Quantification and characterization of

fibers emitted from common synthetic

materials during washing

Microplastic fibers discharged from a fleece shirt during washing

Amanda Folkö

Examensarbete i miljö- och hälsoskydd 15 hp till magisterexamen, 2015

Stockholms universitet och Käppalaförbundet

Handledare: Kristina Svinhufvud (Käppalaförbundet), Matthew MacLeod och Berit Gewert

(Stockholms universitet)

Abstract

Microplastics, which generally and in the present study are defined as plastic debris ≤5 mm,

are accumulating in the marine environments worldwide. Microplastics can be ingested by a

variety of aquatic organisms, nevertheless their ability to bioaccumulate is still uncertain.

However, they can cause inflammatory response and reduced feeding activity in important

marine species. Further, microplastics might also pose a toxic hazard as they may contain

toxic additives or adsorb organic contaminants from the environment. Since microplastics are

more concentrated in marine environments around cities, and mainly consists of synthetic

fibers, sewage treatment plants have been suggested as one of the emission pathways. As the

global consumption of synthetic fibers is increasing, the discharge of fibers from machine

washing of polyester and polyamide garments was examined in the present study. Effluent

from a washing machine was filtered through a nylon mesh (20 µm) and the amount of fibers

was quantified. The main finding is that the discharged microplastic fiber mass decreased

from the first to the fourth wash, while the mean fiber length increased. The results suggest

that washing of new clothing accounts for a significant proportion of the emissions. Further, a

Swedish sewage treatment plant with ≈ 500 000 connected persons is estimated to receive up

to 16.9 ton microplastic fibers per year as a consequence of washing new synthetic textiles.

Sammanfattning

Microplaster definieras vanligtvis samt i denna studie som plastpartiklar ≤5 mm. Dessa plaster

ackumuleras i marina miljöer runt om i världen och kan tas upp av en mängd olika

vattenlevande organismer. Dock är det fortfarande osäkert i vilken utsträckning de

bioackumuleras. Däremot kan de orsaka inflammationer och reducera födointaget hos flera

viktiga marina arter. Vidare kan mikroplaster även utgöra en toxisk fara eftersom de kan vara

bärare av giftiga tillsatser eller adsorbera organiska föroreningar från omgivningen. Eftersom

antalet mikroplaster generellt är högre i marina miljöer kring städer samt huvudsakligen

består av syntetiska fibrer, misstänks avloppsreningsverk utgöra en betydande spridningsväg.

Då den globala konsumtionen av syntetfibrer ökar har utsläppet av fibrer från maskintvätt av

polyester- och polyamidkläder undersökts i denna studie. Utgående vatten filtrerades genom

ett nylonfilter (20 µm) och den avgivna mängden fibrer kvantifierades. Resultaten visar att

massan avgivna mikroplastfiber minskade från den första till den fjärde tvätten, medan den

genomsnittliga fiberlängden ökade. Detta tyder bland annat på att tvätt av helt nya kläder kan

stå för en betydande del av utsläppen. Baserat på dessa resultat uppskattas ett svenskt

reningsverk med ≈ 500 000 anslutna personer ta emot upp till 16.9 ton mikroplastfibrer per år

till följd av tvätt av nya syntetiska textilier.

Table of Contents 1. Background ...................................................................................................................................... 1

1.1 Definition and abundance ............................................................................................................. 1

1.2 Biological interactions ................................................................................................................... 1

1.2.1 Ingestion and accumulation ................................................................................................... 1

1.2.2 Non-toxic impacts ................................................................................................................... 1

1.2.3 Toxic impacts .......................................................................................................................... 2

2. Introduction ..................................................................................................................................... 2

2.1 Sources to microplastics in wastewater ........................................................................................ 2

2.2 Microplastic fibers ......................................................................................................................... 3

2.3 Aim and hypotheses ...................................................................................................................... 4

3. Materials and methods ................................................................................................................... 4

3.1 Filtering and analysing machine effluent ...................................................................................... 4

3.2 Statistical methods ........................................................................................................................ 5

4. Results ............................................................................................................................................. 5

4.1 Fleece shirt .................................................................................................................................... 5

4.2 Sports sweater ............................................................................................................................... 6

4.3 Fibers entering the sewage treatment plant ................................................................................ 6

5. Figures ............................................................................................................................................. 6

6. Discussion and conclusions ........................................................................................................... 12

6.1 Outlook ........................................................................................................................................ 13

7. Acknowledgments ......................................................................................................................... 13

8. References ..................................................................................................................................... 14

8.1 Articles ......................................................................................................................................... 14

8.2 Reports ........................................................................................................................................ 15

8.3 Remaining references .................................................................................................................. 16

1

1. Background

1.1 Definition and abundance

Microplastics is the term for tiny plastic fragments, fibers and granules, which are by origin

divided into two groups, called primary and secondary microplastics (Cole et al., 2011).

