Asbestos-related diseases or conditions
| Disease or condition |
Other causes besides asbestos |
Comment |
| Interstitial fibrosis |
Over 100 |
asbestosis
when cause is asbestos |
| Pleural plaques/fibrosis |
Several |
Best visualized on a
chest CT scan.
|
| Benign pleural effusion |
Many |
Rarely from asbestos |
| Lung cancer |
Cigarettes alone in
>90% of cases |
Asbestos synergistic
with cigarettes |
|
Malignant mesothelioma
|
About half the cases are of unknown cause |
Asbestos assumed cause if there has been documented remote
exposure |
Interstitial fibrosis.Lung tissue is very thin, delicate tissue that consists
of millions of air sacs surrounded by blood vessels and connective tissue; that
portion of the lungs surrounding the air sacs is collectively called the
"interstitium." If scarring occurs in the interstitium it is called
interstitial fibrosis. Now if thin asbestos fibers are inhaled and get
into the interstitium they can be a cause of this fibrosis.
When this occurs the patient has
asbestosis,
i.e., intersititial fibrosis from inhaled asbestos.
Interstitial fibrosis can actually occur from many products and diseases (well over 100),
and is by itself a non-specific disorder; other causes include drug reactions,
infections, arthritis-related diseases, and chronic heart failure. Again,
asbestosis is interstitial fibrosis specifically due to inhaled asbestos.
Like any case of interstitial fibrosis, asbestosis can lead to shortness of
breath and ultimately be fatal.
References for this condition
Pleural plaques and pleural fibrosis. Sometimes the scarring is not in the
lung tissue itself, but in the outside linings of the lung, called the pleura or
pleural membranes. These are thin, glistening membranes that completely cover the
lungs. When visible on a chest x-ray, this scarring is termed pleural plaques
or pleural fibrosis. However, they are often difficult to discern on plain
chest x-ray, and are much better vizualized on a
chest CT scan.
Disease confined to the pleural membranes is not asbestosis,
a mistake in diagnosis frequently made by physicians reading chest
x-rays. Unlike asbestosis, pleural plaques and fibrosis rarely cause symptoms
or any discomfort. Sometimes calcium is deposited into these plaques, and
then they are much more easily seen on chest x-ray (because calcium is so
dense). Several other conditions can cause pleural scarring and calcium
deposits, such as healed tuberculosis and other infections. However, a
particular distribution of pleural plaques/fibrosis on the chest x-ray (for
example, covering both diaphragm muscles, especially if calcified)
can be attributed to asbestos, if there is a history of exposure and no
other cause is evident.
References for this condition
Benign Pleural effusion. Pleural effusion - a collection of fluid around
the lung - is a very common medical problem; like interstitial fibrosis, there
are many potential causes (e.g., pneumonia, congestive heart failure, cancer, kidney
disease, rheumatoid arthritis, tuberculosis). Asbestos can cause two very different
types of pleural effusion - benign and malignant. Benign pleural effusion is
a frequent condition, but is only rarely from asbestos. Malignant pleural effusion
can be due to either lung cancer or mesothelioma, conditions which are discussed
separately. Benign pleural effusion, when attributable to asbestos, is
presumably due to inflammation generated by reaction to asbestos fibers.
When the pleural fluid becomes substantial (usually over a pint or 500 cc's)
the patient may have symptoms (usually shortness of breath) and the
chest x-ray will show the fluid collection. Asbestos is actually a
rare cause of pleural effusion (pleural scarring and pleural plaques
are a much more common result of asbestos inhalation). The only way to
to reliably diagnose most causes of pleural effusion is to sample the
fluid via a needle in the pleural space, and examine it in the lab.
This is an invasive procedure (because it involves a needle)
called 'thoracentesis', and is routinely performed in hospitals.
References for this condition
Lung cancer. Lung cancer is the most difficult disease to attribute to
asbestos for one principal reason: Over 90% of lung cancers are due to cigarette smoking
and virtually all lung cancer patients with asbestos exposure also have a
strong smoking history. (In over two decades I have come across only one
case of lung cancer in an asbestos worker who never smoked.) Lung cancer
is common, with about 180,000 new cases a year in the U.S. Since we
know asbestos is potentially carcinogenic, every patient with lung
cancer and a history of friable asbestos exposure should be evaluated to see
what role, if any, asbestos played. Lung cancer in patients with a
history of asbestos exposure frequently leads to litigation. The
litigation often ends up pitting expert against expert, all quoting
from the abundant literature on the subject (see references). This point
is discussed further in
What is the Browne Hypothesis?
References for this condition
Malignant Mesothelioma. This is cancer of the thin membranes that
surround the lungs and abdominal organs. Malignant mesothelioma occurs much more commmonly
in the chest than in the abdomen. Asbestos-caused mesothelioma in the abdomen is
thought to arise from fibers entering the lungs and then penetrating through
the diaphragm muscles.
Fortunately, mesothelioma is a rare cancer, affecting only about 2000 people
a year in the U.S. Unlike lung cancer, it is not due to smoking;
in fact, the only known cause of mesothelioma in this country is
remote asbestos exposure (there are other, rare causes of mesothelioma, such as the fibrous
material "erionite," mined in Turkey). The lag time from first exposure to diagnosis is
20 to 40 years. However, in about half the cases there is no history of asbestos
exposure, and the cause is unknown. A documented history of asbestos
exposure and the diagnosis of malignant mesothelioma will invariably be linked, so
in the area of asbestos litigation these cases are straightforward -- medically,
at least.
References for this condition
Are asbestos-related diseases treatable?
