After years of feeding her family with homegrown vegetables, Ravensbourne resident Ruth Bayne is questioning whether she has been doing the right thing.
It was with horror she read in the Otago Daily Times last week that tests on vegetables from several Ravensbourne gardens recorded fluoride levels many times the recommended safe maximum as a result of emissions from the Ravensdown Fertiliser works.
“I have sat down to eat with a feeling of satisfaction and pride when using vegies and fruit that I have grown myself, and I have always felt that this was a healthy choice for my family,” Ms Bayne said.
Food standard guidelines for water put the maximum fluoride content at 1.5mg per litre, while regulations covering vegetables set an upper level of 10 parts per million. The maximum daily recommended intake from all sources is 6mg.
Tests on vegetables in Ravensbourne have regularly found levels 10 times as high.
Ravensdown has confirmed high emission levels had damaged some pine trees in the area.
“Sure I have seen the damaged pine trees on Ravensbourne Rd, but somewhat naively had not considered that there may be any other impact on my life,” Ms Bayne said.
Ravensdown had a responsibility to ensure it did not have a negative impact on the environment or people who lived nearby, she said.
Ravensdown has to renew its air discharge consents next year and has closed for a month to install a $2.5 million scrubber to reduce fluoride emissions.
Public Health South health protection officer Andrew Shand said he was working with Ravensdown on putting appropriate monitoring in place.
The New Zealand Food Safety Authority was also working on some health guidelines for the area, he said.
The main health risk of overexposure to fluoride was to bones.
A public health consultant employed by Ravensdown has reported that the emissions are not harmful but recommended seasonal monitoring of a wider range of vegetables.
Ravensdown is required by its consents to monitor air quality in Ravensbourne and check vegetation every two years. Vegetation monitoring in November 2001 confirmed damage to trees and monitoring was expanded to include pine needles, vegetables and pasture.
However, Ravensbourne residents’ gardens have only been tested on request.
Ravensdown works manager Craig Hendry said the company monitored ambient atmospheric fluoride levels at Ravensbourne Rd, Adderley Tce and Matai St.
“Some results at the Ravensbourne Rd site did exceed the guidelines on occasions over the last two years, but now are below the guidelines,” he said.
Results at Adderley Tce and Matai St sites were clearly below air quality guidelines.
Ravensdown had also taken samples of open leaf vegetables within the Ravensbourne area over the six months and sought advice from a public health expert, who confirmed the vegetables were safe to eat as part of a normal diet. It also planned to do a wider range of vegetable monitoring, beginning this month.
The company expected the new scrubber to substantially reduce fluoride levels and would install further control measures if necessary.