Primary microplastics are constructed to be of microscopic size, while secondary

microplastics originate from degradation of macroplastics. There is not yet a clear definition

of the size-range of microplastics, the classification has varied from study to study, however a

diameter of <10 mm has been the upper limit (Cole et al., 2011). Further, the National

Oceanic and Atmospheric Administration define microplastics as ≤5 mm (National Oceanic

and Atmospheric Administration, 2015) which also has been suggested by others (Moore,

2008; Thompson et al., 2004).

In recent years microplastics have accumulated in the marine environments. Micro debris

concentrations in seawater has been reported to reach levels of 100 000 particles per m3 in

hotspots (Norén et al., 2009). Further, measurements from the Pacific Ocean showed a

microplastic abundance of 334 271 particles per km2 and a total mass of 5114 g per km2

(Moore, 2001). This proved to be an approximately six times larger mass than the measured

mass of plankton. Due to slow degradation and increasing production microplastics are likely

to increase in the environment over time, causing a matter of potential concern (Andrady,

2011).

1.2 Biological interactions

1.2.1 Ingestion and accumulation

Due to their size, microplastics can be ingested by aquatic organisms such as copepods,

lugworms, amphipods, barnacles, sea-cucumbers and fish (Cole et al., 2015; Graham and

Thompson, 2009; Lusher et al., 2013; Thompson et al., 2004). A study of langoustines

showed that plastic fibers were present in the stomach of 83 percent of the individuals

collected from the north Clyde sea (Murray and Cowie, 2011). Further, approximately 36

percent of the examined fish collected from the English Channel contained microplastics

(Lusher et al., 2013). To sum up, previous studies have shown that microplastics ranging from

2 µm to 2000 µm can be ingested by a variety of aquatic organisms (Cole et al., 2011).

Microplastics have also been found in higher tropic level organisms, for instance plastic

fragments were recorded in scat from Hooker’s sea lions associated with ingested fish prey

(McMahon et al., 1999). It has also been shown that microplastics can be ingested by mussels

and transferred into their hemolymph (Browne et al., 2008). However, the literature regarding

accumulation of microplastics in marine organisms is still limited (Wright et al., 2013b).

1.2.2 Non-toxic impacts

Regarding the impacts of non-polluted microplastics a study of (Cole et al., 2015) showed that

a concentration of 75 polystyrene microplastics (20 µm) per mL significantly altered the

feeding behavior of copepods. The ingested carbon biomass was reduced and prolonged

exposure resulted in copepods producing smaller eggs with reduced hatching success. Further,

microplastics have been shown to cause inflammatory response and to reduce feeding activity

2

and energy reserves in the important marine lugworm species Arenicola marina (Wright et al.,

2013a). Further, microplastics may cause similar physical damage to smaller animals as larger

plastic items harm larger animals, for instance by blocking feeding appendages (Cole et al.,

2011). Additionally, microplastics also have been shown to compose substrates for growth of

diverse bacterial communities (Zettler et al., 2013). However, the knowledge of the non-

polluted microplastics impact on the environment is still limited (Cole et al., 2011; Derraik,

2002).

1.2.3 Toxic impacts

Microplastics may also pose a toxic hazard as they might contain toxic additives which could

leach to the environment, or adsorb and concentrate organic contaminants from the marine

environment (Cole et al., 2011; Teuten et al., 2009). Whether microplastics act as vectors

which could transfer organic contaminants to marine organisms is still under investigation.

Results from modelling indicates that the relative importance of microplastics as vectors

likely is limited (Gouin et al., 2011). The results suggests that ingestion of microplastics even

could lead to reduction in body burden concentrations of some nonpolar organic chemicals.

However, it has been shown that nonylphenol and phenanthrene, desorbed from particles of

polyvinyl chloride were transferred into gut tissues of lugworms (Browne et al., 2013).

Nevertheless, sand contributed to transferring a larger amount of pollutants to the tissues.

2. Introduction

Previous studies have shown that the abundance of micro debris found in the marine

environment is more concentrated close to industrial areas, cities and sewage treatment plants

(Browne et al., 2011; Magnusson and Norén, 2014; Norén et al., 2014). The micro debris

consisted mainly of textile fibers, plastic and combustion particles, thus, sewage treatment

plants were suggested as one significant emission pathway. To which extent micro debris is

separated by the sewage treatment is still under investigation. However, studies from Swedish

and Norwegian sewage treatment plants have shown a capture rate of 70 - 100 percent.

