Lead update - from Medical Officer of Health Dr Susan Jack

Including testing for past and part-time residents, and interpreting blood lead levels

We acknowledge that there has been considerable anxiety in the community since the advice was given last week to not drink the water in Waikouaiti, Karitane and Hawksbury while we explore potential contamination for lead. We have seen a very strong response to the free blood testing clinics in Waikouaiti and Karitane.

To date around 1340 people have undertaken blood tests through the clinics, and a number of others have undergone tests via their GP.

We understand how important it has been for members of the community to learn whether they may have been exposed to lead, and any impact this may have had for them and their families. Further, in terms of the work we need to do, this outstanding response will provide us with excellent information to analyse and consider whether there is evidence of long-term exposure to lead as a result of potential contamination of the water supply.

While we have had an adequate response to undertake the analysis we need, people are understandably interested in their personal lead exposure. If people have not been able to attend the free clinics this week, they can organise testing through their own GP which will also be free for next week (until Friday 19 February). 

Thank you to everyone who has come forward to have a blood test and help with this investigation. And sincere thanks to everyone who has assisted with these clinics, including WellSouth PHO, Southern Community Labs, all the nurses and phlebotomists, the Waikouaiti Coast Community Board and Puketeraki marae for helping with the venues, logistics and getting messages to the communities.

Results are still coming through and it is too early to draw any conclusions from the results we are seeing. Most people have detectable but very low levels of lead as we would expect in any community. There are a small number of more elevated results coming through as well; again this is not unexpected. For each of these cases, we are providing follow up advice and any care that may be needed. This will include carrying out an assessment of any other sources of potential lead exposure, such as old paint, or through other occupations or pastimes. As previously advised, we will analyse the results and share these at a collective level with the community.

Testing for past or part-time residents

There have been a number of queries from those who have recently lived in one of the affected communities, or who stay there part-time. The risk to people who do not permanently live or work in Waikouaiti, Karitane or Hawksbury is low, and we are not calling for people in these groups to have a test, however we understand they may wish to.

We have undertaken to enable free testing for the following groups:

• people who have lived or worked for at least one month in Waikouaiti, Karitane or Hawksbury over the past 12 months
• pregnant women and formula fed babies who have spent at least two weeks in these towns over the past 12 months.

You will need to contact your GP to arrange a test. The funding mechanism for this is being currently being worked on. If you are charged for a test, please keep your receipt. We also ask that you contact Public Health South so that we can send you a questionnaire – the same questionnaire people have been asked to fill out at the testing centres in Waikouaiti and Karitane. Please email publichealth@southerndhb.govt.nz

We ask that the tests are carried out over the next week (by Friday 19 February).

A note on interpreting blood lead level readings

We have had questions regarding interpreting the readings, asking why there are different blood lead levels even within families with similar exposure, and whether we need to be concerned about levels below 0.24 umol/L.

There can be a range of reasons for differences in blood lead levels, including hydration at the time of the test, and individual metabolic processes.

However, generally, the younger and smaller you are, the more likely a similar exposure to lead will result in a higher concentration in your blood. This is because, relative to one’s size, the amount of lead you have absorbed is proportionately greater.

This is why we are particularly concerned to prevent pregnant women, babies and children from being exposed to lead – and an important reason why the no-drink notice was issued as a precaution until we understood the unusual readings in the Waikouaiti water supply.

Those with results below 0.24 umol/L do not need to be concerned. This is a very low level of concentration. It is set low, because there is no known safe level of lead in blood, but it is expected that all people in the developed world will have had some exposure to lead.

Children’s blood lead levels may reduce over time, as they grow (so their ongoing exposure becomes proportionately less in terms of their body size) and they slowly excrete lead.

Please note the 0.24 umol/L threshold we are using is in line with international guidance. The current guidance in New Zealand is that results showing levels of 0.48 umol/L should be notified to the Medical Officer of Health. However, this notifiable level is due to be reduced in New Zealand this year. We have asked to be notified at the new, lower level for this investigation.