Polychlorinated biphenyls (PCBs) are mixtures of up to 209 individual chlorinated compounds (known as congeners) and refer to a class of chlorinated, chemical compounds that includes numerous different substances favored for their low conductivity, high boiling point, chemical stability, and flame retardant properties., "There are no known natural sources of PCBs. PCBs are either oily liquids or solids that are colorless to light yellow. Some PCBs can exist as a vapor in air. PCBs have no known smell or taste. Many commercial PCB mixtures are known in the U.S. by the trade name Aroclor."2 Monsanto Company, the sole manufacturer of PCBs in the United States from 1929-1977, produced over 700,000 tons of PCBs.1 PCB's were often used for insulating and cooling electrical equipment, particularly in transformers, large capacitors, and fluorescent lamp ballasts due to their low flammability.1The EPA suggests that "PCBs are released into the environment from (1) items that contain PCBs introduced deliberately for their useful chemical properties, (2) inadvertent generation during certain production processes, and (3) storage and disposal facilities" as primary sources.1 PCB's, now mostly banned were previously used in the production of dielectric fluids for transformers, capacitors, and other electrical components as well as synthetic resins, epoxy paints, protective coatings, and hydraulic and heat transfer fluids.1
A group of persistent and widely distributed environmental pollutants, PCB's are known to cause neurotoxic effects, endocrine disruption, cancer, and reproductive abnormalities. Individuals may suffer exposure through the use old fluorescent lighting fixtures, electrical devices, and appliances that were made at least 30 years ago. Food borne exposure is common when eating fish, especially sport fish caught in contaminated lakes or rivers, as well as some meats and dairy products.2 Other sources of exposure include hazardous waste sites, contaminated well water, and workplace exposure during repair and maintenance of PCB transformers, fluorescent lights, and other old electrical devices.2 An example of a common source of non-occupational exposure is a leaking power transformer on an electrical pole on a residential street.
Symptoms of PCB exposure include skin conditions such as acne and rashes, stomach problems, thyroid gland injuries, cancer, changes in the immune system, behavioral alterations, impaired reproduction, liver damage, and death.2 Laboratory tests can determine levels of PCB in blood, body fat, and breast milk.2 However, like many tests for toxicants, it is rarely ordered by physicians and no specific limits are set for cases of poisoning.
The EPA has set a limit of 0.0005 milligrams of PCBs per liter of drinking water (0.0005 mg/L).2 Infant foods, eggs, milk and other dairy products, fish and shellfish, poultry and red meat may contain no more than 0.2-3 parts of PCBs per million parts.2 However, it is conceivable that no amount may be safe. Each little bit adds to the overall environmental and body burden. Since PCBs are a persistent pollutant, each little bit adds to the bits before for an ever increasing PCB burden.
PCBs are recognized as persistent environmental pollutants, which are resistant to degradation and can be found in surface soil. They accumulate in animal tissues and have been known to interfere with reproductive processes. This accumulation has been found in many human tissues, including follicular fluid, uterus, placenta and ovarian/uterine cells In addition, PCB's have been shown to bioaccumulate in rivers and seas, as well as detritivorous fish and bluefin tuna. Fish intake was associated with elevated PCB levels in pregnant women from Taiwan.14 A study showed concentrations of PCBs were significantly higher in otters that died of infectious disease, suggesting an association between elevated PCB concentrations and infectious diseases.15
Since PCB's present no odor, determining if there is a clear and present danger can be difficult. Testing is required to determine exposure.
PCBs are resistant to metabolism and can accumulate and biomagnify.16 PCB's are easily stored in body fat and losing weight may mobilize PCB's and other toxicants, causing illness. "The pharmacokinetic behavior of dioxinlike compounds and PCBs is largely governed by three major factors: 1) lipophilicity, 2) binding to CYP1A2 leading to hepatic sequestration, and 3) relative rates of metabolism. v controls the rate and extent of absorption, tissue distribution, and passive elimination."16
Therefore, the main detoxifying mechanism for PCB's is to convert this fat-soluble substance into a water-soluble substance for ease of excretion. Sauna therapy may be helpful as the sauna heats body fat, which may mobilize PCB's into the blood stream where they can be then be excreted. Adequate nutrition and supplementation may also play a key roll to ensure the liver
detoxification system is supported and properly functioning. And, as always, avoiding exposure in the first place is the best measure!