Despite this, the effluent still contained significant levels of micro debris (Magnusson and

Wahlberg, 2014; Magnusson, 2015). Hence, the focus of the present study will lie on

upstream sources to microplastic contamination of wastewater.

2.1 Sources to microplastics in wastewater

A study of the Swedish nature Conservation Society (Naturskyddsföreningen, 2013) showed

that microplastics are commonly used as an additive in hygiene products. Polyethylene (PE)

was the most frequent polymer found in the examined products, although some products also

contained fragments of polymethylmethacrylate (PMMA) and polytetrafluoroethylene

(PTFE). Toothpaste, shower gel, facial cleaners, and deodorant are some examples of

products which have been shown to contain microplastics (Fendall and Sewell, 2009;

Naturskyddsföreningen, 2013). These are all products likely to end up in the wastewater.

Another study showed that the majority of the microplastics found on the surface of the

Laurentian Great Lakes were multi-coloured spheres, suspected to be microbeads from

consumer products such as facial cleansers (Eriksen et al., 2013). Since more environmentally

friendly substitutes are available, the phasing out of microplastics in hygiene products has

started (Naturskyddsföreningen, 2013; Stockholms universitets Östersjöcentrum, 2015). Some

companies have, due to the pressure from environmental organisations, promised to stop

3

adding microplastics in their products. Further, some states of America have prohibited the

use of microplastics in hygiene products and a suggestion for prohibition has also been

brought up in the EU (Stockholms universitets Östersjöcentrum, 2015).

The use of polymers for local drug delivery, which has expanded the spectrum of drugs

available for the treatment of brain diseases (Patel et al., 2009), is another application and

potential source to plastic particles ending up in the wastewater. Further, plastic Media Air-

blasting, which is a technology for cleaning engines and stripping paint from metallic

surfaces, is another potential source (Gregory, 1996). Plastic media used for cleaning aircrafts

and machine parts can also be contaminated with heavy metals, suggesting that industrial

application sites may be sources of microplastics contaminated with heavy metals. Further,

storm-water and relining of sewers are two potential sources of microplastics in wastewater

mentioned in the literature (Cole et al., 2011; Norén et al., 2014).

Samplings of wastewater from washing machines have shown that one single garment of

polyester can emit >1900 fibers per wash (Browne et al., 2011). In the same study it has been

shown that the composition of microplastics in wastewater, which mainly contained polyester

fibers, was consistent with the composition of microplastics found in sediments worldwide.

This indicates that a major part of the marine microplastics might come from sewage

treatment plants due to washing of textiles.

2.2 Microplastic fibers

A study conducted along the west coast of Sweden showed that more than 90 percent of the

captured micro debris consisted of fibers (Norén et al., 2014). The average distribution

between synthetic fibers and non-synthetic fibers was 43 respective 57 percent. Findings from

Belgian costal sediments showed that 59 percent of the microplastics encountered consisted of

fibers (Claessens et al., 2011). This is also consistent with results from examined fish which

showed that approximately 68 percent of the ingested microplastics consisted of fibers

(Lusher et al., 2013). Further, fibers have been suggested as the most commonly encountered

form of microplastic in the marine environment (Wright et al., 2013b).

The global consumption of synthetic fibers has increased steadily since the early 1990s and

represented during 2010 approximately 60 percent of the world apparel fiber consumption

(Shui and Plastina, 2013). The most widely produced synthetic fibers are polypropylene,

acrylic, polyamide and polyester (Tecnon OrbiChem, 2014). Polyester is predicted to make up

95 percent of the future global synthetic fiber production growth, and the global synthetic

fiber volume growth is predicted to constitute 98 percent of future total fiber production

increases. Global acrylic fiber production has decreased with 30 percent since 2004. Further,

polypropylene and polyamide production is predicted to increase with respectively 1 - 2

percent annually until 2025 (Tecnon OrbiChem, 2014). Polyester has been shown to be the

most abundant microplastic found in both sediments worldwide and in wastewater, followed

by acrylic and polyamide (Browne et al., 2011). Further, particles of polypropylene and

polyethylene were also identified in sediment samples. Microplastics (including fibers)

consisting of polyester, acrylic, polypropylene, polyethylene and polyamide were identified in

wastewater from three Swedish sewage treatment plants (Magnusson and Wahlberg, 2014).

Additionally, microplastics of polyester, polyamide, polypropylene and polyethylene were

identified in seawater samples from the Swedish west coast (Norén et al., 2014). Due to their

4

abundance in the marine environments and their predicted increase in production volumes,

polyester and polyamide were selected as study materials for the present study.

