Download PDF - Olyset Net

Registered trademark of Sumitomo Chemical Co. Ltd.
The Next-Generation Net with Added Protection
Olyset ® Plus is a durable long-lasting
mosquito net with fast action against
mosquitoes and additional efficacy
against Pyrethroid-resistant mosquitoes.

Olyset Plus – meeting the world’s changing needs.
Contents
Introduction and Background....................................................................1
Controlled Release Technology ................................................................5
Biological Efficacy ......................................................................................6
Technical Specifications ..........................................................................10
Usage and Safety ......................................................................................12

Introduction and Background
Introduction
Mosquito nets have a long history of protecting people
from malarial mosquitoes but it was not until the introduction
of treating nets with pyrethroid insecticides that
bed nets changed from being a physical barrier to being
an insecticidally active tool which both deters and kills
mosquitoes. The original method of dipping nets in
insecticide solution was very labour intensive and
logistically difficult in the field and the treatment rarely
survived more than three washes. The situation changed
dramatically with the introduction of factory-treated,
wash-proof, long lasting insecticide treated nets (LLINs)
in which the insecticide is either bound to the surface of
the net fibre or incorporated inside the fibre itself.
Olyset ® Net – Pioneering Technology with Added Durability
Sumitomo Chemical was the first company to develop and
pioneer fibre incorporation technology. We realised that
incorporation of insecticide into the fibre, using controlled
release technology that allows insecticide to migrate to
the surface and maintain a regular supply, is better than
`gluing` to the fibre surface which leaves the insecticide
vulnerable to removal by abrasion or washing. In addition,
the use of high-density polyethylene (HDPE) rather than
polyester as the fibre material gives major advantages in
both the strength and durability of the net. Olyset Plus,
like the original Olyset Net, has a denier of >150 whereas
commonly available polyester nets are 75 – 100 denier. As
denier is one of the major contributors to strength and
durability in the field, Olyset Plus is therefore approximately
1.5 - 2 times stronger than typical 75 – 100 denier
polyester LLINs.
Olyset Net was the first LLIN to pass the World Health
Organization Pesticide Evaluation Scheme (WHOPES).
Since then, many more nets have passed WHOPES with
either interim or full recommendation. However, all these
nets—including Olyset Net—are manufactured using a
single class of insecticides known as pyrethroids, on
account of their excellent activity against mosquitoes and
low mammalian toxicity.
Emerging insecticide resistance – a real threat
Due to the excellent results from using LLINs, donors
campaigned and advocated for mass distribution of bednets
throughout Africa and in many other endemic countries.
Universal coverage (at least 80% coverage with LLINs of
at-risk populations) was achieved in many African
countries by early 2011. The pressure of only using
pyrethroids in LLINs, and their extensive use in indoor
residual spraying programs as well as in agriculture, has
resulted in insecticide resistance in mosquito vector
populations in some parts of the world, particularly in
Africa. ‘At the time of this report, resistance to at least
one insecticide has been identified in 64 countries with
on-going malaria transmission. Resistance to pyrethroids
Key Features
• Fine mesh.
• Softer feel.
• Excellent biological performance
against mosquitoes.
• Enhanced knockdown and kill
against pyrethroid-resistant
mosquitoes.
• Contains the synergist –
piperonyl butoxide (PBO) on
all surfaces.
• Insecticide and synergist
incorporated inside fibres.
• Insecticide and synergist
migrate to fibre surface
continuously over many years.
• Re-generation of both
active ingredients.
• Unique to market.
• A second generation of the
well proven Olyset Net.
• Japanese technology.
seems to be the most widespread.*’ The extent and
threat of resistance to the use of LLINs and on actual
malaria cases is not well understood and there are large
programmes planned to monitor and check the impact
on transmission.
* WHO Global Plan for Insecticide Resistance Management in malaria
vectors (GPIRM), 2012
1

