Asbestos: An Overview

ASBESTOS

An Overview

What Is Asbestos?

• Silicate minerals – naturally occuring

• Separates into long flexible fibers

• Fireproof, used to resist heat and corrosion

• Non-conducting

• Chemically resistant

Six Minerals Defined as Asbestos

• Chrysotile

• Amosite

• Crocidolite

• Tremolite

• Anthophyllite

• Actinolite

Chrysotile

• Mg3(Si2O5)(OH)4 • Routes of exposure

include absorption by inhalation

• Long-term exposure is linked to pulmonary fibrosis and mesothelioma

• Serpentine series

Amosite

• (FeC2+Mg)6·Si8O22(OH)2

• Routes of exposure include skin contact, inhalation, and ingestion

• Known human carcinogen

• Amphibole Series

Crocidolite

• Na2O·Fe2O3·3FeO·8SiO2·H2O

• Routes of exposure include inhalation, skin contact, and ingestion

• Known human carcinogen – most hazardous of amphibole series

Tremolite

• Ca2Mg5Si8O22(OH)2

• Associated with Vermiculite

• Found in Libby, Montana

• Sold as housing insulation

• Sold as soil conditioner

• Recently discovered in CSI: Crime Scene Investigation Fingerprint Examination Kit

Anthophyllite

• (Mg, Fe)7Si8O22(OH)2 • Some forms are

fibrous and used as asbestos

• Used in refractory cements

• Known human carcinogen

• Found in talc

Actinolite

• Ca2(Mg,Fe)5Si8O22(OH)2

• Fibrous varieties used in industrial applications

• Once used as insulator, but was banned because it caused cancer

Effects of Asbestos Exposure

Mesothelioma – cancer of the mesothelium

Asbestiosis – breathing disorder

and

Lung Cancer

Mesothelioma

• Approximately 2000 cases per year are diagnosed in the United States

• Occurs more often in men than women

• A history of working with asbestos is reported in 70-80 percent of all cases

• Symptoms may appear 30 to 50 years after exposure

Asbestiosis

• Breathing disorder caused by inhaling asbestos

• Can cause scarring of lung tissue and shortness of breath

• Symptoms range from mild to severe

• Using safety precautions limits likelihood of contracting asbestiosis

Symptoms Safety Precautions

• Shortness of breath• Coughing• Chest pain• Decreasing tolerance

for physical activity• Permanent lung

damage

• Call professional to remove

• Wear safety equipment provided by your employer

• Respiratory air masks• Gloves• Protective eyewear

Lung Cancer

• Symptoms include:– Persistent Cough– Chest Pain– Weight Loss– Loss of appetite– Bloody or rust colored phlegm– Recurring bronchitis or pneumonia– Wheezing

Healthy Lung Cancerous Lung

Vulnerable Industries

• Shipbuilding• US Navy• Construction• Insulation• Oil & Chemical• Power Plant• Railroad

• Automotive• Steel/metal• Asbestos

manufacturing• Paper Mill• Ceramics/Glass

Vulnerable Occupations

• Pipefitter

• Boilermaker

• Maintenance

• Machinist

• Electrician

• Sheet metal

Non Occupational Exposure

• Contact with asbestos worker

• Proximity to asbestos mining operations

• Long term exposure in buildings constructed with asbestos materials

Uses for Asbestos:1950’s through the 1970’s

• Building materials

• Roofing tiles

• Pipe insulation

• Brake liners

• Fireproof clothing

• Oven mitts

Asbestos in Drinking Water

• Asbestos was used in concrete pipes that transport water

• Asbestos fibers bind the concrete and made the pipes lighter and easier to install

• 25% asbestos: 75% concrete• Originally intended to be used for irrigation• Cheap materials and readily available• Used in municipalities across the US and Canada• There is an estimated 200,000 miles of

asbestos/concrete pipe across the USA

Can asbestos that is swallowed cause cancer?

• Scientific studies to answer this question were conducted in the 1970s and 1980s

• Animal models and “natural experiments” were used

• Direct injection used in animal models included rats injected with asbestos directly into body cavities caused tumors

Direct Injection: Effects

• 41 rats injected with asbestos in the lung cavity

• 5 developed mesotheliomas in the abdomen

• 20 developed mesotheliomas of the lining of the lung cavity

Direct Injection: Effects cont

• 20 hamsters injected in the abdominal cavity• 15 developed abdominal tumors

• Rabbits injected with asbestos in the abdominal cavity developed tumors within 5 to 6 years

• Monkeys developed asbestiosis and precancerous lesions after injections into the trachea and pleura

Conclusions of Direct Injection through 1983

• Direct application into the body will cause cancer in animals

• It is likely that asbestos fibers can migrate to other tissues

• There are both positive and negative studies

• There is a question of the suitability of animal studies as they relate to humans

Humans and Oral Exposure to Asbestos

• Studies conducted using those humans who have been inadvertently exposed

• Comparisons made in communities with known and substantial amounts of asbestos in drinking water versus communities believe to have less exposure

• Information found to be inadequate to determine a credible risk of cancer due to asbestos in drinking water

Recommendations to limit exposure by ingestion

• Eliminate asbestos cement pipe in water systems

• Eliminate the use of asbestos filters in processing beverages and pharmaceuticals

• Reduce asbestos fibers in drinking water supplies

• January 29, 1986 – EPA proposed a prohibition of the manufacture of asbestos /cement pipe

Studies from 1980s until 2005

• A baboon was given asbestos orally and was found to have asbestos fibers in the spleen, stomach, heart, pancreas and blood

• Rats given asbestos fibers while pregnant had transmitted asbestos fibers to their pups

Woodstock, New York

• Study published in 2005

• Examined incidence of cancer between 1980 and 1998

• Town water asbestos contamination

• 304.5 million asbestos fibers from asbestos/ concrete pipes

• Pipes installed in 1950; discovered in 1985

The Study: Woodstock, NY

• 1852 people analyzed• Cancer rates observed between 1980 – 1998• Follow-up from 5 to 20 years• Comparison was with New York State and did not

include New York City• Pancreatic cancer was the only significant increase• Small numbers in study and minimal latency

period affected validity of conclusions

References

• Berry, M. (1996) Mesothelioma Incidence and Community Asbestos Exposure, Environmental Research 75, 34-40, 1997

• Browne, M. L., D. Varadarajulu, E. Lewis-Michl, and E. F. Fitzgerald (2004) Cancer incidence and asbestos in drinking water, Town of Woodstock, New York, 1980-1998, Environmental Research (2005), 224-232

• Jacobs, D. E. (2005) A qualitative review of housing hazard assessment protocols in the United States, Environmental Research (2006), 13-21

• Longley, A (ND) Asbestos in drinking water, Pacific Sciences Institute, Seattle, Washington

• Mineralogy database, updated 3/8/2009, accessed in May 2009 at http://webmineral.com/

• Occupational Safety and Health Administration (2002) OSHA Fact Sheet accessed on May 15, 2009 at http://www.osha.gov/OshDoc/data_AsbestosFacts/asbestos-factsheet.pdf

• Roggli, V. L., T. D. Oury, T. A. Sporn (2004) Pathology of asbestos-associated disease, 2nd edition, Springer