Laboratory Analysis: A Look at Asbestos Exposure in a Clinical Environment
You went to college. You got a steady job in a laboratory doing important work for a hospital or a chemical plant or a university. The employment was interesting and you were relieved to not be toiling in an industrial setting or at hard manual labor. All those hours of studying paid off with a career that allowed you to wear nice clothes beneath your lab coat. You worked 9:00 to 5:00 and had weekends off. You knew there were risks associated with occasional chemicals you might have encountered in your vocation, but you paid attention and were careful to follow the instructions provided with the protective gear and literature at hand to assure your safety. But what you might not have known is that there was another danger lurking in the lab: the use of asbestos materials everywhere!
Asbestos, a fibrous, naturally occurring mineral mined from the earth, was found as early as 3000 B.C. to be fire and heat resistant. Ancient Greeks named the mineral asbestos, meaning inextinguishable. By the early 1900s, asbestos was widely used throughout the civilized world in all kinds of products, ranging from industrial fireproofing and insulation to building materials like asbestos cement boards, powdered plasters and roof, ceiling and floor tile.
Known since the 1930s to cause lung disease, cancers and eventually found to cause the deadly asbestos cancer, mesothelioma, asbestos was eliminated from most products by the late 1980s. If you didn’t work at an industrial site or in a commercial building trade, you might have assumed that you escaped the danger of exposure to asbestos in your work environment. But technicians throughout the middle of the last century suffered a surprising amount of inadvertent exposure to asbestos-containing equipment in a laboratory setting. Here is a sampling.
Bunsen Burner Diffuser Mats
Where there’s fire, there’s asbestos. From the 1930s through the 1970s, laboratory workers frequently used asbestos pads or mats to diffuse heat on a Bunsen burner when a laboratory product, whether liquid or solid, needed to be heated in a gentle, steady manner. This mat, often woven from pure asbestos fiber, diffused heat from the intense flame evenly across the its width, providing a more precise and gradual rise in temperature of the product being heated. Once worn, these fibrous mats deteriorated, releasing microscopic asbestos strands into the air all around the lab worker.
A centrifuge separates a mixture of solid and liquid by spinning it at an incredibly high speed. After spinning, the solids settle to the bottom of the test tube, leaving the remaining solution clear, making centrifugation a valuable tool in a laboratory. Because rotation at high speed generates heat, insulation is needed to keep the solution cool while spinning or to regulate temperature if heat is desired. Insulation also keeps the machine from becoming too hot to touch by the lab technician. Many early centrifuges were lined with asbestos insulation and frequently, when the centrifuge malfunctioned or broke down, a maintenance worker would overhaul it right there in the lab, taking apart the sides of the unit and exposing the insulated walls or end plates.
Due to the microscopic size of asbestos fibers, asbestos based filtering devices were widely used in many industries for the filtration of very fine materials from liquids and gases. Both chrysotile and amphibole asbestos fibers were used in fiber and powder form for filtration of fuel and industrial oils, and were especially helpful in the chemical industry, where asbestos was used for filtering acids and other corrosive and caustic fluids since it was naturally resistant to those substances. In these and other laboratory applications, asbestos filters were generally re-cleaned, acid washed, or purified, and then used over and over again. Eventual breakdown of the screens released the toxic asbestos fibers into the air.
A fume hood is a ventilation device designed to limit exposure to toxic or hazardous fumes, vapors or dust in the laboratory. There are ducted exhaust hoods, which are vented outside, and there are ductless hoods, which filter the vapors and then recirculate them. Starting in the 1940s, fume hoods were typically designed to protect the laboratory technician and were most commonly used in laboratories where hazardous or noxious chemicals were released during testing, research, development or teaching. Fume hoods remove dangerous chemical fumes by drawing air from the front, where the laboratory technician is working, and pushing those fumes through the exhaust ventilation or ductless filtration system. Fume hoods from the 1940s through the 1970s were often lined with asbestos-cement panels, known as transite, which made them more resistant to corrosive chemicals and heat, and some college campuses in the United States were known to still have asbestos-lined fume hoods in their laboratories as recently as 2012. While maintenance on fume hoods generally did not require exposing the asbestos lining, damage to a fume hood through earthquake, severe weather, fire or corrosion would have released the lining’s hazardous fibers into the laboratory air.
The microscopic fibers of raw asbestos made it ideal for weaving into protective textiles such as lab coats, aprons, mitts and blankets, all resistant to high temperatures, flame and corrosive substances. Since the early 1900s, when several cotton mills in North and South Carolina were converted into asbestos textile factories due to an abundance of naturally occurring asbestos in both states, protective clothing and acid-proof mitts have been made using up to 100% asbestos fiber. Once these textiles became worn and began to fray or were damaged with constant use, the asbestos fibers became airborne and were inhaled by the technician wearing them.
Don’t think that because you had a college education and a white-collar job you were immune from exposure to the hazards of asbestos. Laboratory workers and other professionals had plenty of opportunity for exposure to the deadly carcinogen in the workplace. Asbestos disease has never been the exclusive domain of the blue-collar worker. This terrible killer, and the manufacturers who incorporated it into so many products, did not discriminate.