Figure 1. Possible scenario for resistance development
in a mosquito population.
Reproduced by kind permission of IRAC
Figure 2. Distribution of pyrethroid resistance in Africa using
data collected between 2000 to 2010.
Sumitomo Chemical’s original Olyset Net remains one
of the best and most durable LLINs on the market.
However, Sumitomo recognised that for some markets
improvements could be made by increasing the speed of
action and efficacy against both susceptible and resistant
mosquitoes. This led to the development of Olyset Plus.
Olyset Plus introduces many new features, including
the addition of piperonyl butoxide (PBO), a synergist
which increases the performance of the active ingredient
Permethrin and in particular enhances activity against
pyrethroid-resistant mosquitoes (see below for more
information on PBO).
Olyset Plus is the first and only net on the market to
incorporate PBO into every fibre and all surfaces of the
net, providing enhanced knockdown and kill against
pyrethroid-resistant mosquitoes.
Insecticide Resistance
Insecticide resistance is defined by the Insecticide
Resistance Action Committee (IRAC) as: ‘a heritable change in
the sensitivity of a pest population that is reflected in the repeated
failure of a product to achieve the expected level of control when used
according to the label recommendation for that pest species.’
The development of insecticide resistance occurs for the
following reasons:
Key:
An. pharoensis
An. labranchiae
An. funestus
An. gambiae s.l.
An. arabiensis
An. gambiae s.s.
Resistant
Resistance suspected
Susceptible
Ranson et al, Trends in Parasitology, February 2011, Vol. 27, No. 2.
• Natural selection allows pre-adapted insects with
resistance genes to survive and pass this resistance trait
onto off-spring.
• As more product is applied, the resistant population
keeps growing while the susceptible individuals are
eliminated by the insecticide. The product therefore
is no longer fully effective.
Other key points to note :
• Speed of resistance development depends on speed of
reproduction, the persistence of the insecticide applied
and the proportion of susceptible species.
• Resistance has appeared in a wide range of public
health vectors to most chemical classes of insecticides.
• The resistance problem in vector control is exacerbated
2

y extensive use and misuse of the same classes of
insecticides in agriculture.
The map (see Figure 2) indicates that there is a spread of
pyrethroid resistance into many areas of Africa where
LLINs are being deployed. While the impact of this resistance
on the efficacy of LLINs and malaria transmission is
still unknown, there is a growing consensus that high
levels of resistance may in the future result in operational
failure of mass LLIN distribution programmes. Insecticide
resistance in malaria vectors is therefore one of the major
issues concerning stakeholders today.
There are several types of resistance mechanism:
• Metabolic resistance.
• Target site resistance (Knockdown resistance (Kdr)
or nerve insensitivity).
• Behavioural resistance.
• Reduced penetration resistance.
Amongst these mechanisms, metabolic resistance is
probably the most important, although the impact of Kdr
resistance is also significant. The only chance to overcome
most types of resistance is by using a totally new class of
insecticide which as yet is not available. Ideally, a new
insecticide would have all the attributes of pyrethroids:
Olyset Plus is the first and only net on the market to
incorporate PBO into every fibre and all surfaces of
the net, providing enhanced knockdown and kill
against pyrethroid-resistant mosquitoes.
fast action, high intrinsic activity against target insects,
and low mammalian toxicity combined with ease of
formulation. These characteristics make the task of
identifying suitable chemistry an extremely challenging,
costly and long-term undertaking.
While companies such as Sumitomo Chemical are
playing a leading role in the synthesis, screening and
development of new chemistry for use in disease vector
control, the best solution in the interim is to continue to
formulate LLINs with pyrethroids and to use the synergistic
properties of PBO to improve insecticidal activity
against both susceptible and resistant mosquitoes.
For further information on insecticide resistance,
monitoring and management strategies see `Prevention
and Management of Insecticide Resistance in Vectors of
Public Health Importance` published by IRAC (CropLife
International) – see (www.irac-online.org)
What is Olyset Plus
Olyset Plus is a durable polyethylene net containing 2%
permethrin and 1% of the synergist piperonyl butoxide
(PBO) which are incorporated in all fibres. In this way,
all sides and also the roof are treated. Using Sumitomo
Chemical’s unique Olyset controlled-release technology, net
fibres have been designed to release the two ingredients at
a constant ratio of 2:1 thus ensuring enhanced efficacy for
the life of the net against all mosquitoes, including those
which are resistant.
It has been shown that while many mosquitoes
approach the roof of the LLINs a similar proportion go to
the sides to get at the sleeping host. (Ref. Severin, L.
University d` Abomey – Calavi Calvi, pers. comm.)
Based on the above, it is clear that any net seeking to
provide enhanced levels of protection from susceptible and
3

