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Polybromated Biphenols

Polybromated Biphenols. Andrea Leasure BIOL 464. Structure of the Compound. Physical & Chemical Properties. Colorless to off-white solids Low vapor pressure Soluble in fat, organic solvents (solubility decreases w/ increasing bromine number) Insoluble in water

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Polybromated Biphenols

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  1. Polybromated Biphenols Andrea Leasure BIOL 464

  2. Structure of the Compound

  3. Physical & Chemical Properties • Colorless to off-white solids • Low vapor pressure • Soluble in fat, organic solvents (solubility decreases w/ increasing bromine number) • Insoluble in water • Relatively stable & chemically unreactive • Photodegrade upon exposure to UV light

  4. Uses & Applications • Flame retardant additives in synthetic fibers & molded plastics. • Added to plastics to make them difficult to burn • Ex: Home electrical appliances, textiles, plastic foams.

  5. Production History • No longer produced in the United States (1976) • PBBs are still around in the environment because they do not degrade easily or quickly • Formerly produced in 3 primary forms: • Hexabromobiphenyl • Octabromobiphenyl • Decabromobiphenyl

  6. Production History • In 1973, several thousand pounds of hexabromobiphenyl were accidentally mixed with livestock feed in Michigan • 1.5 million chickens • 30,000 cattle • 5,900 pigs • 1,470 sheep • Bitter Harvest, 1981 film

  7. Mode of Entry in Aquatic Environment • PBBs entered the air, water & soil from • poorly maintained hazardous waste sites • Improper incineration of plastics containing PBBs. • Lower brominated PBBs are widely spread in the environment & bioaccumulate in aquatic biota • Higher brominated PBBs primarily bind to sediment & will hardly spread in aquatic systems or accumulate in biota.

  8. Chemical Reactivity • 209 congeners (congener pattern found in fish samples is different from that in commercial products) • 3,3',4,4',5,5'-hexaBB (BB-169) was found to be the most toxic PBB • Half-life in humans 7.8-12 years

  9. Toxicity to Aquatic Life • Exposed PBB water birds, nesting on islands in Lake Michigan, had no effect on reproduction. • Zebra mussels (Dreissena polymorpha) • Concentrations ranged from 0.85 to 22.44 (ng/g ww) with no effect • Freshwater Tilapia (Oreochromis niloticus ) • 6 h EC50 6.6 × 10−6 M • 24 h EC50 7.3 × 10−6 M

  10. Toxicity Effects • Reduction of feed consumption (decrease in body weight) • Causes skin disorders, nervous and immune systems effects, and effects on the liver, kidneys, and thyroid gland • Changes in the metabolism of vitamin A (retinol compounds and retinoic acid), which is important for cellular growth and differentiation

  11. Mode of Entry into Organisms • Gills • Ingestion • Breast milk

  12. Molecular Mode of Toxic Interaction • Induces CYTP450 • Induction of metabolic enzymes of hepatic microsome (arylhydrocarbon hydroxylase) • Interaction w/AHH receptors cause alteration in the expression in a number of genes.

  13. Biochemical Metabolism • Higher brominated PBBs are metabolized at a much slower rate than the lower brominated isomers. • The most frequently reported route of PBB metabolism was hydroxylation • aryl hydrocarbon hydroxylase (AHH system)

  14. Defense Strategies • Excretion through feces • Excretion through breast milk • Treatment to increase elimination of PBB in animals or humans was usually unsuccessful

  15. Bibliography • Primary cultured cells as sensitive in vitro model for assessment of toxicants- compasion to heptocytes and gill epithelia. Aquatic Toxicology, Volume 80, Issue 2, 16 November 2006, Pages 109-118 Bingsheng Zhou, Chunsheng Liu, Jingxian Wang, Paul K.S. Lam, Rudolf S.S. Wu • Microcontaminant accumulatoin, physiological condition and bilateral asymmetry in zebra mussels (Dreissena polymorpha) from clean and contaminated surface waters. Aquatic Toxicology, Volume 79, Issue 3, 12 September 2006, Pages 213-225 Judith Voets, Willem Talloen, Tineke de Tender, Stefan van Dongen, Adrian Covaci, Ronny Blust, Lieven Bervoets • http://www.inchem.org/documents/hsg/hsg/hsg083.htm Accessed April 17,2008 • http://ntp.niehs.nih.gov/ntp/roc/eleventh/profiles/s148pbb.pdf Accessed April 17, 2008 • http://www.atsdr.cdc.gov/tfacts68.html Accessed April 17, 2008 • http://www.michigan.gov/documents/mdch_PBB_FAQ_92051_7.pdf Accessed April 28, 2008 • http://www.ehponline.org/docs/1978/023/toc.html Accessed April 28, 2008 • http://www.meti.go.jp/english/report/downloadfiles/gED0306e.pdf Accessed April 30, 2008

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