Microplastic detection in
freshwater ecosystems and drinking water
Anna Winkler
University of Milan
Department of Environmental Science and Policy
Seminari Limnologici 19 novembre 2019
Microplastic
https://riverfriends.org
Synthetic polymer < 5 mm in size
(Hartmann et al., 2019)
Surface water, sediment, soil, air, animals…
Food, drinking water, human stool
Sources: wastewater, fragmentation, atmospheric deposition…
Projects Microplastic in drinking water
Returnable
PET Glass
Single-use
PET Carton Tap Ground
water
Projects
Microplastic release from plastic water bottles
Microplastic in drinking water
Samples all across the word with a max of 9 MPs/L
Not related to
development of country
± 14
± 2857 ± 5432 ± 2531
± 52 ± 8
± 88
Projects
Microplastic release from plastic water bottles
Microplastic in drinking
water ± 14
± 2857
± 253
Projects
Microplastic release from plastic water bottles
Microplastic in drinking water
Considering detected particle sizes:
Excl. Mason et al. 2018 as they did not provide size information
more than 98% were < 5 µm
Projects
Microplastic release from plastic water bottles
more than 98% were < 5µm
• Small particles contribute
enormously to the total number of individual particles at very low mass concentrations
• few larger plastic particles hardly contribute to the particle number i.e. 1,000,000 PS particles of 1 µm have the same mass as 1 particle of 100 µm
Calculated relation of particle size and particle mass for spherical PS particles with a density of 1.04 g/mL.
Source: Eitzen et al. 2019
Mass concentration
Number concentration
Size
matters!
Microplastic release from plastic water bottles
Objective:
evaluating single use PET bottles as one of the proven sources of MP intake by humans
Main questions:
a) MP concentration?
b) Does mechanical stress (daily use) causes an increase of MP release from the bottle material?
c) Are there differences in water bottle MP between (3)
brands?
Microplastic release from plastic water bottles
Objective:
evaluating single use PET bottles as one of the proven sources of MP intake by humans
HDPE
Microplastic release from plastic water bottles
Scanning Electron Microscopy
electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons
electrons interact with atoms in the sample, producing various signals
a detector counts the number of low energy secondary electrons, or other radiation, deriving from each point on the surface
the topography of the sample surface
Inkson et al. 2016
Microplastic release from plastic water bottles
Scanning Electron Microscopy
electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons
electrons interact with atoms in the sample, producing various signals
a detector counts the number of low energy secondary electrons, or other radiation, deriving from each point on the surface
the topography of the sample surface
Inkson et al. 2016
200 X
60 X 1,000 X
Up to 50,000 X
Microplastic release from plastic water bottles
Energy dispersive X-ray spectroscopy
detector measures the energy of the emitted X-rays
specific for each element
PET elemental ratio of C:O = 73:27 (C 10 H 8 O 4 ) n
Inkson et al. 2016
http://www.chem.ucla.edu/~harding/IGOC/P/pet.html
Identification limit: 3 µm
Microplastic release from plastic water bottles
Filtration process is
applicable
Microplastic
release from
plastic water
bottles
Projects
PET bottlenecks and HDPE caps present a serious source of MP
Chances of MP ingestion by humans
High differences in density on caps among brands structural design?
63,400 MPs/cap
Results: bottle closure (cap)
1,225,500 MPs/cap
333,800 MPs/cap
Microplastic
release from
plastic water
bottles
Projects
Microplastic release from plastic water bottles
63,400 MPs/cap
Extent of MP release was not related to lubricant content!
Spectra of GC/MS analysis showing characteristic peaks of lubricant substance (behenamide) and peaks detected in extracted solvent from caps of the three brands..
Not present Brand 1
Brand 2 Brand 3 Standard
0.08% behenamide 1% behenamide
Brand 1 Brand 2 Brand 3
Microplastic release from plastic water bottles
Results: bottle closure (cap)
Projects
Results: bottle closure (cap)
Microplastic
release from
plastic water
bottles
Projects
Results: bottle closure (cap)
Microplastic
release from
plastic water
bottles
Projects
Microplastic release from plastic water bottles
Microplastic release from plastic water bottles
Results: bottle closure (neck)
Projects
Results: filtered water
148 ± 253 MPs/L
MP occurrence in water samples was not sign.
related to treatments or brand
Microplastic release from plastic water
bottles PET material was resistant
towards mechanical stress
(squeezing/crushing test)
Projects
Microplastic release from plastic water bottles
Implications
MP in filtered water from contamination of
the water before bottling
Variety in the plastic
behavior optimization of the admission criteria for
food contact substances
Differences in the extent of MP release of
bottlenecks/caps between brands
SEM/EDS was suitable for our experimental set
high-resolution images
Microplastic
release from
plastic water
bottles
Carbery et al. 2018
Human health
Lack of hazard and fate data
Very fine particles could be capable of crossing cell membranes or the blood-brain barrier
i.e. Schirinzi et al. 2017: cytotoxicity of MPs and NPs
in-vitro tests in cerebral and epithelial human cells
PE (3–16 μm + 100 and 600 nm) and PS (10 μm + 40 and 250 nm).
oxidative stress is one of the mechanisms of cytotoxicity at cell level
Oxidative stress occurs when there is an
imbalance between the production of free radicals
and the body's ability to counteract their damaging
effects through neutralization with antioxidants.