2.3 Aim and hypotheses

As described in the introduction, washing of textiles is likely to constitute a significant source

of microplastic contamination in the environment. Since other sources might be easier to

phase out, the present study, in collaboration with the Swedish sewage treatment plant

Käppalaförbundet aimed to examine the emission of microplastic fibres from washing. It has

been hypothesised that microplastic fibers are broken down within the sewage treatment plant,

meaning that the number of microplastic fibers theoretically could increase within the sewage

treatment plant. Therefore, weighting was chosen as the method for quantification in the

present study, instead of counting the number of fibers which has been done previously

(Browne et al., 2011).

Part of the aim was to develop a method for quantification of microplastic fibers discharged

during washing. Hence, the present study should be considered as a pilot for further work.

Further, the aim was to examine if there is a correlation between the number of times a

garment has been washed and the mass and size of the discharged synthetic fibers.

Additionally, the aim was to estimate the importance of washing as a source to microplastic

contamination of the wastewater entering Käppala sewage treatment plant.

3. Materials and methods A front loading washing machine (Cylinda professionell PT 3140) was used to wash a brand

new fleece shirt (100 percent polyester) and a sports sweater (57 percent polyamide and 43

polyester). Detergent and softener were not used in order to avoid blocking the filters

(Browne et al., 2011). Several “blank washes” (empty cycles) were performed to clean the

washing machine before the start of the experiment. The garments were washed for 30 min,

40º C and 1400 RPM, each cycle referred to as one “test wash”.

3.1 Filtering and analysing machine effluent

An attempt to filter all the wastewater directly through a nylon mesh with a mesh size of 20

µm (Browne et al., 2011; Magnusson and Wahlberg, 2014; Magnusson, 2015) was conducted.

However, the wastewater from washing a fleece shirt clogged the filter immediately, thus all

wastewater could not be filtered. Instead, to avoid back pressuring the washing machine, the

wastewater was collected in an 80 L barrel covered with a lid. The water was well stirred and

a smaller sample was taken out for filtration. Each sample was filtrated trough a nylon mesh

(mesh size 20 µm) attached on a pipe with a rubber covered metal ring (figure 1). The

filtration was suspended when a layer of particles became visible on the filter surface.

Before filtering, the filters were examined using a stereo microscope (Leica ZOOM 2000,

10,5x - 45x) with top lightning. Detected contaminants, which mainly consisted of different

fibers were removed. Aluminium foil was used to store the filters, both before and after

filtering to minimize contamination. Then, filters were weighted using an analytical balance

(accuracy 0, 0001). As a last step before the filtration the filters were rinsed with water to

minimize contamination.

5

After filtering, the barrel was rinsed and the filters were dried at 80º C for 24 h. Then, filters

were taken to visual sorting under the stereo microscope, which is considered the most

commonly used method for identification of microplastics (Hidalgo-Ruz et al., 2012). By

using a fine tweezer the filters were cleared from dust, soil, particles >5 mm and fibers which

were identified as cotton fibres according to the literature (Norén, 2007). However, the filters

mainly contained clean fibers (figure 2). In some cases, dust and fibers formed complexes

which could not be easily separated, if these complexes mainly consisted of fibers they were

not removed during the visual sorting (figure 3). After visual sorting and humidity

acclimation the filters were reweighted. Further, fibers from each test wash were measured by

using the mesh size as a yardstick. The dried filters were stored in aluminium foil and kept in

the dark under stable temperature conditions between the different steps (Hidalgo-Ruz et al.,

2012). The time filters had to be kept outside the aluminium foil was minimized to avoid

contamination.

3.2 Statistical methods

Regression analysis were conducted to test for correlations between mass concentrations,

mean fiber lengths and the wash numbers. Since the amount of discharged fibers should

depend on the total amount of fibers within the garment at the moment, the correlations were

expected to fit a first order rate model. Thus, the data was log transformed to fit the

assumptions of an exponential model. Further, an ANOVA was conducted to test if the mean

fiber lengths differed between the different test washes. The program R 3.2.0. (R Core

Development Team, 2015) was used for the statistical analysis.

4. Results

Each of the two garments were washed four times. In-between the test washes three blank

washes were conducted to minimize cross-contamination (Browne et al., 2011), the effluent

from the last blank wash was always filtered and used as a control. Thus, the effluent from

eight test washes and eight related control washes were analysed. Further, a randomized

sample of fibers (n=10) from each test wash was measured and analysed.

4.1 Fleece shirt

The four controls showed to be significantly correlated to the wash numbers (R2 = 0.89, P <

0.05) (figure 4). Thus, the control mass was subtracted from the related test wash mass to

control for contamination of old fibers and dust which could not be separated from the fibers.

