PCBs BISC 312 Simon Fraser University Onkar Bains

PCB’s BISC 312 Simon Fraser University Onkar Bains

What are PCBs? n ______________ n Man-made n _____ possible structures (congeners) n No known smell or taste n Either oily liquids or solids and are colorless to light yellow

PCBs are very lipid soluble !! From http: //www. atsdr. cdc. gov/toxprofiles/tp 17 -c 4. pdf

What are PCBs? n 150 million pounds of PCBs are dispersed throughout the environment, an additional 290 million pounds are located in landfills and storage in the USA

Basic Structure n Consists of biphenyl (two benzene rings with carbon to carbon bond) with varying number of chlorines n As # of chlorines increase = substance becomes less ______ and is more ______ (thus resistant to biodegradation) From http: //www. atsdr. cdc. gov/toxprofiles/tp 17 -c 4. pdf

Toxicity n Toxicity of PCBs increase due to: n increasing _____ content n structural placement of _____ n Ortho, meta and para positions

Ortho, meta, para

Ortho, meta, para PARA and META positions filled = INCREASED TOXICITY !!

Health and Toxic Effects n Toxic effects of PCBs in humans include: n __________________ n _________ From http: //www. foxriverwatch. com/monsanto 2 a_pcbs. html

Cancer n Animal studies: PCBs cause cancer liver cancer in rats n possible thyroid, stomach, colon cancer in rats n PCBs act as co-carcinogens in both rats and mice n n Human studies: n Some suggestive findings, but no consistent evidence linking PCBs with cancer in humans

Cancer n Conclusions of expert agencies: n EPA: “probable human carcinogen” (Group B 2) n IARC (International Agency for Research on Cancer): “probably carcinogenic to humans (Group 2 A) n NTP (National Toxicology Program within the US Department of Health and Services): “reasonably anticipated to be human carcinogens”

Immune Effects n Studies in monkeys and other animals have revealed serious effects on immune system following exposures to PCBs, including: n Significant decrease in size of the thymus gland in infant monkeys n Reductions in the response of the immune system following challenge with sheep red blood cells n Decreased resistance to Epstein-Barr virus and other infections in PCBexposed animals

Reproductive Effects n Reduced ____________ n Decrease in ________

Endocrine Effects n Shown that PCBs decrease thyroid hormone levels in rodents n Thyroid hormone levels are critical for normal growth and development as well as lipid and CHO metabolism!! From http: //arbl. cvmbs. colostate. edu/hbooks/pathphys/endocrine/thyroid/chem. html

History of PCBs n 1881—Reportedly formulated this year n 1929—Commercially produced by ______ (only U. S. manufacturer of PCBs) Producing them under the trade name _____ n Main products: ____ 1242, 1254, and 1260 n n “ 12” comes for the number of ____ on biphenyl n Last 2 numbers indicate ____________ of PCB mixtures Cl in

History of PCBs n Why did Monsanto produce PCBs? n Due to their desirable properties for use in wide range of industrial and consumer products: ________, very ____ and have low ______ at normal temperatures

History of PCBs n Until 1957, PCBs used almost exclusively in electrical transformers and capacitors n After 1957, PCBs still used primarily for transformers and capacitors, but numerous other applications became widespread: n n n __________________ wood preservatives paints and sealants…and the list keeps going on and on

History of PCBs n Late 1960 s—Discovery of PCBs in birds in Sweden and poisoning of 1, 300 people in Japan after eating rice-bran oil (yusho) containing PCBs

The “Yusho Incident” n _______ n Many showed immediate symptoms including severe _____, respiratory ailments, and failing ____ n Two out of 12 children were stillborn and nearly all of the babies showed signs of PCB diseases n Nine years after, there was _____ in livercancer deaths among affected men and _____ among women n Total serum levels of Ig. A and Ig. M, but not Ig. G, were ____

History of PCBs n 1977—Monsanto stopped manufacturing PCBs in U. S. and General Electric finally stopped dumping PCBs into _____ (1. 3 million pounds of different types of PCBs were dumped into river from 1946 until 1977) n Dr. Robert Korns published his population study on people from Poughkeepsie, NY who were drinking water from Hudson as high as 100 ppm PCBs n Increased incidences (5 to 10 times) of colorectal cancer in men

History of PCBs n 1978—President Jimmy Carter declared _________ (section of Niagara Falls, New York) a disaster area and ordered the evacuation of all homes in the area

From http: //www. chej. org/Love. Canal. pdf

Love Canal n From 1920 -1953, canal was used to dump hazardous wastes (20, 000 tons of PCBs and other chemicals) by Hooker Chemical Company n In 1953, canal area was covered with dirt and presumed safe n In 1953, Hooker sold land to Board of Education for one dollar n Hooker included in deed transfer a "warning" of chemical wastes buried on property and disclaimer absolving Hooker of any future liability

History of PCBs n 1978—Dr. Robert Dougherty, at Florida State, released his report which showed that sperm counts had fallen so low among students that 23% were functionally sterile n n He attributed this trend in part to increased levels of PCB in their semen 1979—EPA issued final regulations banning the manufacture of PCBs

Environmental Fate n PCBs have been released to the environment solely by human activity !! n PCBs can evaporate from water to air, but because PCBs are only slightly soluble in water, they adhere strongly to any soil or sediments present n Have been found in air, plants, and water as far away as the Arctic and Antarctic !!

Environmental Fate n Atmospheric transport is most important mechanism for global dispersion of PCBs n n n Biphenyls with ____ chlorines remain in atmosphere Biphenyls with ____ chlorines gradually migrate toward polar latitudes in a series of volatilization/deposition cycles Biphenyls with ____ chlorines remain in mid-latitudes Biphenyls with ____ chlorines remain close to the source of contamination PCBs enter atmosphere from volatilization from both soil and water surfaces—present both in vapor phase and sorbed to particles

Environmental Fate n PCBs in water are transported by diffusion and currents n PCBs are removed from water column by: n n sorption to suspended solids and sediments (higher chlorinated congeners) volatilization from water surfaces (lower chlorinated congeners) concentrating in biota Not likely to be found in GROUND water

Environmental Fate n Due to their lipophilicity, PCBs in water and sediments ________ in fish and marine life n PCBs also bioaccumulate in plants, birds, terrestrial animals, agricultural livestock, and domestic animals n PCB concentrations increase by orders of magnitude as they rise through the food web, particularly as they reach higher organisms n In this way, a major route of human exposure to PCBs is through ____

From http: //www. science. uwaterloo. ca/course_notes/chemistry/chem 404/notes/03 -organic_compounds. pdf

Environmental Fate n Ability of PCBs to be degraded or transformed in environment depends on degree of chlorination of biphenyl molecule as well as on isomeric substitution pattern n Vapor-phase reaction of PCBs with hydroxyl radicals is dominant transformation process in atmosphere n Photolysis appears to be only viable chemical degradation process in water n Biodegradation has been demonstrated under both aerobic and anaerobic conditions n Major degradation process for PCBs in soil and sediment