New Fabric A Fabric A rinsed, sit 3 days Fabric A rinsed, left for 2 weeks Polypropylene signal Insecticide B signal William J. Gabler, Chandler Probert, Tyler Pickett, R. Bryan Ormond Measuring Transfer from Insecticide Treated Textiles 1. Hayes, D. g. in Functional Textiles for Improved Performance, Protection, and Health (eds. Pan, N. & Sun, G.) 404–433 (Woodhead Publishing Limited, 2011). 2. Clausen, P. A. et al. Experimental estimation of migration and transfer of organic substances from consumer articles to cotton wipes: Evaluation of underlying mechanisms. J. Expo. Sci. Environ. Epidemiol. 26, 104–12 (2016). 3. Ivancic, W. A. et al. Development and evaluation of a quantitative video-fluorescence imaging system and fluorescent tracer for measuring transfer of pesticide residues from surfaces to hands with repeated contacts. Ann. Occup. Hyg. 48, 519–532 (2004). Theory/assumptions 3 : • Insecticide on the surface of the polymer, C s , exists in equilibrium with the bulk concentration in the polymer, C o • Transfer from the polymer to a contact surface occurs by: • Mechanical transfer to the other surface • Chemical attraction to the other surface • Diffusive transfer over extended contact times, D • A characteristic transfer efficiency exists for a contact surface/wiping technique: T r = M recovered /M surface • Insecticide migrates in the polymer based on Fick’s laws Surface Analysis Time-of-Flight Selected Ion Mass Spectrometry (TOF/SIMS) provides spatial concentration on surface by bombarding with ion beam and detecting the abundance of characteristic mass fragments. Possible to validate findings or detect lower quantities? Insecticidal Textiles Insecticide treated textiles are important tools for controlling the transmission of infectious disease by insects around the world. Some fabrics are created with the insecticide incorporated into the fiber polymer so reapplication is not necessary and distribution/implementation is simpler. These textiles are preferred over residual spraying techniques for vector control in certain applications. The textiles have a layer of insecticide on the surface which is replaced from the bulk of the polymer over time. 1 Manufacturers want to know: What is the surface concentration? How much transfer occurs from contact with the textiles? What is the effect of different cleaning methods on the concentration of the surface and performance of the product? Three different non-halogenated insecticides were investigated, identified as: Future Work • Need to combine wipe transfer values with diffusion and fiber dimensions to estimate rate - develop predictive model of transfer and recovery • Compare different washing/treatments– detergents, environmental ageing, contaminants, and field-deployed samples etc. – effect on Cs • Expand TOF/SIMS work to monitor sample in different conditions • Explore other contact sampler materials • Correlate surface concentration values with bioefficacy • Incorporate findings into improved product design and information for users Diffusion from the pellets to an extraction solution were modeled by sorption/desorption equation for a sphere. Concentration over time of pellets submerged in acetone (solubility in water was too low – showed no diffusion) – providing an (over)estimation of diffusion rate. Extraction and Chemical Analysis Bulk extraction using Buchi Speed Extractor E-916 Pressurized Fluid Extractor (PSE). Methods verified by performing cycles to exhaustion on ~200 mg samples. Fabric – 80°C, 100 barr, 10 mL cell, 15-20mL acetone, 1 cycle, 10 minute hold. Pellets – 135°C, 100 barr, 10 mL cell, 45-60 mL acetone total, 3 cycles, 30 min hold Detection – All analysis performed on Agilent Infinity 1260 HPLC, Poroshell 2.7 μm C18 column, ACN/H 2 O solvent, with a Diode Array Detector monitoring absorbance wavelength for each insecticide. Based on 6-point calibrations between 0.05 and 150 μg/mL. Limits of quantitation