Asbestos was strong, durable and heat resistant, “so it was used in lots of products,” says mesothelioma lawyer Joseph Belluck. “Every year we learn about more and more products that asbestos was used in.”
Belluck was among the speakers at the 10th annual Upstate Cancer Symposium, which focused on occupational cancers. He pointed out that asbestos is still used industrially today, “and there are still many people being exposed to asbestos every day in this country.”
Jerrold Abraham, MD, provided this image from a paper he co-authored in 2002 in the American Journal of Respiratory and Critical Care Medicine, from a case about someone who died from asbestosis 50 years after a brief exposure in a Vermiculite expansion plant.
Lung cancer, bladder cancer and the aggressive cancer of the lining of the lungs and abdomen called mesothelioma account for the majority of work-related cancers in America. Belluck told symposium attendees that patients diagnosed with mesothelioma in the United States have the cancer because of asbestos.
Because mesothelioma has a lengthy latency period, people may not develop symptoms for 10 to 40 or more years after exposure. An estimated 27.5 million people were exposed to asbestos from 1940 to 1979. Early symptoms can be vague: pain in the lower back or side of the chest, shortness of breath, cough, fever, excessive sweating, fatigue, weight loss, trouble swallowing and swelling of the abdomen, face or arms.
Some 3,000 people from a variety of occupations are diagnosed with mesothelioma each year. Among them are shipworkers, construction workers and people who worked in steel mills and factories, but also school teachers, carpenters and electricians.
Michael Lax, MD, medical director of Upstate’s Occupational Health Clinical Center, says that assessing a person’s exposure to cancer-causing chemicals including asbestos over a lifetime is tricky to do with accuracy. He says at least 24,000 to 60,000 deaths per year are thought to be attributable to occupational carcinogens.
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“The estimates we have should be considered under-estimates,” Lax says, because only 2 percent of chemicals are tested for carcinogenity before they are put into use. He says that makes American workers unwitting participants in a giant experiment to determine which workplace chemicals may lead to disease. While other organizations recognize more than 110 substances as carcinogenic, the federal Occupational Safety and Health Administration regulates only 27 as cancer-causing.
Lax and Belluck say it’s important for doctors to recognize if a cancer is work-related so that patients can seek treatments that may be effective and compensation to pay future medical bills. Also, such documentation can help researchers trace cancer causes, and possibly lead to safer workplaces.
The first asbestos-related death was documented in 1906, Belluck says, adding that today’s laws regarding workplace safety make companies responsible not just for what they knew, but for what they should have known. The link between asbestos and mesothelioma has been clear since the 1960s, and the link between asbestos and lung cancer since the 1930s, says pathology professor Jerrold Abraham, MD, another speaker at the symposium that attracted cancer specialists and medical students.
Patients may be aware of asbestos exposure, and that should make a doctor aware of the risk for developing mesothelioma, which is diagnosed with imaging tests such as X-rays and computerized tomography, and biopsies. Abraham emphasized that occupational exposures may be evident in patients’ biopsy tissues, but may go unnoticed by inexperienced pathologists.
Hopefully soon, a blood test will be able to aid in diagnosis.
Upstate Cancer Center Medical Director Leslie Kohman, MD introduced a mesothelioma expert at the symposium by saying, “Imaging and history are important, but they will eventually be eclipsed by what we can learn from blood biomarkers.”
Harvey Pass, MD, chief of thoracic oncology at New York University Langone Medical Center, spoke of his dream to be able to screen people for asbestos-related diseases such as mesothelioma before they develop symptoms, or to determine which genes make one susceptible to the disease.
“The earliest we will actually have a validated biomarker is probably within the next four or five years,” Pass told the symposium group.
Already, a molecule has been identified that promotes the growth of mesothelioma. A blood test can tell the difference between someone who was exposed to asbestos and someone with mesothelioma. And, 25 percent of patients with the disease have been found to have a particular genetic mutation.
So, progress is being made.
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27 cancer-causing chemicals
The Occupational Safety and Health Administration regulates these substances as cancer-causing:
- asbestos
- 4-Nitrobiphenyl
- alpha-Naphthylamine
- Methyl chloromethyl ether
- 3,3′-Dichlorobenzidine (and its salts)
- bis-Chloromethyl ether
- beta-Naphthylamine
- Benzidine
- 4-Aminodiphenyl
- Ethyleneimine
- beta-Propiolactone
- 2-Acetylaminofluorene
- 4-Dimethylaminoazobenzene
- N-Nitrosodimethylamine
- Vinyl chloride
- Inorganic arsenic
- Hexavalent chromium
- Cadmium
- Benzene
- Coke oven emissions
- 1,2-dibromo-3-chloropropane
- Acrylonitrile
- Ethylene oxide
- Formaldehyde
- Methylenedianiline
- 1,3-Butadiene
- Methylene chloride
Silica is one example of a substance that is not on the list, despite the World Health Organization and the Centers for Disease Control and Prevention saying it can cause cancer.
