In 2021 the small communities of Waikouaiti, Karitane and
Hawkesbury just north of Dunedin had several detections of
high lead levels in drinking water – leading to a
coordinated public health response involving Dunedin City
Council (DCC), the Ministry of Health, Public Health South
(Southern DHB), and ESR.
Now, a review of this
response by a team that includes ESR toxicologist Dr Belinda
Cridge is being published as a paper for the recent Water NZ
conference (18-20 October), ahead of International Lead
Poisoning Prevention Week (23-29 October). The review
illustrates the larger potential issue of lead exposure from
drinking water due to corrosion of lead plumbing fixtures in
Aotearoa New Zealand. One of the key outcomes was to
recommend that people flush a cup of water from household
taps first thing in the morning before drinking or cooking
with it.
Dunedin City Council had previously detected
several spikes in lead levels at multiple sites, while doing
regular testing in these communities. On 29 January 2021,
they detected lead within the raw water reservoir coming
into the drinking water plant and issued a “Do Not
Drink” notice. A public health response was launched to
investigate the source of lead found in the water and to
determine the extent of lead exposure in the community
through blood screening. Dr Cridge says ESR’s role was to
“help figure out what the potential risk of lead exposure
to the community was,” and to support the council and
public health unit in their efforts.
No amount of lead
exposure has been deemed safe, and it is regarded as a
toxin. Children and babies are most vulnerable to lead
exposure because they absorb a greater amount of lead into
their bodies. “We need to be particularly careful with
young children. Their brains are still developing so
they’re quire sensitive to the effects of lead, and with
long-term lead exposure, we see neurological changes like a
decrease in IQ,” explains Dr Cridge. Lead exposure in
adults can cause high blood pressure and
hypertension.
After an exhaustive six-month
investigation in Waikouaiti, the “Do Not Drink” notice
was removed. At that point, it was determined that there was
no contamination of the main drinking water supply. “There
hadn’t been any accumulation of lead in the population,”
says Dr Cridge, and people who had drunk the contaminated
water did not have higher blood lead levels than those who
had not drunk it. The investigation indicated that the
source of the high lead levels was corrosion of
lead-containing plumbing, which caused lead to leach into
the water.
Dr Cridge says that this incident
highlights a larger potential issue relevant for the whole
country: “We put a lot of work and time into this
investigation in Waikouaiti, but this happens everywhere.
The explanation we came down to is that water is slightly
corrosive and there was corrosion in the plumbing materials.
It could happen in any town.” Lead pipes and fittings are
often present in the infrastructure of homes and buildings
without people knowing about them. And many towns in
Aotearoa New Zealand have water that is slightly corrosive,
so when it sits in the pipes for a long time, the water
begins to accumulate lead.
Luckily, the solution to
this issue is relatively simple, and that is to flush your
taps if the water has been sitting in the pipes for a while.
“For most people that means when you get up in the
morning, you should run about a cup full of water through
your tap before using water for cooking or drinking,”
explains Dr Cridge. “By doing that you bring in freshwater
from the pipe and the street rather than drinking water
that’s been sitting in contact with the household plumbing.
We know that the main water supply is compliant, as long as
your supplier is compliant with the drinking water
standards.”
This International Lead Poisoning
Prevention Week (23-29 October), ESR aims to amplify this
message throughout Aotearoa New Zealand. Flushing your taps
is the best way to make sure you’re drinking water that is
healthy and safe for everyone. For more information, check
ESR’s handy Q&A about how to flush your taps: Frequently
asked questions about lead in drinking water |
ESR.
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