Asbestosis is not treatable, although symptoms in the worst cases can be
ameliorated with oxygen, steroids and other measures.
Pleural plaques and pleural fibrosis are also not treatable, but they generally
cause no symptoms or discomfort.
Pleural effusion is treatable with removal of the fluid; if the fluid comes back,
there are procedures that can be taken to keep this from happening.
Lung cancer is curable only by removing the cancer through surgery;
however, at the time of diagnosis most lung cancers can't be removed, and then
treatment will be with radiation or (less commonly) chemotherapy. Radiation and
chemotherapy are considered palliative, as they rarely will cure lung cancer, only
slow it down.
Mesothelioma is not resectable, since it involves the lining of the
lung and the adjacent chest wall. Rarely, in highly selected cases, a few surgeons
will attempt to remove the entire lung with its lining and parts of the chest wall;
this procedure, called "radical pneumonectomy", might prolong survival in a few
individuals but is not an option for most patients. Radiation and chemotherapy
are not effective for mesothelioma, and most patients succumb within 12 months
of the diagnosis.
What are the symptoms of asbestos-related lung disease?
The symptoms are the same as would be seen in any cause of
interstitial fibrosis, pleural plaques/fibrosis, benign pleural effusion,
lung cancer or mesothelioma, and generally depend on two factors:
- extent of the disease, both within the chest (usually
determined from the chest x-ray or CT scan) and, for cancer, spread
to other parts of the body;
- co-existing conditions, such as smoking-related lung disease.
In early interstitial fibrosis there are usually no symptoms, but as the disease
advances shortness of breath is the principal complaint.
Benign pleural effusion is asymptomatic when the amount of fluid is small,
but in moderate to large effusions shortness of breath is common; sometimes patients
can also complain of chest pain worse with a full breath (so-called pleuritic pain).
Lung cancer causes no symptoms in the early stages, even though it may be
seen on chest X-ray. In fact, by the time the cancer does cause symptoms it is
usually far advanced. Symptoms from lung cancer can include shortness of breath,
coughing up blood, and chest pain. (If lung cancer has spread outside the chest it
can cause other symptoms, depending on location.)
Mesothelioma generally causes symptoms earlier than lung cancer, because it grows
between the lung and the chest wall, an area more sensitive to pain than inside the
lung (where lung cancer starts). As a mesothelioma grows it can cause
shortness of breath, chest pain, decreased appetite and weight loss.
Pleural plaques/pleural fibrosis cause no symptoms unless the amount
of scarring is very extensive, over both lungs; then it can cause shortness of
breath. However, extensive scarring of the pleura from asbestos is rare,
so the vast majority of workers with pleural plaques/pleural fibrosis have no
symptoms.
In summary, the main symptom from asbestos-related lung conditions is either "none"
or "shortness of breath." The medical term for shortness of breath is dyspnea.
Dyspnea is such a common symptom, with so many causes, that it has no
specificity by itself. Given a randomly-chosen, middle-aged man who was exposed to
asbestos in the past, any shortness of
breath he has is statistically most likely from a non-asbestos-related condition.
The most common causes of dyspnea in this population: poor physical fitness with
or without obesity; smoking-related lung disease; and heart disease.
How does smoking affect asbestos diseases?
Smoking does not cause asbestosis, pleural scarring, pleural effusion or
mesothelioma. However, there is some evidence that smoking - since it affects
the lungs' natural protective mechanisms - makes people more vulnerable to
inhaled asbestos and more likely to develop asbestosis. Also, a patient with any
asbestos-related disease might have shortness of breath due to mainly or exclusively
from his smoking-related disease.
Many workers who were exposed to asbestos were also heavy cigarette smokers.
Because the latency of asbestos-related diseases is 20 years or more, by the time
these workers are checked for asbestos diseases they often have a very long smoking
history and therefore smoking-related disease -- principally chronic obstructive
pulmonary disease (COPD). COPD includes two separate pulmonary diseases,
which commonly overlap in a given patient - chronic bronchitis and emphysema.
Chronic bronchitis and emphysema are just different manifestations
of lung damage from smoking.
Smoking is also the major cause of lung cancer. Since both asbestos and smoking
can independently cause lung cancer, it is obviously important that anyone
who might have been exposed to friable asbestos never smoke. Smoking not only
adds to lung cancer risk in some asbestos workers, it can heighten the risk --
a process known as synergism. This has been demonstrated with certainty only
if the worker has lung scarring from asbestosis. Synergism means that if, for
example, the risk of developing lung cancer from asbestosis is 1% and the risk
from smoking is 2%, that the risk in the smoking asbestosis patient is
significantly higher than 3%.
One of the most contentious areas in asbestos claims is whether mere
asbestos exposure -- without any apparent scarring in the lungs -- also
acts synergistically with smoking to increase lung cancer risk. The published
evidence suggests that it does not. This point is discussed extensively in
What is the Browne Hypothesis?
References for this question
What other diseases can occur from asbestos?
Rarely, patients can get mesothelioma in the abdomen from inhaled asbestos.
Other conditions often attributed to asbestos, like colon cancer and throat cancer,
are unproven and so are often the subject of litigation when they occur. Common
respiratory illnesses like asthma, sinusitis, bronchitis, emphysema and pneumonia
are not due to asbestos.
How is asbestos lung disease diagnosed?
