perlite’s distinctive fracture pattern are often called “perlite” if they contain enough water to expand in a similar fashion. Description, Distribution, and Forms Perlite is a form of natural glass. Natural glasses form when molten lava from volcanoes is cooled rapidly. The lava hardens too quickly to allow crystals to grow, resulting in a substance with a glassy rather than a stony texture. Perlite is distinguished from other forms of natural glass in that it contains many tiny curved fractures structured like the layers of an on- ion. These fractures may be microscopic or may bevis- ible to the naked eye. Because of these fractures, perlite breaks apart into small, round, pearl-like parti- cles. Perlite has a waxy or pearly luster and may be gray, green, brown, blue, or red. The term “perlite” is also more loosely used to mean any natural glass that expands into a light, frothy material when heated. Most of the world’s perlite is found in the western half of the United States. New Mexico supplies about three-quarters of the nation’s perlite. Because under- ground deposits of natural glass slowly crystallize into stony substances over time, perlite is almost always found at or near the Earth’s surface. Greece, Hun- gary, Japan, Mexico, and Turkey are also major pro- ducers of perlite. History Though perlite has been known as a volcanic rock for more than two thousand years, it was not used indus- trially untilthe twentieth century. By the 1970’s, itwas a commonproductusedinthehorticultural industry. Obtaining Perlite Because perlite is found near the surface, it is mined using the open-pit method. It is then crushed to the desired particle size and transported to a processing center, where it is heated to expand it. Uses of Perlite The expanded perlite is used as an aggregate; that is, it is mixed with other substances such as gypsum to form plaster or cement to form concrete. Although perlite is not as strong or inexpensive as other aggre- gates such as sand or gravel, it has the advantages of being light, fire-resistant, and a good insulator ofheat and sound. Perlite is also used as insulation or filler and in ceramics and filters. Rose Secrest Web Site U.S. Geological Survey Mineral Information: Perlite Statistics and Information http://minerals.usgs.gov/minerals/pubs/ commodity/perlite/ See also: Cementand concrete; Glass; Gypsum; Igne- ous processes, rocks, and mineral deposits; Magma crystallization; Open-pit mining; Pumice; Volcanoes. Peru Categories: Countries; government and resources Peru is extraordinarily rich in mineral resources, some of which, silver and gold especially, were produced in large quantities in the Spanish colonial period, as early as the mid-sixteenth century. After gaining inde- pendence, Peru took on global importance as a source for a number of other key minerals, especially copper, tin, and, by the late twentieth century, petroleum and natural gas. However, Peru suffers from the fact that a large proportion of the exploitation of its natural re- sources is undertaken by foreign companies. The Country Peru rises from its long western coast along thePacific Ocean eastward toward the peaks of the Andes Moun- tains. It has borders with Bolivia and Chile to the south, with Ecuador,Colombia, to the north, and with Brazil to the east. Although much of the country con- sists of high mountains, low coastal regions are hot and dry, running southward to join similar terrain in coastal Chile. By contrast, the vast northeastern inte- rior of Peru joins the Amazon River basin, which is characterized by hot, humid tropical forests. Peru’s largest city and governmental capital, Lima, is located on the Pacific coast. Tin Peru is the third largest producer of tin in the world, topped only by China and Indonesia. In contrast to most of Peru’s capital-intensive mining ventures, the tin sector is dominated by a family-owned company, Minsur,foundedin1966.TheBrescia family kept con - trolling interests following incorporation in 1977. Minsur’s operations are concentrated in the south - 918 • Peru Global Resources Global Resources Peru • 919 Peru: Resources at a Glance Official name: Republic of Peru Government: Constitutional republic Capital city: Lima Area: 496,261 mi 2 ; 1,285,216 km 2 Population (2009 est.): 29,546,963 Languages: Spanish and Quechua Monetary unit: nuevo sol (PEN) Economic summary: GDP composition by sector (2008 est.): agriculture, 8.5%; industry, 21.2%; services, 70.3% Natural resources: copper, tin, silver, gold, petroleum, timber, fish, iron ore, coal, phosphate, potash, hydropower, natural gas Land use (2005): arable land, 2.88%; permanent crops, 0.47%; other, 96.65% Industries: mining and refining of minerals; steel, metal fabrication; petroleum extraction and refining, natural gas; fishing and fish processing, textiles, clothing, food processing Agricultural products: asparagus, coffee, cocoa, cotton, sugarcane, rice, potatoes, corn, plantains, grapes, oranges, pineapples, guavas, bananas, apples, lemons, pears, coca, tomatoes, mango, barley, medicinal plants, palm oil, marigold, onion, wheat, dry beans, poultry, beef, dairy products, fish, guinea pigs