Environmental & Health Concerns

Groundwater/Surface Water

Several studies over the past 15 years have shown that the use of coal combustion products in construction projects has resulted in little to no impact on groundwater and surface water quality, but some precautions are necessary. The use of engineering standards and guidelines will help ensure that the use of coal combustion products does not negatively impact the environment.

Environmental concerns are largely determined by local circumstances, such as groundwater depth and proximity to drinking water wells. The studies mentioned above show that while leaching of constituents of coal combustion products is possible from unencapsulated uses, it does not occur in practice at high concentrations and has not been shown to migrate far from the site when appropriate engineering practices are followed.

Vegetation and Food Chain

EPA, in 2000, determined that the use of CCPs as a highway fill material or even as a substitute for lime in agricultural applications did not pose a risk of concern. In addition, several EPRI (Electric Power Research Institute) studies have shown that the use of CCPs in unencapsulated highway construction projects poses limited risk to roadside vegetation. Studies of road construction projects in Arizona, Arkansas, Georgia, Illinois, and Kansas indicate that while metal constituents from coal fly ash and bottom ash might enter plant tissues through absorption, the concentrations of these elements are found to be well below the toxic limits.

In addition, studies examining the effects of ingestion of constituents of CCPs by animals have not suggested any associated health problems. Some tests showed slightly elevated levels of some elements in blood and various organs, while other tests found no constituent increases. These results indicate little potential for elements of CCPs from construction projects to accumulate in soil and increase in concentration by food chain biomagnification (the process by which animals feeding on affected plants can, in turn, accumulate the same constituents and build up these constituents in their tissues).

Air Quality and Inhalation

Air inhalation of dust from CCPs is primarily a worker safety issue. Nevertheless, proper precautions should be taken to protect the public from dusting during delivery and construction, when CCPs are first laid down. CCPs can become airborne during storage and processing, from traffic on roads, and through wind erosion during placement. Dust is not an issue when CCPs are used in concrete or in a slurry form.

Occupational Concerns


Workers involved with handling dry CCPs, concrete grinding, or demolition activities can come in contact with fugitive dust containing CCPs. Health risks associated with the inhalation of these fugitive dusts in occupational settings can be limited by following Occupational Safety and Health Administration (OSHA) standards and practices. These standards and practices are applicable whether or not CCPs are used in concrete. Workers should request Material Safety Data Sheets (MSDS) from coal combustion product suppliers when they are not sure of the proper precautions.
Skin Contact

Power plant workers and people involved in producing cement, concrete, or other ash based products can have skin contact with CCPs. In construction applications, skin contact is likely limited to workers working with dry CCPs. While most contact with CCPs can be controlled by proper handling and construction safety practices, if contact does occur, CCPs can cause skin irritation or contact dermatitis.

Environmental Toxins


Although mercury in CCPs can potentially be released into the environment through leachate in water or as emissions to the ambient air, studies conducted by the University of North Dakota Energy and Environmental Research Center and the University of Nevada, which tested bituminous, subbituminous, and lignite coals, have shown that mercury releases from CCPs to the environment are negligible. Results from water leachate tests showed that mercury was very stable in CCPs and leached less than 1 percent of the initial mercury concentrations. Studies on the release of mercury from CCPs to the ambient air show only minute losses to the environment.

EPA has proposed a new regulation called the Clean Air Mercury Rule (CAMR) that would require reductions in mercury emissions from coal-fired power plants. This proposed regulation might affect the amount of mercury found in CCPs, but whether this regulation will increase mercury concentrations in CCPs or not is not clear at this time because this is the first time ever that EPA has regulated mercury emissions from power plants. EPA’s conclusions in this document are based on the regulations currently affecting power plants. EPA will reassess its position if it appears that there is a significant increase in the level of mercury in CCPs after the CAMR is promulgated.

Radon and Radioactivity

Coal contains naturally occurring radioactive elements. After combustion, these elements and their decay products can remain in CCPs. EPA has classified CCPs as diffuse, naturally occurring radioactive materials, which is EPA’s most benign radioactive classification.

Studies have shown that the level of radioactivity in combustion products is about the same as the level found in surface rocks and soil. A long-term Tennessee Valley Authority study of a 42-acre site that used more than 1 million cubic yards of fly ash in structural fill indicated that ambient radon levels measured directly over the fly ash fill were comparable to the levels measured in control areas without fly ash. Studies have also shown that radon releases from concrete blocks manufactured using coal fly ash are well below EPA’s radon action levels.