There must be a history of substantial exposure to friable asbestos AND a lung
condition that could be related to asbestos exposure AND no evidence for another
cause. For example, a positive exposure history plus interstitial lung disease on chest
x-ray plus the absence of any other cause, would be a presumptive diagnosis of
asbestosis. However, note that:
- A history of asbestos exposure, without a documented lung condition
related to asbestos exposure = no diagnosis of asbestos-related disease. Example:
A 65-year-old man with a history of asbestos exposure and a previously
clear chest x-ray suddenly develops pulmonary edema (water in the lungs);
his pulmonary condition is not one related to asbestos exposure.
- No history of asbestos exposure, with a condition that could otherwise be
due to inhaled asbestos = no diagnosis of asbestos-related disease. Example:
A 45-year-old woman with no history of asbestos exposure develops malignant
mesothelioma. This pulmonary condition is commonly linked to asbestos exposure,
but absent such history the cause in her case remains unknown.
The vast majority of asbestos lung diseases occur from
remote exposure at the workplace. Given a documented history
of asbestos exposure, there are three ways to diagnose asbestos lung disease:
- A chest x-ray or chest CT scan (more detailed than a regular chest x-ray)
diagnostic of or consistent with an asbestos-related condition.
- A lung biopsy diagnostic of an asbestos-related condition.
- An autopsy diagnostic of an asbestos-related condition.
Well over 95% of cases can be diagnosed with just the history of friable
asbestos exposure and an abnormal chest x-ray or chest CT scan. It is rare
to make the diagnosis using lung tissue or autopsy, because these exams are
rarely obtained.
Obtaining a portion of lung tissue usually requires surgery. While tiny pieces
of lung tissue can be obtained without surgery (through an instrument called a
bronchoscope), they are usually too small to diagnose asbestos-related diseases.
When lung tissue is available the pathologist will look for ferruginous bodies (see
What are ferruginous bodies?) as
well as other signs of asbestos-related pathology.
Surgical removal of lung tissue obviously presents some risk to the
patient, and won't be attempted unless there is perceived benefit. For example,
since asbestosis is not treatable, physicians won't recommend an operation if they
strongly suspect only this condition. On the other hand, a patient may have
surgery to remove a lung cancer, and then there will be sufficient lung tissue
to also look for asbestosis.
Autopsy is even rarer than operation for lung tissue, because most
diagnoses are made while the patient is living. Also, the vast majority of deaths are
no longer autopsied in this country. In fact, most families of asbestos-exposed
workers refuse permission, even though an autopsy, because it allows
for complete examination of both lungs, would definitively make the diagnosis
if the disease is present.
Why is there so much argument over asbestos?
"Asbestos" is a term fraught with dispute. Decades ago it was a widely-used mineral
in thousands of manufacturing processes, with no hint of the dangers it might impose.
Today its use is highly constricted, in this country only to chrysotile, and then only
in selected products. There are few parallels to the changed perception of asbestos in
just a few short decades. (The closest parallel is cigarettes;
another might be nuclear power plants.)
Like tobacco companies, asbestos manufacturers knew more about the harm of their
product than they admitted, and they did not take proper safeguards to protect the
people most exposed (in this case blue collar workers, not consumers of the product).
Then, when workers started developing disease years after exposure, numerous
law suits ensued, eventually putting many companies out of business. (See Kook Sim, 2001
in References). When all or virtually all people truly sick with asbestos disease either
died or were compensated, attorneys sought out workers not sick but who might become ill from
remote asbestos exposure; this has generated the tens of thousands of claims extant today.
A result of all this activity is tremendous polarization on the subject. On the
web you will find (as expected) widely divergent viewpoints, from
The National Association
of Manufacturers to the
"American Association for Justice" (new name for the
Association of American Trial Lawyers).
Underlying disputes in each claim (see next two questions)
are fundamental philosophical differences between plaintiff lawyers and
defendants. Plaintiff lawyers believe the asbestos industry -- companies
engaged in mining, manufacturing or supplying the product --
should pay every worker ever exposed to asbestos, irrespective of the
worker's medical condition (in other words, pay the lawyers who solicited these
workers to file claims). To this end the plaintiff's bar conducts seminars
on how to file claims when there is no demonstrable medical condition (Schmitt 2001).
The defendants of asbestos claims -- as well as many judges, congressmen and
physicians - feel this is an illogical position, self-serving only for the lawyers,
and that only workers who have actually have demonstrable asbestos-related disease
should be compensated.
Anyone involved or who plans to become involved in asbestos disease evaluation
should understand this fundamental philosophical rift, as it helps explain claims
that seem preposterous in the light of medical science. For plaintiffs' lawyers, the
reports their physician experts provide -- all too often medically bogus -- are
merely a means to one of two ends. First, and preferable, is to obtain mass settlements;
a few legitimate cases are bundled with the bogus claims, and defending companies often
settle the whole lot without investigating the merits of individual cases.
Second, if a defending company chooses to fight a case to trial, the plaintiff's lawyers
are then fully prepared to proclaim the sins of asbestos suppliers, and argue that
these sins justify compensation for any worker exposed to asbestos in the past regardless
of the medical condition. In other words, Doctor A may say asbestos disease and
Doctor B may say there is none, but the "sins" and the "worker's exposure" will be
argued as equally (if not more) important issues.
References for this question
What are the principal disputes in asbestos-related claims?
In this context, "claim" means that an individual or his estate:
- is claiming he was exposed to asbestos, and
- has (or had if deceased) a condition or disease arising from such exposure,
and
- is demanding another party pay him (or his estate) money for the
disease or condition.