The emitted microplastic fiber mass was significantly correlated to the wash numbers (R2 ≈

0.87, P < 0.05) (figure 5). The total microplastic fiber mass emitted was ≈ 1.09 g which

corresponded to ≈ 0.46 percent of the garments initial weight. The initial microplastic fiber

mass emitted from the first wash was halved after ≈ 3.8 washes based on the equation (figure

5). Further, ≈ 64 percent of the total emitted mass was discharged during the two first cycles.

The mean length of the fibers was significantly correlated to the wash numbers (R2 ≈ 0.95, P

< 0.05) (figure 6), however there were no significant difference between the four groups

(figure 7).

6

4.2 Sports sweater

The four controls showed to be significantly correlated to the wash numbers (R2 ≈ 0.98, P <

0.05) (figure 8). Thus, the control mass was subtracted from the related test wash mass to

control for contamination of old fibers and dust which could not be separated from the fibers.

The mass emitted from the fourth test wash was equal to the control, therefore the fourth

sample could not be used for the analysis. This since it could not be proved that the garment

had discharged any new fibers during the fourth wash. The emitted microplastic fiber mass

was not significantly correlated to the wash numbers (R2 ≈ 0.91, P > 0.05), however there was

a clear declining trend (figure 9). The total microplastic fiber mass emitted was ≈ 0.14 g

which corresponded to ≈ 0.10 percent of the garments initial weight. The initial microplastic

fiber mass emitted from the first wash was halved after ≈ 1.6 washes based on the equation

(figure 9). Further, ≈ 75 percent of the total emitted mass was discharged during the first

cycle. The mean length of the fibers was significantly correlated to the wash numbers (R2 ≈

0.99, P < 0.05) (figure 10), however there were no significant difference between the three

groups (figure 11).

4.3 Fibers entering the sewage treatment plant

During 2013 the inflow of clothing and home textiles to Sweden was approximately 12.5 kg

per person (Naturvårdsverket, 2013). As the global consumption of synthetic fibers

approximately represents 60 percent of the world apparel fiber consumption (Shui and

Plastina, 2013), the inflow of synthetic textiles to Sweden could roughly be estimated to 7.5

kg per person and year. Assumed that these new synthetic textiles are washed at least four

times and that the materials used in the present study are representative, these 7.5 kg could

discharge 7.5 - 34.5 g microplastic fibers per person to the wastewater annually. During 2013

Käppala sewage treatment plant had ≈ 490 000 private persons connected, hence, 3.7 - 16.9

ton microplastic fibers could have entered the sewage treatment plant as a consequence of

washing synthetic textiles. It should be noted that these estimations do not take washing of

older textiles into account. Further, these numbers should be seen as rough estimations which

mainly gives an indication of the actual amounts.

5. Figures

7

Figure 1. The filtration set-up, the filter (20 µm nylon mesh) attached to a pipe by a rubber covered

metal ring.

Figure 2. Microplastic fibers captured in the filter after filtering the effluent from washing the fleece

shirt.

8

Figure 3. A complex of microplastic fibers and dust discharged from the sports sweater which was left

in the filter after the visual sorting.

Figure 4. The correlation between control mass concentration and wash number for the fleece shirt, R2

≈ 0.89 and P < 0.05.

y = 7E-05e0,6349x

0,00E+00

1,00E-04

2,00E-04

3,00E-04

4,00E-04

5,00E-04

6,00E-04

7,00E-04

8,00E-04

9,00E-04

0 1 2 3 4

Mas

s co

nce

ntr

atio

n (

g/L)

Wash number

Control (fleece shirt)

9

Figure 5. The correlation between mass concentration and wash number for the fleece shirt, R2 ≈ 0.87

and P < 0.05.

Figure 6. The correlation between mean fiber length and wash number for the fleece shirt, R2 ≈ 0.95

and P < 0.05.

y = 0,0092e-0,291x

0

0,001

0,002

0,003

0,004

0,005

0,006

0,007

0,008

0 1 2 3 4

Mas

s co

nce

ntr

atio

n (

g/L)

Wash number

Fleece shirt

y = 155,51e0,2943x

0

100

200

300

400

500

600

0 1 2 3 4 5

Mea

n le

ngt

h (

µm

)

Wash number

Mean fiber length (fleece shirt)

10

Figure 7. A scatterplot showing mean values and standard deviations of the fiber lengths (n = 10)

from each wash of the fleece shirt. The groups are not significantly different.

Figure 8. The correlation between control mass concentration and wash number for the sports sweater,

R2 ≈ 0.98 and P < 0.05.

