Activities undertaken to ensure the scientific soundness of advisory materials

All incoming information is questioned as to the credibility of its source and as far as possible, is investigated by seeking the references cited.

For example, from time to time a caller will tell us that their doctor or pathology result claims that the average blood lead level for Australian adults is x. Knowing that there has never been a national study or even a localised blood lead study of any adult (non-occupationally exposed) population in Australia, we request the written evidence for the claim. No such evidence has ever been forthcoming and thus we NEVER quote an average blood lead level for Australian adults though callers continue to ask us for this information. The answer given is, "in the absence of any Australian blood lead survey and knowing that Australia eliminated lead from petrol 7 years after the USA, one can only predict that if Australia was to also introduce compulsory notification about lead hazards of home-buyers and renters and legislative controls of renovation as has been done in the United States, then the low US geometric mean blood lead level for people over the age of 20 years, of 1.75 micrograms/decilitre (1999-2000 published by CDC, 2003) might be able to be attained in Australia at some point in the future."

If the reference cited for a particular piece of information is not web-published, then we proceed to the next stage of contacting an author of a journal article in order to verify or disprove a statement made in the press for instance. A recent example is that a Washington Times article stated:

"Researchers at Johns Hopkins University studied 2,125 adults and found those with high levels of the metals lead or cadmium -- both of which still were well within considered safety limits -- were up to three times more likely to develop PAD [Peripheral Arterial Disease] than those with the lowest blood levels."

Tracing the statement back to the source, we found that the American Heart Association (AHA) had also stated the same over-simplification of the results:

"In a study of 2,125 adults, those with the highest blood concentrations of lead or cadmium were almost three times more likely to develop PAD than those with the lowest levels of the two metals. Yet the highest levels were well within what is currently considered safe levels, said senior author Eliseo Guallar, M.D., DrPH, an assistant professor of epidemiology at the Johns Hopkins University Bloomberg School of Public Health in Baltimore."

We then found that the web-published Abstract of the research by Navas-Acien et al (2004) did not include the range of blood lead levels and the full article was only web-published for subscribers. So we wrote to Professor Eliseo Guallar who kindly sent the full article and the following response:

"Only one of 2125 study subjects exceeded the OSHA limit of 1.93 micromoles/litre PbB & only 35 or 1.6% exceeded the CDC 0.48 micromoles/litre level."

Thus the statement made in The LEAD Group's media release of 14^th June 2004 was:

"Worryingly," says O'Brien, "practically all (98.4%) of the 40+ year old adults in the study had blood lead levels equal to or below the acceptable Australian blood lead level 0.48 micromoles/litre and the average was only 0.10 micromoles/litre."

Not all efforts to question the scientific soundness of advisory materials are so straight forward.

We got our fingers burned when responding to an initiative of the South Australian Dept of Human Services to question the scientific basis of an editorial by Leonie Lloyd-Smith in The Recorder newspaper in Port Pirie on 9/01/03 about the study by Lustberg and Silbergeld entitled "Blood Lead Levels And Mortality".

The editorial reported:

The national co-ordinator of The Lead Group, Elizabeth O’Brien, reported that the study was conducted over a 20-year period, testing over 20,000 people between 30 and 74 years of age.

"Anyone in this group who recorded a blood lead level of 20-29 micrograms per decilitre of blood at the time of testing was followed up over that 20-year period," she said.

"When the survey concluded in 1992, it was discovered that this group was more likely to die earlier, especially from circulatory disease or cancer than adults with less than ten micrograms per decilitre blood lead level."

Ms O’Brien said the study is hugely significant for Australia.

"The likelihood is that an even larger percentage of Australians than Americans, more than 15% of the population, could be at risk of premature death," she said.

"Apart from people exposed to lead in their working environment, such as in Port Pirie’s smelter, lead petrol and paint are the most significant contributors to increased blood lead levels.

"An Australia wide blood lead survey is vital."

Ms O’Brien said the US study shows the common belief that high blood lead levels are only dangerous in childhood is incorrect.

On 27^th March 2003, after having received a copy of the newspaper article from the Lead Advisory Service Australia, South Australian Minister for Health the Honorable Lea Stevens wrote in a letter to Elizabeth O'Brien:

With regard to the "Recorder" article to which you refer, I am advised by expert epidemiologists that the report you promote (Archives of Internal Medicine 2002 162:2443-9) is not sufficiently robust in design to support the position of the LASA in relation to lead poisoning in the wider Port Pirie adult community. Clearly, further evidence on adult community impacts is needed. Health warnings of this nature ought to be considered by members of the expert scientific community, which is in the best position to make recommendations based on an assessment of all relevant information. Although it is important that people at potential risk are provided with adequate information, it is also important that this information is accurate so that the community is not unduly alarmed.