esistant insects should have PBO on all surfaces so that
the mosquitoes cannot avoid contacting both insecticide
and synergist at the same time.
What is Piperonyl Butoxide
Piperonyl butoxide (PBO) is a synergist which has long
been used to improve the performance of pyrethroid
insecticides especially household aerosols. Synergists are
chemicals that lack insecticidal activity of their own but
enhance the insecticidal performance of other chemicals.
How does Piperonyl Butoxide combat resistance
All insects, whether susceptible or resistant, have enzymes
that can metabolise insecticides into harmless components.
Some of these enzymes, known as cytochrome P450s, are
powerful oxidising agents that can detoxify an active
ingredient before the desired effect is achieved; PBO is a
powerful inhibitor of these enzymes and therefore blocks
this action.
In resistant insects the activity of these enzymes can
be greatly enhanced which can significantly reduce the
efficacy of an insecticide. PBO acts on these enzymes in
resistant insects and inhibits the breakdown or the
metabolism of insecticides, rendering the insecticide more
effective. PBO also increases the activity of pyrethroids to
susceptible insects, so adding PBO to an LLIN has a benefit
even in areas where there is no resistance.
There are many scientific papers which demonstrate
the impact of PBO on pyrethroid resistance, and some
specifically highlight the impact on permethrin resistance.
See for example: Evidence of multiple pyrethroid resistance
mechanisms in the malaria vector Anopheles gambiae sensu stricto
from Nigeria. Awolola, T.S. et al., Transactions of the Royal Society
of Tropical Medicine and Hygiene Vol: 103, Issue: 11, Pages: 1139-
1145 (2009).
Piperonyl Butoxide Key Points:
• Inhibitor of P450 enzymes.
• Enhances insecticide penetration.
• Used in many household aerosols and space sprays
products.
• Not an insecticide but a synergist.
• Low mammalian toxicity.
• Known and used for >50 years.
Olyset Plus Regeneration
Rapid regeneration of surface active ingredients after
washing -- and therefore the provision of an almost
continuously available insecticide plus PBO barrier against
mosquitoes -- is required to maximise the protective effect.
This is especially important in areas where resistant mosquitoes
have been found. The rate at which permethrin
and PBO migrate from the internal reservoir in the fibre
to the surface of the net (known as the ‘bleed rate’) has
been adjusted in Olyset Plus to provide a rapid rate of
regeneration, making the net active again within 1 – 2
days after washing.
Full efficacy in less than 2 days after washing.
4

Controlled Release Technology
Incorporated Polyethylene Controlled-Release Fibres vs “Coated” Polyester Fibre
Permethrin and PBO
Year 1 Year 2 Year 3
Standard Net
Above: Olyset Plus, permethrin and piperonyl
butoxide migrate to the surface of the net fibre over
a period of three years or longer, maintaining a
biologically effective surface concentration.
Insecticide particles
“glued” to net surface
Left: For “coated” LLINs, surface concentration
of insecticide declines over time.
Year 1 Year 2 Year 3

