Thursday, May 10, 2007

Who Is Exposed?

Exposure to asbestos is much more common than believed. However, certain industries and workers are much more likely to be occupationally exposed to asbestos.

Due to its properties of heat resistance and impermeability, asbestos use tended to focus heavily in the mechanical, construction and ship building industries. The construction business has the largest number of trades involved with past exposure or current exposure to legacy asbestos. These include the following trades: plumbers, electricians, roofers, pipe fitters, sheet metal workers, masons, carpenters, drywallers, painters, tile setters, plasterers, insulators, joiners and common laborers.

The shipbuilding industry and the navy, which used the ships, are where most military personnel were exposed. Trades here include: steamfitters, ironworkers, welders, boilermakers, ship fitters, machinists, electricians, millwrights and operating engineers.

The above is hardly an exhaustive list and effectively illustrates the scale of the problem. Hardest to accept is the fact that no level of exposure is deemed safe when dealing with asbestos and consequently a significant cadre of patients has appeared in the category of secondary or stealth exposure. Examples here are family members of asbestos workers, who were exposed through contact with contaminated clothing or tools brought home from work. The general laborer category fails to adequately identify those casual, summer, or part-time workers who assisted the principal trades. They would be cleaning up work sites, removing debris or doing light, unskilled labor in a contaminated environment. This often took place without adequate or even any protective equipment.

A substantial number of white collar workers who work in contaminated office spaces, schools or businesses have also developed mesothelioma. This group includes teachers and other office workers not associated with industrial or work-related asbestos exposure.

The stealth element comes from the lack of understanding of where and why asbestos was used in construction. Many of the buildings containing asbestos remain standing today. Since 2000, many cases of stealth exposure have been in the news. As an example, school workers in Texas were exposed while re-glazing school windows where asbestos laced putty had been used. In this case, not only the workers but students and teachers using those class rooms were exposed to asbestos dust and debris without any protection whatsoever.

New sources of exposure are being identified constantly, such as environmental exposure. In certain areas of the world, asbestos occurs naturally and can be found on the surface where it is easily disturbed. Examples of problems are the growing expansion of the population and new housing development that has followed. Sometimes this has encroached upon heavily asbestos contaminated soils, potentially exposing the future residents to long term, low level amounts of asbestos.

The tainted vermiculite problem is another issue where millions of homes have been insulated with vermiculite filler that will release asbestos when disturbed. Home renovations, new wiring or furnace repairs may all cause unwitting workers to release clouds of asbestos dust that will expose both themselves and the building occupants to danger.

In summary, not only blue collar trades are at risk from asbestos induced mesothelioma. Many people in "safe" occupations and individuals who do not believe themselves to be at risk may well be on track to developing this tumor in the future. Even once asbestos is someday banned in the U.S., all the individuals who have already been exposed, and all those who will continue to be exposed to the asbestos already present in our environment, will remain at risk for mesothelioma’s suffering and death unless effective treatments are developed now.

The Hazards of Asbestos

For all its wonderful properties, asbestos was also recognized early on as the cause of respiratory diseases. The Roman historian Pliny the Elder noted that the slaves who worked in the asbestos mines were less healthy than other slaves. (g) He recommended that such slaves not be purchased since they would “die young”.

Pliny the Elder wasn’t the only sage to notice that asbestos wasn’t mother’s milk. Strabo, a 1st century geographer, also observed the rise of health problems among asbestos workers. Since it was noted that asbestos exposure caused primarily a respiratory disease, Pliny the Elder suggested the use of a respirator made of transparent bladder skin to protect workers from asbestos dust. (i)

Modern medicine first documented an asbestos-related death in 1906. Insurance companies began to cut their coverage of asbestos workers. Soon, medical reports began to identify a mystery tumor. The term mesothelioma entered the medical literature in 1931 when it was identified Klemperer and Rabin, and by the 1940’s it was being associated with asbestos exposure. Still, at the urging of industry, public authorities and the medical establishment continued to resist recognizing the connection between mesothelioma and asbestos. Finally, the link became incontrovertible with a 1960 article published in Lancet entitled "Primary Malignant Mesothelioma of the Pleura."