Exports (2008 est.): $31.53 billion Commodities exported: copper, gold, zinc, crude petroleum and petroleum products, coffee, potatoes, asparagus, textiles, fishmeal Imports (2008 est.): $28.44 billion Commodities imported: petroleum and petroleum products, plastics, machinery, vehicles, iron and steel, wheat, paper Labor force (2008 est.): 10.2 million Labor force by occupation (2005): agriculture, 0.7%; industry, 23.8%; services, 75.5% Energy resources: Electricity production (2008 est.): 30.57 billion kWh Electricity consumption (2008 est.): 28.97 billion kWh Electricity exports (2008 est.): 0 kWh Electricity imports (2008 est.): 0 kWh Natural gas production (2008 est.): 3.4 billion m 3 Natural gas consumption (2008 est.): 3.4 billion m 3 Natural gas exports (2008 est.): 0 m 3 Natural gas imports (2008 est.): 0 m 3 Natural gas proved reserves ( Jan. 2008 est.): 334.7 billion m 3 Oil production (2008 est.): 110,800 bbl/day Oil imports (2007 est.): 109,000 bbl/day Oil proved reserves ( Jan. 2008 est.): 930 million bbl Source: Data from The World Factbook 2009. Washington, D.C.: Central Intelligence Agency, 2009. Notes: Data are the most recent tracked by the CIA. Values are given in U.S. dollars. Abbreviations: bbl/day = barrels per day; GDP = gross domestic product; km 2 = square kilometers; kWh = kilowatt-hours; m 3 = cubic meters; mi 2 = square miles. Lima Peru Bolivia Brazil Chile Colombia Ecuador Pacific Ocean eastern high-mountain region near Juliaca, more than seven hundred kilometers from Lima. Minsur also controls the Funsur tin smelting and refining in- stallation in Pisco, south of Lima. Annual production from its San Raphael mine was more than 38,000 met- ric tons in2005. Tin mining in Peru, like othersectors of the mining industry, suffers from recurring strikes of its workers.In midsummer 2008, forexample, both the San Raphael mine and Funsur smelting opera- tions were shut down as miners tried to pressure the Peruvian government to pass legislation improving working conditions and wages not only in tin mining but also in the copper, gold, silver, and iron ore sec- tors. Silver Silver mining has been extremely important for Peru’s economy since the 1500’s. The Spanish colo- nial administration based in Lima began to exploit a number of rich veins from the mid-sixteenth century forward. Particularly rich were mines in the region around the legendary “silver capital” in Potosí (now in Bolivia), from which Spain shipped animperialfor- tune in silver ingots both to Europe and to China. In modern times the Caylloma mining district (about 200 kilometers northwest of Arequipa), among others areas, continued to mine enough silver to make Peru the second largest producer in the world, with potential annual output averaging around 2.8 million kilograms. The Vancouver, British Columbia, mining firm Fortuna Silver obtained 100 percent fi- nancial control over the main Caylloma operation in 2005, investing major funds to modernize both min- ing methods and processes used to extract silver from ore. Fortuna transports silver to the port city ofCallao for export marketing. Although the Peruvian-run Buenaventura mining company does not limit itself to silver mining, its extensive operations place it among the ten major producers of silver in the world. In the first decade of the twenty-first century, mining compa- nies like the Canadian Silver Standard and Colorado- based Apex Silver financed new prospecting projects along the Pan-American highway transportation net- work, with particular interest in prospects in Peru. Such projects can run substantial risks (Apex, for ex- ample, filed preliminary bankruptcy claims in 2009). Pan AmericanSilver of British Columbia, another rel- ative “newcomer” founded in 1994, has obtained at least two Peruvian silver mines that rank among the top fifteen producers of silver in the world. Peru’s sil - ver output continues to rise, marking gains of almost 10 percent per year (up 9.78 percent between 2008 and the first quarter of 2009). However, apparent ad- vances can be offset by a number of limiting factors. One of these is the volatility of global silver prices. An example of Peru’s tactical response to down- ward trends in world silver prices occurred in 1989, when the government attempted to restrict supplies of silver globally by buying silver from local mining companies (with a premium of 5 percent more than prevailing prices) and stockpiling what it purchased in hopes that prices would recover within a few months. Not only did such tactics fail to attain their goals, but also Peru was criticized internationally for introducing fears of shortages (and price increases) by disregarding normal world market supply-and- demand principles. Another factor affecting silver output in Peru is la- bor unrest. Striking workers at Buenaventura’s Uchuc- chacua mine (deemed to be the largest silver mine in Peru), in Oyón Province near Lima,have caused peri- odic closures, forcing the company torely on continu- ing but precarious labor cooperation in two other Buenaventura mines (Orcopampa and Antapite) to maintain acceptable levels of production. Gold Estimates indicate