Biological Efficacy
The objectives of testing Olyset Plus were as follows:
• Confirm efficacy meets WHOPES standards.
• Confirm the regeneration time for insecticide and
synergist is rapid.
• Evaluate efficacy against susceptible mosquitoes.
• Evaluate efficacy against pyrethroid resistant
mosquitoes.
% mortality
% KD at 60 minutes
%
Figure 3. Olyset Plus tested unwashed and at intervals after
three times washing — mortality at 24 hours.
100
80
60
40
20
0
100
80
60
40
20
0
100
64
74
85 85 87 87 84
0 1 2 3 4 5 6 7
Days post-washing
Rossignol, B. Luce, MN Lacroix and F. Chandre, DOC/LIN/IRD/01/11
Figure 4. Effect of washing Olyset Plus net (WHO cone test)
100
80
60
40
20
0
100 100 100 99 99
0 3 5 10 15 20 25
Number of washes
Rossignol, B. Luce, MN Lacroix and F. Chandre, DOC/LIN/IRD/01/11
Figure 5. Speed of regeneration of Olyset Plus against field
caught pyrethroid resistant mosquitoes (WHO cone test).
100
100
Olyset Plus
unwashed
100
73.2
Olyset Plus
washed
KD
Mortality
Ref. Sumitomo Chemical Health and Crop Sciences Laboratory Report, 2011
95 95
1. Regeneration, wash resistance and efficacy of Olyset Plus against
susceptible Anopheles gambiae.
To evaluate speed of regeneration, Olyset Plus was tested
unwashed and then washed and dried 3 times and tested
each day afterwards. Results (Figure 3) demonstrate that
the net rapidly recovers killing efficacy and retained 100%
knockdown activity after washing. From this (noting the
fact that confidence intervals for mortality between day 2
and 7 overlapped) regeneration time was determined to be
2 days.
To evaluate wash resistance nets were tested after
repeated washing using the cone test. From the data
generated above the interval between washes was set at 2
days to allow the net to fully regenerate. Results indicate
that knockdown (KD) of mosquitoes exposed to Olyset
Plus hardly changes over 25 washes. As these tests were
conducted only 24 hours after each washing, the rapid
regeneration of active ingredient on the fibre surface is
clearly shown (See Figure 4).
2. Evaluation of Olyset Plus vs. Olyset Plus without PBO unwashed
and one day post washing against field caught pyrethroid resistant
mosquitoes.
Tests were conducted using the World Health Organisation
(WHO) cone method (3 minute exposure) against field
caught Anopheles arabiensis which were metabolic mechanism
pyrethroid resistant. Olyset Plus was very effective
unwashed and had regenerated very rapidly after 1 day to
give 100% KD and 73.2% mortality (See Figure 5).
3. Evaluation of Olyset Plus two days after 20 washes against
pyrethroid resistant mosquitoes using the WHO tunnel test.
Olyset Plus was washed 20 times using the standard
WHO method and then tested in the WHO tunnel test only
2 days after the last wash against Anopheles gambiae G3
strain (moderately metabolic resistant to pyrethroids).
Mosquitoes were introduced at one end of the tunnel and
a small animal at the other end. The netting sample was
placed in between with nine holes cut in it according to
the WHO protocol. If mosquitoes can pass through the
holes in the net this indicates the net has little repellency
6