The demand could be against a company, a state worker's compensation board
or a bankruptcy court. Most asbestos claims are disputed because of disagreement
over one or more of the following:
- the claimant's asbestos exposure history
- the responsible company or companies
- the diagnosis
The first and second disputes don't involves physicians, since they are based
on employment records, job descriptions, co-worker affidavits, plant documents,
previous court documents, etc. The third dispute always involves physicians, one
way or another, because lawyers need physicians to read the chest x-rays and state
the medical diagnosis.
What are the specific reasons for most asbestos litigation?
Since there is no specific treatment for asbestos-related disorders,
disagreements about diagnosis would be only "academic" if there were no legal
claims. However, since most asbestos diagnoses are linked to monetary claims at
some point, dispute is inevitable. Here are the most common specific
reasons for asbestos litigation.
- For many years the hazards of asbestos were known by companies
involved in its mining and manufacture, but proper safeguards were not
taken to protect workers. For this reason any worker who later develops
an asbestos-related condition can make a claim against the
miner/manufacturer. In other words, the worker can claim that he was
exposed unnecessarily to an unsafe product, and that the product caused
disease.
- Asbestos-related conditions have a long latency period, often two decades
or more after first exposure before a condition becomes manifest.
Because many companies once in the asbestos business have merged or
gone out of business, it is often difficult to even identify the responsible
company years later, when a claim is filed. Company X may be sued, but
argue that it was really company Y that supplied the asbestos 30 years
earlier. Or, several companies may have supplied the asbestos, and end up
litigating over who supplied what proportion for which factory process.
- Even when the responsible company is known, the worker
still must prove he was exposed to friable asbestos in the workplace, and in
sufficient amount to have caused the condition. Yet job descriptions are often
sketchy or non-existent decades later. Many times the claimant is
deceased, and the lawsuit is brought by the widow or the estate; in those
situations co-worker affidavits are often used to establish work place
exposure for the deceased. Understandably, companies often dispute the
exposure history.
Since World War II many people have worked in factories where asbestos was
present, but it was not necessarily friable asbestos. For example many plants had,
and continue to have, pipes covered with asbestos but wrapped so that no friable
asbestos is released. If the worker's job was to cut, repair and replace
these pipes all day long, chances are good he would be exposed to much friable
asbestos during his career. Now suppose another worker drove a tow motor in
the same plant and was never exposed to the pipes except in their intact state.
Any lung condition that the first worker developed would have to be closely
examined for an asbestos cause. Any lung condition that the second worker
developed would be unlikely related to asbestos. The fact is, in many cases we
don't know exactly what, or to what extent, workers were exposed to decades ago.
In places like Canada and Montana, where there are asbestos mines, exposure
history is often more apparent than in most American factories.
- Lung cancer is almost always due to smoking, and virtually every
ex-asbestos worker with lung cancer is a smoker or ex-smoker. All experts
believe that asbestos is contributory when there is definite asbestos
scarring (asbestosis) along with the lung cancer. Many researches feel that
one must demonstrate radiologic or histologic (on lung tissue) asbestosis
to link asbestos exposure as a cause of lung cancer (the Browne
Hypothesis). Understandably, other researchers disagree, and this point is
often the subject of debate - and a reason for litigation - in lung cancer
claims.
- Even granted that a patient's lung cancer was due to both asbestos and
smoking, different courts treat this information differently. Some award
maximum damages if asbestos was any percentage of the cause; others
only award compensation based on the percentage attributed to asbestos, a
percentage which is subject to wide interpretation.
- Pleural plaques are almost never associated with any physical impairment.
Controversy arises over whether they are associated with increased risk of
developing lung cancer. (See next two questions).
- Mesolthelioma is invariably linked to asbestos if exposure can be
documented. When cause and effect is so clearly established, attorneys for
patients usually seek jury trial to maximize the award.
- The American Thoracic Society formulated standard criteria for the
diagnosis of asbestosis, which were published in the mid 1980s. However,
many physicians feel they are too restrictive and will argue a more liberal
diagnosis in court.
- Claims based only on the chest x-ray are the most common type of claim
today. Since these cases were solicited by plaintiff's attorneys from union
rolls, the sued companies often hire their own physicians to examine the
claimants. The companies' experts often disagree with physicians hired
by plaintiff's attorneys.
Why is There Controversy over Diagnosis of Pleural Plaques?
Pleural plaques from inhaled asbestos are relatively common (compared to
other asbestos-related conditions), and are benign. In one study of asbestos-
exposed factory workers who had pleural plaques, the size of the plaques averaged
47.9 sq. cm, or 2.4% of the typical pleural surface of 2000 sq. cm. Interestingly,
the size of the plaques was not related to asbestos exposure intensity. Also, the
lung function of workers with pleural plaques was the same as a comparable group
of workers with no plaques or history of asbestos exposure (Van Cleemput 2001).
Though a marker of remote asbestos exposure, plaques are sometimes difficult to
diagnose on a plain chest x-ray because other shadows (particularly overlying body fat)
may confuse the picture (Muller 1993). This is particularly true if the plaques are
not calcified.
While a chest CT scan can usually separate out pleural plaques from other
shadows, CT scans are not routinely done in most asbestos claimants. Most claims
filed for pleural plaques are based on the chest x-ray alone, resulting
in much interpretive controversy.
Though a marker of remote
References for this question
Do Pleural Plaques Lead to Cancer?
The only way to answer a question like this one is by population studies, i.e.,
identifying a group with and without pleural plaques, and then following each group
for a long period of time. However, since lung cancer is almost always due to
smoking, and since most asbestos-exposed workers have a smoking history,
the two groups must be carefully controlled for smoking as well as other
variables like how the initial chest x-ray was interpreted (see above question), the
subjects' age, and any associated lung conditions. Published studies show either no
relationship between plaques and cancer, or suggest a slight statistical association.
