Chemicals in the Landscape

The nation’s commerce depends greatly upon the development and use of chemical products, and over the past 50 years, the use of such chemicals has increased significantly. The Toxic Substances Control Act chemical inventory now identifies more than 76,000 chemicals currently or recently used in the country. Nearly 10,000 of those, excluding inorganic polymers, microorganisms, naturally occurring substances, and non-isolated intermediaries, are produced or imported in quantities greater than 10,000 pounds per year; for about 3,100 chemicals, the quantities exceed 1 million pounds per year. Associated annual production and import volumes increased by 570 billion pounds (9.3 percent) to 6.7 trillion pounds between 1990 and 1998.⁴² Commercial and industrial processes such as mining, manufacturing, and electrical generation all use and release chemicals. Pesticides are used in homes, yards, factories, and office buildings and, most frequently, to support agricultural production, where they have contributed to an increase in agricultural productivity levels over the past 50 years. Fertilizers, used to supplement soils for enhanced plant growth, have also contributed to those productivity increases.

The use and release to the environment of chemicals have created a range of challenges for protecting human health and the environment. Toxic chemicals, including some pesticides, can lead to a variety of acute or chronic health problems, and excess fertilizers carried in runoff may contribute nutrients to aquatic ecosystems that harm water quality and aquatic life.

How much and what types of toxic substances are released into the environment?

Many industries release toxic substances into the air, soil, and water through their manufacturing and production activities. Under the Emergency Planning and Community Right-to-Know Act of 1986 and the Pollution Prevention Act of 1990, facilities are required to calculate and report to EPA and states their releases of more than 650 toxic chemicals and chemical compounds. EPA makes these toxics release data available to the public through the Toxics Release Inventory (TRI). In 2000, total TRI releases reached 7 billion pounds. Of these releases, 58 percent were to land, 27 percent were to air, 4 percent each were to water and underground injection at the generating facility, and 7 percent were chemicals disposed of off-site to land or underground injection. Between 1998 and 2000, toxic releases decreased overall by about 409 million pounds, or 5.5 percent. Of that total, releases to land decreased by approximately 276 million pounds (Exhibit 3-4).⁴³ Of the original set of chemicals from industries that have reported consistently since 1988, total on- and off-site releases decreased 48 percent between 1988 and 2000, a reduction of 1.55 billion pounds.⁴⁴

Exhibit 3-4: Total TRI releases across industry, 1998-2000
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Some of the releases reported in the TRI include chemicals that are managed under EPA regulations. For example, the above figures for total releases in the TRI include chemicals in waste disposed of in hazardous waste disposal units regulated under Subtitle C of the Resource Conservation and Recovery Act (RCRA), whether at the generating facility or after being transferred to another facility. Approximately 206 million pounds of toxic chemicals in waste were disposed of in RCRA Subtitle C facilities in 2000, which corresponds to approximately 2.9 percent of total TRI releases in 2000.⁴⁵ In addition to the 7 billion pounds of toxic chemicals released in 2000, 31 billion pounds of toxic chemicals were managed and transferred for treatment (50 percent), recycling (39 percent), and burning for energy recovery (11 percent). The total amount of toxic chemicals managed and transferred between 1998 and 2000 increased by almost 29 percent, a net increase of 8.4 billion pounds.⁴⁶ For the past few years, EPA has tracked three metals—lead, mercury, and cadmium—and 27 organic chemicals, which were identified as the highest priorities for waste minimization. The Agency uses those waste minimization priority chemicals (WMPC) to measure the total weight of particularly toxic chemicals going to disposal. Trend data are available for 17 of the 30 WMPCs and show that releases of those 17 have been steadily declining since 1993 (Exhibit 3-5). Overall, between 1991 and 1998, there was a 44 percent reduction in WMPC quantities generated in industrial and hazardous waste.⁴⁷

Exhibit 3-5: Trends in TRI waste minimization priority chemicals, 1991-1998
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Persistent bioaccumulative toxic (PBT) chemicals, including dioxins, lead, mercury, and PCBs, are tracked because they persist and accumulate in the environment. In 2000, PBTs represented 12.1 million pounds (less than 1 percent) of the released chemicals that TRI tracks.⁴⁸ Although they constitute a fraction of overall toxic releases, PBTs are significant even in small quantities, given the chronic risks they pose to ecosystems and humans through bioaccumulation.

What are the volume, distribution, and extent of pesticide and fertilizer use?