or killing effect. Blood Feeding Inhibition (BFI) shows the
percentage of mosquitoes prevented from reaching the animal
and feeding. Mortality is the total number of mosquitoes
killed in their attempts to feed.
Figure 6. Olyset Plus 2 days after 20 washes against
pyrethroid-resistant mosquitoes (WHO Tunnel test).
100
80
94.6
79.6
Sumitomo Chemical was the first company to develop
and pioneer fibre incorporation technology.
%
60
40
20
0
BFI
Mortality
Results (Figure 6) show that blood feeding inhibition
was very high and mortality was almost 80% despite the
mosquitoes being pyrethroid resistant. This test demonstrates
how quickly efficacy is restored to Olyset Plus
following 20 washes and only 2 days regeneration time.
4. Olyset Plus vs. a Polyester LLIN against field caught pyrethroid
resistant mosquitoes.
These tests were conducted against field caught Anopheles
arabiensis which are pyrethroid metabolic resistant. Both
nets were new and unwashed. The polyester LLIN used was
a commercially available net treated with deltamethrin,
widely used in malaria control programmes.
The standard WHO cone test (3 minute exposure) was
used. The results (Figure 7) show that the resistant
Anopheles were knocked down and killed by Olyset Plus
but the impact of the commercially available pyrethroid
net was much less, demonstrating the superior efficacy
of Olyset Plus against resistant mosquitoes.
5. Impact of the addition of PBO on Olyset Plus and performance after
1 day post-wash against resistant mosquitoes.
Tests were conducted against field caught Anopheles
arabiensis which were pyrethroid metabolic resistant.
To evaluate the impact of PBO, an experimental Olyset Plus
net was made with no synergist present. Both nets were
washed once and tested after 1 day using the WHO cone
test (3 minute exposure).
The results (Figure 8) show showed that while there
was no noticeable impact on knockdown there was a
dramatic difference in mortality as a result of the action
of PBO blocking the metabolic resistance mechanism.
%
Figure 7. Olyset Plus vs. a Polyester LLIN against field
caught resistant mosquitoes (WHO cone test).
100
80
60
40
20
0
100
80
60
%
40
Ref. Sumitomo Chemical Health and Crop Sciences Laboratory Report, 2011
20
0
100
73.2 75.6
KD
24.4
Mortality
Polyester LLIN
Olyset Plus
Ref. Sumitomo Chemical Health and Crop Sciences Laboratory Report, 2011
Figure 8. Impact of PBO in Olyset Plus against resistant
mosquitoes 1 day after washing (WHO cone test).
100
KD
100
14.6
73.2
Mortality
Ref. Sumitomo Chemical Health and Crop Sciences Laboratory Report, 2011
Olyset Plus without PBO
Olyset Plus with PBO

%
Figure 9. Blood Feeding Inhibition in hut trials against resistant
mosquitoes in Benin.
100
90
80
70
60
100
80
60
%
40
%
100 100
Kisumu before
washing
100
95.1
Kisumu after
washing
(3x+7 days)
84.6
82
70.2
KDR +
Metabolic
before
washing
Ref: C.Pennetier, V.Corbel et al. DOC/IRD/CREC/02/10
20
0
87.1
KDR +
Metabolic
after washing
(3x+7 days)
97.4 100 88
Metabolic
before
washing
BFI
Olyset Net
Olyset Plus
96.1
Metabolic
after washing
(3x+7 days)
Figure 10. Experimental hut trials in Cameroon: Olyset Net and
Olyset Plus
.6
Control
97.4
75.8
Olyset Net
Unwashed
100 97.5
Olyset Plus
Ref: C.Pennetier, V.Corbel et al. DOC/IRD/CREC/02/10
100
80
60
40
20
0
.5
Control
88.0
38.0
Olyset Net
3 washes + 7 days
Figure 11. WHOPEs Phase II experimental hut trials,
Malanville, Benin.
83.2
80.6
Olyset Plus
unwashed
79.4
67.3
Olyset Plus 20
times washed
Ref: CREC/IRD WHOPES Phase II report 31/1/2012
81.6
Blood Feeding Inhibition
Mortality corrected
for control
41.7
Olyset Net
unwashed
59.9
36.3
Olyset Net 20
times washed
Mortality
96.1
68.6
Olyset Plus
These studies also demonstrated that Olyset Plus
regenerated very rapidly and was active again 1 day after
washing.
6. Olyset Plus compared with Olyset Net in experimental huts – Benin.
Trials were conducted in Cotonou, Benin using experimental
huts to compare activity of Olyset Net and Olyset Plus.
The washing methodology and experimental protocol
followed the WHO Guidelines for testing long lasting nets
(WHO/CDS/WHOPES/GCDPP/2005.11). Both LLINs had six
holes cut in them to simulate torn nets and a volunteer
slept under the nets. Mosquitoes therefore had access to a
blood meal or were inhibited from feeding and exited the
hut to a veranda trap. Three An. gambiae strains were used
– susceptible (Kisumu), Kdr + metabolic resistant and
metabolic only resistant. The mosquitoes were released
into the hut in known numbers on different nights and
Blood Feeding Inhibition (BFI) recorded to demonstrate
the varying degrees of protection the test nets provided.
The results are shown in Figure 9 where it can be seen
that with susceptible mosquitoes there was little difference
before washing, while after washing the Olyset Plus
The unwashed Olyset Net performed well especially
considering the resistance present but Olyset Plus gave
better mosquito mortality.
was slightly more effective due to faster regeneration and
also to the additional performance enhancement that
comes from the synergistic effects of PBO. When both nets
were tested against Kdr + metabolic resistant mosquitoes
the performance was not dissimilar before washing but
after washing there was a dramatic difference as the BFI
was far higher with Olyset Plus showing a protective
effect. The BFI in this Olyset Plus treatment was 87.1%
which is good considering that with Kdr resistance
(caused by insensitivity of the insect nervous system to
insecticide) PBO would be expected to add little benefit.
When tested against metabolic only resistant mosquitoes
8

