Activity concentrations of (137)Caesium and (210)Polonium in seafood from fishing regions of New Zealand and the dose assessment for seafood consumers.
A study was undertaken to determine activity concentrations for (134)Caesium, (137)Caesium and (210)Polonium in New Zealand seafood, and establish if activity concentrations varied with respect to species/ecological niche and coastal region. Thirty seafood samples were obtained from six fishing regions of New Zealand along with a further six samples of two commercially important species (hoki and arrow squid) with well-defined fisheries. (134)Caesium was not detected in any sample. (137)Caesium was detected in 47% of samples, predominantly in pelagic fish species, with most activities at a trace level. Detections of (137)Caesium were evenly distributed across all regions. Activity concentrations were consistent with those expected from the oceanic inventory representing residual fallout from global nuclear testing. (210)Polonium was detected above the minimum detectable concentration in 33 (92%) of the analysed samples. Molluscs displayed significantly elevated activity concentrations relative to all other species groups. No significant regional variation in activity concentrations were determined. Two dose assessment models for high seafood consumers were undertaken. Dose contribution from (137)Caesium was minimal and far below the dose exemption limit of 1 mSv/year. Exposure to (210)Polonium was significant in high seafood consumers at 0.44-0.77 mSv/year (5th-95th percentile). (137)Caesium is concluded to be a valuable sentinel radionuclide for monitoring anthropogenic releases, such as global fallout and reactor releases, in the marine environment. (210)Polonium is of importance as a natural radionuclide sentinel due to its high contribution to dietary committed dose in seafood consumers.
Ministry for Primary Industries, PO Box 2526, Wellington 6140, New Zealand; University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand. Electronic address: andrew.pearson@mpi.govt.nz.
Andrew J
AJ
Pearson
University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand. Electronic address: sally.gaw@canterbury.ac.nz.
Sally
S
Gaw
Institute of Environmental Science & Research Ltd, PO Box 29-181, Christchurch 8540, New Zealand. Electronic address: Nikolaus.Hermanspahn@esr.cri.nz.
Nikolaus
N
Hermanspahn
University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand. Electronic address: chris.glover@canterbury.ac.nz.
Chris N
CN
Glover
D002588:Cesium Radioisotopes / Q000032:analysis*; D005507:Food Contamination, Radioactive / Q000032:analysis*; D006801:Humans; D009520:New Zealand; D011059:Polonium / Q000032:analysis*; D011829:Radiation Dosage; D000069079:Radiation Exposure; D011834:Radiation Monitoring; D018570:Risk Assessment; D017747:Seafood / Q000032:analysis*; D014875:Water Pollutants, Radioactive / Q000032:analysis*
D002588:Cesium Radioisotopes; D014875:Water Pollutants, Radioactive; D011059:Polonium
Caesium; Dietary radionuclide activity; New Zealand; Polonium; Risk assessment; Seafood