Not unexpectedly, experts can select studies to support both sides of the issue.
In one population study suggesting a relationship between pleural
plaques and cancer, Hillerdal wrote (1994):
"From the general population in the county of Uppsala, Sweden, 1,596
men with pleural plaques fulfilling strict radiologic criteria were identified
from 1963 until June 1985. The men have been followed prospectively for
16,369 person-years...The risk for patients with pleural plaques without
asbestosis was increased 1.4 times, which was statistically significant."
An opposing editorial in the same journal (Smith 1994)
was highly skeptical of Hillerdal's findings, as well as other studies on the subject.
Smith pointed out the difficulty of quantitating asbestos exposure and true smoking
histories, and of even confirming pleural plaques on the chest x-ray. After providing
numerous citations and cogent arguments against Hillerdal's findings, Smith wrote:
"The study of Hillerdal does not demonstrate a significant enough increase
in risk to overcome the experimental limitations in his study. This study is
just another study that has failed to demonstrate convincing evidence of a
significant risk of lung cancer associated with pleural plaques without
asbestosis."
References for this question
What is the Browne Hypothesis?
In 1986 Dr. K. Browne published a paper in the British Journal of Industrial
Medicine titled: Is asbestos or asbestosis the cause of the increased
risk of lung cancer in asbestos workers? Dr. Browne's basic conclusion was that
asbestos per se may not be completely carcinogenic:
"neoplastic change [cancer] may appear only in the wake of inflammation and subsequent
fibrosis...it is not asbestos per se but asbestosis which prepares the soil for subsequent
malignancy."
This assessment was based on epidemiologic and biological evidence that
lung cancer in asbestos exposed workers was due to asbestosis and not to asbestos
exposure per se. This hypothesis, to put it mildly, is hotly debated. The
implications are obvious. If Browne's hypothesis is accepted, then simply being
exposed to asbestos is not enough to implicate asbestos as a cause of cancer; the
history of smoking (almost always present in lung cancer patients claiming an
asbestos cause) should be sufficient to explain the cancer. If Browne's hypothesis
is not accepted - if the worker has no evidence of an asbestos-related disease, but
merely the history of exposure - then asbestos could be claimed as a co-contributor
to lung cancer, along with cigarettes.
Since 1986 dozens of articles have appeared favoring or disputing the Browne
Hypothesis. The issue was put into perspective by a review in the British medical
journal Thorax (Jones 1996). After surveying the literature the authors wrote:
"Asbestos is the most studied of all occupational carcinogens and, apart
from tobacco, the most studied cause of lung cancer. It may therefore
surprise the general reader that there is an important area of uncertainty
about the relationship between inhaled asbestos and the resulting increase
in risk of lung cancer. At issue is whether asbestos-attributable lung
cancers are always associated with asbestos-induced lung fibrosis -- that is,
asbestosis. This uncertainty has engendered a heated controversy, fuelled
by important implications for regulation, workers' compensation, and
litigation." (Page S9)
Jones, et. al. summarized their assessment of the issues as follows (page S14).
- "Lung fibrosis of many causes - known and unknown - is associated
with increased risk of lung cancer.
- The much discussed synergism between asbestos "exposure" and
smoking found in mortality studies of insulation workers turns out to be
a synergism involving asbestosis, not just asbestos exposure.
- The site of origin and cell type of a lung cancer are not regarded as
reliable indicators of causation (or non-causation) by asbestos.
- In asbestos inhalation experiments animals develop excess lung tumours
only when lung fibrosis is also produced.
- Pleural plaques have not proved to be a reliable marker for increased
risk of lung cancer.
- Excess lung cancer deaths in populations exposed to asbestos are
generally first detected at about the same cumulative exposure levels as
those at which asbestosis begins to appear."
In 1999 Dr. William Weiss reviewed 39 English language reports of cohorts
exposed to asbestos in an attempt to address this question. In his paper,
Asbestosis: A Marker for the Increased Risk of Lung Cancer Among Workers Exposed to
Asbestos, Weiss wrote:
"The adequately designed studies in the literature support [the Browne]
hypothesis. The summary relative risk for lung cancer was 1.00 in seven
cohorts with no deaths from asbestosis. In addition, there is a high
correlation between asbestosis rates and lung cancer rates in 38 cohorts in
contrast to a poor correlation between cumulative exposure data and lung
cancer relative risks in eight cohorts with adequate data. The evidence
indicates that asbestosis is a much better predictor of excess lung cancer
risk than measures of exposure and serves as a marker for attributable
cases."
Recognizing the controversy involved, the editors invited an
editorial response to Dr. Weiss's paper, in which other physicians
wrote:
"Asbestosis is an indicator of high exposure and contributes additional risk
to lung cancer beyond that conferred by sufficient asbestos exposure
alone. In our opinion, the hypothesis that the excess lung cancer risk in
worker cohorts exposed to asbestos occurs only among those with
asbestosis is insufficient to explain this heightened risk of
carcinogenicity."
Even accepting the Browne Hypothesis, the problem still arises as to how one
defines and diagnoses asbestosis. As already pointed out, physicians
hired by plaintiff attorneys are much more liberal in their definitions
than are most other physicians.
References for this question
What are the standard criteria for diagnosing asbestosis?
In the mid 1980s the American Thoracic Society helped formulate
criteria for diagnosing asbestosis. In the ATS medical journal a group
of experts proposed the following criteria for
diagnosing asbestosis (Murphy 1986; here paraphrased).
