The Ministry of Health does not believe routine blood lead surveillance testing is necessary in the wake of the East Otago drinking water scare.
Waikouaiti River, Otago. Photo: Google Maps
On Wednesday night, residents of Waikouaiti, Karitane and Hawksbury Village were told it was unlikely their exposure to lead through contaminated drinking water had caused long-term health effects.
The East Otago communities were told five weeks ago the Dunedin City Council had first known about the contaminated drinking water in August following a spike in lead levels in a test performed in late July.
Intermittent spikes in the level of lead, the highest almost 40 times the acceptable level, meant a no drink notice was issued on 2 February.
It remained in effect and could be so for months.
Since then several investigations and reviews had been launched and a widespread blood testing campaign carried out.
More than 1500 blood tests carried out in the wake of the revelation showed the number of residents with higher blood-lead levels was not substantially different from what was expected nationally.
Children in the area did show slightly higher blood-lead levels than the national average, but there was not a large amount of data and it was unclear if children's blood-lead levels were higher than should be expected.
The scare did reveal how little was known about lead exposure among communities around New Zealand.
The Dunedin City Council only detected the lead fortuitously while testing for the water supply's corrosivity.
But a Ministry of Health spokesperson said the ministry had no plans to implement further blood-lead surveillance.
"The ministry regularly reviews its public health surveillance portfolio and makes decisions on where available resources are best directed. At this stage, the ministry is not recommending that routine blood lead surveillance testing be carried out on New Zealand communities," the spokesperson said.
"Blood lead levels are already notifiable to public health when they exceed a certain threshold to ensure appropriate follow up. The ministry has just reviewed the notifiable level and on 9 April 2021 the level will be halved to 0.24 micromoles per litre. This is the level the community around Waikouaiti were assessed against.
"Periodic surveillance has been undertaken in the past, such as the biomonitoring survey carried out between 2014 and 2016. This has provided some useful comparison information for this situation. However, there are a number of limitations with this type of survey. For example, young children are not routinely included."
A review into the health response in East Otago was underway and key ministry staff, other health staff and local stakeholders had been interviewed as a result, the spokesperson said.
"The review has been commissioned by, and will report back to the director-general of health at the end of this month.
"It is important to remember that the review is just looking at the health response and not the response or activities undertaken by the water supplier. Recommendations will be shared with the Department of Internal Affairs and Taumata Arowai as they are responsible for building the new regulatory system.
"The ministry expects to report back to the government on the preliminary findings and suggested actions next month."
An internal review of the Dunedin City Council's handling of the scare will then follow.