bfr

Information about bfr

Published on January 22, 2008

Author: Manfred

Source: authorstream.com

Content

Brominated Flame Retardants: Cause for Concern?:  Brominated Flame Retardants: Cause for Concern? Linda S. Birnbaum, Ph.D., D.A.B.T. Michael DeVito, Ph.D. NHEERL/ORD/US EPA Why BFRs?:  Why BFRs? Fire Regulations require a high degree of protection Flame Retardants save lives Fires generate PHDDs/PHDFs 75 different BFRs 50% are new substances ( testing required) BFRs:  BFRs Large variety of chemicals ~75 BFRs – and not all alike! BFRs may be as common as PCBs Banned production of PCBs with less information than we currently have on BFRs Identify data gaps and research agenda Large variety of issues Production of BFRs:  Production of BFRs Worldwide - ~500,000 tons/yr of bromine $2 billion/year industry BFRs- ~ 40% of total bromine usage Bromine Br-chemicalsBr-polymersBFRs Worldwide demand in 2000 for BFRs 300x106 BFRs kg/year Greatest increased use – Asia US usage - ~100X106 kg/yr Why should there be action at international level?:  Why should there be action at international level? Global, transboundary problem Persistence Potential for bioaccumulation Potential risk for future generations Very limited knowledge base Precautionary Principle Miminize production, emissions, use, exposure (Risk/Risk Trade-offs?) Major BFR Classes:  Major BFR Classes Br-Bisphenols Br-Diphenyl Ethers Br-Cyclododecane Br-phenols Br-phthallic acid derivatives +++++others Global Market Demand for BFRs in 1999 (metric tons):  Global Market Demand for BFRs in 1999 (metric tons) Tetrabromobisphenol A (TBBPA):  Tetrabromobisphenol A (TBBPA) TBBPA (Tetrabromobisphenol A):  TBBPA (Tetrabromobisphenol A) Reactive and Additive BFR Phenolic –OH-polymerization Major Use –printed circuit boards Detected in air, sediment, sewage, sludge Highly lipophilic, low water solubility Limited data in biota Dimethyl-TBBPA metabolite eliminated in bile Little retained in tissues TBBPA (con.):  TBBPA (con.) Acute tox data – oral LD50: 5-10 g/kg Low chronic toxicity Not teratogenic or mutagenic Affects thyroid hormones; estrogenic Soil Degradation –aerobic and anaerobic t1/2~2mos Photodegradation t 1/2~<<1day Health Effects of TBBPA:  Health Effects of TBBPA Immunotoxic Inhibits T cell activation : blocks CD25 (<3µM) Hepatotoxic Toxic to primary hepatocytes: destroys mitochondria; membrane dysfunction (inhbits CYP2C9) Endocrine Disrupting Health Effects of TBBPA (con) Endocrine Disruption:  Health Effects of TBBPA (con) Endocrine Disruption AhR Effects Not relevant for commercial product Thyroid TBBPA>T4 in relation to binding to transthyretin Observed in vivo Estrogenic Inhibits sulfotransferase (decreases estrogen clearance) Mostly in vitro data Hexabromocylododecane (HBCDD):  Hexabromocylododecane (HBCDD) HBCDD (hexabromocyclododecane):  HBCDD (hexabromocyclododecane) Major use – polystyrene resins>textiles ~10,000tons/yr Highly lipophilic, low water solubility, low vapor pressure, high BCF, persistent Ecotox – Algae, daphnia, NOEC = 3 ug/L Fish, LC 50>water solubility; PNEC=.03ug/L HBCDD (con):  HBCDD (con) Toxicity High absorption; mild irritant and skin sensitizer; liver effects after repeated exposures (LOEL (rats) ~13 mg/kg/day) Need more info: repeated dose studies, repro tox Concern for Occupational Settings Fulfills POPs Critera Persistence, bioaccumulative, toxic, long range transport PBDEs :  PBDEs Major Industrial Products (~67 metric tons/year):  Major Industrial Products (~67 metric tons/year) DBDE – largest volume (75% in EU) 97% DBDE; 3% NBDE Polymers, electronic equipment>textiles OBDE 6%HxBDE; 42%HpBDE; 36% OBDE; 13%NBDE; 2%DBDE – multiple congeners (unclear if any PeBDE) Polymers, esp. office equipment PeBDE Textiles – esp. polyurethane foams Recommended ban in EU(no production/only import) Mainly PeBDE+TeBDE, some HxBDE Properties:  Properties Solids with low