Not wishing to upset the Minister by questioning who these unnamed expert epidemiologists were and where had they managed to have published their views on the robustness in design of the Lustberg and Silbergeld study, we wrote instead to Lustberg and Silbergeld, seeking at the same time, responses to the issue from The LEAD Group's Technical Advisory Board.

The letter from Elizabeth O'Brien to the study authors on 23/5/03 said in part:

It is interesting to ponder whether the Minister's definition of "accurate information" is information which does not alarm the community.

I would like to refute the Minister's claim that your report "is not sufficiently robust in design to support the position of the LASA [Lead Advisory Service Australia] in relation to lead poisoning in the wider Port Pirie adult community". She presumably means your report can't support my statement as reported by the journalist, that "the US study shows the common belief that high blood lead levels are only dangerous in childhood is incorrect."

Professor Ellen Silbergeld sent the following reply on 24/5/03:

Subject: Re: Please respond to criticism of early death research conclusions

There is a great deal of research associating lead exposures with hypertension and death from cardiovascular diseases related to hypertension, such as stroke. Our paper is not novel in that regard. Please consult papers by Schwartz, Pirkle, Hertz-Picciotto, Harlan, and others. Also, the EPA health assessment document on lead draws this same conclusion.

In addition there is a large literature on the effects of lead on kidney function in adults, and on neurocognitive effects in adults.

Thus it does NOT require a rebuttal by me, to defend our paper, which was published in one of the most prestigious journals in the US, and a journal which routinely rejects most of the papers submitted to it.

You may also wish to note our [Nash et al] more recent paper in the Journal of the American Medical Association, in March 2003, which describes hypertension in women exposed to low levels of lead.

Yours, Ellen Silbergeld, Professor, Johns Hopkins University School of Public Health, Baltimore MD USA 21205

Elizabeth again wrote to Professor Silbergeld to thank her for her response and note the presence in our library of some of the supporting documents she had mentioned (by Landrigan et al, Nash et al and Pirkle et al) and our desire to receive any other supporting articles from Professor Silbergeld or members of our Technical Advisory Board. Several Technical Advisory Board members' responses implied that our process for ensuring scientific soundness of advisory materials was adequate and in addition Dr Garth Alperstein from the Board provided our library with a hardcopy of the full text of the Nash et al article. Dr Ben Balzer from the Board stated:

Your claims are not an over reaction and the original press release is in keeping with the international response [eg in the Chicago Tribune]. Please add in the Canfield data as showing that the situation with lead is even worse than Silbergeld indicates.

Thus it was that by the start of this financial year, our activities to ensure the scientific soundness of advisory materials included setting the policy to trust articles published in peer-reviewed journals ahead of statements purportedly made by unnamed "experts". We have systematically added Australian lead experts to our Technical Advisory Board over the years and are happy that constant interchanges to gain their views ensure scientific soundness of advisory materials.

An unmet emerging need in Australia is for well-researched advice on which level of HEPA filtration is adequate or effective in vacuum cleaners, both for the domestic and industrial markets. Previously, we have requested that the Australian Consumer's Association (ACA) test the various HEPA vacs on the market to determine which one has the optimal HEPA filter grade, filter area, placement of filter, motor power rating and power head in order to remove the maximum amount possible of lead dust from a carpeted room. The other criterion we requested was whether the vacuum cleaner can be emptied without exposing the operator to dust. ACA's policy however is only to test all those vacuum cleaners against one another that are in the same price bracket (eg less than $750 - "Not do dusty" in Choice Magazine, 1997) and to test which vacuum cleaner retains the most dust without also testing which vacuum cleaner takes up the most dust in the first place. ACA has not to our knowledge tested how much of the finest particulate size dust is taken up or retained by any vacuum cleaner. Yet this is precisely the kind of information that someone who has been to the store and come back with umpteen brochures on HEPA vacs with various ratings such as S-class or H5 or H13 filters wants to know. HEPA vacs now sell for as little as $120 so clients want to know if this is an adequate HEPA vac for lead dust control.

Previously also, WorkCover Authority NSW tested industrial HEPA vacs at their Londonderry lab but their list is so old (1998) now as to be practically useless for comparing vacuum cleaners that are actually in the market place. Jason Bawden Smith of JBS Environmental Services and Technologies undertook a comparison of 3 HEPA vacs (all he could afford) and declared the NILFISK GD930S2 to be the best of the three on all the relevant lead-dust pick-up and retention at low particle size criteria and the minimal dust exposure while emptying the machine criterion. However, clients report that although for instance David Jones and Myer sell other NILFISK HEPA vacs, they no longer stock that particular model so LASA clients are left with inadequate information on which to base a purchase decision. We would appreciate advice from our funding agencies on dealing with this problem. The best advice offered by the Asthma Foundation for instance, is to take up carpets and we certainly offer this advice in regard to lead dust but not every householder is going to be able or willing to take up carpet so we still need advice on which HEPA vac is most efficient or at least adequate to the task of reducing lead hazards.