Human Health Effects Associated with the Commercial Use of Grunerite Asbestos (Amosite): Patterson, NJ; Tyler, TX; Uxbridge, UK
Asbestos does not refer to a single type of mineral, but to a family of six individual minerals that share common structural properties. The most common form of asbestos used in commerce was chrysotile. It is known as serpentine asbestos because of its short, curly fibers. The other five types of asbestos—crocidolite, amosite, anthophyllite, tremolite, and actinolite—are known as amphibole fibers and are characterized by long, rigid, needle-like fibers. The amphibole fibers are considered the most carcinogenic of the asbestos family, but all fiber-types are dangerous and are documented causes of malignant mesothelioma and lung cancer.
Amosite, known officially as grunerite asbestos, was one of the major amphibole fibers used commercially. It is considered among the most dangerous of the amphiboles, although its mechanisms of actions are not fully understood. In fact, scientists are still identifying the precise physiological effects that asbestos exposure has on the human body. Researchers from the National Institute of Environmental and Occupational Health in Israel have recently summarized the available literature on amosite in an effort to better understand its carcinogenic properties.
There have been three epidemiological studies on populations exposed to amosite in the workplace. The first study looked at a factory in Patterson, NJ. This factory closed in 1954 and then moved to Tyler, TX. The second study looked at the cohort of workers employed by the Tyler factory. The last study looked at amosite and chrysotile factory in Uxbridge, United Kingdom.
Record indicate that the Patterson, NJ factory only used amosite asbestos, so it makes an excellent study on the health effects of amosite exposure. A total of 820 workers were employed at the facility between 1941 and 1954 (the year the factory closed). It was an older, mainly white workforce. Through 1989, when the last study on Patterson was completed, 740 of the 820 employers had died and of those, 17 had mesothelioma. Previous studies reported at least 111 deaths attributable to lung cancer and 31 from asbestosis, but the 1989 study that listed mesothelioma deaths at 17 did not report on these other diseases. There were 8 cases of pleural mesothelioma and 9 cases of peritoneal mesothelioma. The average latency period of the disease was 31 years for both, but the mean duration of employment was quite different: 25.6 months for pleural mesothelioma and 43.8 months for peritoneal mesothelioma. Interestingly, the pleural group survived, on average, 12 months after diagnosis, while the peritoneal group only averaged 8 months. This is notable because peritoneal mesothelioma often presents with a slightly better prognosis.
The concentration of asbestos in the air was never definitely measured in Patterson, although estimates exist that place the levels between 14–75 f/ml. As a point of reference, current US regulations regarding asbestos concentration demand a figure of less than .1 f/mL.
After the Patterson factory closed, it was moved to a location in Tyler, TX, where the same equipment was reinstalled and used again. The cohort of workers studied here was employed between 1954 and 1972, when the plant closed for good. Unlike the Patterson location, air quality was measured and the levels varied between 15.9 f/ML and 91.4 f/ML for different parts of the factory. To put the latter number into prospective, with concentrations that high, a worker who only spent six months in that part of the factory would have a cumulative lifetime exposure level of greater than 45 f/mL years, which is 11-times higher than the 4 f/mL years figure for someone who worked forty-years at the current legal levels.
For workers of the Tyler, TX facility, 6 were diagnosed with mesothelioma, 35 with lung cancer and only three with asbestosis.
The last of the studies focused on a factory in Uxbridge in the United Kingdom. The factory was operational between 1947 and 1979. Between 1947 and 1972 the factory processed both amosite and chrysotile. Starting in 1972, the factory processed amosite only. The air quality of the Uxbridge factory got better over time. Although no studies were completed in the 1950s, exposure levels were estimated at over 100 f/mL. In 1964, efforts were made to reduce the dust that workers were exposed to and by the late 1960s, air studies returned a value of 30 f/mL for asbestos concentration. This was reduced to 2 f/mL by the early 1970s.
A total of 4820 workers were studied here. There were 5 mesotheliomas, of which 4 were pleural and 1 was peritoneal. There were also 57 cases of lung cancer and 9 of asbestosis.
The preceding descriptions indicate the malignant potential of grunerite asbestos. While asbestos exposure is always potentially harmful, certain forms of the mineral, such as amosite, are certainly more harmful than others. The studies summarized in this article clearly show that asbestos is too dangerous a substance for anyone to use.