Analysis, prevalence and impact of microplastics in ... · Smallest particle size considered (µm)...

Analysis, prevalence and impact of

microplastics in freshwater and estuarine

environments: an evidence review.J Iwan Jones1, John Murphy1, Amanda Arnold1, James Pretty1, Kate Spencer2, Arjen Markus3, Dick

Vethaak3

1School of Biological and Chemical Sciences, Queen Mary University of London, London, E14NS, UK2School of Geography, Queen Mary University of London, London, E14NS, UK3Deltares, Delft, The Netherlands

© JI Jones, J Murphy, A Arnold, J Pretty, K Spencer, A Markus, D Vethaak. All rights reserved

Systematic review procedure to address three questions

• Are the current sampling and analytical methods scientifically robust and appropriate?

• What are the sources of the microplastics found in freshwater environments?

• What is/are the impact(s) of microplastics on freshwater and estuarine biota?[Microplastics = all plastic particles sizes ≤ 5 mm including nano-sized (≤ 0.1 μm) plastic particles?]


Systematic review procedure

Objective way of searching for, reviewing and summarising evidence to help

answer specific questions

Pre-defined protocol

Set of clearly defined questions

Set of pre-defined search terms

Consistent approach for evaluating the relevance of evidence to the questions Consistent approach for evaluating the robustness of evidence


PICO elements

Population

Intervention

Comparator

Outcome

Capturing the evidence base


Population

plastic* freshwater* wetland potable

micro* river* marsh reservoir

microplastic stream* swamp aquifer

nanoplastic brook wastewater* groundwater

*plastic lake* drinking water sewage

pool aquatic outfall

pond ecosystem* estuar*

transitional

An initial wide search to establish the population of evidence in

published and grey literature

with Boolean Operators© JI Jones, J Murphy, A Arnold, J Pretty, K Spencer, A Markus, D Vethaak. All rights reserved

BioOne

COPAC

DART-Europe E-theses Portal

EBSCO Open dissertations

EThOS: Electronic Theses Online Service

European Commission Research Publications

European Sources Online

GoogleScholar

MedLine

Jstor

SciFinder

Open Access Theses and Dissertations

OpenGrey

PubMed

PLoS

Scopus

SciFinder

Web of Science

holdings of relevant environmental regulators

>3000 unique sources

(after removal of duplicates)


Stages of evidence gathering

Identification

Screening

Eligibility

Identification

Scoring


Are the current sampling and analytical

methods scientifically robust and appropriate?


A second set of pre-defined search terms relevant to the

question

Population Intervention Comparator Outcome

aggregate* spectroscop* count

colloid* raman quantif*

floc* particle analysis abundance

plankton* pyrolysis concentrat*

sediment* sampl* density

diet* separat* substance

content identif* state

*fibre flotat* morphology

*fiber floatat* dimension

*bead microscop* composition

fragment* digest*

pellet* centrifug*

flake* buoyan*

nurdle

dust

© J

I Jo

nes

, J M

urp

hy,

A A

rno

ld, J

Pre

tty,

K S

pen

cer,

A M

arku

s, D

Vet

haa

k.A

ll ri

ghts

res

erve

d

Map of evidence identified as relevant

[Cut-off date April 2019]


2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019

(part)

0

10

20

30

40

50

60

70

80

All

Freshwater

Estuarine

Other

Evid

ence

so

urc

es p

er

ye

ar

Volume sampled

0.000001

0.00001

0.0001

0.001

0.01

0.1

1

10

100

1000

10000

m3

Freshwater Estuary

a)

Volume sampled

0.00001

0.0001

0.001

0.01

0.1

1

Freshwater Estuary

m3

b)

Volume sampled[Note Log Scale]

Water Sediment


0.00001

0.0001

0.001

0.01

0.1

1

10

100

1000

10000

0.0

1

0.1 1

10

10

0

10

00

10

00

0

Smallest particle size considered (µm)

Vo

lum

e o

f sa

mp

le (

m3)

0.001

0.01

0.1

1

10

100

1000

10000

100000

1000000

10000000

0.1 1 10 100 1000 10000

0.01

0.1

1

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1000

10000

100000

1000000

10000000

0.0

00

01

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00

1

0.0

01

0.0

1

0.1 1

10

10

0

10

00

10

00

0

Volume of sample (m3)