Olyset Plus gave very good BFI that was superior to Olyset
Net due to the presence of PBO.
7. Olyset Plus compared with Olyset Net in experimental huts –
Cameroon.
Experimental hut trials to compare Olyset Net and Olyset
Plus were conducted in Pitoa, Cameroon. As above, the
washing methodology and protocol followed WHO
Guidelines. The local population of An. gambiae were
pyrethroid metabolic mechanism resistant.
Blood Feeding Inhibition (BFI) rates were recorded to
demonstrate the varying degrees of protection the test
nets provided. The results (Figure 10) demonstrate that
the untreated control nets gave little protection before
washing.
The unwashed Olyset Net performed well especially
considering the resistance present but Olyset Plus gave
better mosquito mortality. After 3 washes and 7 days
Olyset Net gave good levels of BFI (88%) while Olyset Plus
gave even better protection with 96% BFI. Olyset Plus also
had a better overall impact on mortality (69% vs 38% for
Olyset Net).
8. WHO Phase II Evaluation of Olyset Plus – Benin.
As part of the evaluation of Olyset Plus, Phase II experimental
hut trials were conducted in Benin by WHOPES.
These were carried out in Malanville, in an area where
increased resistance of malaria vectors to pyrethroids
(22% mortality to 0.75% permethrin) has been recently
reported. Results for wild, free flying An.gambiae are
shown in Figure 11. These show that while both nets have
given good initial levels of protection from blood feeding
before washing, Olyset Plus continues to give excellent
protection after 20 washes. Levels for Olyset Net while
still good, have declined. Mortality data follows a similar
trend, indicating that Olyset Plus is likely to have a
greater mass killing effect on these resistant populations
over time compared with Olyset Net.