that nearly one-half the value (not output) of all mining exports from Peru is earned from gold. In2003,Peru’s mines producedmorethan 170,000 kilograms of gold, marking clear increases over previousyears.AlthoughPeru enjoys major earn- ings from gold exports (more than $2 billionin 2003) closer examination of the sectorshowsthatit relies on a very heavy concentration of foreign companies to exploit this vital resource. An example of this is the huge Yanacocha gold mine near Cajamarca in north- ern Peru, considered by many to be the largest and richest gold mine in the world. It has produced more than $7 billion of gold, mined out of an open pit measuring more than 250 square kilometers. The Peruvian-run mining corporation Compania de Minas Buenaventura (CMB) holds only 43 percent of the mine’s capital, while Newmont Mining, of Denver, Colorado, holds more than 50 percent, with remain- ing capital supplies by the International Finance Cor- poration (under World Bank aegis). This giant mine, together with the Pierina mine in central northern Peru (developed by the giant Cana - dian Barrick Gold Corporation), has been strongly 920 • Peru Global Resources criticized by environmental and human-rights groups, which charge that irresponsible operations, especially dangers created by cyanide leach tailing dams, have gone uncorrected and should be subject to closer control by the Peruvian authorities. Copper Peru ranks as the world’s third largest producer of copper (preceded by Chile and the United States). In 2008, production figures totaled more than 1.2 mil- lion metric tons, most of which was exported. Copper mines are located in several regions of the country, some (the Toquepala and Cuajone mines) high in the Andes, 400 kilometers southeast of Lima; others (mainly the La Granja copper mine) also in the Andes, northeast of the capital. The Toquepala and Cuajone mines, originally discovered by a German freelance miner/explorer, have been exploited for more than a century. Since the mid-1950’s a giant firm, the Southern Peru Copper Corporation (SPCC, with major stakesatthattimeheldbyfourU.S.compa - nies), has been the prime motor for exploitation of ToquepalaandCuajone.SPCChasundergone a num- ber of major changes, especially between 1968 (when a Peruvian military junta cancelled large parts of its concession) and the conclusion of agreements in the mid-1970’s,leadingto expansion of production in the Cuajone mining zone. In the 1990’s, SPCC profits set records when global copper prices were at an all-time high. In 1999, another major change came when Grupo Mexico bought out the Tucson, Arizona, com- pany ASARCO’s shares in SPCC (at a cost of $2.5 bil- lion), thereby gaining a 54 percent majority interest in the giant firm. Although theSPCC’s activities are unique, one can gain an impression of the overall status of Peruvian copper on the international market from SPCC’s an- nual production and export sales figures. When cop- per prices slumped in 1999 (eventually reaching the lowest point in sixty years, at about twenty-seven cents per kilogram), SPCC was producing more than 337 million kilograms yearly (yielding about 250 million Global Resources Peru • 921 Peruvians depend on water provided by glaciers like this one in the Andes Mountains of Patawasi. (Getty Images) kilograms of refined copper). Leading up to what be - came a turning point at the end of the 1990’s, sales of SPCC’s Peruvian copper were going to Northern Eu- rope (about 34 percent), Asia (30 percent), other Latin American countries (about 15 percent), and the United States (4 percent). Even though a partial recovery of global prices brought copper back to nearly two dollars per kilogram by 2006, chances of continued fluctuation continued to suggest that the halcyon days of copper returns were unlikely in the first decade of the twenty-first century. However,some developments after 2000suggested that Peru’s global position could change, as plans for exploiting new or previously only partially exploited reserves went forward. Notable new developments were symbolized by the emergence after October, 2001, of the Antamina company’s exploitation of what may be one of the largest reserves of copper and zinc in the world. Antamina operations are located almost 300 kilometers north of Lima and have a state- of-the-art pipeline connection capable of carrying slurry, or processed and concentrated ore mixed with water, to coastal transshipment facilities. Joint partici- pating members of the Antamina operation include one-third capital subscription by Noranda, Incorpo- rated (one of the world’s largest mining companies, originally founded in Ontario, Canada); one-third held by BHP Billiton Base Metals (a multinational gi- ant originally involved in tin mining in the nineteenth century in the Dutch East Indies—later Indonesia— taken over by Royal Dutch Shell in the 1970’s); and the remainder split between Teck Cominco (of Van- couver, British Columbia) and the Mitsubishi Corpo- ration of Japan. This situation of Peruvian depen- dence on foreign investment for exploiting mineral resources is as visible, and potentially even more con- troversial, in