18 BFRs & PFAs Flashcards
what is the outline of this lecture?
-what are BFRs? what are their applications?
-source and chemodynamics of BFRs
-exposure and toxicity to BFRs
-novel BFRs: what do we know about them?
-what are PFAs? sources and chemodynamics of PFAs
-exposure and toxicity of PFAs
what does BFR and PFA mean?
-brominated flame retardants
-polyfluoroalkyl substances
what is the definition and statistics of flame retardants?
statistics:
-every year in North America, there are over a million fires reported
-direct losses account for billions in damages
definition
-a substance added or a treatment applied to a material to suppress, or significantly reduce or delay the combustion of the material
why has the use of BFRs increased?
due to
-high standards of flame retardancy
-FR industry values at 2.3 billion (USD)
-synthetic polymers, household furniture, electronics
-all more flammable than wood/metal
-BFRs help save lives: extra time to vacate/get out of your burning pants suit
what is the global consumption of FRs?
what is the chemical reactivity of halogenoalkanes?
what are the three subgroups of BFRs?
what are PBDE commercial mixtures?
what is the physiochemical properties of selected BDFs?
what are the major flame retardant exposure pathways?
why do we say “they-re everywhere”?
PBDEs are now ubiquitous environmental contaminants:
-indoor and outdoor air
-house and office dust
-rivers and lakes and sediments
-sewage sludge
-food
-biota (terrestrial and marine mammals, fish, humans)
-remote arctic regions (i.e. long-range transport)
what was tested in BC?
what were the results on exposure and accumulation of BC?
what are some new and emerging POPs?
what are PBDEs in polar food web?
what are the recent trend in legacy BFR (e.g. HBCDD) in the arctic?
what are the human exposures to PBDEs?
-breastmilk
-maternal transfer to fetus
-diet (esp., fish, meat, dairy)
-indoor, house and office dust, outdoor air
-occupation
what is the dust exposure route?
what is the trend in breast milk?
what are indoor dust samples?
what are children’s exposure to flame retardants?
-indoor environments are often more polluted than outdoor environments (PBDEs in dust»_space;»»> PBDEs in soils)
-children have a high number of hand-to-mouth contacts
-children are physically in contact with many FR treated products
what else can cause a major form of exposure?
exposure via e-waste
-estimated 60-80% of global e-waste is important illegally to southeast asia and other underdeveloped parts of the world
-leads to highest reported levels of human exposure to PBDEs
what are the graphs of human exposure in e-waste areas?
what are the health effects of BFRs?
liver as target organ: penta/octaBDEs
-increased enzymatic activity (phase I and phase II enzymes), increased liver weight, histopathological changes
developmental neurotoxicity:
-likely due to disruption in thyroid hormone signaling
endocrine disruption
what is the thyroid?
thyroid: regulates critical homeostatic processes
-metabolism, temperature regulation, in utero growth and neonatal development
what are thyroid toxicities of PBDEs?
-thyroid regulates processes through signaling hormones
hydroxylated PBDEs similar to T4
-potential for interaction with similar targets
thyroid toxicities of PBDEs mainly results from disruption of hormone transportation system
-major hormone transport protein-transthyretin binding protein (TTR)
-i.e. 6-OH-BDE-47, 3x greater binding affinity for TTR than T4
though disruptive for adults, we have several transport proteins for thyroid hormones
what are the developmental toxicities of BDEs?
-during pregnancy the mother requires precise concentrations of hormones to orchestrate the complex process of fetal development
-developing fetus does not produce T4 until second trimester, and rely on mother as major source of T4 for duration of pregnancy
what is the maternal transfer of T4?
-TTR major transport enzyme of T4 to developing fetus-crosses placental barrier
-TTR binds hydroxylated PBDEs with greater affinity than natural hormone
what are the effects of developmental toxicities?
-new meta-analyses
-309 women
followed children for 5 years
-4.5 points lower IQ
-3.3 point increase hyperactivity
what are NBFRs?
novel brominated flame retardants
-deemed “novel” though many have been in use since 1970s
-many compounds are simple derivatives of known BFRs
what are the properties of NBFR?
what are the total NBFR levels in various aquatic environments around the world?
what is the potential toxicity of NBFRs?
what are NBFRs in marine polar food webs?
what is the summary of BFRs?
what is the background of PFAs?
what are the uses of PFAs?
what are the fate and behavior of PFAS?
-extremely persistent, long half-life of many PFAS: >40 years
-ionic/short-chain PFAS (e.g. PFCAs, PFSAs) are highly water soluble and non-volatile, transported long-distance by water/ocean currents
-neutral PFAS (e.g., FTOH) are volatile, typically found in the atmosphere, and transported long-distance by wind
-PFAS undergo abiotic and biotic transformation (e.g., WWTPs) to form more stable perfluoroalkyl products-do not degrade under ambient environmental conditions
what are the human exposure and effects of PFAS?
what are PFAS regulations in canada?
what was the results of the test of arctic indigenous peoples?
