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Our plain-English summary of [Not Available], by M. Erba, S. Cantoni (La Medicina del Lavoro, 2019).

The study

• Authors: M. Erba, S. Cantoni
• Journal: La Medicina del Lavoro
• Published: 2019;110(3):202-214
• Language: Italian
• Read it: PubMed · Publisher · Free full text

Abstract

Unlabelled: «Asbestos in fresh water fish of a pond in Milan. Where is it coming from?».

Introduction:: Cement-based material containing asbestos was found in the water of a pond in the city of Milan, Italy, where recreational fishing activities take place. Some fishes are in ‘no-kill’ fishing areas, others are caught and consumed.

Objective:: To verify the presence of asbestos in water, sediments and some fish species living in the pond. To verify the presence of asbestos in fish feed and to test fish exposure by ingestion.

Methods:: Samples of water, sediments, fish feed and fish species have been collected and the presence of asbestos fibers has been ascertained in the different matrices.

Results:: No traces of asbestos were found in water. Instead, the asbestos content in sediments was beyond regulatory limits. Asbestos was detected also in benthic fish species, and in rainbow trout (Oncorhynchus mykiss) that does not reproduce in the pond but must be restocked periodically through aquaculture. In the meat of the grass carp (Ctenopharyngodon idella) 36,000,000 fibers/100 g of wet cloth have been found. Values up to 15,000,000 ff/100 g of wet cloth have been detected in the rainbow trout. Asbestos has also been found in animal feeds, in particular crocidolite fibers and asbestos tremolite bundles.

Conclusions:: Benthic fish species have likely been contaminated by their close contact with the polluted bottom of the pond. Instead, the presence of asbestos in the trout is probably linked to a previous contamination during farming, since this fish spend a brief period of time in the water of the pond. Asbestos distribution and concentration exclude a risk for public health; however, some values of asbestos found in fish meat deserve attention. Accordingly, precautionary indications have been given to the Municipality of Milan and to the fishermen association. A larger scale monitoring of water, food and animal feed is worth performing to better assess exposure by ingestion.

In plain English

This Italian study examined an artificial pond (cava Casati) in Milan's Parco delle Cave, used for sport fishing, after cement-based waste suspected of containing asbestos surfaced in spring 2016. The authors sampled the waste, pond water, bottom sediments, several fish species and trout feed. The waste contained chrysotile and crocidolite. No asbestos was detected in the water. Some sediment samples at 0, 2 and 4 m from the waste pile exceeded the 1000 ppm legal limit, with values from 2000 to 6500 ppm. Asbestos was found in the muscle of a grass carp (36,000,000 fibers per 100 g of wet tissue, chrysotile), an eel and an American catfish. It was also found in rainbow trout, which are restocked from a fish farm, at up to 15,000,000 fibers per 100 g in trout sampled before release. Crocidolite and tremolite asbestos were found in trout feed. The authors concluded that bottom-dwelling fish were likely contaminated by the sediments and the trout at the farm. They judged that the data exclude a public health risk, though some values were not negligible, and that wider monitoring was needed.

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: Environmental field investigation: sampling and laboratory analysis (diffractometry and scanning electron microscopy) of waste material, water, sediments, fish and fish feed
• Who was studied: An artificial pond (cava Casati) in the Parco delle Cave on the outskirts of Milan, Italy, investigated from spring 2016. Samples taken: 3 waste fragments, 11 sediment samples plus a reference point about 60 m away, 5 water samples, and 2 types of trout feed. Fish sampled: one each of grass carp, carpa regina, bream, mirror carp, largemouth bass, eel and American catfish, plus one freshwater mussel, one large rainbow trout and 20 smaller rainbow trout (200-300 g).
• Exposure: Cement-based construction waste containing asbestos (chrysotile and crocidolite, with amosite below 1%) lying in the pond. Fish were exposed through contaminated sediments, and possibly through feed and fish-farm origin.
• Main results:
  • All 3 waste fragments contained asbestos. Table 1 shows chrysotile at 7%, 8% and 6% and crocidolite at 1%, 2% and 1% by weight; the method's detection limit was 1%.
  • No asbestos was detected in the pond water. Any values were below the method's detection limit of 1000 fibers per litre.
  • Sediments at 0 m from the waste pile: 2 of 4 samples contained 2000 and 6500 ppm asbestos. The legal limit is 1000 ppm.
  • Sediments at 2 m: 1 of 3 samples contained 2200 ppm. Sediments at 4 m: 1 of 4 samples contained 3000 ppm.
  • Grass carp: muscle tissue contained 36,000,000 fibers per 100 g of wet tissue (chrysotile). This was the only grass carp tissue that gave a meaningful result.
  • Eel: 880,000 fibers per 100 g wet tissue (chrysotile). American catfish: 2,200,000 fibers per 100 g wet tissue (chrysotile and crocidolite).
  • Five rainbow trout sampled before release into the pond (one of them analysed at 2 points) contained 3,400,000 and 1,700,000, 15,000,000, 4,000,000, 780,000 and 2,400,000 fibers per 100 g wet tissue.
  • 4 of 5 rainbow trout sampled after release contained 3,600,000, 860,000, 2,600,000 and 880,000 fibers per 100 g wet tissue. Mean concentrations in pre-release trout were 3 times higher than in post-release trout.
  • No asbestos fibers were detected in the mirror carp, common carp, bream, largemouth bass or the large rainbow trout. A freshwater mussel had one bundle of chrysotile (qualitative analysis).
  • In a second sampling (5 trout of uncertain origin and 5 pre-release trout taken from the fish farm's truck), muscle and kidney contained metal oxides with silicon-aluminium and titanium fibers, but no asbestos.
  • Fish feed: the first sample showed crocidolite fibers. After the fishermen's association changed feed, tremolite asbestos bundles were found in all 4 aliquots of the second feed.
  • The authors compared intake with a 150 mg dose taken from a rat feeding study. At the highest trout value (15,000,000 fibers per 100 g), a person would need to eat 2 portions a day of about 50 kg of rainbow trout to ingest 150 mg of asbestos.
• The authors' conclusion: The authors concluded:
• Bottom-dwelling resident fish were likely contaminated by living in contact with the polluted pond bottom.
• The trout were probably contaminated at the fish farm of origin.
• The data exclude a public health risk, but some asbestos values in fish meat are not negligible.
• Large-scale monitoring of water, food and feed is needed.
• Precautionary indications were given to the Municipality of Milan and to the fishermen's association.
• Limitations the authors state:
  • The feed analysis was qualitative only, recording presence or absence of asbestos.
  • The grass carp's gills could not be analysed because they disintegrated during sample preparation.
  • Analysis of the grass carp's intestine and intestinal contents was difficult because interfering inorganic material could not be removed.
  • The main cause of the asbestos fibers in trout muscle was not identified; it could be water or food sources, including feed.

Topics

Medical terms in this study, explained in our Lexicon: Fluorescence In Situ Hybridization (FISH), Crocidolite, Tremolite.

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