Download AEBR 335 Chemical contaminants in kaimoana in New Zealand’s coastal environments

MPI has responded to concerns raised by Te Tau Ihu Fisheries Forum about the possibility of ongoing environmental pollution impacts on kaimoana in the Waimea Estuary.
This research report was aimed at assessing the risks posed by past and present land-based chemical pollutants led by mātauranga Māori of kaimoana in in the estuary in combination with a review of western knowledge about the toxicology of synthetic chemical compounds.
Historically, the Waimea Estuary has been the receiving environment for a wide range of persistent pesticide chemicals, including DDT and its breakdown products (DDX), and also dieldrin and lindane, associated with the operation of the Fruitgrowers Chemical Company in Māpua from 1931 to 1988.
Samples of seafloor sediments, tītiko (mud-snails), tuangi (cockles), kūtai (mussels), and pātiki (flounder) were analysed for a wide range of heavy metals and organochlorine pesticides and residues (OCPs).
Results showed DDX levels in tītiko collected from closest to the former FCC site to be the highest, and at levels that are unsafe for human consumption, however, concentrations in tītiko further away had safe levels.
All tuangi, kūtai and pātiki samples had safe or undetectable levels of DDX.
Overall, the results of this study indicate that OCP residues persist at relatively low levels in some marine organisms and sediments in the immediate vicinity of the chemical plant in Mapua but are not of major concern for human consumption.
The low levels of pesticide residues are unlikely to explain localised mortality events in tuangi beds in the Waimea Estuary.