- A definite history of exposure to friable asbestos
- A definitely, unequivocally abnormal chest x-ray showing changes
typical of asbestosis
- A definitely abnormal breathing test, showing a certain degree of
impairment that could be due to asbestos inhalation.
- Findings on physical exam of the lungs compatible with the diagnosis,
and not due to some other condition.
Physicians adhering to these criteria would obviously not diagnose asbestosis
in patients with only subtle shadows on chest x-ray, or with normal lung function
tests, or with another diagnosis (e.g., congestive heart failure) to explain any
abnormalities.
The authors of the ATS article recognized that true asbestosis is a serious disease,
for which there is no effective treatment. Patients are short of breath, at least on
exertion. They have abnormal chest x-rays. They have abnormal breathing tests.
The authors specifically chose not let the diagnosis encompass 'healthy' people
with equivocal chest x-rays.
Understandably, attorneys for claimants (and their experts) do not agree with
this definition. They opine that the disease must be recognized early, before there
are symptoms and before the x-ray is unequivocally abnormal. However, this
position opens up a pandora's box of extreme bias in chest x-ray interpretation,
as discussed above.
At present many physicians won't certify a diagnosis of asbestosis unless the
findings meet the strict ATS criteria. However, other physicians will argue just
as strongly for their own personal criteria for diagnosing asbestosis.
The result, of course, is not only medical controversy, but
another (and major) reason for litigation.
References for this question
What are the Helsinki Criteria?
In January 1997 a group of experts met in Helsinki, Finland to "discuss disorders of the
lung and pleura in association with asbestos and to agree upon state-of-the-art-criteria
for their diagnosis and attribution with respect to asbestosis." Their report, nicknamed
The Helsinki Criteria, was published in a Scandinavian medical journal (see References).
Prior to the Helsinki Criteria the only published consensus report about clinical
diagnosis of asbestos diseases was the American Thoracic Society article published in 1986
(see above). Unfortunately, the Helsinki report does not refer to the ATS article; also,
it does not offer any new research or even any references to earlier research or opinion.
For these reasons the Helsinki report does not replace the 1986 ATS report, and is at best
an editorial comment by a group of international experts.
Principal points raised in the Helsinki Criteria article include:
- Reliable work histories provide the most practical and useful measures
of occupational asbestos exposure;
- High resolution CT scan can facilitate detection of asbestosis and
asbestos-related pleural abnormalities, but is not recommended as a screening tool;
- New imaging techniques (MRI, gallium scanning, PET scanning) are not
recommended for clinical diagnosis;
- Radiologic findings of small opacities, ILO grade 1/0, "are usually
regarded as an early stage of asbestosis." (A score of "1/0" means the first
impression is there is some scarring (1)/but a second impression is that
the film may also be negative, that is, show no scarring (0).)
This last point is in contrast to the ATS report, which opined that the threshold of
diagnosis should be a radiologic score of 1/1 (both the first and second impression
is that there is some scarring on the chest x-ray).
However, the Helsinki report also states that "Smoking effects should be considered in the
evaluation of early asbestosis." This is a very important point often overlooked by
people interpreting chest x-rays of known asbestos claimants.
References for this question
How are claims based only on the chest x-ray?
To understand this situation, you must first understand that medical diagnosis
of many conditions is often imprecise, or is based on imprecise tools. Asbestosis
is defined as lung tissue scarring from inhaled asbestos. Pleural plaques/fibrosis
is scarring of the lining of the lungs. These definitions seem straight forward, but
how do we actually diagnose this scarring? As already pointed out, direct
examination of lung tissue for evidence of asbestos scarring (lung biopsy and/or
autopsy) is rarely performed. Instead, the vast majority of cases are diagnosed by
"shadows" seen on the ordinary chest x-ray or chest CT scan (performed much
less commonly than the chest x-ray). In this sense the diagnosis is usually
inferential.
Inferential diagnosis is accepted when you have a classic presentation -
unequivocal exposure history, unequivocal chest x-ray. But the vast majority of
the unequivocal patients were long ago diagnosed and compensated. What is left
now are tens of thousands of workers and ex-workers whose exposure history and
chest x-ray are far from unequivocal. Their cases are, in fact, very equivocal.
And when you start with equivocal abnormalities on a chest x-ray, you are entering the
realm of subjective interpretation, of inherent biases, of one doctor's opinion vs.
another's (it is only physicians who are trained to interpret chest x-rays). For this
reason, in most current claims there is often significant disagreement over chest
x-ray interpretation and, ultimately, diagnosis.
Years ago the U.S. Department of Labor set up a special program to train
physicians to read chest x-rays of workers (principally coal miners) exposed to
coal and silica dust. (Coal miners can develop a disease from inhaled coal and
silica dust known as "black lung".) The goal of the training program was to bring
some standards to the reading of these workers' chest x-rays, and to identify the
workers with early dust disease. Because these physicians passed 'Part B' of DOL's
training course, they are collectively known as 'B-Readers.'
Now it turns out that coal, silica and asbestos dust can give similar
appearances on the chest x-ray. For this reason B-Readers are usually called upon
to read the chest x-rays of asbestos workers. It is now practically a legal
requirement that any asbestos claim (based on chest x-ray) be certified by a B-reader.
Yet studies have shown that B-Readers as a group display enormous
variation in chest x-ray interpretation.
