2012-13 Survey of Australian Wild-Caught Prawns for Analysis of Cadmium and Selenium Project No. 2009/787 1 1 2 Ian Stewart , Jessica Tan , Rob Kenyon , Andreas Kiermeier1, Navreet Malhi1, Amanpreet Sehmbi1, Catherine McLeod1,3 1 South Australian Research and Development Institute 2 CSIRO Wealth from Oceans, Brisbane 3 Seafood Safety Assessment April 2014 This project was conducted by: SARDI Food Safety and Innovation CSIRO Wealth from Oceans GPO Box 397 GPO Box 2583 ADELAIDE BRISBANE 4001 SA 5001 Ph: (07) 3833 5934 Ph: 08 8303-9623 ISBN: 978-1-921563-59-1 Copyright, 2014: The Seafood CRC Company Ltd and the Fisheries Research and Development Corporation. This work is copyright. Except as permitted under the Copyright Act 1968 (Cth), no part of this publication may be reproduced by any process, electronic or otherwise, without the specific written permission of the copyright owners. Neither may information be stored electronically in any form whatsoever without such permission. 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Material presented in these Administrative Reports may later be published in formal peer-reviewed scientific literature. 2 Contents EXECUTIVE SUMMARY ............................................................................................................................ 5 RECOMMENDATIONS: ........................................................................................................................ 6 1.1. GLOSSARY ......................................................................................................................................... 7 1.2. LIST OF ABBREVIATIONS .................................................................................................................. 9 2. AIMS AND BACKGROUND ................................................................................................................. 10 2.1. Cadmium concentrations in prawns from around the world .................................................... 10 2.2. Cadmium in the environment: sources and sinks; uptake into aquatic and marine animals .... 11 2.3 SELENIUM .................................................................................................................................... 14 2.3.1. Sources of selenium, bioavailability .................................................................................... 14 2.3.2. Selenium as an essential micronutrient, selenium toxicity ................................................ 15 2.3.3. Dietary selenium: recommended and maximum intakes ................................................... 15 2.3.4. Selenium in seafoods .......................................................................................................... 16 3. METHODS .......................................................................................................................................... 16 3.1. Australian wild-capture prawn fisheries .................................................................................... 16 3.2. Sample size estimates ................................................................................................................ 18 3.3. Random sampling program. ....................................................................................................... 19 3.3.1. Northern Prawn Fishery: ..................................................................................................... 19 3.3.2. Queensland East Coast Fishery ........................................................................................... 20 3.3.3. South Australian Prawn Fishery .......................................................................................... 22 3.3.4. Western Australia prawn fisheries ...................................................................................... 22 3.4. Random sampling program design ............................................................................................ 23 3.5. Collection of samples from the Australian prawn fisheries ....................................................... 24 3.5.1. South Australian prawn fisheries: ....................................................................................... 24 3.5.2. Western Australia prawn fisheries: ..................................................................................... 24 3.5.3. Northern Prawn Fishery: ..................................................................................................... 24 3.5.4. Queensland east coast prawn fisheries .............................................................................. 25 3.6. Sample collection protocol ........................................................................................................ 25 3.7. Cooking of prawns in the laboratory ......................................................................................... 25 3.8. Sample preparation ................................................................................................................... 26 3.9. Sample analysis for cadmium and selenium .............................................................................. 30 3.9.1. Supplementary tissues analysis and additional quality assurance ..................................... 31 3.10. MOISTURE CONTENT OF PRAWN MUSCLE TISSUES ................................................................ 33 3.11. Statistical analysis of cadmium and selenium in prawns ......................................................... 33 3.12. IDENTIFICATION OF PRAWN SAMPLE SPECIES ........................................................................ 35 3 4. RESULTS ............................................................................................................................................. 36 4.1. PRAWN SAMPLING ..................................................................................................................... 36 4.2. Summary statistics: cadmium and selenium analyses ............................................................... 37 4.3. Cadmium: correlation coefficients and hypothesis tests........................................................... 40 4.3.1. Residuals, logarithmic transformation of data ................................................................... 40 4.3.2. Cadmium vs. prawn fishery ................................................................................................. 40 4.3.3. Cadmium vs. genus and species .......................................................................................... 41 4.3.4. Cadmium and other explanatory variables: prawn weight, season ................................... 44 4.3.5. Regression modelling: cadmium in prawn muscle tissue ................................................... 46 4.4. SELENIUM: correlation coefficients and hypothesis tests ......................................................... 47 4.4.1. Selenium vs. prawn fishery ................................................................................................. 47 4.4.2. Selenium vs. genus and species .......................................................................................... 48 4.4.3. Selenium and other explanatory variables: prawn weight, season .................................... 52 4.4.4. Regression modelling: selenium in prawn muscle tissue ................................................... 53 4.5. SUPPLEMENTARY TISSUES ANALYSIS AND ANALYTICAL QUALITY ASSURANCE ........................ 54 4.5.1. Routine laboratory QA ........................................................................................................ 54 4.5.2. Cadmium supplementary tissues analysis .......................................................................... 55 4.5.3. Selenium supplementary tissues analysis ........................................................................... 57 4.6. ISOLATED PRAWN GUT TUBES AND HEPATOPANCREAS ........................................................... 59 4.6.1. Cadmium in prawn gut tube and hepatopancreas ............................................................