-LS
References
1. U.S. Environmental Protection Agency (1998). Great Lakes Binational Toxics Strategy Stakeholder Forum. PCB's Workgroup. Retrieved on July 22, 2007 from: http://www.epa.gov/glnpo/bnsdocs/pcbsrce/pcbsrce.html
2. ToxFAQsT for Polychlorinated Biphenyls (PCBs). Agency for Toxic Substances and Disease Registry. February 2001. Retrieved on July 22, 2007 from: http://www.atsdr.cdc.gov/tfacts17.html.
3. Frame GM, Cochran JW, Bowadt SS (1996). Complete PCB congener distributiosn for 17 Aroclor mixtures determined by 3 HRGC system optimized for comprehensive quantitiative congener-specific analysis. Journal of High Resolution Chromatography. 19:657-658.
4. Ren N, Que M, Li YF, Liu Y, Wan X, Xu D, Sverko E, Ma J (2007). Polychlorinated biphenyls in Chinese surface soils. Environ Sci Technol. Jun 1;41(11):3871-6.
5. Arnold DL, MEs J, Bryce F, Karpinski K, Bickis MG, Zawidzka ZZ, Stapley R (1990). A piolot study on the effect of Aroclor 1254 iingestion by Rhesus and Cynomologuys monkeys as a model for human ingestion of PCB's. Food and Chemical Toxicology. 28:847-857.
6. Kamarianos A, Karamanalis X, Goulas P, Theodosiadou E, Smokovitis A (2003). The presence of environmental pollutants in follicular fluid of farm animals. Reproductive Toxicology. 17:185-195.
7. Lindenau A, Fisher B, Seiler P, Beier HM (1994). Effects of persistent chlorinated hydrocarbons on reproductive tissues in female rabbits. Human Reproduction. 9:772-780.
8. Panasen M (1999). The expression and regulation of drug metabolism in human placenta. Advanced Drug Delivery Reviews. 14:81-97.
9. Kotwica J, Wrobel M, & Mlynarczuk J (2006). The influence of polychlorinated biphenyls (PCBs) and phytoestrogens in vitro on functioning of reproductive tract in cow. Reproductive Biology. 6(1):189-194.
10. Rowe AA, Totten LA, Xie M, Fikslin TJ, Eisenreich SJ (2007). Air-water exchange of polychlorinated biphenyls in the Delaware River. Environ Sci Technol. 2007 Feb 15;41(4):1152-8.
11. Zhang P, Song J, Liu Z, Zheng G, Zhang N, He Z (2007). PCBs and its coupling with eco-environments in Southern Yellow Sea surface sediments. Mar Pollut Bull. Jun 25
12. Colombo JC, Cappelletti N, Migoya MC, Speranza E (2007). Bioaccumulation of anthropogenic contaminants by detritivorous fish in the Rio de la Plata estuary: 2-Polychlorinated biphenyls. Chemosphere. Jul 10.
13. Corsolini S, Sara G, Borghesi N, Focardi S (2007). HCB, p,p'-DDE and PCB ontogenetic transfer and magnification in bluefin tuna (Thunnus thynnus) from the Mediterranean Sea. Environ Sci Technol. Jun 15;41(12):4227-33.
14. Huang MC, Chao HR, Wang SL, Hung HC, Wang YS, Pan WH (2007). Food Addit Contam. 2007 Jul;24(7):784-91. Associations of diet with body burden of dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (PCBs): observations on pregnant women from central Taiwan. Food Addit Contam. Jul;24(7):784-91.
15. Kannan K, Perrotta E, Thomas NJ, Aldous KM (2007). A Comparative Analysis of Polybrominated Diphenyl Ethers and Polychlorinated Biphenyls in Southern Sea Otters that Died of Infectious Diseases and Noninfectious Causes. Arch Environ Contam Toxicol. 2007 Aug;53(2):293-302. Epub 2007 Jun 11.
16. Van den Berg M, LBirnbaum L, Bosveld A, Brunström B, Cook P, Feeley M, Giesy JP, Hanberg A, Hasegawa R, Kennedy SW, Kubiak T, Larsen JC, Rolaf van Leeuwen FX, Djien Liem AK,14 Nolt C, Peterson RE, Poellinger L, Safe S, Schrenk D, Tillitt D, Tysklind M, Younes M, Wærn F, & Zacharewski T. Toxic Equivalency Factors (TEFs) for PCBs, PCDDs, PCDFs for Humans and Wildlife. Environmental Health Perspectives Volume 106, Number 12, December 1998.