another key sector: petroleum and natu- ral gas. Petroleum and Natural Gas Beginning in the 1970’s, the Upper Amazonian area of Peru promised to offer an important addition to the country’s exportable resources. From relatively modest 1977 figures (export values of $52 million), production increased rapidly to almost $650 million in 1985. By 2000, estimates of known oil reserves topped 350 million barrels. By 2001, production was more than one hundred thousand barrels a day. In addi - tion, Peru possesses, at Camisea, deep within the Am - azonian rain forest, what is deemed to be the largest natural gas field in South America. Although the exis- tence of natural gas reserves was known for some time, operational exploitation of the Camisea field dates from only 2004. Gas was initially transported by impressive pipelines over the Andes to the Pacific Ocean port of Pisco. In 2007 and 2008, following rising controversy over pipeline leakage, two foreign firms, Suez Energy and Kuntur Gas Transport, pre- sented the Lima government with proposals to build two more efficient pipelines, one of which would end and be combined with a gas-run power plant at the port zone of Ilo in southern Peru. In 2009, Suez En- ergy predicted that its pipeline facilities could be- come operational by 2011. It is impossible to discuss plans to expand exploita- tion of Peru’s petroleum and natural gas resources without mentioning operations in the northern pre- Amazon, with a proposed pipeline system oftransport to Talara on the Pacific coast. The Camisea Project, which aims at involving a number of multinational companies in exploitation of northern Amazonian re- serves, projects delivery of gas and oil to the United States, Mexico, and other countries bordering the Pa- cific. In 2003, inorderto encourage the Camisea Proj- ect, the Peruvian government reduced royalties that would normally be owed to it by foreign concession- aires. As plans moved ahead, an unprecedented pub- lic reaction—mainly from ecologists abroad—criti- cized the project as not only ecologically destructive but also a menace looming over the lives of indige- nous tribal populations in the tropical forest area to be affected. Critics underline Camisea’s apparent dis- regard for respecting the ecological conditions that traditionally support very rare flora; among them ex- ist approximately seventy plants that are considered important in pharmaceutical treatment of cancer. Other Resources Peru is not a major producer of iron, although the one important company involved in iron-ore mining (Shougang Hierro Peru, a Chinese-owned business with head offices in Lima) has succeeded in increas- ing the country’s production of ore in stages. From a production level of about 3 million metric tons of ore exported in 2003, valued at about $95 million, the company registered a notable annual increase, reach- ing 4 million metric tons in 2005. Shougang Hierro Peru operates several open-pit mines in the coastal desert region about 500 kilometers south of Lima. A 922 • Peru Global Resources combination of conveyor belts and a trucking net - work connects the mines to the Pacific coast port of San Nicolas, from which the ore is exported. Although there is only one significant manganese mining area in Peru (at Berenguela in the southeast- ern zone), already existing exploitation of copper and silver at that location was substantial enough for one company, Lampa Mining, to hold exclusive min- ing rights for more than half a century (between 1905 and 1965). About 500,000 metric tons of ore were ex- tracted by Lampa, but only a small part of the manga- nese content of this mass was processed for sale. In later decades manganese extraction became more economically viable and attracted a Canadian firm, Blackstone Resources, to acquire 80 percent interest in a Peruvian holding company venture, the Mining Society of Bernguela (SOMINBESA). Byron D. Cannon Further Reading Arellano-Yanguas, Javier. A Thoroughly Modern Resource Curse? The NewNatural Resource Policy Agendaand the Mining Revival in Peru. Brighton, East Sussex, En- gland: Institute ofDevelopment Studies at the Uni- versity of Sussex, 2008. DeWind, Josh. Peasants Become Miners: The Evolution of Industrial Mining Systems in Peru. New York: Gar- land, 1987. Dore, Elizabeth. The Peruvian Mining Industry: Growth, Stagnation, and Crisis. Boulder, Colo.: Westview Press, 1988. Hall, Anthony L. Amazonia at the Crossroads: The Chal- lenge of Sustainable Development. London: Institute of Latin American Studies, 2000. See also: Copper; Ecozones and biogeographic realms; Forests; Gold; Silver; Tin. Pesticides and pest control Categories: Environment, conservation, and resource management; pollution and waste disposal Pesticides are agents used to killorotherwisecontrol or- ganisms that are harmful to humans or crops. In addi - tion to chemical agents, alternative pest-control meth - ods are available. Background An animal or plant is regarded as a pest if it causes a nuisance or harm to humans or crops or otherwise negatively impacts human health, well-being, or qual- ity of life. Pests such as silverfish consume paper and