Polybromated Biphenols Andrea Leasure BIOL 464 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 Relatively stable & chemically unreactive Photodegrade upon exposure to UV light

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

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

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

Mode of Entry in Aquatic Environment G PBBs entered the air, water & soil from G poorly maintained hazardous waste sites G Improper incineration of plastics containing PBBs. G 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. G PBBs entered the air, water & soil from G poorly maintained hazardous waste sites G Improper incineration of plastics containing PBBs. G 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.

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 years

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 (ng/g ww) with no effect Freshwater Tilapia (Oreochromis niloticus ) –6 h EC × 10−6 M –24 h EC × 10−6 M

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

Mode of Entry into Organisms Gills Ingestion Breast milk Gills Ingestion Breast milk

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.  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.

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)

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

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 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 Judith Voets, Willem Talloen, Tineke de Tender, Stefan van Dongen, Adrian Covaci, Ronny Blust, Lieven Bervoets  Accessed April 17,  Accessed April 17,  Accessed April 17,  Accessed April 28,  Accessed April 28,  Accessed April 30,  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 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 Judith Voets, Willem Talloen, Tineke de Tender, Stefan van Dongen, Adrian Covaci, Ronny Blust, Lieven Bervoets  Accessed April 17,  Accessed April 17,  Accessed April 17,  Accessed April 28,  Accessed April 28,  Accessed April 30,