Moolgavkar: Environmental exposure risks for Libby overestimated
In an attempt to discredit the testimonies of prosecutorial expert witnesses, Dr. Saresh Moolgavkar, an epidemiologist and witness for the defense, suggested Thursday afternoon that the Environmental Protection Agency had overestimated the environmental exposure risks for the community of Libby, Mont.
“There is … no evidence of an increased risk at Libby from environmental exposure,” he said.
In direct examination under defense attorney David Bernick, Moolgavkar explained that he had analyzed both the findings of Dr. Aubrey Miller and Dr. James E. Lockey in 2008 and subsequently found oversights in both their work.
Moolgavkar said that the techniques of Miller, who found an environmental exposure risk of 1 in 10,000 for Lincoln County, did not allow for data to be as precise as one would get using an epidemiological study.
Citing a decades-long mortality study done by the Agency of Toxic Substances and Disease Registry, Moolgavkar said, “A risk of 1 in 10,000 could never be observed in this kind of epidemiological study.”
Moolgavkar also argued that Lockey’s pleural plaque threshold, or the minimum amount of asbestos exposure needed for one to be at risk for that disease, was underestimated. The witness cited flaws in data analysis and Lockey’s own admission that he may have underestimated due to outside, independent risk factors not related with asbestos.
“If a man smokes 40 cigarettes a day for 40 years, and walks past a bar and gets a whiff of cigarette smoke and gets lung cancer, I don’t think we can say that the secondhand smoke caused it,” Moolgaykar said.
In cross-examination, Moolgaykar was asked by prosecutor Kris McLean to provide the government with the data he used for his analysis. However, in redirect, defense attorney David Bernick said that Moolgaykar’s data was lifted from the government’s own documents.
At one point, McLean began to press Moolgaykar on his connections with W.R. Grace. Moolgaykar said that he had testified for the company twice since 2002 and had worked once previously with Bernick.
Court is set to resume Tuesday at 9:00 a.m.
- Nate Hegyi (posted 5:58 p.m.)
Posted: April 30th, 2009 under News.
Tags: Hegyi, Moolgavkar
Comments
Comment from neil nelson
Time May 1, 2009 at 7:41 am
this Moolgavkar drinks a lot of Disgrace bought and paid for koolaid
Comment from Bruce Case
Time May 1, 2009 at 12:23 pm
It is quite true that we do not know what exposure levels were environmentally in Libby, and Dr. Moolgavkar is of the witnesses cited certainly the most credible, based on his publication record. But, we DO know with some certainty what the OCCUPATIONAL exposures to Grace Workers suggest as to disease causation.
These were extrapolated by McDonald and colleagues in a 2004 paper on Libby (Grace) workers in Occupational and Environmental Medicine, as follows, in part, with my own emphases in CAPITALS and a few notes in parentheses: forgive what may appear to be “jargon”; this is important information and I urge anybody interested to refer to the paper itself and the MANY papers that came before it, which are referenced in the paper:
“…Probably the most robust measure of
occupational risk is provided by the all cause linear model which estimates a 14% increase in mortality after 100 f/ml
years exposure that is, 0.14% increase per fibre/ml year.
This estimate was obtained from workers exposed for about eight hours a day, 240 days a year.
If we assume that relative risk from residential exposure is also proportional to cumulative exposure (NOTE: THIS MEANS DURATION TIMES INTENSITY), which is potentially for 24 hours a day for 365 days per year, the appropriate increment is 0.14 6(24/8) 6(365/240) or 0.64% per f/ml.y.
Thus over a lifetime of, say, 50 years,
an ambient exposure level of 0.1 f/ml would imply UNDER THIS MODEL AN EXCESS RISK OF 3.2% IN ALL CAUSE MORTALITY, (RR=1.032) A NOT INSIGNIFICANT IMPACT (emphasis added).
Exposures of this magnitude may indeed be relevant to the residents of Libby, Montana and PERHAPS EVEN SOME CONSTRUCTION AREAS IN NORTHERN CALIFORNIA (emphasis added, and the reference here is almost certainly to El Dorado County, as Terry Trent can tell you…).
These risk estimates should be regarded
with considerable caution, since they depend on extrapolation from the exposure levels and working conditions of Libby mine workers to populations with much lower exposure living in quite different circumstances. However, a recent report (NOTE: refers to Wright RS et al. in Am J Respir Crit Care Med 2002: volume 165. pp 1145–1149) of fatal asbestosis in a man with a high lung burden of tremolite fibres, whose only known exposure was in two summer jobs on a vermiculite expansion plant 50 years earlier, suggests that these estimates should not be lightly dismissed”.
(from: McDonald JC, Harris J, Armstrong B. (2004) Mortality in a cohort of vermiculite miners exposed to
fibrous amphibole in Libby, Montana. Occ Env Med 61:363-366).
None of this is offered re any innocence or guilt as to any party. But I am getting a little tired of not seeing actual published exposure and disease data in peer-reviewed journals (of which there is a great deal) mentioned in this Blog (I do not of course know whether it is even being mentioned in court).
Comment from Steve Erickson
Time May 1, 2009 at 9:50 pm
re: Grace’s expert:
In my line of work (wetlands/plants) we call them biostitutes. The statistical analysis always argues for less (or no) protection. The BPJ (Best Professional Judgement) is always that the reduced (or no) buffer is sufficient protection. The plant community, soils, or hydrology are not hydric. The survey never finds the rare plants the local people have been observing for decades.
Comment from Terry Trent
Time May 3, 2009 at 12:18 pm
Mr. Erickson – Laughing out loud!! If Tremolite were a rare species of plant, it hadn’t been seen in California for 35 years, even though there were maps from the 1950’s that showed precisley where it was located! Yup, strangest case of extinction in human history. 
TTrent
Comment from Terry Trent
Time April 30, 2009 at 7:16 pm
I was hoping for better. Neither MIller, Lockey or Moolgaykar, know what exposure levels were present environmentally. Certainly don’t know what dose people were exposed to. And that is simply because EPA does not use the correct methods to determine what highest level exposure, therefore risk, possibility is. Never have (and appears never will). So estimating the risk is beyond anyone’s capabilities..other than “quite high” because it is amphibole. If it were Chrysotile fibers most would have a pretty good idea at this point, what the highest risk/exposure levels environmentally are. Close to or actually zero for mesothelioma. Since it is Tremolite (Richotrite, Winchite..which these two fibers have absolutely no risk information ever gleaned from anywhere…they could just as easily have a 56 year latency period and be just as bad as Erionite fibers for all we know???) nobody has the slightest clue. Over estimate, under estimate. One would do just as well knowing the true estimate by asking any man on the street anywhere USA for his best guess. There is no correct answer…yet. But it defintiely is not zero or none, it will prove to be quite high for such minor exposures.
TT