1 2 3 4

05

00

10

00

15

00

20

00

Wash number

Fib

er

len

gth

(µ

m)

y = 0,0016e-0,521x

0

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

0,0007

0,0008

0,0009

0,001

0 1 2 3 4 5

Mas

s co

nce

ntr

atio

n (

g/L)

Wash number

Control (sports sweater)

11

Figure 9. The correlation between mass concentration and wash number for the sports sweater, R2 ≈

0.91 and P > 0.05.

Figure 10. The correlation between mean fiber length and wash number for the sports sweater, R2 ≈

0.99 and P < 0.05.

y = 0,0047e-1,099x

0

0,0002

0,0004

0,0006

0,0008

0,001

0,0012

0,0014

0,0016

0,0018

0,002

0 1 2 3 4

Mas

s co

nce

ntr

atio

n (

g/L)

Wash number

Sports sweater

y = 329,31e0,2125x

0

100

200

300

400

500

600

700

0 1 2 3 4

Mea

n le

ngt

h (

µm

)

Wash number

Mean fiber length (sports sweater)

12

Figure 11. A scatterplot showing mean values and standard deviations of the fiber lengths (n = 10)

from each wash of the sports sweater. The groups are not significantly different.

6. Discussion and conclusions

The main findings of the present study is that the microplastic fiber mass discharged from the

garments decreased from the first to the fourth wash, which also indicates that the method

used for quantification is adequate. As mentioned, the present study should be considered as a

pilot, now further studies of other materials are needed to get a clear view of the

environmental impacts of washing textiles.

The fleece shirt discharged 64 percent of the total emitted mass during the two first washing

cycles and the sports sweater discharged 75 percent during the first washing cycle. Further,

the effluent sample from the fourth wash of the sports sweater did not contain enough

microplastic fibers to be quantified by this method. This suggests that washing of brand new

clothing contribute to a substantial part of the emissions of microplastic fibers discharged

during washing. Thus, an increased use of second hand clothing and a more conscious

approach to washing could be recommended to decrease the emissions of microplastic fibers

to the environment. Additionally, it could be questioned whether the discharged fibers,

coming from the first crucial cycles could be collected.

The fleece shirt discharged ≈ 0.46 percent of its initial weight during the experiment while the

sports sweater discharged ≈ 0.10 percent. This is consistent with previous findings which have

shown that fleece material can discharge >180 percent more fibers then other polyester

1 2 3

05

00

10

00

15

00

20

00

25

00

Wash number

Fib

er

len

gth

(µ

m)

13

materials (Browne et al., 2011). Further, the decline rate of fiber releases from the fleece shirt

was slower than for the sports sweater (figures 5 and 9). This suggests that fleece might be

considered as an extreme. Thus, the choice of material could be crucial, materials emitting

fewer and more easily biodegradable fibers should therefore be preferred.

The mean fiber length seems to increase proportionally to the wash number in both cases.

This may seem contradictory since heavier particles are the first to settle during differential

centrifugation. However, the results suggests that smaller fibers, which might be loose fibers

from the manufacturing process get washed out earlier. Larger fibers might be parts of the

garment and therefore it takes more wear to make them detach. Further, the sports sweater

controls were inversely proportional to the wash number while the fleece controls increased

proportionally to the wash number (figures 8 and 4). This could be due to the fleece shirt

contaminating the washing machine, meaning that the three bank washes were not enough to

decontaminate it in-between the tests. The sports sweater discharged less fibers, thus the

control followed a similar decreasing pattern as the test washes (figure 9).

Although a substantial amount of microplastics passes through the sewage treatment plants

and ends up in the seas, the majority is captured in the sewage treatment plants (Magnusson

and Wahlberg, 2014; Magnusson 2015). This suggests that end of pipe solutions are not

sufficient, meaning that actions are needed to prevent microplastics from ending up in the

wastewater. The estimates of 7.5 – 35.5 g per person annually may be rough, but should not

be ignored since they indicates that washing of synthetic textiles might presents an area of

environmental concern.

6.1 Outlook

It has been shown that the number of silver ions released into the wastewater during washing

of textiles is depending on the washing conditions (Geranio et al., 2009). Thus, it could be of

interest to investigate whether factors as detergents, temperature, loading combination and

centrifugation affects the discharge of fibers.

Further, some suggestions of improvement would be to develop a method for separating the

microplastic fibers from the dust particles. This should reduce the time spent on visual

sorting, making the work less time consuming and more accurate. Furthermore, the filters

should also be dried before the initial weighting to rule out underestimation of the discharged

fiber mass. In the present study, the filters were acclimated to the environment for some hours

before reweighting, but this improvement should increase the accuracy further. Additionally it

could be interesting to estimate the number of fibers from each filter to be able to compare the

results with previous studies from sewage treatment plants. In the present study there were a

vast number of fibers on each filter, and the fibers were not equally spread which made it

difficult to estimate the number concentration.