Technical Specifications
Olyset Plus – meeting the world’s changing needs.
Specifications
Category
Odour
Colour
Shape
Dimensional Stability to
washing (ISO 5077)
Net attachment
Active ingredient
Packaging
Synergist
Insecticide and
synergist location
Storage stability
Duration of Insecticide
& Synergist efficacy
from first use
Specification
Odourless
Blue or white
Rectangular or Conical
Not exceeding 5% of the initial dimension
Rectangular – A minimum of 6 suspension
points (one at each of the four corners of
the top panel and one equidistant at each of
the sides) attached by fabric loops.
Conical – single suspension point
Permethrin 2.0% w/w (+/- 0.5%w/w),
20g/kg (+/- 5g/kg)
Nets individually packaged in sealed and
tamper proof polypropylene bags
incorporating a label
Piperonyl Butoxide 1.0% w/w
(+/- 0.25%w/w), 10g/kg (+/- 2.5g/kg)
Incorporated into yarn
In storage tests, net material contains
>95% of the original a.i. content after
2 weeks at 54ºC
3 years (minimum)
Fire Safety Classification Class 1
16CFR 1610
(Textiles – acceptable for use in clothing)
Yarn
150 denier (+/- 30) high density polyethylene
monofilament fibre
Mesh Size (holes/inch²) Not less than 80 holes per inch 2
Weight of netting 40 g/m 2 (+/- 10g/m 2 )
Weave type
Raschel
Bursting strength Main Fabric: 250KPa (min)
Seam: 250KPa (min)
Seams
Polyester sewing thread
Fabrication
Warp Knitted
ISO 13938-1-1999
Sizes Available (cm)
Rectangular Nets
Description Length Width Height Number of
Loops (min)
Double 180 100 150 6
Family 180 130 150 6
Large Family/High 180/180 160/160 150/210 6
Extra Family/High 190/190 180/180 150/210 6
Conical Nets
Description Circumference Height Roof Top Ring
(diameter)
Small 850 220 56 Flexible metal
Medium 1050 220 56 Flexible metal
Large 1250 250 65 Flexible metal
Note : Rectangular and conical net sizes +/- 10% measured hanging up
Active Ingredient Content of Olyset Plus
Permethrin (Ref VBC/DS/84.51)
The following information refers to permethrin, the active
ingredient in Olyset Plus. Permethrin has been used for
public health and agricultural insect control for over 30
years and has an excellent track record. Registered uses of
Permethrin include human skin applications for scabies
control and as an insect repellent.
SYNOPSIS: Permethrin is a broad spectrum, non-cumulative
synthetic pyrethroid; and is a fast acting neurotoxin
with good contact, limited stomach and no fumigant
action. It is moderately stable in the environment and has
good residual action on inert surfaces. Permethrin is
non-systemic in plants; of low mammalian toxicity, and is
readily metabolised with immediate loss of toxicity.
Common name: Permethrin (ISO, BSI, ANSI)
Identity:
IUPAC: 3-Phenoxybenzyl(1RS)-cis,trans-3-(2,2-
dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate.
Molecular Formula: C21H20Cl2O3
Molecular weight: 391.3
10

Structural formula:
Piperonyl Butoxide content
Permethrin content
Declared content is 20g/kg (+/-5g/kg, 2% w/w (1.5-2.5%
limits), cis:trans isomer ratio 50/50 to 30/70).
Ecotoxicology
Exposure of non-target organisms to permethrin in Olyset
Plus is unlikely when used in accordance with the label
instructions. Permethrin is toxic to fish under laboratory
conditions, so contamination of fish-bearing water should
be avoided. Nets should be gently washed in containers
using a mild soap as necessary, and not in natural water
sources such as streams, rivers, ponds and lakes.
Piperonyl Butoxide
The following information refers to piperonyl butoxide
(PBO) a synergist used in Olyset Plus. PBO has been used for
public health and agricultural insect control since 1947 and
has an excellent track record. Registered uses of PBO
include consumer aerosols, space sprays, shampoos for head
lice and even skin applications for treatment of scabies.
SYNOPSIS: Piperonyl butoxide is a synergist which
enhances the activity of insecticides by inhibiting or
blocking enzymes in the insect which would de-toxify
the insecticide. It is particularly effective when used in
conjunction with pyrethroids. It has low mammalian
toxicity. It is non-cumulative in the environment.
IUPAC: 5-[2-(2-butoxyethoxy) ethoxymethyl] -6-propyl-1,3-
benzodioxole
Molecular formula: C19H30O5
Molecular weight: 338.438
Declared content is 10g/kg (+/- 2.5g/kg), 1% w/w
(0.75 – 1.25% limits).
Ecotoxicology
Researchers evaluated the disappearance of piperonyl
butoxide in soil and water and determined that the chemical
is short-lived in the environment. Piperonyl butoxide
has a moderate to low potential to contaminate groundwater.
Researchers consider piperonyl butoxide moderately
toxic to fish and highly toxic to other aquatic organisms.
It is not likely to accumulate in fish. Piperonyl butoxide
is low to very low in toxicity when eaten by birds.
Disposal Considerations
The net should be changed when biological performance
declines. Normally this will occur after approximately
3 years. Disposal should conform to recommendations of
International organizations and should comply with all
federal, state and local regulations.
Transport Information
Hazard Class: Not classified as a hazardous material
U.N. Number: Not applicable
Storage
Store in a cool, well-ventilated place away from sources
of ignition and direct sunlight.
Analytical
Full analytical methodology is available for permethrin in
CIPAC/4503/m Permethrin (June 2006). Piperonyl Butoxide
Method extension of CIPAC 32+33+345/TK/M;
Determination of Piperonyl Butoxide in Polyethylene
Matrix by GC-FID 33/LN(M)/-
11

