Here's what the EPA says about the health effects of landfill gas emissions, and how hazarous air pollutants (HAP) are formed by decomposition of waste in landfills.
What are the health effects associated with municipal solid waste landfills?
The proposed rule ensures reductions of emissions of nearly 30 HAP including, but not limited to, vinyl chloride, ethyl benzene, toluene, and benzene. The degree of adverse effects to human health from exposure to these HAP can range from mild to severe. The extent and degree to which the human health effects may be experienced are dependent upon the ambient concentration observed in the area (as influenced by emission rates, meteorological conditions, and terrain); the frequency of and duration of exposures; characteristics of exposed individuals (genetics, age, preexisting health conditions, and lifestyle), which vary significantly with the population; and pollutant-specific characteristics (toxicity, half-life in the environment, bioaccumulation, and persistence).
Vinyl Chloride. Acute (short-term) exposure to high levels of vinyl chloride in air has resulted in central nervous system (CNS) effects, such as dizziness, drowsiness, and headaches in humans. Chronic (long-term) exposure to vinyl chloride through inhalation and oral exposure in humans has resulted in liver damage. There are human and animal studies showing adverse effects which raise a concern about potential reproductive and developmental hazards to humans from exposure to vinyl chloride. Cancer is a major concern from exposure to vinyl chloride via inhalation. Vinyl chloride exposure has been shown to increase the risk of a rare form of liver cancer in humans. The EPA has classified vinyl chloride as a Group A, known human carcinogen.
Ethyl Benzene. Acute exposure to ethyl benzene in humans results in respiratory effects, such as throat irritation and chest constriction, irritation of the eyes, and neurological effects such as dizziness. Chronic exposure to ethyl benzene by inhalation in humans has shown conflicting results regarding its effects on the blood. Animal studies have reported effects on the blood, liver, and kidneys from chronic inhalation exposure to ethyl benzene. No information is available on the developmental or reproductive effects of ethyl benzene in humans, but animal studies have reported developmental effects, including birth defects in animals exposed via inhalation. The EPA has classified ethyl benzene in Group D, not classifiable as to human carcinogenicity.
Toluene. Acute inhalation of toluene by humans may cause effects to the CNS, such as fatigue, sleepiness, headache, and nausea, as well as irregular heartbeat. Repeated exposure to high concentrations may induce loss of coordination, tremors, decreased brain size, involuntary eye movements, and impaired speech, hearing, and vision. Chronic inhalation exposure of humans to lower levels of toluene also causes irritation of the upper respiratory tract, eye irritation, sore throat, nausea, dizziness, headaches, and difficulty with sleep. Studies of children of pregnant women exposed by inhalation to toluene or to mixed solvents have reported CNS problems, facial and limb abnormalities, and delayed development. In addition, inhalation of toluene during pregnancy may increase the risk of spontaneous abortion. The EPA has developed a reference concentration of 0.4 milligrams per cubic meter for toluene. Inhalation of this concentration or less over a lifetime would be unlikely to result in adverse noncancer effects. No data exist that suggest toluene is carcinogenic. The EPA has classified toluene in Group D, not classifiable as to human carcinogenicity.
Benzene. Acute inhalation exposure of humans to benzene may cause drowsiness, dizziness, headaches, as well as eye, skin, and respiratory tract irritation, and, at high levels, unconsciousness. Chronic inhalation exposure has caused various disorders in the blood, including reduced numbers of red blood cells and aplastic anemia, in occupational settings. Reproductive effects have been reported for women exposed by inhalation to high levels, and adverse effects on the developing fetus have been observed in animal tests. Increased incidence of leukemia (cancer of the tissues that form white blood cells) has been observed in humans occupationally exposed to benzene. The EPA has classified benzene as a Group A, known human carcinogen.The proposed rule reduces nonhazardous air pollutant volatile organic compound (VOC) emissions as well. Emissions of VOC have been associated with a variety of health and welfare impacts. Volatile organic compound emissions, together with nitrogen oxides, are precursors to the formation of tropospheric ozone, or smog. Exposure to ambient ozone is responsible for a series of public health impacts, such as alterations in lung capacity; eye, nose, and throat irritation; nausea; and aggravation of existing respiratory disease. Ozone exposure can also damage forests and crops.
What source categories are affected by this proposed rule?
The proposed rule applies to all MSW landfills that are major sources or are co-located with a major source, and some landfills that are area sources. However, most requirements are proposed to take effect when landfills emit equal to or greater than 50 megagrams per year (Mg/year) nonmethane organic compounds (NMOC) and have a design capacity equal to or greater than 2.5 million Mg and 2.5 million cubic meters (m3).
We estimate that all MSW landfills that are major sources of HAP have a design capacity equal to or greater than 2.5 million Mg and 2.5 million m3 and emit or will emit 50 Mg/yr or greater of NMOC. Therefore the requirements of the proposed rule would apply to all MSW landfill major sources. Several MSW landfill area sources would also be subject to the requirements of these proposed standards.
What are the primary sources of emissions and what are the emissions?
The majority of emissions of HAP at MSW landfills come from the natural anaerobic (without air) decomposition of municipal solid waste. Typical municipal solid waste contains household and commercial rubbish, paints, solvents, pesticides, and adhesives, which contain numerous organic compounds. During the decomposition process, landfill gas is generated. This gas is primarily composed of methane and carbon dioxide. The organic compounds in the decomposing waste are stripped from the waste by these gases and transported to the surface, or the organic compounds travel underground to other locations prior to their release.
A second but significantly lesser source of emissions of HAP comes from the collection, storage and treatment of landfill leachate. Landfill leachate is a liquid generated during the waste decomposition process. This liquid contains a much smaller concentration of the same HAP contained in landfill gas. During collection, storage and treatment, small amounts of HAP may volatilize to the air or may come in contact with groundwater.
Regardless of the emission pathway, it is the decomposition of organic-containing solid waste that is the source of the HAP. Landfills have been identified as the source of nearly 30 HAP, including but not limited to toluene, ethyl benzene, vinyl chloride and benzene. Estimated uncontrolled emissions from all landfills can be as high as 36,000 tpy.