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Asbestos study suggests bias in experts

August 5, 2004 By Emma Marris This article courtesy of Nature News.

Majority of US claims are invalid, says team of radiologists.

Most asbestos lawsuits in the United States are being brought by claimants who are probably not sick, a study warns. The researchers found that experts hired to interpret lung X-rays in these cases are vastly exaggerating the damage caused, with potentially devastating effect on the companies required to pay compensation.

Asbestos, once widely used as a fireproof insulator, is made of microscopic mineral fibres that are easily inhaled and work their way deep into the lung. Once lodged in the lung tissue, they are attacked by the body's defences and become surrounded by scar tissue.

The particles are particularly nasty because they are long and sharp, and can cut their way through lung tissue, unlike more spherical particles such as coal dust. The cumulative toll on health is called asbestosis; sufferers' lung function is affected, they cough and wheeze, and may even die. Some people also get a specific type of cancer, called mesothelioma.

The health effect commonly take a few decades to appear. The peak exposure in the United States, for workers in shipyards, building sites, and asbestos mining and manufacturing, was between the 1940s and the 1970s, so the number of emerging cases should now be dropping. Instead, more and more people are bringing cases every year.


To assess damage to a potential claimant's lungs, his or her chest is X-rayed and examined by a certified expert called a "B-reader", hired by the claimant's lawyer. If the lungs are judged to be harmed by asbestos, the lawyer seeks compensation for the claimant from their former employer, or from the numerous trusts set up for workers suffering from the disease.

Hundreds of thousands of people sue every year and billions of dollars are awarded in compensation, with disastrous effects on many of the companies involved. According to the study, published in August's Academic Radiology2, "More than 60 US companies have sought voluntary bankruptcy to deal with such claims."

The problem, according to Otha Linton, co-author of the paper and director of the International Society of Radiology, is that most of these claimants aren't actually sick.

Linton and his team studied X-ray films of the lungs of 492 claimants. B-readers retained by the plaintiffs' lawyers had diagnosed 95.9% of them with "parenchymal abnormalities", enough scar tissue to make them officially ill. Linton then gave the same films to six B-readers who had no idea what the study was about.

The interpretation of the independent experts was staggeringly different. They diagnosed parenchymal abnormalities in only 4.5% of the cases.

Biased readings?

The finding is as disquieting as it is startling
Murray Janower and Leonard Berlin
Reading X-rays can involve a degree of subjectivity, and B-readers do sometimes disagree on how badly damaged a lung is. But Linton says that such a fundamental difference in interpretation is unheard of.

He believes the results show that the B-readers hired by claimants' lawyers are producing biased readings, whether intentionally or not. And if one expert does not find damage to a lung, a lawyer is likely to keep trying until he finds an expert who does, Linton says. "If I am a plaintiff's lawyer, I am going to find witnesses who will, rightly or wrongly, honestly or dishonestly, agree with me."

The finding is “as disquieting as it is startling”, say radiologists Murray Janower and Leonard Berlin in an editorial that accompanies the study2, although they are careful not to say that the data point to outright fraud.

The latest paper is not the only study that casts doubt on certain B-readers. A 2002 report by the non-profit RAND Institute for Civil Justice, and a 1990 paper in the Journal of Occupational Medicine3 both conclude that lots of healthy people, and lawyers, are getting cash they do not deserve.

However, Dave Chervenick from Goldberg, Persky and White, a law firm based in Pittsburgh, Pennsylvania, that specializes in asbestos cases, says his firm's screeners find asbestos damage in only 15% of cases. He does not think there is a widespread problem. "It's my sense that not a whole lot of this is going on," he says.


  1. Gitlin J., Cook L., Linton O.& Garrett-Mayer E. Acad. Radiol., 11. 843 - 856 (2004).
  2. Janower M. & Berlin L. Acad. Radiol., 11. 841 - 842 (2004).
  3. Reger R., Cole W., Sargent E. & Wheeler P. J. Occup Med, 32. 1088 - 1090 (1990).


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