Carbery et al. 2018
Human health
Zimmermann et al. 2019:
benchmark plastic consumer products, according to their toxicological and chemical signatures (using in vitro
bioassays and nontarget high-resolution mass spectrometry)
• Extracts of polyvinyl chloride (PVC) and polyurethane (PUR) induced the highest toxicity,
• whereas PET and HDPE caused no or low toxicity
consumer plastics contain compounds that are toxic in vitro but remain largely unidentified
Since the risk of unknown compounds cannot be assessed, this poses a challenge to manufacturers, public health
authorities, and researchers alike
“Little is known with respect to the human health risks of MPs, and what is known is surrounded by considerable uncertainty;
however, the relevant conclusion […] is that we have no evidence of widespread risk to human health from NPs and MPs at present.”
Science Advice for Policy by European Academies, 2019 (funded consortium of EU’s Horizon 2020 Programme)
Carbery et al. 2018
Half-
time
MP detection in the
environment
Sampling
Extraction
Chemical digestion Density separation
Analysis
Quantification Identification
Research methodology
Research challenge
No standard technique for sampling, extraction, analysis
available (Koelmans et al. 2019)
difficulty in comparing results
Consider MP to become a monitoring parameter for water quality
Few data on MP pollution in Italian rivers (Campanale et al. 2019)
Microplastic in the Ticino river
• Reporting the abundance, composition and fate of MP along the Ticino river by sampling:
Water Sediment
Fish Macrobenthos
• Ticino river represents one of the most natural rivers in Italy
Main questions:
a) Does MP concentration in samples increase with the length of the river?
b) Are applied sampling, extraction and analytical technique suitable for this purpose?
Projects
o 6 sampling sites
o Just below main input sources
Microplastic in the Ticino river
Canale scolmatore di Nord Ovest Canale scaricatore
Depuratore di Vigevano
Depuratore di Pavia e Naviglio di Pavia Naviglio Sforzesco
Microplastic in the Ticino river
Objective:
• evaluating WWTP effluent as potential main input of MPs
• assessing chosen sampling, extraction and identification methodology
• analysing morphology and
polymer type to give indications
on their origin
Projects
Microplastic in the Ticino river
sampling extraction analysis
Neuston trawl, nylon, 60 µm mesh size
Microplastic in the Ticino river
Surface water
Projects
Microplastic in the Ticino river
sampling extraction analysis
Microplastic in the Ticino river
Surface water
Projects
Microplastic in the Ticino river
Electro fishing
Catfish (Silurus glanis) sampling extraction analysis
Microplastic in the Ticino river
Fish
Projects
Microplastic in the Ticino river
Hydropsychidae
Handpicking from stones
sampling extraction analysis
Shovel and aluminium tray
Microplastic in the Ticino river
Sediment and Macrobenthos
Projects
Chemical digestion
Microplastic in the Ticino river
sampling extraction analysis
Fish and
macroinvertebrates
KOH solution (w/v 33%) for 1 h at 50°C
Water and sediment H2O2 with
FeSO4*7H2O + H2SO4 for 1 h at 50°C
Microplastic in the Ticino river
Fenton’s
Reagent
Projects
Density separation
Microplastic in the Ticino river
sampling extraction analysis
• 6 g NaCl per 20 mL solution
• Floats MP with density <
1.2 g/cm 3 (discrimination of heavier plastics such as PET, PVC)
• Duration: overnight
• Repeat with settled material
Filtration Microplastic
in the Ticino river
• of supernatant on filter
membrane
Projects
sampling extraction analysis
• Dissecting stereo microscope
Microplastic in the Ticino river
• Identification by properties
(Hidalgo-Ruz et al., 2012) :
o Homogeneous colour o Gloss
o Shape
o Absence of cellular structures
Strategy!
Water sample
Transfer to filter for analysis
Visual identification
magnification 25x magnification 25x
magnification 16x magnification 35x
Projects
Visual identification
sampling extraction analysis
Sediment
Microplastic in the Ticino river
Surface water
Projects
Visual identification
sampling extraction analysis
Microplastic in the Ticino river
magnification 16x magnification 35x
magnification 16x magnification 8x
