with cancer also increase cytochrome P-450-dependent monooxygenases, which are abundant in bronchiolar (lung) Clara cells
• PCBs may promote tumors by inhibiting intercellular communication and/or by stimulating cell proliferation
• furans induce necrosis (cell death) and epoxide formation to their target cells, which might result in lung cancer [PCBs are usually contaminated with furans]
• PCBs stimulate production of lung macrophages
• several chemicals (including tobacco constituents) were mutagenic or more mutagenic in the presence of lung enzymes induced by PCBs
• enzymes may increase the lung cancer risk from these chemicals
• humans exposed to complex combustion mixtures will have higher DNA adduct levels in lung cells
• adduct levels depend on the genotoxic and DNA adduct-forming potency of the mixture
• PCBs showed a significant excess of all cancers
• one study showed statistically significant increased human mortality from all malignancies (33 observed, 15.5 expected), including from lung cancer (8 observed, 2.5 expected).
• second study showed intragastric administration of PCBs to mice increased the incidence of lung tumours induced by intraperitoneal administration of N-nitrosodimethylamine (a tobacco chemical).
• PCB induced enzymes may alter the metabolism and the pattern of DNA adducts formed in human lung tissue as a result of certain carcinogenic pollutants
• PCBs and dioxins are tumor promoters
• PCBs and dioxins may interact with genetic susceptibilities in the K-ras gene, resulting in lung cancer
• dioxin caused a significant increase in K-ras p21 in lung cell membranes in some but not all mouse strains
• study of DNA-adducts may serve to pinpoint genetic susceptibility to cancer
• PCBs are measurable in human lung and are being studied to assess enzyme induction in the lung

enzyme presence can predict the presence of important DNA-adducts associated with cancer

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The Human Studies

Upcoming Research

Summary of Animal Studies of Lung Cancer and PCBs

The Animal Studies 1 - 31

The Animal Studies 32 - 32

Upcoming Research

Studies Without Abstracts

Links to More Information

References