The problem is manifest most acutely in the thousands of claims that started
with screening chest x-rays. In this situation there are no real patients,
no pre-existing diagnoses in people who worked around asbestos; instead, there are
attorneys looking for claimants. In the 1980s and early 1990s plaintiff's attorneys
visited unions of many plants known to have used asbestos in the past. Working
from union rolls, the attorneys then offered free screening chest x-rays to tens of
thousands of factory workers and ex-workers with one goal in mind -- to look for
asbestos-related disease in order to file mass claims.
(For a succinct history of asbestos litigation, see
A History of Asbestos Use and Asbestos Litigation
and
Asbestos Litigation History.)
The plaintiff attorneys have justified this solicitation as an important service to
the workers, since previously-unrecognized asbestos disease could be a precursor to
crippling disease later on. Since a chest x-ray is harmless, and there is no up front
cost to the workers, most of them signed up for the program (in many cases a breathing
test was also done).
The attorneys then sent the chest x-rays to B-Reader physicians hired
specifically to interpret them. These B-Readers - who never saw the workers and
had no direct knowledge about their asbestos exposure or medical history -- read
the chest x-rays looking for asbestos-related disease. In fact,
physicians hired by the attorneys are paid extra to find asbestos disease, and in some
cases a particular chest x-ray will be shopped around to other B-readers until the attorney gets the reading desired
(small opacity profusion of 1/0 or greater, or evidence for pleural plaques/thickening).
(See
Egilman D. Asbestos screenings. Amer J Indust Med 2002;42:163).
Physicians reading the x-rays send their reports directly to the attorneys.
When their reports indicated the possibility
of asbestos disease, a lawsuit was filed on behalf of the worker against all the known
asbestos suppliers of the worker's plant. Subsequent analysis of these cases -- on an
individual basis, by other physicians -- shows that these attorney-generated chest
x-rays were (and are) often over interpreted for asbestos-related disease.
Smokers, in particular, can have subtle "opacities" on chest x-ray
that are often mis-interpreted as due to asbestos disease. Such
mis-interpretation can be shown with a
high resolution CT scan.
Also, many other diseases can manifest x-ray changes
similar to asbestos-related disease; without proper investigation these cases
are erroneously assumed to be asbestos-related. Remember, physicians
hired to read these thousands of chest x-rays know nothing about the
workers' medical histories.
References for this question
What results from claims based only on the chest x-ray?
There are so many attorney-generated cases filed in the U.S. that no one judge
or court system has a handle on them all. There is currently a huge backlog of
claims. Each worker may file claims against a dozen or more asbestos suppliers;
the settling of a claim by one supplier does not eliminate outstanding claims
against other suppliers. For companies that choose to defend themselves, it is
expensive just to prove a worker doesn't have asbestos disease; proof involves
hiring experts to examine the worker, obtain and interpret a new chest x-ray,
file a report, etc.
Even though the vast majority of these claimants have no evidence for asbestos-related disease by objective criteria,
it is usually cheaper to 'pay up' than to fight each case in court. As one corporation (USG) has publicly stated,
"Many defendant companies have tens of thousands of cases filed against them by people who are not sick -
those cases can usually be settled out of court
for only a couple of thousand dollars per claim. To challenge
each of these cases in court would cost many times more than the settlement cost."
Some workers are found with real disease, but not many. This is because most
patients with real disease will have seen a physician, already had a chest x-ray,
and if something was found filed a claim. Screening has uncovered a small
percentage of abnormal chest x-rays which do reflect remote asbestos inhalation.
But because these cases are lumped together with all the bogus claims, patients
with undisputed disease (such as mesothelioma) tend to get short shrift, as
some funds to pay their claims are apportioned for claimants without real disease.
Another result is that workers without symptoms or true abnormality on chest
x-ray are subjected to numerous examinations, hearings, chest x-rays and doctor
visits. Many have stated, spontaneously, that they wish they had never become
involved in the process, since (so far) the monies received (by some company
settlements) are small and the inconvenience not worth it.
They understand that their claims serve mainly
the attorneys who solicited them and that they are but pawns in the litigation.
Plaintiff's attorneys can claim, with some justification, that workers
deserve to be compensated if they have asbestos lurking in their lungs,
since they could develop real disease (e.g., cancer) at any time. If the attorneys
truly uncovered many workers with a ticking time bomb, the mass effort would be
justified. But the vast majority of claims have been filed for workers
with no asbestos disease evident on the chest x-ray. How can this be?
The problem is in the interpretation of the chest x-ray. Smokers, in particular, can
have "shadows" that are often mis-interpreted as asbestos disease. Also, many other
conditions (e.g., congestive heart failure) can mimic chest x-ray
changes that are mis-interpreted as due to asbestos.
Remember, physicians reading the chest x-rays know nothing about the workers'
individual medical histories.
Is there a solution to the asbestos-litigation problem?
In this context "the problem" is the manufacture of thousands of cases by
attorneys looking for claimants, resulting in clogged courts, disappointed
claimants, legitimate claims frustrated by interminable delays, and companies
held hostage to junk science and trumped up diagnoses. The problem is perceived
to be so bad that, in fact, a bill was introduced into Congress to forge a
solution, but was never passed. It called for a
"national claims facility to expedite fair and
prompt compensation" to evaluate all claims, and eliminate those not based
on real disease or impairment.
According to an editorial in the Wall Street Journal (The Job-Eating Asbestos Blob, Wednesday,
January 23, 2002) the congressional bill
"would have created a company-funded, government-run procedure to compensate anyone
who's sick or becomes sick from asbestos exposure. The [plaintiff] lawyers nuked it, however, because they increasingly
depend on collecting money for clients who claim exposure but aren't sick. The lawyers won partly because most of
corporate America stayed on the sidelines. This was shortsighted, to say the least. "
It is not clear just how the government-run, national claims facility was to
function, but I will offer offer my own vision of a reasonable solution, from
the perspective of a practicing pulmonologist.