solubility (< 1ug/kg), high log Kow (~6.2) Lower congeners are more bioaccumulative, persistentStrong adsorption to soil/sediment/sludge;No significant bodegradation in air/water Bioaccumulation - BCF > 5000, Log Kow >5 Long Range Transport - Evidence of remote contamination (e.g., Arctic) Persistence- t 1/2 Atmospheric >2 days;Water >2 mos; Soil, sediment >6 mos Sources of Environmental Release:  Sources of Environmental Release Polymer Processing Formulating/applying to textiles Volatilization and leaching during use Particulate losses over use/disposal PBDEs in Biotic and Abiotic Samples:  PBDEs in Biotic and Abiotic Samples Air: 47>99>100>153=154 Sediment: 99>47 (pattern reflects commercial PeBDE); also some nona and deca Sewage Sludge: 1-3mg/kg in US; pattern ~PUFs Point sources (~DBDE) --->0.1-5 mg/kg Biota: 47>99=100 except if near manufacturing site (pattern does NOT reflect commercial PBDEs) Invertebrates<Fish<<marine mammals PBDEs (con) Ecotoxicity:  PBDEs (con) Ecotoxicity PeBDE>>OBDE>DBDE Highly toxic to invertebrates DBDE/OBDE May be low risk to surface water organism and top predators Concern for waste water, sediment, and soil organisms CONCERNS: Presence of lower brominated congeners in OBDE Photolytic and/or anaerobic debromination Formation of PBDDs/PBDFs PBDEs (con) Photolytic Debromination:  PBDEs (con) Photolytic Debromination DBDE-NBDE+OBDE (t ½ = 15 hr) OBDE-HpBDE+HxBDE (t ½ = 40 hr) PeBDE-lower PBDEs+ PBDFs Composition of photoproducts is not the same as the commercial PBDE mixtures PBDEs (con) Congener Patterns:  PBDEs (con) Congener Patterns Commercial Products Environmental Samples Human Tissue Samples Exposure Routes:  Exposure Routes Fish Dairy Meat OTHER? Pharmacokinetics of PBDEs:  Pharmacokinetics of PBDEs Absorption – DBDE is poorly absorbed Distribution – lipid binding is important Fat: 47>99>>>209 Liver: covalent binding from 99,209 Metabolism – hydroxylation, debromination, O-methylation Excretion – feces is major route Neurotoxic Effects:  Neurotoxic Effects Developmental Neurotoxicants Perinatal; neonatal 47,99,153,209 Spontaneous behavior (mice)/hyperactivity Permanent changes in brain function Developmental exposure -Increased susceptibility of adults exposed to low doses of PBDEs Endocrine Disrupting Effects:  Endocrine Disrupting Effects AhR Effects not relevant for commercial BFRs But combustion can produce PBDDs/PBDFs Thyroid OH-PBDE metabolites bind to transthyretin Effects on T4 seen in vivo Estrogenic OH-PBDEs Inhibit sulfotransferase (decreases estrogen clearance) Mostly in vitro data Key Issues: PBDEs :  Key Issues: PBDEs Potential adversity to human health and environment In vivo and in vitro studies Liver effects; Developmental neurotoxicity; Endocrine disruption Contaminants and Combustion Products –PBDFs/PBDDs (Are they present in the environment and in biota?) Research Needs t ½ in environment; Remote monitoring data; Chronic health effects End of life cycle – release? Breakdown? PBDEs in Human Samples:  PBDEs in Human Samples Pattern of congeners is different from commercial mixtures (and food) 47>99 in US and Europe(others: 100,153,183, 209?) In Japanese, 99 and 153>47 Large interindividual differences Increasing time trends – levels doubling every 2-5 years PBDEs and PCBs levels are not correlated In most samples today, PCBs>PBDEs different sources and/or time sequence Time Trends of Biotic Levels:  Time Trends of Biotic Levels Rapid increases from 70s thru 90s Maybe slight decrease in Sweden Ban on use of PeBDE? Levels still increasing in America Continued use of PeBDE? ARE LEVELS HIGH ENOUGH TO SEE EFFECTS??? NEED MORE TOX DATA! What next?:  What next? More systematic human and environmental monitoring More tox data Focus on congeners present in people and wildlife, NOT commercial products since they are altered in the environment

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