on the order of 0.5 μg/mL in acetone. Surface Transfer and Wipe Experiments Wipe Experiments Characterize transfer by measuring recovery from a spiked surface and from fabrics using different wipes • Cellulosic wipe (KW)– absorbing wipes, low extractables –represent cotton and paper • C18 - solid phase extraction disk, oleophilic surface – intended to represent oily skin Conditions: • Dry (D) – no solvent • Water (W) – typical cleaning solution • Acetone (A) - solvent in which insecticides have high solubility Insecticide Molar Weight log (K ow ) Water Solubility (mg/L) at ~20°C, pH 7 A 873.1 3.99 <0.01 B 421.5 5.01 0.023 C 306.4 5.71 0.102 Fabric / Insecticide Basis Weight (g/m 2 ) Mass Content (%) Areal Content (average ug/cm2) Fiber Diameter (μm) C s , Surface Conc. (ug/cm 2 estimated)* Fabric 1 A B 104 ± 13 0.06 ±0.005 0.35 ±0.005 6.2 36.4 32 ± 1.5 0.7 10.6 Fabric 2 A C 0.06 0.35 6.2 36.4 0.9 6.23 ∞ = 6 √ ± = 95% CI *Mass extracted per gram of fabric from surface <5 sec solvent rinse of the fabric, converted to cm 2 using basis weight } T r = ∞ = r = radius, cm (average pellet dimensions) D = diffusion coefficient, cm 2 /sec D (cm 2 /s) A 1.94E-12 B 1.73E-10 C 4.88E-09 Example 5-cm diameter fabric swatch containing insecticide A and B, cut for extraction and contact sampling Example ~3mm polymer pellets containing 17% insecticide B by weight Products were provided by Vestergaard Frandsen: Two polypropylene spunbond nonwovens, manufactured from insecticide impregnated pellets. Concentrations verified using bulk extraction: Pellet A – 9% by weight, Pellet B – 17% by weight, Pellet C – 14% by weight. Diffusion Transfer Rates Key Findings • Insecticide is not evenly distributed on surface. • Little insecticide is detectable 3 days after samples were rinsed with water, but after 2 weeks the insecticide appears to have returned in a new distribution pattern on the surface. • Insecticide A did not have a strong enough response for analysis Metal cylinder – 5-6 kPa (~0.8 psi) Dry or wetted sampler Insecticide treated surface or fabric Static for long duration or active sampling (dragging) across fabric in order to sample larger surface area. Sampler removed and extracted with acetone then analyzed to determine transferred mass. % recovered, T r , from a spiked hard surface What affects transferred amount? Pressure, contact area, duration, solubility, migration rate Contact area of hands pressed on metal surface Ivancic, et al. 4 • Wetted cellulosic wipe provided highest mass removal • A water wipe gives higher transfer than solubility limit allows – mechanical transfer enhanced by wet wipe, performs as well as acetone wipe • Static wet sampling appears to provide similar transfer to active wipe – both remove <10% of estimated C s (only one side of fabric sampled) • C18 samplers had low recoveries – sampler surface may be too fragile • Orders of magnitude differences in D unexpected • Diffusion rates attained could be used to predict rate of regeneration of insecticide – more work required 1psi – 76cm 2 0.1psi – 54cm 2 1psi smudge – 146cm 2 μg/cm 2 of insecticide B recovered from static cellulosic wipe + water over time of Fabric 1 μ g/cm 2 of insecticide B recovered from active cellulosic wipe + water repeated on same fabric μ g/cm 2 recovered from active wipe both fabrics using different samplers Acknowledgements: Research funded by Vestergaard Frandsen Approaches cumulative mass of ~ 1 μ g/cm 2 Approaches cumulative mass of ~ 1.75 μ g/cm 2 Insecticide B in pellet – exists in localized concentrated regions =2∗ ∗ / Regeneration initially modeled with simplified equation for diffusion from a cylinder. Greatly overestimated rate. = = , / 3 estimated from typical density of polypropylene A and B on dry wipes were detected but below method LOQ = of 0.004 ug/cm 2 A and B on dry wipes were detected but below method LOQ = of 5% recovery Textile Protection and Comfort Center (TPACC)