Polybromated Biphenols

Andrea LeasureBIOL 464

Structure of the Compound

Physical & Chemical Properties

Colorless to off-white solidsLow vapor pressureSoluble in fat, organic solvents (solubility

decreases w/ increasing bromine number) Insoluble in waterRelatively stable & chemically unreactive

Photodegrade upon exposure to UV light

Uses & Applications

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

Mode of Entry in Aquatic Environment

PBBs entered the air, water & soil from poorly maintained hazardous waste sitesImproper 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.

PBBs entered the air, water & soil from poorly maintained hazardous waste sitesImproper 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.

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

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

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

Mode of Entry into Organisms

• Gills• Ingestion • Breast milk

• Gills• Ingestion • Breast milk

Molecular Mode of Toxic InteractionMolecular 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 StrategiesDefense 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

BibliographyBibliography 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

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