Pesticides are substances or mixtures used to destroy or repel various pests, including insects, animals, plants, and microorganisms. EPA’s most recent Pesticide Industry Sales and Usage report shows that annual use of pesticides for all purposes declined by about 15 percent between 1980 and 1999.⁴⁹ This decline has not been steady, with pesticide use higher in 1999 than it was in the early 1990s. Excluding chlorine used for disinfection, the largest use of pesticides is in agricultural production, and that use fluctuates, depending on a number of factors such as weather or type of crop. According to the National Center for Food and Agricultural Policy (NCFAP) , a private, non-profit research organization, use of agricultural pesticides increased between 1992 and 1997 from 892 million to 985 million pounds.⁵⁰ The recent EPA report shows a similar increase in use of all pesticides in this same timeframe, with a leveling of use between 1997 and 1999.⁵¹

Approximately half of those pesticides are herbicides used to control weeds that limit or inhibit the growth of a desired crop. Pesticides are also used in smaller quantities in rights-of-way, businesses, and home lawns and gardens. Based on EPA’s national pesticide sales estimates, industrial, commercial, and governmental pesticide applications—many of which occur in urban environments—totaled 148 million pounds in 1999. Home and garden pesticide use was estimated to be 140 million pounds.⁵²

The use of insecticides, which as a class tend to be the pesticides most acutely toxic to humans and wildlife, significantly declined between 1997 and 2001. The number of individual chemical treatments per acre (acre-treatments) for insecticides labeled “danger for humans” decreased by 43 percent. In that same period, acre-treatments for insecticides labeled “extremely or highly toxic to birds” declined by 50 percent, and acre-treatments of those labeled “extremely or highly toxic to aquatic organisms” dropped by 23 percent.⁵³

The use of nitrogen, phosphorus, and potash, the most prevalent fertilizer supplements in commercial farming, rose from 7.5 million nutrient tons (tons of a chemical nutrient in a fertilizer mixture) in 1961 to nearly 24 million nutrient tons in 1981. Exhibit 3-6 displays trends in the use of fertilizer over the past 40 years. Although aggregate use dipped in 1983, it increased most recently between 1996 and 1998 to more than 22 million nutrient tons.⁵⁴ Use of most major fertilizers is concentrated on croplands in the Midwest.⁵⁵ (Chapter 2 – Purer Water discusses some of the effects of fertilizer use on water quality.)

Exhibit 3-6: Use of fertilizer, 1960-1998.
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What is the potential disposition of chemicals from land?

Chemicals and nutrients can move from their location of use or origin to a place in the environment where humans and other organisms can become exposed to them. People are exposed to chemicals in all aspects of their daily lives, through their clothing, use of everyday products, housing, automobiles, and buildings.

Pesticide residues on food are one way people can be exposed to pesticides. The U.S. Department of Agriculture's Pesticide Data Program (PDP) measures pesticide residue levels in fruits, vegetables, grains, meat, and dairy products from across the country, sampling different combinations of commodities each year. In 2000, PDP collected and analyzed a total of 10,907 samples: 8,912 fruits and vegetables, 178 rice, 716 peanut butter, and 1,101 poultry which originated from 38 States and 21 foreign countries. Approximately 80 percent of all samples were domestic, 19 percent were imported, and less than 1 percent was of unknown origin.⁵⁶

The simple presence of detectable pesticide residues in foods should not be considered indicative of a potential health concern. The PDP uses analytical methods that are very sensitive and are capable of detecting extremely small (or “trace”) quantities of pesticides that are orders of magnitude lower than those raising potential health concerns. Overall, approximately 42 percent of all samples contained no detectable pesticide residues, 22 percent contained a detectable residue of a single pesticide, and 35 percent contained detectable amounts of two or more pesticides. Testing found that no more than 1.4 percent of samples exceeded regulatory limits (also known as “tolerance levels”). Residues exceeding the pesticide tolerance level established by EPA for that food were detected in only 0.2 percent of all composite samples. Residues of other pesticides for which no tolerance level had been set by EPA for that food were found in 1.2 percent of all samples. These residues were generally at low concentrations and may be due to spray drift, crop rotations, or cross-contamination at packing facilities. USDA reports all such exceedances to the Food and Drug Administration for further investigation and any needed follow-up.⁵⁷

Pesticide and fertilizer runoff into surface and ground water can also expose humans and the environment to the effects of chemicals. Models that use data from the USDA NRI, the NCFAP, and other sources show that the highest potential for pesticide runoff is predominantly associated with the upper and lower Mississippi and Ohio River valleys.⁵⁸ Similarly, EPA has developed models based on land cover characteristics to assess the risk of nitrogen and phosphorus runoff into watersheds. Those studies also show that the areas with the highest risk for nitrogen and phosphorus runoff are concentrated in the midwestern states and other agricultural areas.⁵⁹ (See Chapter 5 – Ecological Condition for additional discussion of how nutrient runoff can affect the chemical characteristics of ecosystems.)

In addition to runoff, chemicals can enter land through pesticide “spray drift,” the physical movement of a pesticide through air at the time of application, or soon thereafter, to any site other than that intended for application. Both modeling and incident reports indicate that spray drift is a route of disposition.⁶⁰