A critique of some of those involved in the dispute about Rosebery

By Kay Seltitzas and Isla MacGregor, Toxic Heavy Metals Taskforce Tasmania (THMTT

Dr Roscoe Taylor:  In denial about complex mixtures?

[Ed’s note: Dr Roscoe Taylor is Director of Health, Tasmania. In a press release in April 2010 he stated there was no evidence of heavy metal poisoning in 10 current and former residents of Rosebery : www.tasmaniantimes.com.au/index.php/pr-article/experts-rule-out-heavy-metal-poisoning
-at-rosebery   ]

An article by Dr Taylor in an Australian Government document titled: The Need To Consider Complex Mixtures, outlines issues relating to synergistic action of the components of “complex mixtures” of toxic chemicals.

Roscoe Taylor (then working with the Qld Dept of Health) and Andrew Langley (also from the Qld Dept of Health) produced a paper for the Commonwealth Dept of Health .

The paper was entitled: Exposure Scenarios and Exposure Settings.

It is a rather complicated Guide concerning contaminated sites and risk assessments.

“Exposure scenario” is broadly defined as a set of facts, assumptions and inferences about how exposure takes place that aids the exposure assessor in evaluating, estimating or quantifying exposures. However, there are two specific references.

Page 12 (para 2)

'Complex mixtures of contaminants are beyond the scope of this paper, but the possibility of additive and/or synergistic effects on health needs to be considered (Pollack 1996).'

Page 15 (last paragraph)

'…..the implications of complex mixtures for health risk assessment may need further development in future versions of the Guidelines.'

In the References section at the end of the Guide, there is no listing of this particular reference. This is despite the fact that the specific paper is referred to in the Guidelines, and it is proper scientific procedure to correctly source all references used in a scientific paper.

The paper by John Pollack, published in 1996, is entitled “The Problems Posed by Xenobiotics (chemicals foreign to life) in Chemical Mixtures and the Role of Mixed Function Oxidases”.

At the time John Pollack was at Sydney University Medical School. In Paragraph 3 of this paper, John Pollack states:

'Chemical mixtures may produce additive, synergistic or also antagonistic effects due to the induction and action of mixed Function Oxidases. Hence it is essential to consider the overall exposure to chemicals in evaluating the effects of chemical mixtures on public health and the ecology.'

This research exposes a fundamental and crucial problem (by omission) for Dr Taylor concerning his attitude to 'Public Health Investigations of heavy metal contamination in Rosebery'.

Clearly, Dr Roscoe Taylor has been well aware for many years of the need to take into account the combined effect of the various toxic chemicals in the mixture of heavy metals and metalloids in the Rosebery environment.

Publicly, he has steadfastly adhered to the outmoded concept of “single” chemical “safe health limits” of the heavy metals when considering the health of the Rosebery residents.

Roscoe Taylor appears to have “conveniently” forgotten his own important (published) findings!!

His adherence to this outmoded viewpoint is unacceptable for the functions of a Director of Health, particularly given his major role in the Rosebery investigations.