7. Acknowledgments

I would like to express my sincere thanks to my engaged supervisors: Kristina Svinhufvud at

Käppalaförbundet, Professor Matthew MacLeod and PhD student Berit Gewert at Stockholm

University. Thank you for giving me this opportunity and for your great support. I would also

14

like to express my thanks to Rebecka Pergel, student at the Royal Institute of Technology at

Stockholm and to Nadja Stadlinger, project coordinator at Stockholm University. Further, I

would like to thank Kerstin Magnusson and Fredrik Norén at the Swedish Environmental

Research Institute IVL for your generous advices.

8. References

8.1 Articles

Andrady, A.L., 2011. Microplastics in the marine environment. Mar. Pollut. Bull. 62, 1596-1605.

Browne, M.A., Crump, P., Niven, S.J., Teuten, E., Tonkin, A., Galloway, T., Thompson, R., 2011. Accumulation

of microplastic on shorelines woldwide: sources and sinks. Environ. Sci. Technol. 45, 9175–9179.

Browne, M.A., Dissanayake, A., Galloway, T.S., Lowe, D.M., Thompson, R.C., 2008. Ingested microscopic

plastic translocates to the circulatory system of the mussel, Mytilus edulis (L.). Environ. Sci. Technol. 42, 5026–

5031.

Browne, M.A., Niven, S.J., Galloway, T.S., Rowland, S.J., Thompson, R.C., 2013. Microplastic Moves

Pollutants and Additives to Worms, Reducing Functions Linked to Health and Biodiversity. Curr. Biol. 23,

2388–2392. doi:10.1016/j.cub.2013.10.012

Claessens, M., De Meester, S., Van Landuyt, L., De Clerck, K., Janssen, C.R., 2011. Occurrence and distribution

of microplastics in marine sediments along the Belgian coast. Mar. Pollut. Bull. 62, 2199–2204.

doi:10.1016/j.marpolbul.2011.06.030

Cole, M., Lindeque, P., Fileman, E., Halsband, C., Galloway, T.S., 2015. The Impact of Polystyrene

Microplastics on Feeding, Function and Fecundity in the Marine Copepod Calanus helgolandicus. Environ. Sci.

Technol. 49, 1130–1137. doi:10.1021/es504525u

Cole, M., Lindeque, P., Halsband, C., Galloway, T.S., 2011. Microplastics as contaminants in the marine

environment: a review. Mar. Pollut. Bull. 62, 2588–2597.

Derraik, J.G., 2002. The pollution of the marine environment by plastic debris: a review. Mar. Pollut. Bull. 44,

842–852.

Eriksen, M., Mason, S., Wilson, S., Box, C., Zellers, A., Edwards, W., Farley, H., Amato, S., 2013. Microplastic

pollution in the surface waters of the Laurentian Great Lakes. Mar. Pollut. Bull. 77, 177–182.

doi:10.1016/j.marpolbul.2013.10.007

Fendall, L.S., Sewell, M.A., 2009. Contributing to marine pollution by washing your face: Microplastics in facial

cleansers. Mar. Pollut. Bull. 58, 1225–1228.

Geranio, L., Heuberger, M., Nowack, B., 2009. The behavior of silver nanotextiles during washing. Environ. Sci.

Technol. 43, 8113–8118.

Gouin, T., Roche, N., Lohmann, R., Hodges, G., 2011. A Thermodynamic Approach for Assessing the

Environmental Exposure of Chemicals Absorbed to Microplastic. Environ. Sci. Technol. 45, 1466–1472.

doi:10.1021/es1032025

Graham, E.R., Thompson, J.T., 2009. Deposit-and suspension-feeding sea cucumbers (Echinodermata) ingest

plastic fragments. J. Exp. Mar. Biol. Ecol. 368, 22–29.

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Gregory, M.R., 1996. Plastic “scrubbers” in hand cleansers: a further (and minor) source for marine pollution

identified. Mar. Pollut. Bull. 32, 867–871.

