People have used asphalt for decades as a means of paving roads, airport runways, paths and floors. It is even used under water to help control beach erosion. Though the Environmental Protection Agency has approved it, the carcinogenic and toxic compounds in asphalt have made it an environmental concern. Exposure to the chemicals that make up asphalt can cause adverse health effects in both humans and animals.
Effects on Ecosystems
Trace levels of polynuclear aromatic hydrocarbons (PAHs) in asphalt fumes make it a potential environmental threat, particularly for delicate ecosystems. Even though the effects of decomposing asphalt within aquatic habitats remains inconclusive, its toxins and carcinogens may eventually leak into rivers, streams and other water sources. PAH compounds have been found in some water pipes.
Effects on Humans
One of the most common human exposures to asphalt is by inhalation. Throat and eye irritation, skin rash, fatigue, headache and cough are some of the acute, or immediate, effects of breathing in asphalt fumes. Chronic exposure of inhaled asphalt fumes may lead to lung or stomach cancer. Prolonged exposure of fumes to the skin may cause a pigment change made more noticeable by exposure to sunlight. Research conducted by the National Institute for Occupational Safety and Health shows that products containing asphalt are carcinogenic to laboratory animals. The organization therefore urges humans to limit their exposure to asphalt.
Certain types of asphalt can be highly flammable and lead to explosions or fires, especially when hot. Cigarettes, sparks and flames can act to ignite stray fumes. Burns are common occupational injuries sustained where hot asphalt is used.
National parks have been documented to contain high concentrations of PAHs in the air following asphalt-paved roads being burned by forest fires or lava flows. In aquatic environments, asphalt appears as a dark, tarry substance and sinks to the bottom of a body of water.
Asphalt Plant Pollution
An EPA assessment on hot mix asphalt facilities reveals that these plants emit 770-2,000 hazardous air pollutants (HAPs) each year. HAPs, also called toxic air pollutants or air toxics, include PAHs. Asphalt processing and roofing facilities may be responsible for some air pollutants such as hexane, phenol and formaldehyde. According to one of two studies conducted by the Blue Ridge Environmental Defense League, property value for residential homes near asphalt plants have reported losses of up to 56 percent. Of those residents, 45 percent reported via survey that they experienced deteriorating health conditions after the asphalt plant opened. Health conditions reported include high blood pressure, sinus problems, shortness of breath and headaches.