Lockey studies showed tremolite toxicity
Physician James Lockey testified Wednesday afternoon about a pair of studies examining symptoms of asbestos exposure in workers at an O.M. Scott plant in Marysville, Ohio. The plant used Libby vermiculite in its gardening products. Under direct examination from prosecutor Kris McLean, Lockey testified that some of the workers suffered localized plaques, diffuse thickening and bloody effusion in the linings of their lungs, even at the relatively low doses seen at the Scott plant.
The first study looked at chest x-rays of workers in 1979 and 1980, the year the plant stopped using Libby vermiculite. The second looked at the same group of workers in 2004 and 2005, excepting those who had died in the interim.
The studies established, possibly for the first time in medical literature, the particular toxicity of tremolite fibers as opposed to other forms of asbestos. Lockey attributed that extra toxicity to several factors, especially the shape of the fibers, their tendency to splinter into multiple fibers and their durability in lung tissue, which he claimed exceeded that of chrysotile asbestos, by far the more common type. The studies also established a strong relationship between the dose of fibers and the likelihood of disease.
“[Tremolite fibers] have a long residence time – they get in your lung and they stay there,” Lockey said. “One fiber may deposit in your lung, but over time it may get thinner and thinner, splitting longitudinally. You may inhale one tremolite fiber and end up with a hundred in your lung … the longer someone works in the work site, the more likely they are to have a disease.”
Lockey also testified that Grace knew about the results of his study in 1982. He presented his findings at a conference attended by Dr. Julie Yang, a chemist employed by Grace at the time, and was subsequently invited to present his findings at Grace headquarters in Cambridge, Mass., at a meeting called by defendant Jack Wolter.
Though the prosecution asked him, Lockey was not permitted to talk about any discussion with Grace employees of a possible study at Grace’s Libby mine or mill sites. Lockey was interested in doing such a study because of the higher exposure rates expected at those sites compared to the O.M. Scott plant. He wanted to see if his original study was “really showing what I think its showing,” Lockey said.
In 2004, when he conducted a follow-up study of the same O.M. Scott workers, Lockey found that many more of them had symptoms. Among living workers who agreed to participate in the second study, an average of 28 percent had developed noticeable changes on their chest x-rays. Those who had higher occupational exposure to the fibers had much higher rates of disease, but all workers had elevated rates relative to the general population.
“A relatively low cumulative exposure to this particular fiber is a definite risk factor,” Lockey said. “Whatever is going on in the lungs … continues after exposure ceases.”
Defense attorney David Bernick, taking up cross-examination of Lockey, spent some time diagramming the various parts of the lung and discussing the nature of changes to the lung and related tissues described in the study. In a lighter moment, Bernick apologized for a poor illustration. Lockey replied saying, “Michelangelo, you are not,” to chuckles from the jury.
–Daniel Doherty (posted at 4:32pm)