Hidalgo-Ruz, V., Gutow, L., Thompson, R.C., Thiel, M., 2012. Microplastics in the Marine Environment: A

Review of the Methods Used for Identification and Quantification. Environ. Sci. Technol. 46, 3060–3075.

doi:10.1021/es2031505

Lusher, A.L., McHugh, M., Thompson, R.C., 2013. Occurrence of microplastics in the gastrointestinal tract of

pelagic and demersal fish from the English Channel. Mar. Pollut. Bull. 67, 94–99.

doi:10.1016/j.marpolbul.2012.11.028

McMahon, C.R., Holley, D., Robinson, S., 1999. The diet of itinerant male Hooker’s sea lions, Phocarctos

hookeri, at sub-Antarctic Macquarie Island. Wildl. Res. 26, 839–846. doi:10.1071/WR98079

Moore, C.J., Moore, S.L., Leecaster, M.K., Weisberg, S.B., 2001. A comparison of plastic and plankton in the

North Pacific central gyre. Mar. Pollut. Bull. 42, 1297-1300.

Moore, C.J., 2008. Synthetic polymers in the marine environment: a rapidly increasing, long-term threat.

Environ. Res. 108, 131–139.

Murray, F., Cowie, P.R., 2011. Plastic contamination in the decapod crustacean Nephrops norvegicus (Linnaeus,

1758). Mar. Pollut. Bull. 62, 1207–1217.

Patel, M.M., Goyal, B.R., Bhadada, S.V., Bhatt, J.S., Amin, A.F., 2009. Getting into the brain. CNS Drugs 23,

35–58.

Teuten, E.L., Saquing, J.M., Knappe, D.R., Barlaz, M.A., Jonsson, S., Björn, A., Rowland, S.J., Thompson,

R.C., Galloway, T.S., Yamashita, R., others, 2009. Transport and release of chemicals from plastics to the

environment and to wildlife. Philos. Trans. R. Soc. B Biol. Sci. 364, 2027–2045.

Thompson, R.C., Olsen, Y., Mitchell, R.P., Davis, A., Rowland, S.J., John, A.W., McGonigle, D., Russell, A.E.,

2004. Lost at sea: where is all the plastic? Science 304, 838–838.

Wright, S.L., Rowe, D., Thompson, R.C., Galloway, T.S., 2013a. Microplastic ingestion decreases energy

reserves in marine worms. Curr. Biol. 23, R1031–R1033. doi:10.1016/j.cub.2013.10.068

Wright, S.L., Thompson, R.C., Galloway, T.S., 2013b. The physical impacts of microplastics on marine

organisms: a review. Environ. Pollut. 178, 483–492.

Zettler, E.R., Mincer, T.J., Amaral-Zettler, L.A., 2013. Life in the “plastisphere”: microbial communities on

plastic marine debris. Environ. Sci. Technol. 47, 7137–7146.

8.2 Reports

Magnusson, K., 2015. Mikroskräp i avloppsvatten från tre norska avloppsreningsverk (C71). Stockholm: IVL

Svenska Miljöinstitutet.

Magnusson, K., Norén, F., 2014. Screening of microplastic particles in and down-stream a wastewater treatment

plant (C55). Stockholm: IVL Svenska Miljöinstitutet.

Magnusson, K., Wahlberg, C., 2014. Mikroskopiska skräppartiklar i vatten från avloppsreningsverk (B2208).

Stockholm: IVL Svenska Miljöinstitutet.

Naturskyddsföreningen., 2013. Raklödder till fiskarna: Om skräp i havet – Källor, problem och lösningar.

Stockholm: Naturskyddsföreningen.

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Norén, F., 2007. Small plastic particles in Costal Swedish waters (KIMO Sweden). Lysekil: N-research.

Norén, F., Ekendahl, S., Johansson, U., 2009. Mikroskopiska antropogena partiklar i Svenska hav. Lysekil: N-

research.

Norén, F., Norén, K., Magnusson, K., (IVL Svenska Miljöinstitutet). 2014. Marint mikroskopiskt skräp

(2014:52). Västra Götalands län: Länsstyrelsen.

Shui, S., Plastina, A., 2013. World apparel fiber consumption survey (ISBN

9780979390395). Washington DC: Food and Agriculture Organization of the United Nations and the

International Cotton Advisory Committee.

Stockholms universitets Östersjöcentrum., 2015. Mikroplaster i hygienartiklar – ett första steg för att minska

utsläppen till Östersjön. Stockholm: Stockholms universitet.

8.3 Remaining references

National Oceanic and Atmospheric Administration., 2015. Detecting Microplastics in the Marine Environment.

http://marinedebris.noaa.gov/research/detecting-microplastics-marine-environment. Date visited 27 May 2015.

Naturvårdsverket., 2013. Textilavfall. http://www.naturvardsverket.se/Miljoarbete-i-samhallet/Miljoarbete-i-

Sverige/Uppdelat-efter-omrade/Avfall/Avfallsforebyggande-program/Textil/. Date visited 27 May 2015.

Tecnon OrbiChem., 2014. Global Fibers Overview. Pattaya: Synthetic Fibres Raw Materials Committee.