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NHMRC Draft Information Paper: evidence on the effects of lead on human health submission

ID: 
3
Personal Details
First Name: 
Geralyn
Last Name: 
McCarron
Questions
Q1. Is the draft Information Paper presented and written in a manner that is easy to understand?: 

Yes

Q2. Does the draft Information Paper clearly outline how the evidence was reviewed and interpreted by the Lead Working Committee?: 

How it was reviewed- yes. How it was interpreted- no. 

Q3. Is there additional evidence on the health effects in humans of exposure to lead that needs to be considered? : 

First I wish to acknowledge and commend the extensive work involved in the literature search and analysis undertaken by Rebecca Armstrong and the other members of the team commissioned by NHMRC to provide an independent evaluation of the evidence.

 

The draft document states, “The NHMRC Strategic Plan 2013-2015 has identified ‘new and emerging health threats’ (including infectious diseases, environmental hazards, and changes in the human environment) as major health issues for consideration.”  However, given this statement, the limitations of the scope of the draft NHMRC review is concerning.  The purpose of this review is to update NHMRC’s 2009 public statement on lead.  The potential health impacts of lead particularly in children are a matter of concern for medical practitioners and parents alike and I believe that the community expectation for the NHMRC’s review is for a comprehensive review of all current knowledge and wise direction both for further research and the identification and mitigation of risks.

 

One omission of concern is the absence of any reference to papers dealing with the issue of unstable lead (e.g. lead-214, lead-212 or lead-210).  I am uncertain if this is because the topic was excluded from the remit given to the researchers or whether in fact there were no research papers to evaluate.  I would appreciate it if you could inform me which is the case. 

As I am sure you are aware, 98.6% of all today’s Crustal stable lead (i.e. lead-206, lead-207 and lead-208) was derived from nuclear decay, and that such nuclear transformations continue.  Natural and living systems do not typically differentiate between stable and unstable lead isotopes, such that in developing the cancer risk coefficients for the unstable lead isotopes and their progeny, experts employ the same absorption, retention, chemical and biochemical considerations that your paper references wrt lead in general.  Exposure to unstable lead by ingestion or inhalation would bring with it an added raft of potential health impacts, so failure to include it in the remit would possibly leave a significant data gap.

 

I also note with concern that the scope of the review excluded studies conducted in communities living in known lead-contaminated regions.  Mining certainly ticks all the boxes for environmental health threats and changes in the human environment. Extensive mining leases having been issued throughout most states and territories in the past few years. This, together with the philosophical bent towards co-existence with indigenous industries and residents, will inevitably increase the proportion of the Australian public at risk. In light of that, the failure to review the knowledge base relating to lead contaminated regions is difficult to understand.

 

Further, unconventional gas extraction and processing operations (CSG/Shale) cover an even wider landscape and have a much bigger geographical ‘footprint’ than most traditional mining, and thus deserve special consideration on account of the large numbers of families and communities impacted.  Exhumed and re-mobilised stable and unstable lead isotopes are of particular concern if they end up in drinking water and agricultural foods.

 

It is stated in the draft document that “For people living in areas where there are higher amounts of lead in the environment, special management strategies are needed. Health authorities oversee these programs in each state and territory.” This is not reassuring when it is noted in the evaluation of evidence that:  “Surveys every five years of representative samples of children in high and low exposure areas have been recommended: however, these surveys have not been implemented.”  This recommendation was made no less than 12 years ago and underlines the absolute need for a comprehensive national approach to dealing with the health impacts of lead. The Lead Working Committee, derived from academia and state health services throughout Australia are no doubt fully conversant with the obstacles and limitations of implementing piecemeal changes at State level. The NHMRC, as the peak national body for supporting health and medical research, has or ought to have a significant role in providing fully researched knowledge and direction for a national strategy.

 

As it currently stands, the NHMRC reviewers recommend that a national screening program is not warranted.  However I feel it is essential that the background lead level in areas without known contamination is accurately defined by further research. The draft document estimates the background blood level at 5micrograms per decilitre whereas in the USA 5ug/dL is actually on the 97.5th percentile. There have been two research projects undertaken in Australia. The study of pre-schoolers in Sydney in 2006 showed a geometric mean of 2.6ug/dL (presumably this would reflect heritage contamination in a major city from leaded petrol and paint.) In Fremantle in 2005 the geometric mean was 1.83ug/dL.

 

If one does not know with reasonable accuracy what the background level is expected to be, then as a doctor in Australia one would not be alerted to a situation when a remediable source of contamination might be present.  This is particularly important because the EPA-ISA (US EPA 2013) found clear evidence of cognitive function decrements in young children with mean or group blood lead levels measured at various life stages and time periods between 2 and 8ug/dL.  The NTP also reported sufficient evidence of an association of decrements in academic achievement, IQ, cognitive measures, increased inattention disorders and behaviour disorders in children at levels <5ug/dL. The significance of these important finding were questioned by the reviewers in the draft report in view of potential confounding factors such as socioeconomic status, parenting styles etc. For some inexplicable reason the draft recommendation has been made that if a person’s blood level is between zero and 5 micrograms per decilitre, no particular action or treatment is needed.  With respect I would suggest that in view of the major significance to public health if the findings of these two major international studies are ultimately to be confirmed, the more appropriate interim recommendation by the NHMRC might be to promote carefully designed research in the Australian context to eliminate confounding factors. If, as the reviewers state, lead might account for 3-4% variation in IQ, and this is combined with inattention, impulsivity, hyperactivity, and auditory function decrements as reported in both the NTP and EPA-ISA reports, the resulting limitation of achievement potential could have profound negative impacts both at a personal and population level in Australia. One of the significant data gaps (and therefore potential focus for high quality research in Australia) highlighted in the evaluation of evidence report was the vulnerability to health effects of lead exposure in children of differing ages, adults, pregnant women and the elderly.

 

In summary the NHMRC shoulders a heavy responsibility in ensuring that the scope as well as the quality of evidence they present to inform decision making on this significant public health issue is adequate.  In circumstances where it is not, the deficiencies should be clearly articulated with recommendations to address it.  Since the NHMRC is the national body supporting and funding health and medical research as well as being the body advising the Australian people, health professionals and governments, it would be entirely appropriate for the NHMRC in this report to clearly delineate which knowledge gaps exist and recommend the appropriate research.

Q4. Is there additional evidence on the management of exposure to lead in humans in non-endemic areas that needs to be considered? : 

as per Q3

Page reviewed: 19 May, 2015