Is the likelihood of benzene being the cause of a particular multiple myeloma dependent upon the extent of the exposure? --- Yes.
So to form the view that it was a probable cause of the plaintiff's multiple myeloma it would be necessary for you to have some view as to the actual extent of exposure to benzene, wouldn't it? --- Can I qualify my answer before I answer it?
Can you answer it and then qualify it after that? --- Okay.
The answer is yes but the human population shows a variable response to the effects of chemicals. One part per million as an exposure standard protects nearly all workers and not all workers and therefore, whether it's one part per million or a lower number would be debatable in an individual case.
In the epidemiological papers about multiple myeloma there is frequent reference to a latency period between the time of exposure or the beginning of the time of exposure and the development of the multiple myeloma? --- Yes.
That latency period is frequently expressed as being something in the region of 20 years? --- I accept your observation but that's a medical issue I don't have any expertise to comment on.
If you are not taking into account the existence of the latency period how can you answer his Honour's question when you don't know when the plasmacytoma first began? --- In at least one of the papers I read a shorter latency period was suggested.
Were you taking into account a shorter latency period when you answered his Honour's question that in this case it was probable that the exposure to benzene played a role in the plaintiff's plasmacytoma? --- No.
Then how could you answer it as probable without taking into account a latency period? --- When you said "a latency period" I believe you meant 20 years. I believe from my reading the latency period may not be 20 years. I think it may be some other number.
You said you didn't take into account a latency period. You were limiting yourself in that response to 20 years, were you? --- No. If it's 20 years I would say not. I don't think 20 years is an appropriate latency period. Again, that's something I can't answer. It's just an opinion I am giving.
If you can't answer a question as to what the latency period is how can you say that it is more probable than not that exposure less than six years before the discovery of the plasmacytoma was a cause of that? --- Because I don't believe that you can say the latency is any number. Pardon? --- I don't believe you can say the latency for any particular cancer has any particular number.
People can develop multiple myeloma or plasmacytoma without any exposure to benzene, can't they? --- Yes.
Have you got any reason for saying that this plasmacytoma did not develop independently of exposure to benzene? --- No.
Do you have any information as to the rate of growth of plasmacytoma tumours? --- No.
In giving your answer to his Honour about it being more probable than not would it not be important to know what the size of the tumour was at the time of discovery and what its rate of growth was? --- Again, they are medical questions.
So that your answer that it's more probable than not does significantly depend on medical questions which are not in your expertise? --- That's correct.
How then can you say it is more probable than not when you don't have the expertise that allows you to answer the question? --- In the reading of the papers for this case I was not of the view that the latency of the disease was any particular number.
You also didn't have any regard to the rate of growth or the size of the tumour. That's a medical question? --- (The witness nodded).
Your answer depends on both your expertise and knowledge of the medicine relating to plasmacytoma, doesn't it? --- To multiple myeloma. The plasmacytoma was what was first diagnosed? --- But it grew no - - And at that stage there was no multiple myeloma. You understand that? --- Yes.
Well, there may not have been.
MR GORTON: No identified multiple myeloma? --- Yes.
It is essential for a determination as to whether there was a cause from exposure at Palmone Shoes to form a clear view as to when the plasmacytoma commenced to be? --- Yes.
And whether it commenced to be before or after 2002 is something that depends on medical opinion rather than toxicological opinion, isn't it? --- Yes.
So that you are not in a position to express the view that it is more probable than not within your area of expertise, are you?
[There was then discussion about the limits of the witnesses expertise.]
[Previous question read out by his Honour.]
THE WITNESS: I have formed my opinion based on my reading of the literature which did not indicate to me, necessarily, that there was a fixed latency period of 20 years and therefore, my opinion is based on the possibility that this condition could have grown in less time than the time you are specifying.
HIS HONOUR: I do hesitate to ask more questions but I do have a couple more. As a toxicologist you have already told us your discipline often requires you to study epidemiology and the works of epidemiologists? --- Yes.
Which is a fancy way of saying looking at the statistical analyses of the incidence of medical conditions? --- Yes.
Are you able to say from your researches how much more likely the incidence of multiple myeloma is after exposure to benzene as compared to its natural incidence within the normal population? --- No.