Me

an

ab

un

da

nce

of

mic

rop

lastics

(pa

rtic

les m

-3)


Me

an

ab

un

da

nce

of

mic

rop

lastics

(pa

rtic

les m

-3)

a) c)b)

R2 =0.324 R

2 =0.701 R

2 =0.358

0.00001

0.0001

0.001

0.01

0.1

1

10

100

1000

10000

0.0

1

0.1 1

10

10

0

10

00

10

00

0


Vo

lum

e o

f sa

mp

le (

m3)

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1

10

100

1000

10000

100000

1000000

10000000

0.0

00

01

0.0

00

1

0.0

01

0.0

1

0.1 1

10

10

0

10

00

10

00

0

R2 =0.630

0.01

0.1

1

10

100

1000

10000

100000

1000000

10000000

0.1 1 10 100 1000 10000

R2 =0.485


Me

an

ab

un

da

nce

of

mic

rop

lastics

(pa

rtic

les m

-3)


Me

an

ab

un

da

nce

of

mic

rop

lastics

(pa

rtic

les m

-3)

f)e)d)

R2 =0.543

Relationships among particle size, volume of water

sampled and reported concentration

Fre

sh

wa

ter

Estu

arie

s

Particle Size – Sample Vol Sample Vol – Conc Particle Size – Conc

Poin

ts r

epre

sen

t m

ean

per

stu

dy

/ te

chn

iqu

e /

hab

itat

© J

I Jo

nes

, J M

urp

hy,

A A

rno

ld, J

Pre

tty,

K S

pen

cer,

A M

arku

s, D

Vet

haa

k.A

ll ri

ghts

res

erve

d

0.00001

0.0001

0.001

0.01

0.1

1

0.1 1 10 100 1000 10000


Vo

lum

e o

f sa

mp

le (

m3)

1

10

100

1000

10000

100000

1000000

10000000

100000000

0.0

00

01

0.0

00

1

0.0

01

0.0

1

0.1 1


1

10

100

1000

10000

100000

1000000

10000000

100000000

0.1 1 10 100 1000 10000


a) c)b)

0.00001

0.0001

0.001

0.01

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1

0.1 1 10 100 1000 10000

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1000

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1000000

10000000

100000000

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1

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1000

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1000000

10000000

100000000

0.0

00

01

0.0

00

1

0.0

01

0.0

1

0.1 1


Vo

lum

e o

f sa

mp

le (

m3)

Volume of sample (m3) Smallest particle size considered (µm)

d) f)e)

R2 =0.215

Me

an

ab

un

da

nce

of

mic

rop

lastics

(pa

rtic

les m

-3)

Me

an

ab

un

da

nce

of

mic

rop

lastics

(pa

rtic

les m

-3)

Me

an

ab

un

da

nce

of

mic

rop

lastics

(pa

rtic

les m

-3)

Me

an

ab

un

da

nce

of

mic

rop

lastics

(pa

rtic

les m

-3)

Relationships among particle size, volume of sediment

sampled and reported concentration

Fre

sh

wa

ter

Estu

arie

s

Particle Size – Sample Vol Sample Vol – Conc Particle Size – Conc

Poin

ts r

epre

sen

t m

ean

per

stu

dy

/ te

chn

iqu

e /

hab

itat

© J

I Jo

nes

, J M

urp

hy,

A A

rno

ld, J

Pre

tty,

K S

pen

cer,

A M

arku

s, D

Vet

haa

k.A

ll ri

ghts

res

erve

d

The size range of particles captured by the sampling and processing

method used influences the mean abundance of microplastic particles

reported.

Comparison among studies is not possible without consideration of

the size of particles considered.

A range of sample volumes may be necessary to quantify the

abundance of different sized particles adequately.

More research into appropriate sample volumes for sediment is

required.


