The number and range of occupational respiratory concerns are rapidly increasing, and include the following:
· Interstitial Pulmonary Fibrosis
· Popcorn Workers’ Lung
· Wood Dust
· Benzene-Related Diseases
These cases are medical record intensive with many critical details that can be used as ammunition for litigation. Understanding the various medical and diagnostic aspects of each disease etiology is important in knowing what to look for and how to strategize.
All organ systems in the body can be targets of toxic exposure. The respiratory system is both a target organ and a portal of entry for toxicants. As a foundational starting point, let us recall our basic anatomy and physiology. As air is inhaled through the nose and mouth, it collects in the throat and passes through the trachea into the lungs. The windpipe divides into right and left bronchiole tubes. The right lung is divided into 3 lobes, the left into 2. The lungs are surrounded by a membrane, pleura, which separate it from the chest wall. The pleura are mesothelium. The bronchiole tubes are lined with Cilia, hairs that move and combine with mucous, which is the mechanism for carrying unwanted dust, germs and matter up and out of the trachea, which is then coughed up. The smallest subdivisions of the bronchial tubes are called bronchioles, at the end of which, are the air sacs or alveoli. The alveoli are the final destination of the air we breathe and it is here that the exchange of oxygen and carbon dioxide occur in the capillaries.
Picture 1 – Normal bronchioles
As a system of narrowing passageways, any disease or reaction that affects the diameter of the bronchioles impacts breathing, respiration, cardiovascular function, and tissue perfusion. If Cilia and mucus production are impacted, particles are not carried out of the airways. So, any person with pre-existing diseases that restrict airways, such as asthma, COPD (chronic obstructive pulmonary disease), or bronchitis may progress more rapidly with asbestos related disease.
Picture 2 – Asthmatic bronchioles
Most occupational respiratory diseases either manifest as common medical problems or have non-specific symptoms. Etiology distinguishes a disorder as an occupational illness. Unless an exposure history is pursued by the doctor, the etiological diagnosis might be missed, treatment may be inappropriate, and the exposure can continue.
Most people with an illness brought on by exposure to a toxin obtain their medical care from doctors who are not specialists in occupational medicine. Very few providers get information about home, workplace, or community environment as a part of the demographic and social history. There was a recent study of 1000 medical charts in a primary care setting and only 24 percent of charts had any mention of the patients’ occupation, and only 2 percent had exposure history. Although most doctors recognize the importance of taking a work and exposure history to evaluate certain problems, most have little practice in doing so.
Picture 3 – Asbestosis Inflammation
This is a microscopic view of an Asbestos fiber coated by protein surrounded by macrophages. There is conflicting evidence regarding the relative importance of the different physical properties of the asbestos fiber types in causing disease. Certainly, fine fibers are more pathogenic than thick fibers. Larger diameter fibers that are longer tend to become deposited in larger airways, in which they are effectively cleared. In comparison, fibers that are more slender and shorter tend to be deposited in the smaller airways, from which only a portion of them are cleared. Despite differences in their physical properties, all types of asbestos fibers are fibrogenic.
The most recent data from the CDC in 2005 show us that deaths from asbestosis have been on the rise since the late 70’s with a peak in 2000. Asbestosis is reported to develop in 49 percent of adults with industrial asbestos exposure, after a latency period of 20 – 45 years. These patients present clinically with chest pain, pain with breathing, fatigue and clubbing of the fingers.
Asbestosis is diagnosed on the basis of certain clinical, functional, and x-ray findings, as outlined by the American Thoracic Society. These criteria include:
· A Reliable history of non trivial exposure
· Appropriate interval between exposure and detection
· Abnormal chest x-ray
· Abnormal pulmonary function test
· Abnormal diffusing capacity
· Bilateral crackles at the base of the lungs not cleared with coughing
Picture 4 – Diagnostic X-Ray
This x-ray is virtually diagnostic of asbestos exposure with bilateral scattered pleural plaques. Note that there are limitations with x-rays; studies have shown a high rate of both false negative and false positive rates. Extrapleural fat mimics pleural thickening and is a significant cause of false positive readings. 20 percent of asbestos patients have normal chest x-rays. That being said, x-ray is still the preferred modality for initial detection and characterization of pleural disease.
High Resolution Cat Scans are more sensitive and specific than chest x-rays and are playing an increasingly important role in the diagnosis of all asbestos related pleural disease. Other modalities that are being utilized include ultrasound and nuclear medicine, ultrasound to define pleural effusions and guide aspirations, and biopsy. Nuclear medicine is being used to differentiate benign from malignant asbestos-related pleural disease and to give a quantitative index of inflammatory activity.
In looking at the medical records, these studies will all be documented by radiology reports in the diagnostic test section, and will be referenced by physicians in the history and physical, progress notes, consultation notes, and the hospital admission and discharge records.
The mesothelium is a membrane that lines the cavities of the body, such as the chest and abdomen, and covers and protects the body’s internal organs. In the chest the mesothelium is known as the pleura, where it covers the lungs and lines the internal chest wall. In the abdomen it is called the peritoneum. Around the heart it is called the pericardium. The mesothelium is only one cell layer thick.