Usage and Safety
Usage and Care of Olyset Plus
Olyset Plus nets are ready to use. Just unpack and hang
over the bed, using the loops provided to attach string or
cord and suspend from the roof. There is no need to ‘air’
the net before use, unlike some other net products.
Ensure the net hangs over the bed with sufficient netting
hanging below the mattress or mat to tuck under at night.
The net is factory-treated with insecticide and synergist
and never needs re-treatment.
Olyset Plus nets may be washed using soap and water to
remove dirt. It is recommended that nets are washed a few
times a year, as if a net becomes really dirty it could
inhibit performance by masking the insecticide.
To avoid damaging the net, gentle washing (with no
bleach) is recommended. After washing the net should be
dried in the shade before re-hanging over the bed. Once
washed, the net will rapidly re-generate insecticide and
synergist to the surface of the fibres, replacing any lost
during washing.
Safety
Permethrin is a pyrethroid insecticide with low
mammalian toxicity. Piperonyl butoxide is a synergist of
low mammalian toxicity. Moreover, the majority of both
chemicals are contained within the fibre matrix. However,
sufficient active ingredient is still available on the net
surface to provide excellent biological performance
against mosquitoes.
The risks from handling the net are negligible.
Permethrin and piperonyl butoxide are virtually
non-irritant, so no adverse effects should result from
contact during handling or while sleeping under the net.
World Health Organization Pesticide Evaluation Scheme (WHOPES)
In accordance with Sumitomo`s ethical policies Olyset Plus
has been submitted to WHOPES to be evaluated through
all WHOPES test phases, and results so far are very positive.
The WHOPES Working Group have met and after considering
all the relevant scientific data have granted Olyset Plus
an interim recommendation.
WHO Risk Assessment of Olyset Plus (abstract)
A risk assessment was conducted according to the WHO
generic risk assessment model to support the use of a
new long lasting insecticidal net (LLINs) to protect against
malaria carried by mosquitoes. The polyethylene net
contains permethrin 2% w/w and piperonyl butoxide
and insecticidal synergist (1% w/w).
Since the nets are manufactured and pre-treated with
permethrin and piperonyl butoxide in the factory, the
treatment of nets by the end user is not required.
Therefore the only relevant exposure scenarios considered
in this risk assessment were exposure during the washing
of nets and exposure while sleeping under the nets,
including exposure from potential oral ingestion by
infants and children sucking or chewing the nets. The
potential exposures of Permethrin and PBO during these
activities were assessed using conservative assumptions,
parameters and default values defined in the WHO model.
All calculated exposures to permethrin and PBO
achieved acceptable margins of safety for adults, children
and infants for the relevant activities noted above.
Therefore the combination of Permethrin and PBO in
LLINs was considered safe.
12

Olyset Plus nets are ready to use. Just unpack and hang over
the bed, using the loops provided to attach string or cord and
suspend from the roof. There is no need to ‘air’ the net before
use, unlike some other net products.

Find out more at www.olyset.net
Olyset Customer Service Department
Horatio House
77-85 Fulham Palace Road
London W6 8JA
United Kingdom
Tel: +44 (0)208 600 7700
Email: info@olyset.net
Olyset® is a Registered trademark of Sumitomo Chemical Co.Ltd