Nake

d E

ye

Op

tica

l m

icro

sco

py

Op

tica

l m

icro

sco

py &

FT

IR

Op

tica

l m

icro

sco

py &

Ram

ma

n

Op

tica

l m

icro

sco

py &

SE

M

Op

tica

l m

icro

sco

py &

Pyr-

GC

/MS

Op

tica

l m

icro

sco

py &

FT

IR &

Ram

ma

n

Op

tica

l m

icro

sco

py &

FT

IR &

SE

M

Op

tica

l m

icro

sco

py &

FT

IR &

Pyr-

GC

/MS

Op

tica

l m

icro

sco

py &

Ram

ma

n

& S

EM

Op

tica

l m

icro

sco

py &

Ram

ma

n &

XR

F

TE

D-G

C-M

S

Th

erm

al a

na

lysis

Sh

ort

wa

ve

in

fra

red

sp

ectr

osco

py

To

F-S

IMS

Ma

ss

0

5

10

15

20

25

30

35

40

45

50

% o

f so

urc

es

Estuary

0

5

10

15

20

25

30

35

40

45

% o

f so

urc

es

Water

Sediment

Biota

Freshwater

Techniques used to quantify and characterise

microplastic particles

A range of techniques have been used

to quantify and characterise particles:

Spectroscopic

(e.g. FTIR, Raman, near infrared)

Thermoanalytical

(e.g. Py-GC-MS, TED-GC-MS)

Chemical

(e.g. ICP-MS)

Each return information on different

characteristics of the microplastics

present in the sample


Due to the variety of techniques that have been used to quantify

and characterise microplastics, as well as variation in the volume

sampled and size of particles considered, it is not possible to

assess differences in the microplastic profile among studies using

the data currently available.


1. Sampling methods

2. Sample size

3. Sample processing and storage

4. Laboratory preparation

5. Clean air conditions

6. Negative control

7. Positive controls

8. Target component (for Biota only)

9. Sample treatment

10. Polymer identification

Scored 0 – 2 per criterion following

Hermsen et al. (2018) and Koelmans et al. (2019)

Reliability of Studies


0

2

4

6

8

10

12

14

16

18

10

8

6

4

2

0

2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020

To

tal A

ccu

mu

late

d S

co

reN

um

be

r o

f Z

ero

s

Date

Change in Reliability Scores over time

Two measures of reliability:

Total Accumulated Score (0 – 18)

Number of Zeros (9 – 0)


Reliability of studies of microplastics in freshwaters and estuaries has

increased over time


What is/are the impact(s) of microplastics on

freshwater and estuarine biota?


Map of evidence identified as relevant

[Cut-off date April 2019]


2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019

0

5

10

15

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25

30

35

40

All

Freshwater

Estuarine

Evid

en

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urc

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Ye

ar

1. Validity criteria

2. Adequate controls

3. Identity of test substance

4. Source of test substance

5. Identity of test organisms

6. Source of test organisms

7. Appropriate for test substance

8. Appropriate for test organism

9. Gradient of exposure

10. Exposure duration

11. Verification of exposure

12. Biomass loading

13. Adequate replication

14. Appropriate statistical methods

15. Raw data available

Reliability of Experimental

Studies

Scored 0 – 2 per criterion following

CRED (Criteria for reporting and

evaluating ecotoxicity data) method of Moermond et al. (2016)


0

5

10

15

20

25

30

15

13

11

9

7

5

3

1

Cu

mu

lative

Sco

re

Nu

mb

er

of

Ze

ros

Reliability of Experimental

Studies

Box indicates 25th and 75th percentiles, whiskers

minimum and maximum, and line median size of particles

(n = 103)

Total Cumulative Score (0 – 30) and

Number of Zero scored categories (15 – 0)


0

5

10

15

20

25

30

10

8

6

4

2

0

2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020

To

tal A

ccu

mu

late

d S

co

reN

um

be

r o

f Z

ero

s

Date

Change in Reliability Scores over time

Two measures of reliability:

Total Accumulated Score (0 – 30)

Number of Zeros (10 – 0)


The majority of studies of the impact of microplastics on freshwater

and estuarine biota were unreliable in several aspects.

Published studies have become less reliable over time.


