Microplastics in eviscerated flesh and excised organs of dried fish

Our plain-English summary of Microplastics in eviscerated flesh and excised organs of dried fish, by A. Karami, A. Golieskardi, Y.B. Ho, et al (Scientific Reports, 2017).

The study

• Authors: A. Karami, A. Golieskardi, Y.B. Ho, V. Larat, B. Salamatinia
• Journal: Scientific Reports
• Published: 2017;7(1):5473
• Cited by: 183 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

There is a paucity of information about the occurrence of microplastics (MPs) in edible fish tissues. Here, we investigated the potential presence of MPs in the excised organs (viscera and gills) and eviscerated flesh (whole fish excluding the viscera and gills) of four commonly consumed dried fish species (n = 30 per species). The MP chemical composition was then determined using micro-Raman spectroscopy and elemental analysis with energy-dispersive X-ray spectroscopy (EDX). Out of 61 isolated particles, 59.0% were plastic polymers, 21.3% were pigment particles, 6.55% were non-plastic items (i.e. cellulose or actinolite), while 13.1% remained unidentified. The level of heavy metals on MPs or pigment particles were below the detection limit. Surprisingly, in two species, the eviscerated flesh contained higher MP loads than the excised organs, which highlights that evisceration does not necessarily eliminate the risk of MP intake by consumers. Future studies are encouraged to quantify anthropogenic particle loads in edible fish tissues.

In plain English

This laboratory study looked for microplastics, tiny plastic particles, in four kinds of dried fish bought packed from local markets in Malaysia: greenback mullet, Belanger's croaker, Indian mackerel and spotty-face anchovy, 30 fish of each. The authors split each fish into its gills and internal organs ("excised organs") and the rest of the body ("eviscerated flesh"). They dissolved the tissue and identified the recovered particles by Raman spectroscopy. Of 61 particles, 36 (59.0%) were plastics, mostly polypropylene and polyethylene. Another 13 (21.3%) were pigments, 4 (6.55%) were non-plastic items (cellulose or actinolite), and 8 (13.1%) could not be identified. One particle, from the gills and organs of an Indian mackerel, was actinolite. The article describes actinolite as one of six naturally occurring mineral silicate fibers referred to as asbestos. Each fish held between 0 and 3 plastic or pigment particles. In the mullet and the croaker, the flesh held significantly more microplastics than the gills and organs. Toxic heavy metals on the particles were undetectable. The authors concluded that removing gills and organs does not necessarily reduce microplastic intake, but said they could not evaluate health risks.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory analysis of particles in commercially sold dried fish (descriptive field survey with statistical comparisons between tissues and species)
• Who was studied: Four dried fish species (Chelon subviridis, Johnius belangerii, Rastrelliger kanagurta, Stolephorus waitei) bought packed from local markets in Malaysia, 30 fish per species taken from 3 to 6 packs per species; no sampling dates given
• Exposure: Microplastics (0.001 to 1 mm), mesoplastics (1 to 10 mm), macroplastics (over 10 mm) and pigment particles in fish tissue. One particle was identified as actinolite.
• Main results:
  • Of 61 particles isolated from all four species, 36 (59.0%) were confirmed as microplastics and 13 (21.3%) as pigments
  • Of the 61 particles, 4 (6.55%) were non-plastic items (cellulose or actinolite) and 8 (13.1%) remained unidentified
  • Among plastic polymers, polypropylene made up 47.2% and polyethylene 41.6%, followed by polystyrene (5.56%), polyethylene terephthalate (2.77%) and nylon-6 (2.77%)
  • One particle from the excised organs (gills and viscera) of Indian mackerel (R. kanagurta) was identified as actinolite, which the article describes as one of 6 naturally occurring mineral silicate fibers referred to as asbestos
  • Each individual fish contained between 0 and 3 pigment and microplastic particles
  • Across all species, 29 microplastics and 9 pigment particles came from the eviscerated flesh, and 7 microplastics and 4 pigment particles came from the excised organs
  • In greenback mullet (C. subviridis) and Belanger's croaker (J. belangerii), microplastic counts were significantly higher in the eviscerated flesh than in the excised organs (p less than 0.05)
  • In Indian mackerel and spotty-face anchovy, pigment or microplastic counts did not differ significantly between flesh and excised organs (p greater than 0.05)
  • Toxic heavy metals on the isolated particles were at undetectable levels; the instrument's detection limit was around 1000 pg/µg for most heavy metals
  • The authors estimated intake using a dried fish consumption figure of 370 g per person per year reported for Bangladesh. On that basis, consumers of spotty-face anchovy could ingest between 0 and 246 particles per year. For mullet, croaker and mackerel, the estimates were 0 to 68, 0 to 44 and 0 to 6 anthropogenic particles per year.
• The authors' conclusion: The authors concluded that higher microplastic loads in the edible tissues than in the excised organs of two dried fish species indicate that removing gills and viscera does not necessarily reduce microplastic uptake by consumers of dried fish.
• Limitations the authors state:
  • The authors could not evaluate the health risks of eating dried fish
  • Pigment particles were confirmed as man-made, but the authors could not confirm whether they were plastic polymers
  • Raman spectroscopy could not identify 13.1% of the particles
  • Most tested fish contained no microplastic, so the maximum intake estimates are unlikely for an individual
  • Data on global dried fish consumption are insufficient

Topics

Medical terms in this study, explained in our Lexicon: Fluorescence In Situ Hybridization (FISH), Elemental Analysis, Actinolite.

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