An Australian study of five different seafoods has found traces of PVC in every sample tested, as well as other plastics. The PVC was identified using benzene as a marker following a Pyrolysis Gas Chromatography Mass Spectrometry test process. Together with technical experts from the US Vinyl Institute, we are examining if this is an appropriate marker and test methodology.  

Researchers bought oysters, prawns, squid, crabs and sardines from a market in Australia and analysed them using a newly developed method that identifies and measures five different plastic types simultaneously.

The study – by the University of Exeter and the University of Queensland – found plastic levels of 0.04 milligrams (mg) per gram of tissue in squid, 0.07mg in prawns, 0.1mg in oysters, 0.3mg in crabs and 2.9mg in sardines.

"Considering an average serving, a seafood eater could be exposed to approximately 0.7mg of plastic when ingesting an average serving of oysters or squid, and up to 30mg of plastic when eating sardines, respectively," said lead author Francisca Ribeiro, a QUEX Institute PhD student. "For comparison, 30mg is the average weight of a grain of rice.

The findings showed that the amount of plastics present varies greatly among species with PVC particularly noticeable in prawns, oysters and crabs, but present in all species. The researchers noted, however, that there were differences between individuals of the same species. The numbers of each specie tested were very small (5 or 10).

The experimental test method involved treating edible seafood tissues with chemicals to dissolve the plastics present in the samples. The resulting solution was then analysed using "a highly sensitive technique" called Pyrolysis Gas Chromatography Mass Spectrometry which identifies the different kinds of plastic in the sample at the same time, based on presumed markers for each polymer. Benzene was selected as the indicator compound for PVC because of its high peak intensity and sensitivity.

The plastic found in highest concentrations was polyethylene.

The paper, published in the journal Environmental Science & Technology, is entitled: "Quantitative Analysis of Selected Plastics in High-Commercial-Value Australian Seafood by Pyrolysis Gas Chromatography Mass Spectrometry." https://pubs.acs.org/doi/pdf/10.1021/acs.est.0c02337

Source: https://www.exeter.ac.uk 12 August 2020