The New Zealand Food Safety Authority is playing down concerns raised by the Green Party over mercury and arsenic levels in fish sold in Dunedin.
Greens' food safety spokeswoman Sue Kedgley said yesterday new data from the authority suggested "swimming with sharks could be safer than eating some varieties of fish".
She highlighted part of the authority's first-quarter results for its total diet study that showed mercury and arsenic levels in fish from Auckland, Christchurch, Dunedin and Napier.
The results showed battered fish bought in Dunedin contained 0.476mg/kg of mercury (Napier 0.16mg/kg), 0.205mg/kg of methylmercury (Christchurch 0.031mg/kg) and 2.937mg/kg of arsenic (Auckland 0.313mg/kg).
"New Zealanders deserve answers as to why battered fish samples tested in Auckland and Dunedin were significantly higher in mercury than in other areas and why fresh fish from Dunedin was found to have twice the level of arsenic of fish on sale in Auckland," Ms Kedgley said in a statement.
Asked if there was a problem in Dunedin with the level of mercury and arsenic in fish, authority senior programme manager Cherie Flynn said: "No."
Mrs Flynn said samples from two outlets on one day in each centre were tested twice a year to provide a "snapshot" and show "trends over time".
"Because of the small number of samples we are taking, it's not really appropriate to compare among regions, which is why we don't particularly make a point of it."
Ms Flynn said heavy metals like mercury and arsenic occurred naturally in New Zealand because of its volcanic nature.
Health impacts would occur only with a high intake of the toxic forms of the metals, such as methylmercury, over a long period.
"If you were eating large quantities at that level [of the Dunedin sample] constantly, not just over a week but over many, many years, you would be up at, or close to, exceeding the recommended safe level."
In a press release, Ms Flynn said tests on 120 commonly eaten, locally-produced foods showed "the average New Zealand diet presents no chemical residue food safety concerns".