110

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10000000000000000100000000000000000

100000000000000000010000000000000000000

0.01 0.1 1 10 100 1000 0.01 0.1 1 10 100 1000 0.01 0.1 1 10 100 1000

110

1001000

10000100000

100000010000000

1000000001000000000

10000000000100000000000

100000000000010000000000000

1000000000000001000000000000000

10000000000000000100000000000000000

100000000000000000010000000000000000000

0.01 0.1 1 10 100 1000 0.01 0.1 1 10 100 1000

Feeding Growth

Reproduction Survival

a) b)

d) e)T

hre

sh

old

co

nce

ntr

atio

n

(pa

rtic

les m

-3)

Th

resh

old

co

nce

ntr

atio

n

(pa

rtic

les m

-3)

Mean particle size (m) Mean particle size (m)

Behaviour

Mean particle size (m)

c)

Relationships between particle size and reported

ecotoxicological threshold concentrations

Ecotoxicological

endpoints behaviour,

feeding, growth,

reproduction, survival

Lines fitted by least

squares regressionLess reliable studies (<median

score) shown (red symbols) but

excluded

P ≤ 0.0001 P = 0.0002 P ≤ 0.0001

P ≤ 0.0001P = 0.019


Under experimental conditions, high concentrations microplastics can

have a negative impact on the feeding, behaviour, growth,

reproduction and survival of freshwater and estuarine biota.

The concentration required to cause such impacts is related to the size of the particles of microplastic.


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0.01 0.1 1 10 100 1000

Crustacea

Fish

Algae

Plants

Molluscs

Nematodes

Insects

Hyphomycetes


Th

resh

old

co

nce

ntr

atio

n

(pa

rtic

les m

-3

Effect of taxonomic group on size specific threshold

concentrations

Sufficient data to test effect of

taxonomic group on relationship

between particle size and

threshold concentration for

Crustacea, fish and algae using

ANCOVA

F value p

Particle Size 569.85 ≤ 0.0001

Particle Size * Endpoint 0.30 0.8778

Particle Size * TaxaGp 1.71 0.2109

No effect of taxonomic group or

ecotoxicological endpoint on

relationship with particle size


Effect of polymer on size specific threshold

concentrations

Sufficient data to test effect of

polymer on relationship between

particle size and threshold

concentration for polyethylene (PE),

polystyrene (PS), polyamide (PA)

using ANCOVA

F value pParticle Size 807.84 ≤ 0.0001

Particle Size* Endpoint 0.80 0.5360

Particle Size* Polymer 0.91 0.4106

No effect polymer or

ecotoxicological endpoint on

relationship with particle size1

10

100

1000

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100000000

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1000000000000000000

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100000000000000000000

0.01 0.1 1 10 100 1000

PE

PP

PS

PA

PHB

Not given


Th

resh

old

co

nce

ntr

atio

n

(pa

rtic

les m

-3


Differences in reported thresholds could not be attributed to

differences in the taxonomic group of the test organism or to the polymer used.


Particles used

0.01

0.1

1

10

100

1000

10000

Pa

rtic

le s

ize

(

m)

Estuarine Freshwater

0.01

0.1

1

10

100

1000

10000

Sm

alle

st

pa

rtic

le s

ize

co

nsid

ere

d (

m)

a) b)

Size of particles used in ecotoxicological studies

Size of particles used in

ecotoxicological studies (n =

125), and smallest particles

considered in studies of

microplastics in estuaries and

freshwaters (n = 185).

Nanoparticles ≤0.1 μm.

Box indicates 25th and 75th percentiles,

whiskers minimum and maximum, and line

median size of particles.

Lab Studies Field monitoring


The majority of laboratory based toxicological studies have been

undertaken using plastic particles that do not reflect the size of the

microplastic particles that have been described from environmental

samples collected in estuaries and freshwaters.

This mismatch adds uncertainty to our understanding of risk from

microplastics.


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Freshwaters

Estuaries

Thresholds

Pa

rtic

les m

-3

[Minimum] Particle size (m)

Concentrations used in ecotoxicological studies

Threshold concentrations

reported from laboratory studies

Mean concentrations reported

from field collections of


freshwaters

Lines fitted by least squares

regression


Laboratory based toxicological studies have been undertaken using

concentrations of microplastics that are many orders of magnitude

greater than the concentrations that have been reported from samples

collected from freshwater and estuarine environments.


