While the work that farmers do today is different from the work performed during the height of asbestos use in the mid-20th century, asbestos exposure remains a risk to farm workers.
The farming industry has changed a lot thanks to advances in technology. Farmers today produce twice as much food as their parents did using less land, water and energy.
Much of the equipment and machinery used on farms is known to contain asbestos products. Older farm buildings — including farmhouses, barns, silos, pens and sheds — are highly likely to contain asbestos construction materials.
Farmers may also be exposed to asbestos in contaminated vermiculite products or contaminated soil in areas of naturally occurring asbestos.
According to a 1998 study on respiratory health hazards in agriculture, asbestos has long been a documented respiratory hazard to farmers. As early as 1967, researchers were investigating high rates of asbestosis among agricultural workers.
Asbestos in Farming Equipment and Machinery
The following asbestos-containing products were commonly found on farming equipment or machinery:
- Under spray
- Insulation panels
- Hood liners
Additionally, asbestos cement pipes were commonly used as field drains.
Farmers who replace brake linings on tractors are especially at risk of potentially harmful asbestos exposure. Dust-free, wet methods of brake replacement are recommended to limit exposure. Make sure to purchase asbestos-free brake lining replacements, which tend to cost more than traditional brake linings.
Asbestos in Farm Buildings
Most farms in the U.S. are likely to contain asbestos building materials.
Examples of asbestos-containing materials in farm buildings include:
- Roof sheets
- Building partitions
- Insulation materials
- Spray-on coatings
- Exhaust pipes
The U.S. Environmental Protection Agency requires farmers to notify local agencies if they plan to renovate or demolish buildings on a farm that contains a certain threshold of asbestos. The EPA also requires specific safe practices for asbestos removal and disposal.
Farmers are also required to inform farm workers of areas that contain asbestos so workers can take precautions to avoid exposure.
Vermiculite is a natural mineral that has been used in a variety of products such as brake linings, fireproofing materials and potting soils.
An asbestos-contaminated vermiculite mine in Libby, Montana, is reported to have produced 80 percent of the world’s supply of vermiculite when it operated from the 1920s through 1990.
A 1963 study of the Libby vermiculite found it contained 6.2 percent to 22.5 percent tremolite asbestos. It also contains other fibrous asbestiform minerals including winchite and richterite.
This contaminated vermiculite was used by farmers throughout the U.S. for agricultural and horticultural purposes, including:
- Animal feed
- Seed encapsulation
- Soil conditioner
- Potting mix
- Root cuttings
- Seed germination
- Sowing composts
A 1984 study of workers in an Ohio fertilizer plant using Libby vermiculite found an increased incidence of pulmonary changes typically caused by asbestos exposure including pleural plaques, pleural thickening and pleural effusion.
Samples of work areas in the plant revealed tremolite asbestos fibers. Farmers who used Libby vermiculite are also at risk of developing asbestos-related diseases.
Asbestos in Soil
Farmers may also be exposed to asbestos in the soil of their fields. Asbestos in soil may occur naturally, or it may have been added to the soil as a vermiculite-based fertilizer or conditioning agent.
Farms located near naturally occurring asbestos deposits may have the toxic mineral in their soil.
- A 2005 study reported residential proximity to naturally occurring asbestos in soil and rocks in California is directly related to an increased incidence of mesothelioma in farmers. The closer a farm or residence is to naturally occurring asbestos, the higher the risk of developing mesothelioma. For example, a town northeast from Sacramento, California, called El Dorado Hills is being monitored by the EPA for its naturally occurring asbestos. Farms in and around the town may contain elevated levels of asbestos in the soil.
- Farms located in southern Nevada and northwestern Arizona are within an area of naturally occurring asbestos. Winds have transported asbestos throughout the region, leading to exposure in urban and rural settings.
- A case report of a man with pleural mesothelioma documented that his exposure took place on the farm where he grew up in Mexico. His exposure was to erionite, a mineral that is nearly identical to asbestos, occurring naturally in the soil on his family farm. The farm was located along an erionite-rich region that stretches from northern Mexico up into the Sierra Nevada mountain range. This region also contains naturally occurring asbestos deposits including actinolite asbestos. Other asbestiform minerals in the region include winchite and richterite. Scientific studies have documented higher-than-normal rates of mesothelioma in this region.
- Farmers in the Basilicata region of southern Italy have higher rates of mesothelioma because of exposure to tremolite asbestos in the soil. A 2012 study showed agricultural activities increased exposure to asbestos fibers from the natural limit of two fibers per liter of air to 23.6 fibers per liter.
The overall risk of asbestos exposure to the majority of farmers is relatively low. However, farmers who unknowingly work on lands contaminated with asbestos fibers may face a moderate to high risk of exposure.
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