Long-term exposure to lead from water in Waikouaiti area unlikely: Medical Officer of Health

People in the Waikouaiti, Karitane and Hawksbury Village communities generally have blood lead levels below notifiable levels and in line with national data, and long-term exposure to lead from the water supply seems unlikely.

Public Health South is still advising residents to not drink the water while the investigation into the cause of the elevated lead readings is ongoing.

The results from blood testing of the community were shared at a public meeting in Waikouaiti on Wednesday, 10 March. The tests of around 1500 residents followed advice to not drink the water in the area as a precaution, after intermittent elevated lead levels were detected during monitoring of the water supply.

By not drinking the water, the risk of acute exposure to lead was removed. The blood tests aimed to explore if there had been any evidence of long-term exposure to lead.

The results were compared with findings from a national study carried out by researchers at Massey University from 2014-16. This provides the only recent baseline study in New Zealand.

Key findings are:

• No one had a blood lead level that caused acute harm
• Very few blood lead levels were above the new, lower threshold for notification (0.24 μmol/L)
• Blood lead levels in adults and young people aged 10-17 were in line with baseline study
• Blood lead levels in children aged 5-9 years were slightly higher than baseline study. The reason for this is not certain. While the water supply cannot be ruled out, information suggests other environmental reasons including seasonality may be more important.
• The national study did not include children under the age of 5, so no comparison is possible for that age group.
• There was no difference able to be detected for those who only drank the local water supply compared with those who did not, in either children or adults (but very small sample size, especially for children, and some missing data)
• There was no difference in blood lead levels based on where in the townships residents live
• There were two results for children and 36 for adults above the notifiable levels. Assessments found alternative explanations for these lead levels and health officials are providing advice to these individuals.

Southern DHB Medical Officer of Health Dr Susan Jack says that we expect to see low but detectable levels of lead in our communities due to a range of lifestyle and environmental factors. She notes however that lead levels among children are higher than in the baseline study, there were a small number of individuals with lead higher than notifiable levels, and overall New Zealand levels are higher than those reported in the United States.

The findings suggest it is unlikely the communities have experienced long-term exposure to lead through the water supply.

“While lead levels have reduced dramatically in New Zealand over the past generation, the results from the community does shine a light on lead levels in New Zealand, and draws attention to the need to be working to reduce our exposure to lead.”

Her advice includes to be careful when scraping paint in old houses, avoid drinking roof water that may have lead fixtures like lead-head nails, flush your taps every morning, wash your hands and wash dummies and toys frequently – especially if used outside.

Dr Jack also paid tribute to the community, for whom the reports of elevated lead levels in the water supply were understandably worrying.

“We had an incredible response to being tested. While people individually wanted to know whether they had experienced any affects from lead, it was only through this collective response that we could gain the information to understand if this has been an issue for the community as a whole. Your action has enabled this and we – and all your neighbours – are very grateful.”

Anyone with health concerns about their possible exposure to lead is encouraged to discuss this with their GP, Dr Jack says.