The CDC released figures in 2002 showing the breakdown of types of mesothelioma deaths in 1999. Although most malignant mesothelioma occurs in the lung, there are a substantial number of peritoneal occurrences; it may also arise in the ovaries, scrotum, or pericardium. The lifetime risk of developing mesothelioma among asbestos workers is thought to be as high as 10 percent. The average asbestos worker has a 50 percent chance of dying from a malignancy, compared to around 18 percent for the average American.
Asbestos exposure acts synergistically with cigarette smoking to increase the risk of developing lung cancer. Even with the long latency of approximately 30 to 40 years, cigarette smoking is NOT AT ALL associated with mesothelioma.
The earliest manifestations of asbestos-related disease, including mesothelioma, are pleural effusions, which present as shortness of breath or coughs. These typically occur within 10 years of exposure and they can be self-limiting, chronic, or recurrent. The first symptoms mimic so many other illnesses that unless the primary care physician takes a detailed occupational history, all of these other diseases will be ruled out first, which partially explains why the average survival rate is 10 months once diagnosed.
Because the mesothelial layer is only one cell layer thick, mesothelioma is not reliably detected on CT or MRI. The only way to diagnosis it is through tissue biopsy. There are no screening tests, even for those at high risk. There may, however, be some promise in a new blood test recently approved by the FDA. Mesomark is a biomarker assay test that identifies levels of soluble metholin-related peptide levels in persons who have a history of asbestos exposure. Currently, the test is utilized only as a monitoring and management tool in those already diagnosed with mesothelioma, but has potential to be a useful tool in measuring levels of metholin peptides in workers as a screening process for exposure levels.
John – Didn’t you have a case recently where Mesomark could have been helpful?
Silicosis is relatively rare in the US. It has declined by 90 percent from 1968 to 2002. Silicosis is characterized by nodular lesions and progressive fibrosis.
Picture 5 – Healthy Lung & Picture 6 – Diseased Lung
With a lung like this, the patients would have decreased pulmonary function, decreased chest expansion, and abnormal breath sounds. Again, an exposure history is critical. Although the incidence of Silicosis is significantly decreased, it does not stop the litigation; there are 65 cases in California alone.
Valley Fever is a lung infection caused by an airborne fungus that is contracted in arid dessert environment. It is diagnosed through a positive Cocci skin test. So unless a doctor has reason to suspect Valley Fever through a good history, other causes of pleural effusion would be ruled out first. It is very easy to see how this diagnosis would be confused.
Popcorn Workers’ Lung
Another area of potential concern in the Interstitial Pulmonary Fibrosis arena is what is being collectively referred to as “Popcorn Workers’ Lung.”
Picture 7 – Popcorn Workers’ Lung
Bronchiolitis Obliterans is a rare life threatening form of fixed obstructive lung disease. Symptoms present 2 to 8 weeks after a respiratory illness or toxic exposure. There are 14 different toxic fumes which are known to cause this disease, including diacetyl, the agent in flavoring used in popcorn plants. Patients have a dry cough, shortness of breath, and wheezing, so it is often misdiagnosed as asthma, bronchitis, or pneumonia. It is diagnosed by history, spirometry (the measuring of breath), and CAT scan, with a normal diffusing capacity of the lung. It is irreversible and these patients may need a lung transplant. Prevention relies on early detection of abnormal spirometry.
Another area of potential concern is Interstitial Pulmonary Fibrosis and cancer from Wood Dust exposure. Wood dust exposure can cause pulmonary fibrosis and upper respiratory cancers of the nose, sinus, and larynx. These are associated with hard wood exposure. There are too few studies of any type to evaluate cancer risks attributable to exposure to softwood alone.
Currently, there are no consistent findings to indicate that occupational exposure to wood dust has a causal role in cancers of the pharynx, lung, lymphatic, and blood systems, or stomach, colon, or rectum.
To effectively manage and litigate these cases, attorneys must understand the primary diagnosis and the scientific causal link to the exposed toxins. The medical records provide critical information.
Start with a detailed review of the records and imaging studies. Understand not only the “Rule In” but the diseases that were “Ruled Out” and what tests were used to make a diagnosis. Does the diagnosis fit within the disease parameters? Understand the occupational exposure history. Identify all of the plaintiff’s symptoms with the numerous alternative causations possibilities to be explored. Understand the co-existing medical factors that potentiate the disease. Include the employment records in the medical record chronology to easily see the exposure symptom relationship. Use the medical records to determine which experts are needed. Get an early IME.
Benzene causes AML (acute myeloid leukemia), but does it cause all diseases in the universe of leukemia? With benzene known to effect bone marrow, there is a rather large leap that is being taken by plaintiff counsels to link exposure to all types of blood dyscrasias. Take non-Hodgkin’s lymphoma, which has gone from being relatively rare to being the fifth most common cause of cancer in the U.S.
Picture 9 – Lymphoma Incidence
This is something to worry about. From a risk management perspective, the numbers are big. As the fifth most common cancer, the incidence of lymphoma has risen 85 percent in less than 30 years. There are over five hundred thousand people with lymphoma today, 70 thousand new cases this year, with 20 thousand deaths annually.
The key to successful litigation in these cases is in getting a good handle on the medical aspects of the case early. It is Med Legal’s responsibility to abstract the critical information from the medical records, and to identify vital occupational respiratory disease indicators, even when a detailed occupational history is not available. This knowledge is critical to our Clients in making these cases winnable.