Select high value Australian finfish : residues and contaminants of importance to public health and market access

Consumers worldwide expect access to safe seafood products regardless of its origin. Each country judges imported products against its own residue and contaminant standards coupled with differing testing capability, sample collection, sample preparation and data reporting strategies. Australian exporters of finfish whether it is farmed or wild capture origin have to negotiate their way through a series of regulatory hurdles and gate keeper organisations in each market they wish to target. Detention or destruction of product at border control stations can occur if importing country standards are not met. This thesis outlines five separate case studies of how this has been successfully done with select high value Australian finfish species by tackling different issues of public health and market access concern. The General Introduction provides an overview of the researched finfish species and introduces the key residues and contaminants addressed in this thesis. Chapter two introduces dioxins and PCBs data for single season grow- out farmed Australian Southern Bluefin Tuna (Thunnus maccoyii) SBT. The mean concentration of dioxins found was 0.53 pg WHO TEQ/g (range 0.2-1.1) while the mean concentration of PCBs found was 32 µg/kg (range 13-55). Chapter three more comprehensively addresses single season grow-out farmed Australian SBT not just for dioxins and PCBs, but pesticides, antibiotics and metallic elements. Japanese port of entry official sampling methods are discussed. The mean concentration of dioxins in wild SBT was 0.14 pg TEQ/g (range 0.07-0.32) and in farmed SBT was 0.2 pg TEQ/g (range 0.06-0.8). The mean concentration of the sum of dioxins and dioxin-like PCBs in wild SBT was 0.27 pg TEQ/g (range 0.18-0.45) and in farmed SBT was 1 pg TEQ/g (range 0.2-4). Mean PCB concentration in wild SBT was 0.13 pg TEQ/g (range 0.1-0.21) and in farmed SBT was 0.8 pg TEQ/g (range 0.17-3.5). Mean PCB total concentration in wild SBT was 0.47 µg/kg (range 0.4-0.6) and in farmed SBT was 6.6 µg/kg (range 0.8-41). The mean concentration of total mercury in wild SBT was 0.34 mg/kg (range 0.28-0.42) and in farmed SBT was 0.31 mg/kg (range 0.18-0.45). There were no detectable levels of any pesticide or antimicrobial compounds in any sample of SBT. Chapter four introduces farmed Yellowtail Kingfish (Seriola lalandi) YTKF and Mulloway (Argyrosomus hololepidotus). Data on dioxins, PCBs, pesticides, veterinary medicines and metallic elements are presented and discussed in terms of Australia, Japanese and European regulatory standards. The mean concentration of dioxins in YTKF was 0.6 pg TEQ/g (range 0.22-0.8) and in Mulloway was 0.16 pg TEQ/g (range 0.16-0.16). The mean concentration of dioxins and dioxin-like PCBs in the YTKF was 2.6 pg TEQ/g (range 1.4-3.5), while the Mulloway had a mean concentration of 0.67 pg TEQ/g (range 0.57-0.76). The mean concentration of PCBs in YTKF was 21 µg/kg (range 8.6-29) and in Mulloway was 5.4 µg/kg (mean 4.7-6). The mean concentration of dioxin-like PCBs in YTKF was 2.1 pg TEQ/g (range 1.2-2.8) and in Mulloway was 0.51 pg TEQ/g (Range 0.41-0.61). The mean mercury concentration in YTKF was 0.03 mg/kg (range 0.02-0.05) and in Mulloway it was 0.023 mg/kg (range 0.02-0.04). There were no detectable levels of any pesticide or antimicrobial compounds in any sample of YTKF or Mulloway. Chapter five addresses total mercury content in wild Australian SBT. Results are discussed in terms of international regulatory standards and compared with bluefin tunas available in the Japanese market. Mean total mercury concentration was 0.43 mg/kg (range 0.24-0.72). A dietary exposure assessment found that pregnant women and women planning pregnancy could consume one 150 g serving per week, the rest of Australian general adult population could consume up to three 150 g servings per week and children (up to 6 years) could consume one 75 g serving of Australian wild SBT per week. Chapter six investigates total mercury content of canned wild Skipjack Tuna (Katsuwonus pelamis) products. The mean total mercury content found in 2005 was 0.10 mg/kg (range 0.07-0.15) and in 2006 was 0.09 mg/kg (range 0.02-0.22). Testing of condiment canning ingredients identified low levels of mercury in black pepper and cinnamon. A dietary exposure assessment found that pregnant women and women planning pregnancy could consume seven 150 g servings per week, while the rest of the Australian adult general population could consume up to 14 150 g servings per week and children (up to 6 years) could consume eight 75 g servings of these canned tuna products per week. The use of fixed body weight values in exposure assessments may bias results when compared to actual current body weight values of the Australian population. These issues are discussed in conjunction with the inability of consumers to readily identify low mercury content tuna species from back of packaging labelling. Chapter seven describes the causes of detentions and rejections of Australian seafood products in international trade. On a numerically basis, cadmium in Australian crustaceans is ranked the highest notification category. However, caution is urged when assessing these lists without access to qualifying information on frequency of testing, number of tests undertaken, sampling methodology, laboratory analytical techniques and reporting basis. Standards in each notification instance are compared between the importing country and those in Australia. Fish names are discussed and their application to identification of product in trade is highlighted. The General Discussion summarises outcomes of research covered in this thesis and identifies future product integrity research needs and priorities for the Australian seafood industry to meet current and future market access needs.