3.7. SR 10-06-2008 - Laserfiche WebLink

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' ~ fume is generated at 482 degrees Fahrenheit than at 320 degrees Fahrenheit. An estimate from besafenet.com is that "a small asphalt plant producing 100,000 tons of asphalt a year may release up to 50 tons of toxic fugitive emissions into the air" and "stagnant air and local weather patterns often increase the level of exposure to local communities". It is important to note that hot mix asphalt plants must be licensed by the Minnesota Pollution Control Agency (MPCA) for air and water quality issues. Each hot mix plant has a "baghouse" where the majority of chemicals are removed from the air prior to being released to the atmosphere. Hot mix asphalt plants must also submit reports to the MPCA annually, regarding the amount of materials used and total amounts of emissions. Approximately 350,000 asphalt application workers reside in the United States (with approximately 46,000 workers being in the roofing industry). In researching asphalt fume information, it was difficult to find any data regarding "safe exposure limits" for asphalt fumes since complete studies have not been done or levels have not been adopted. For example, fume studies have been conducted at temperatures well below those used in the field (226 degrees vs. 320 or 482 degrees used in field operations). OSHA currently has no permissible exposure limit for asphalt fumes. The original proposed level of exposure was 5 mg/cubic meter in an eight hour work period. Several studies have been done regarding possible effects on human health by NIOSH (National Institute for Occupational Safety and Health). PAHs have been found to "interact with DNA", meaning that mutations may occur due to DNA damage. Airway irritation and airway hyper-reactivity have also been associated with asphalt fumes. Studies have also been conducted on runoff from asphalt pavements to determine environmental toxicity. The main finding with regard to these studies has been that the majority of chemicals in runoff have come from vehicles using the roads or chemicals placed on the roads or roadsides (i.e. de-icers, pesticide/herbicide, crankcase oil, emissions, etc.) rather than the bituminous surfaces themselves. In fact, asphalt has been used to line fish rearing (aquaculture) ponds with good results. Fume, the microscopic chemicals that have evaporated from the hot mix material, is the portion of asphalt most likely to cause health issues for people working with and exposed to asphalt. Fume is obviously inhaled but can also be absorbed through the skin. The main areas of concern for high levels of fume generation and exposure appear to be at the gauging and loading/unloading areas. This would make the most dangerous situation for those workers who are perpetually exposed to the asphalt fumes. Asphalt workers in the roofing industry have the highest risk of forming cancer. Epidemiological information has shown death from cancer of the stomach, respiratory system, and urinary system. Other health effects from asphalt fume exposure include irritation of the eyes, respiratory tract, asthma, bronchitis, and emphysema. Of course, asphalt also poses a threat of severe burning if it comes in contact with bare skin (due to both high heat temperatures and flammability). A Harvard study regarding work risks of asphalt recommended that "to prevent exposure to asphalt" one should work upwind as much as possible, heat the asphalt to the minimum temperature necessary to maintain the quality in order to reduce fume generation, prevent skin contact by wearing protective clothing (long sleeves and gloves), and use ventilation on paving machines. A "State Compensation Insurance Fund" document recommended isolating asphalt operations to minimize worker exposure and to transfer the asphalt automatically by pump whenever possible as well as enclosing the mixing and stirring operations. Ultimately, it appears that there remains a controversy amongst scientists concerning the potential for asphalt to cause serious health issues such as cancer, mainly due to length of exposure (in number of years as opposed to hours or minutes) and other circumstances (such as whether the workers smoke and whether