1) The document summarizes a study measuring the transfer of insecticides from treated textiles onto contact surfaces using various sampling techniques. 2) Key findings include that little insecticide was detectable after 3 days of rinsing but some returned after 2 weeks, and wet wipes resulted in higher transfer than dry wipes. 3) The diffusion rates of the insecticides within polymer pellets were determined but a predictive model for regeneration of insecticides on textile surfaces requires more development.

1. 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/assumptions3:
• Insecticide on the surface of the polymer, Cs, exists in equilibrium
with the bulk concentration in the polymer, Co
• 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: Tr = Mrecovered/Msurface
• 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/H2O 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 (Kow)
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/m2)
Mass Content
(%)
Areal
Content
(average
ug/cm2)
Fiber
Diameter
(μm)
Cs, Surface
Conc.
(ug/cm2
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
𝑀𝑡
𝑀∞
=
6
𝑟
√
𝐷𝑡
𝜋
± = 95% CI *Mass extracted per gram of fabric from surface <5 sec solvent rinse of the fabric, converted to cm2 using basis weight
} Tr
𝑀𝑡 = 𝑚𝑎𝑠𝑠 𝑑𝑖𝑓𝑓𝑢𝑠𝑒𝑑 𝑎𝑡 𝑡𝑖𝑚𝑒 𝑡
𝑀∞= 𝑡𝑜𝑡𝑎𝑙 𝑚𝑎𝑠𝑠 𝑖𝑛 𝑝𝑒𝑙𝑙𝑒𝑡𝑠
r = radius, cm (average pellet dimensions)
D = diffusion coefficient, cm2/sec
D (cm2/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, Tr, 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 Cs (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 –
76cm2
0.1psi –
54cm2
1psi smudge
– 146cm2
μg/cm2 of insecticide B recovered from static
cellulosic wipe + water over time of Fabric 1
μ g/cm2 of insecticide B recovered from active
cellulosic wipe + water repeated on same fabric
μ g/cm2 recovered from active wipe both
fabrics using different samplers
Acknowledgements: Research funded by Vestergaard Frandsen
Approaches
cumulative mass
of ~ 1 μ g/cm2
Approaches
cumulative mass of
~ 1.75 μ g/cm2
Insecticide B in pellet – exists in
localized concentrated regions
𝑀𝑡
𝐴
= 2 ∗ 𝐶 𝑜 𝐷 ∗ 𝑡/𝜋
Regeneration
initially modeled
with simplified
equation for
diffusion from a
cylinder. Greatly
overestimated rate.
𝐴 = 𝑎𝑟𝑒𝑎 𝑢𝑠𝑒𝑑 𝑎𝑟𝑒𝑎 𝑜𝑓 𝑓𝑎𝑏𝑟𝑖𝑐 𝑛𝑜𝑡 𝑎𝑐𝑡𝑢𝑎𝑙 𝑎𝑟𝑒𝑎 𝑜𝑓 𝑓𝑖𝑏𝑒𝑟 𝑠𝑢𝑟𝑓𝑎𝑐𝑒
𝐶 𝑜= 𝑏𝑢𝑙𝑘 𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛, 𝑢𝑔/𝑐𝑚3 estimated from typical density of polypropylene
A and B on dry wipes
were detected but
below method
LOQ = of 0.004 ug/cm2
A and B on dry wipes
were detected but
below method
LOQ = of 5% recovery
Textile Protection and
Comfort Center (TPACC)