Document RjM151R8yZx3qGd4xQ1aKdejn

AR226-2700 AR226-2700 TORONTO WORKSHOP MATERIALS Septem ber 13-14,2004 ) A n (E-Tate (Perspective John Gannon DuPont Central Research & Development, Wilmington, DE M B fe I | The miracles o f scien ce] 1 isiderations for Thou What is the Source of PFCA's in the Environment? What is the potential contribution of emissions from direct PFCA Sources? What is the potential for degradation of the Fluorotelomer-based polymers as an indirect source? es What is the potential contribution of Fluorotelomer raw material residuals as an indirect source? Potential PFCA Sources : F(CF2)n COO 1950's - present Fluoropolymer Manufacture F(CF2)?COONH4+ 7uoropoly*re*' Dispersions F(CF2)nC O O N H 4 T Fluoropolymer Manufacture F(CF2)nCOONH4+ n = 6 -12 APFO Manufacture 1950's - present ECF AFFF Agents PFCA-based Indirect Sources P F C A 's in the Environment AX X X X AFFF Agents C-6 Telomer-based 19705s - present I elomer nufacture, Indus & Consumer Use otential Degra AFFF agents PFOS-based 1 Q 7 rj*3 - p r e s e n t I The miracles o f science' PFCA Impurities in POSF Materials POSF Materials Potential Breakdown to PFCA5s 1950 s - present 3 Emissions from Point Sources mm The miracles o f science] 4 Influence of Particle Size Distribution Particle size categories: Particle diameter (Dp): Dominant Removal M echanism : Typical residence time: Coarse mode D p > 2.5 pm Gravitational settling minutes to days Accumulation mode < 0.1 urn < D p < 2.5 pm W et deposition days to weeks Aitkens nuclei mode <0.1 pm Dry deposition minutes to days Wet Deposition What Happens Next?: ___ _ After material deposited on soil/ in water via gravitational settling / dry deposition: Materials that are volatile or sublime may evaporate back to atmosphere The dominant particle sources (by mass) in air are mineral dust from wind-blown soils and sea-salt particles from wave-breaking. r : .>:ypo;3g X-a/i?: Presence of Rain Event After Material deposited on soil and in water via wet deposition: Water soluble/miscible materials will move with water (e.g., PFCAs) * Water insoluble materials with high adsorption coefficients may adsorb to soil matrix at or near the surface (e.g., fluorotelomer alcohols (FtOH)) Note: TRP soil adsorption studies showed essentially full recovery of FtOH in test soils and soil pore water, but no FtOH in air traps. Adsorption clearly dominant Questions: Would FtOH adsorbed to wind-blown soils be: reactive in the atmosphere? deposited in remote locations as wind-blown soil with adsorbed FtOH? li .. .............................. Hypothesis Wind-blown soils may: account for transport of PFCAs and FtOH from surface of soils to the atmosphere. enhance rate of sublimation for PFCAs from soil surfaces. limit potential for FtOH transformation in atmosphere deposit FtOH in remote locations as wind-blown soil with adsorbed FtOH. The miracles o f science\ 8 -ja -S a lts '. -/t asis 1. PFCAs and FtOH may be deposited in marine boundary layer of ocean and associated with sea-salts. 2. Wave-breaking and winds move sea-salts into atmosphere. 3. PFCAs may enter atmosphere via transport on sea-salts or perhaps evaporate/sublime from marine boundary layer. 4. FtOH may enter atmosphere via transport on sea-salts or volatility, or perhaps it is transformed in marine boundary layer and/or it may be deposited to sediments. ImmThe mincies o f science 9 Interpolated Animation of Global Winds as rom tike NASA SeaWinis Instrument % Potential Distribution via Oceanic Surface Currents Currents flow in complex patterns affected by wind, salinity, heat content, bottom topography, and earth's rotation. Source: Physical Geography .Net I The miracles o f scien ce " Warm Current flohnson Pi Cold Curent Grasshopper Effect & Global Fractionation S t o r e v o l s * l e s*tfts*r*ee Grasshopper Effect: series of air-surface exchange events following an initial emission-deposition event. involves cycles of evaporation/sublimation to the atmosphere, carried by winds for a distance, and then wet deposition (i.e., rain, snow events) to land or water. Global Fractionation: differing behaviors of chemicals as transported phys.-chem. prop, influence residence time and hop probability. mm The miracles ofsclence~\ Potential PFCA Sources : F(CF2)n COO 1950's - prese l-' Sources Fluoropolymer Manufacture F(CF2)7COO-NH4+ APFO Manufacture 1950's - present / ECF 7 / AFFF Agents / / PFCA-based / / /1960's-70's Indirect Sources AFFF Agent C-6 Telomer-based 970's - present Fluoropolymer Dispersions F(CF2)nC O O N H 4 + Fluoropolymer Manufacture F(CF2)nCOO-NH4+ n = 6 -12 A AFFF agents PFOS-based 1970's - present PFCA Impurities in POSF Materials 1950's - 2002 HH1elome nufacture, Indus & Consumer Use tial Degra1 PS- POSF Material Potential Breakdown t PFCA's 1950's - preset Are " telomer-Based ilfitiers Potential Source of PFCAs? To evaluate Fluorotelomer-based Polymers (FTBP) as a potential contributor, we will need to look at the potential for the FTBP to be degraded. I The miracles o f science 4 Evaluating Degradation Potential o f Ftuoro-TeSomer-Based Polymers (FTBP) Abiotic Transformation Hydrolysis * Thermal (incineration Studies) > Photochemical Stability under Industrial & Consumer Use conditions Biodegradability: Sewage Treatment Plant Modified Zahn-Wellens Test per OECD 302B STP Simulation Test per OECD 303A Anaerobic Biodegradability of Organic Compounds in Digested Sludge per OECD 311 # Evaluating Degradation Potential of Fluoro-Telomer-Based Polymers (FTBP) n Biodegradability: Soils and Sediments Aerobic and Anaerobic Biodegradation Studies Range of soils and sediments to allow for evaluation of differences in physical-chemical parameters that may influence biodegradability potential. Expected Duration: 1 year Determine Kinetics (if possible) \ | The miracles o f science] 6 Summary Cannot fully answer questions about PFCA sources in environment and biota without understanding contributions of emissions from all PFCA sources: Need to develop a global distribution model to evaluate relationship of 50 yrs. of PFCA emissions with presence in environment and biota. Need to Understand if Fluorotelomer-based Polymers Transform Potential Distribution Via Air- Global Winds: Circulation Cells and Prevailing Wind Beits | B I> I I The miracles o f scien ce] 18