During this time, the growing awareness of the connection between asbestos exposure and asbestosis and mesothelioma eventually brought some government regulation. (Contrary to popular belief, to this day asbestos has not been banned in the U.S., though it has in numerous other countries.) It also brought litigation. During trial discovery proceedings it became clear that the asbestos industry had known about the hazards of the product for decades. Moreover, they had conspired to hide the facts from both their workers and the consumers of their products. This disregard for the health and safety of both employees and consumers led to thousands of successful lawsuits and settlements against asbestos vendors. Over time this led to over sixty companies seeking refuge in Chapter 11 bankruptcy protection.

History of Asbestos Use

Marco Polo encountered asbestos in China where it was called salamander’s wool. The ancients had many names for asbestos, calling it "mountain leather," "incombustible linen," "rock floss," and “lapis asbestos”. Defined by its uses, the strange material could be braided into rope or used as insulation. The use of oil lamps for illumination was a major application before the invention of the incandescent light bulb. Once braided, asbestos could be turned into a wick that was both indestructible and cheap. Charlemagne had a napkin made from asbestos that he would purify by throwing into a fire.

At the dawning of the industrial age, machinery, steam, and fire became catalysts for the more widespread use of asbestos. By the 1860’s asbestos began appearing as insulation in the United States and Canada. Thousands of different uses appeared by the middle of the 20th century. These included fire retardant coatings, concrete, bricks, pipes and fireplace cement, heat, fire, and acid resistant gaskets, pipe insulation, ceiling insulation, fireproof drywall, flooring, roofing, lawn furniture, drywall joint compound and on and on. Its widespread use caused an avalanche of mesothelioma cases that continues to this day.

What is asbestos?

Asbestos is usually thought of as a single mineral, or at least a family of minerals that is well defined and universally recognized. This is false. In fact, "asbestos" was a label created by the need to describe a group of six commercially available mineral fibers, namely actinolite, amosite, anthophyllite, chrysotile, crocidolite and tremolite (z) in litigation.

Figure B: Amosite Asbestos, The second most common type. Photo: New York State department of Environmental Conservation

The need for the catch-all “asbestos” became apparent when exposure to the fiber and its many products proved hazardous. Lawsuits by the first wave of injured workers led to the creation of an “approved list” of mineral specimens by the EPA, negotiated by the government, asbestos manufacturers, and lawyers representing the injured. It was and it remains an economic and political term, not a scientific one. (e)

Figure C: Tremolite Asbestos, Photo: New York State department of Environmental Conservation

As a result, the term asbestos doesn’t include all the possible fibrous mineral forms of impure magnesium silicate that behave like asbestos. Many of these could be considered just as carcinogenic, if not more so. Examples abound; there are Taconite mines in the United States, and while Taconite isn’t on the asbestos list, its carcinogenic track record certainly qualifies it as a health hazard.

Erionite is another fiber that is missing from the list and was recently identified as a particularly toxic asbestiform fiber. Erionite was found in the home building materials used in Turkish villages of Karain and Tuzkoy. It has been implicated in the deaths of hundreds of villagers over the years. (f) It is no longer disputed that Erionite causes mesothelioma and belongs on the registry of asbestos-like minerals. (ac) Deposits of Erionite have been found in San Bernardino County, California and it may well be found elsewhere in the world.

There are two basic forms of asbestos fibers: amphiboles, which are straight needle-like fibers, and serpentine asbestos, which consists of curled and more pliable fibers. Early studies seemed to indicate that only amphiboles caused cancer and there was a vigorous debate concerning conflicting studies as to whether Chrysotile asbestos was carcinogenic.
Recent research has proven that Chrysotile fibers do cause mesothelioma but but that Tremolite and Crocidolite are even more potent.

Figure D: Crocidolite Asbestos, Photo: New York State department of Environmental Conservation

The list of cancer-causing mineral fibers that should be classified as asbestos is still growing. Banning just those fibers known today as asbestos would resolve only a fraction of the problem. The continuing issue of exposure to asbestos-like materials and their health hazards is unlikely to go away in the foreseeable future.

Understanding Asbestos

In the twentieth century, asbestos was called the “miracle fiber” (b) and found its way into thousands of household and industrial products.

Figure A: Chrysotile Asbestos, The most common form. Photo: New York State department of Environmental Conservation

Such widespread exposure to the natural material has injured generations of workers and created a mountain of litigation that has driven numerous American companies to seek refuge in Chapter 11 bankruptcy. The media has only recently begun to cover the subject of asbestos and its medical as well as economic impact. The 2005 indictments of W.R. Grace Executives, for failing to protect their workers and the general public from exposure to asbestos-tainted vermiculite, has succeeded in making asbestos poisoning prime time news.