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Proposal to Fix the Asbestos Litigation Mess
Two panels of expert physicians should be created: board-certified
radiologists to interpret the chest x-rays, and board-certified pulmonary physicians to
examine any claimants with truly abnormal films. Physicians comprising both
panels would be agreed to before hand by both plaintiff and defense attorneys. As
a practical matter, this would probably entail about 100 radiologists and 200
pulmonary physicians, spread geographically around the country.
Physicians eligible for the two panels would take a course on asbestos-related
diseases, and have to pass some sort of test to be included. For radiologists, the
B-reader exam might suffice. For pulmonologists, a new exam would be designed to
test general knowledge of asbestos-related diseases. This might seem an
expensive enterprise, but the total cost would be far less than what is now
spent on screening evaluations, re-evaluations, and legal costs for the tens of
thousands of claimants.
All chest x-rays would be read in a blinded fashion by radiologists from the
panel. The physicians would be paid for each film read, with the money coming equally
from both sides out of a common fund. Among the chest x-rays submitted for reading
would be a large portion (at least 20%) from patients never exposed to friable
asbestos at work, who are otherwise matched to the workers who were exposed (e.g., similar
smoking history and age). Inclusion of this group of chest x-rays should help
guard against bias in the interpretations. Every chest x-ray would be interpreted on its
own merits, and the radiologist would have no way of knowing anything
about the person whose film is being read. The radiologist would not know if
the subject was ever an asbestos worker, if he was party to any claim, or
even if he ever smoked. In this way the radiologist would have no
attorney to please or displease with his interpretation, and have only his own
integrity to worry about.
In this scheme each chest x-ray would be read by three experienced, unbiased,
board-certified radiologists. If at least two of the three radiologists
found no asbestos disease on the chest x-ray, that worker would not be
allowed to file a claim for asbestos lung disease. Any worker whose claim
is rejected in this fashion would be allowed to re-enter the
review process after three years.
If two of the three radiologists felt there was some asbestos-related disease on
the screening chest x-ray, the individual's work history would be checked; if in
fact he ever worked with or around asbestos, he would then go for a clinical
examination, by the pulmonary physician, to evaluate his overall medical
condition (including lung function tests).
A final report would be filed by the pulmonary physician. He or she would
also be paid from a common fund, and not directly by either side. After the report
is filed any dispute (other than about interpretation of the initial chest x-ray) could
be litigated. In this manner bogus cases based on over interpretation of chest
x-rays would be eliminated.
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What are the legal impediments to a medical solution?
The legal solution is far more complex, of course, since it would have to be
a) passed into law by Congress, and
b) accepted in spirit and practice by plaintiff and defense attorneys.
Understandably, the current bill before Congress is meeting
strong opposition from trial lawyers involved in asbestos litigation. The
Trial Lawyers of America web site states:
"With Congress considering legislation that would trap workers and
citizens injured by asbestos in an elaborate bureaucracy and set up
corporate lawyer-prepared medical criteria that would screen out 60 to 80
percent of potential claimants, it might prove useful to review some quotes
from past court decisions that make clear the asbestos manufacturers'
misconduct."
This statement confuses facts about past company misconduct with the
medical truth about current claims. In fact, if most claims were based on
legitimate criteria, many more than "60 to 80 percent" would be screened out.
In fact, the current scheme of thousands of claims with their interminable delays,
and expert pitted against expert for each contested claim, is far
more "elaborate" than any bureaucracy set up to blindly review chest x-rays.
In any case, "corporate lawyer-prepared medical criteria" are not going to be
acceptable. Furthermore, corporate lawyers have never set the criteria for diagnosing
asbestos-related disease, and it seems unlikely they would do so in any national
legislation.
In my opinion, Congress' job would be simplified if the individual members asked
themselves two basic questions and then acted on their responses:
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1) Do we (the U.S. Congress) wish to compensate people with a possible history
of exposure to friable asbestos, irrespective of any medical information about them?
In other words, should medical information be simply irrelevant in determining
compensation? (This in fact is the philosophical position of plaintiff attorneys, and
is one side of the fundamental philosophical rift mentioned earlier.)
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If Congress agrees with this position -- if the answer to the question is YES --
then Congress should enact legislation to:
remove medical diagnoses and medical testing completely out of the
claim process; this removal would eliminate the need for physicians to opine
that claimants have asbestos-related disease when the evidence is lacking, or
argue about subjective interpretation of chest x-rays. It would also free
all worker claimants from the onerous process of multiple medical evaluations.
develop a worker-compensation schedule based solely on exposure history;
while the exposure history would still be debated among lawyers and employers,
complete absence of medical issues would greatly simplify the evaluation process.
If the answer to the first question is NO, then Congress
should consider the second set of questions:
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2) Given that workers with possible exposure to friable asbestos
should be compensated based on some medical information (first question),
should this information come only from physicians not
hired or paid directly by either side? In other words, should a system be
developed which guarantees the objectivity and integrity of evaluating physicians?
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If the answer to this second question is YES, then legislation should implement
the medical solution outlined above, or some similar fair and unbiased process. If
on the other hand the answer is NO, then Congress should abandon
any attempt to fix the problem, and accept that the current morass created by
attorney-generated, medically-unfounded mass claims will continue ad infinitum.
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