HEALTH EFFECTS OF ASBESTOS EXPOSURE Asbestos is a
HEALTH EFFECTS OF ASBESTOS EXPOSURE
• Asbestos is a hazardous air pollutant • An inhalation hazard in humans • An airborne human carcinogen • If asbestos is allowed to float in the air, and is inhaled, asbestos disease may result. • If asbestos is not allowed to become airborne, there is little or no hazard to humans.
RELATIVE EXPOSURE HAZARDS • Passive or ambient exposure - normal background - passive exposure - low disease potential • Occupational Exposure - workplace exposure - on-going basis - high disease potential
OCCUPATIONAL EXPOSURE • An ongoing exposure as a result of the work being performed, perhaps for a working career: Historically: Factory workers Shipyard workers Today: Construction Industry Maintenance Industry
OCCUPATIONAL EXPOSURE Most of our early data on the health effects of asbestos exposure came from heavily exposed populations in manufacturing and application. Entire populations in factory settings eventually died of this very high unprotected exposure. Since we have not used asbestos in this way since about 1980, this exposure no longer happens. Today, harmful exposure is mainly in the construction industry where employees unknowingly disturb the asbestos materials that are in place in buildings and facilities.
PASSIVE EXPOSURE The next slide shows various ambient air levels, from a very high level measured in New York City in the early 80’s to a low level measured outside buildings in Phoenix, AZ in the 1990’s. The middle 3 are agency threshold levels. The U. S. Army number is what the Corps of Engineers has used as an asbestos clearance level for asbestos projects in buildings, meant to represent the limit of accurate detection of regulated fibers in the air using the PCM microscope.
PASSIVE EXPOSURE The ambient air: New York . 2 f/cc OSHA PEL . 1 f/cc EPA clearance . 01 f/cc U. S. Army clearance . 005 f/cc Phx. background . 0006 f/cc
The NYC number at. 2 f/cc is very high for an ambient air sample. This is probably due to 2 issues, one is the asbestos brake shoe use at that time, and the other is from uncontrolled demolition and renovation activities in that building environment. The second number (0. 1 f/cc) is the current OSHA Permissible Exposure Limit (PEL) for an 8 hour day. The third is final clearance under AHERA (completion of response action; OK for reoccupancy). The forth number at. 005 f/cc is final clearance from a Corps of Engineers specification. The last number is average Phoenix, AZ background taken outside buildings, probably typical of city environments in the Western U. S. The question is, ‘what do these numbers mean’? The following slide represents ambient exposure at. 005 f/cc over a life of 50 years, with no occupational exposure. Still, the accumulated body burden of asbestos fibers is very high. Asbestos disease usually comes from adding occupational exposure on top of normal exposure.
INHALED ASBESTOS FIBERS Average 50 year old person at average background exposure (. 005 f/cc): . 005 x 20, 000 (20 lpm) = 100 x 60 (min. / hr. ) = 6000 x 24 (hr. / da. ) = 144, 000 x 365 (da. / yr. ) = 52, 560, 000 x 50 = 2. 6 Billion fibers
DISEASE PREVENTION • Dr. Selikoff’s One Fiber Theory: - One fiber of asbestos, properly placed in lung tissue, has the potential to cause a tumor. • There is no cure for the disease. • Asbestos disease is dose-response related. • Prevention of exposure will prevent disease.
ANATOMY AND THE DISEASE PROCESS Pleural membrane Upper respiratory Bronchial tubes Alveoli area Peritoneal membrane Mesothelioma occurs on the pleural & peritoneal membranes Lung cancer oc the bronchial tu of the lung Asbestosis occurs
ASBESTOS DISEASES • LUNG CANCER • ASBESTOSIS • MESOTHELIOMA
LUNG CANCER • A cancer of the lung tissue • The most common asbestos disease, therefore the most important • The 5 year survival rate of lung cancer victims is about 7% regardless of treatment • Latency Period = 20 - 30 years • The incidence of lung cancer in occupationally exposed smokers is about 90 times that of the general population
ASBESTOSIS • A scarring of the lungs at the alveoli • Inhibits oxygen transfer to the blood • Latency Period = 15 - 20 years • Diagnosed disease may continue to progress regardless of current exposure
MESOTHELIOMA • A cancer of the tissue which surrounds the lungs and the intestines • An asbestos marker disease • Latency period: 30 - 45 years • No treatment • Uniformly fatal within about 6 months of diagnosis • At least 3 times more common in the abdominal area than in the lung area.
By far, the majority of asbestos disease cases on record are from very heavy, unprotected occupational exposure. However, there are cases on the record of asbestos disease with no occupational exposure at all, although these are rare. Knowing that these two extremes are real, it only makes sense to minimize any further asbestos exposure.
PUBLIC HEALTH SERVICE ASBESTOSIS MORTALITY STUDY 1996
The following data slides show that the death rate from asbestosis is steadily increasing in the U. S. The most affected industry, of hundreds of industries in this country is construction. Your work is considered construction industry work. Janitor and custodial is listed in the top 10 occupations affected by asbestosis death. Mesothelioma deaths are twice as high as asbestosis deaths, and are increasing at a faster rate. All this is in the industry that you work in. The reason for this is simply that people in the construction industry ignore these facts. They don’t know about asbestos issues. They think that they are not asbestos workers. Everyone in the construction industry is an asbestos worker.
Asbestosis death rate is steadily increasing in the U. S.
CDC REPORT 2002 Asbestos Mortality
CDC 2002 Report Each successive report shows an increase in the death rate
CDC 2002 Report
CDC 2002 Report
CDC 2002 Report
CDC 2002 Report
ENVIRONMENTAL WORKING GROUP (EWG) 2004 REPORT
www. ewg. org is the website for both Environmental Working Group and EWG Action Fund
The Asbestos Epidemic Deaths from Asbestos-related diseases Number of deaths per year Disease Mesothelioma 1 2, 509 Asbestosis 2 1, 398 Lung Cancer 3 4, 800 Gastro-intestinal cancer 4 1, 200 Total 9, 907 www. ewg. org is the website for both Environmental Working Group and EWG Action Fund
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