Th

resh

old

co

nce

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atio

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(pa

rtic

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0.01 0.1 1 10 100 1000

Size specific threshold concentrations

Species Sensitivity

Distribution approach not

appropriate

Size Specific Thresholds

fitted to 10%ile by quantile

regression,

i.e. concentration that is

lower than 90% of reported

lethal (dashed line) and all

thresholds (red line) for that

specific particle size

Less reliable studies (<median score)

excluded


Establishing Risk Comparison of reported environmental concentrations and

size specific thresholds

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0.01 0.1 1 10 100 1000 10000

Freshwaters

Estuaries

Thresholds

10%ile All Endpoints

10%ile Survival

Part

icle

s m

-3


a)

b)

0.01

0.1

1

10

100

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10000000000000000

100000000000000000

1000000000000000000

0.01 0.1 1 10 100 1000 10000


10%ile Survival

99%ile Environment

95%ile Environment

90%ile Environment

75%ile Environment

Part

icle

s m

-3


Size Specific Thresholds fitted

to 10%ile by quantile

regression,

i.e. concentration that is lower

than 90% of reported lethal and

all thresholds.

Concentrations reported from

field collections of microplastics

in estuaries and freshwaters


Establishing Risk Comparison of reported environmental concentrations and

size specific thresholds

Size Specific Thresholds fitted

to 10%ile by quantile

regression,

i.e. concentration that is lower

than 90% of reported lethal and

all thresholds.

Quantiles (99%, 95%, 90%,

75%) fitted to concentrations

reported from field collections of


freshwaters

0.01

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1

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0.01 0.1 1 10 100 1000 10000

Freshwaters

Estuaries

Thresholds


10%ile Survival

Pa

rtic

les m

-3


a)

b)

0.01

0.1

1

10

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100000

1000000

10000000

100000000

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10000000000

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10000000000000000

100000000000000000

1000000000000000000

0.01 0.1 1 10 100 1000 10000


10%ile Survival

99%ile Environment

95%ile Environment

90%ile Environment

75%ile Environment

Pa

rtic

les m

-3

[Minimum] Particle size (m)© JI Jones, J Murphy, A Arnold, J Pretty, K Spencer, A Markus, D Vethaak. All rights reserved

The calculated size specific threshold

concentration for lethal effects was higher than

99% of reported environmental concentrations,

suggesting that lethal effects of microplastics on

freshwater and estuarine biota are highly

unlikely.


0.01

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0.01 0.1 1 10 100 1000 10000

Freshwaters

Estuaries

Thresholds


10%ile Survival

Pa

rtic

les m

-3


a)

b)

0.01

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1

10

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0.01 0.1 1 10 100 1000 10000


10%ile Survival

99%ile Environment

95%ile Environment

90%ile Environment

75%ile Environment

Pa

rtic

les m

-3


Over certain size ranges the calculated size specific threshold concentration for

sublethal effects was exceeded by the highest 10% of concentrations reported from

environmental samples, suggesting that there may be a possible risk of some

sublethal effects in a small proportion of sites.

Three Reports to be available from Department for Environment, Food and Rural Affairs here

Evidence Reviews on Analysis, Prevalence & Impact of Microplasticsin Freshwater and Estuarine Environments Evidence Review 1 Are the current sampling and analytical methods scientifically robust and appropriate?

Evidence Reviews on Analysis, Prevalence & Impact of Microplasticsin Freshwater and Estuarine Environments Evidence Review 2 What are the sources of the microplastics found in freshwater environments?

Evidence Reviews on Analysis, Prevalence & Impact of Microplasticsin Freshwater and Estuarine Environments Evidence Review 3 What is/are the impact(s) of microplastics on freshwater and estuarine biota?


0.01

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0.01 0.1 1 10 100 1000 10000

Freshwaters

Estuaries

Thresholds


10%ile Survival

Pa

rtic

les m

-3


a)

b)

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10%ile Survival

99%ile Environment

95%ile Environment

90%ile Environment

75%ile Environment

Pa

rtic

les m

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http://randd.defra.gov.uk/Default.aspx?Menu=Menu&Module=More&Location=None&ProjectID=20192&FromSearch=Y&Publisher=1&SearchText=WT15112&SortString=ProjectCode&SortOrder=Asc&Paging=10#Description

Acknowledgments

This work was funded by the UK Department for

Environment, Food and Rural Affairs through

project WT15112.

We acknowledge the experts who contributed their opinions to the reviews.


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