fabrics. Termites cause serious damage to houses and other wooden structures. Weeds, aphids, and snails play havoc with flower gardens. Beetles and fungi at- tack shade trees, timber, crops, orchards, and stored foods. Mosquitos, ticks, mites, and rodentstransmitvi- ruses and other disease organisms to humans. Pest control is theongoing process of managing in- sects, rodents, weeds, fungi, and other pest organisms where their lives intersect human lives. The twentieth century saw a rapid escalation in the use of chemical pesticides, which have become a mainstay of pest con- trol. These chemicals have suppressed pest popula- tions, increased crop yields, protected property, and kept disease in check. However, indiscriminate use of chemical pesticides has damaged the environment, which has led to governmental regulation of pesti- cides, outright bans on some substances, and increased interest in alternative pest-control methods. Types of Chemical Pesticides Chemical pesticides are often classed based on the or- ganisms that they target. Avicides kill or repel bird pests. Rodenticides are for use against rats and mice. Acaracides and miticides target ticks and mites. Insec- ticides, the largest category of pesticide, are used against insects. Nematicides are used to kill nema- todes, soil- and water-dwelling roundworms that are often parasitic on plants and animals. Fungicides are used to treat crops and other plants for fungal (and sometimes bacterial) conditions such as root rot, smut, gall, rust, and blight. Herbicides target the weeds and other unwanted vegetation that encroach on lawns, gardens, crops, and paths. Defoliants are a class of herbicide that induces leaf fall from trees and other plants. Pesticides can also be categorized on the basis of chemical composition. Mineral pesticides such as ar- senic, borax, copper, lead, and zinc were among the first pesticides employed by humans; these minerals have mostly been replaced bymoreefficient chemical compounds. Botanical pesticides are insecticidal sub- stances derived from plants or are synthetic analogs to such substances. These include pyrethrins, chrysan - themum-derived insecticides which are not highly toxic to humans. Chlorinated hydrocarbons, which Global Resources Pesticides and pest control • 923 include chlorine, hydrogen, and oxygen in their chemical makeup, are highly effective poisons that do not readily degrade in the envi- ronment. Compounds such as aldrin, endrin, dieldrin, chlordane, and dichloro-diphenyl- trichloroethane (DDT) were widely employed before the environmental implications of their persistence were fully understood. Organo- phosphate pesticides are organic phosphate compounds that break down in the environ- ment more easily than the chlorinated hydro- carbons, particularly in the presence of water. Examples include malathion, naled, dichlor- vos, methyl and ethyl parathion, and diazinon. Carbamates, characterized by carbamic acid, include carbaryl, carbofuran, and methylcar- bamate; these compounds degrade more quickly than organophosphates. Pesticides may be categorized further as se- lective or nonselective. A selective pesticide targets a particular pest, while anonselectivepesticide (also called a broad-spectrum or general-usage pesti- cide) is toxic to a wide range of organisms and does not confine its effects to the target species onceitisre- leased into the environment. Selectively toxic chemi- cals minimize the pesticide’s impact on the environ- ment. Chemical pesticides are applied in various forms, including wet sprays, dusts, atomizable fluids, low-pressure aerosols, smokes, gases, and seed treat- ments. History of Use The “first generation” of chemical pesticides was the minerals and botanicals. In 1867, farmers in the United States began using Paris green, a then-com- mon pigment containing arsenic and copper, to con- trol outbreaks of the Colorado potato beetle. Lead arsenate was introduced as an insecticide in 1892. By the 1920’s, pesticide use in the United States had become commonplace, and concerns over arsenical residues in foods had begun to arise. In 1939, the next generation of chemical pesticides was ushered in with the discovery of DDT’s insecti- cidal properties. The compound was first dissemi- nated on a large scale during the Naples typhus epi- demic of 1943-1944, and it found widespread use during the remainder of World War II. DDT and other potent broad-spectrum poisons were popular pesticides from the early 1940’s through the 1960’s. However, as concerns mounted over the environmen - tal impact of these chemicals—contaminated water- sheds; the dying off of beneficial species coupled with pests becoming pesticide resistant; the accumulation of pesticides in the bodies of higher animals, includ- ing humans; and poisoned food chains—use of chlo- rinated hydrocarbons fell into disfavor. Use of DDT and similar chemicals has been banned or restricted in many countries, including the United States. The disadvantages of chemical pesticides have led to an increased interest in alternative pest-control methods. Biological control agents include microor- ganisms that are harmful to pestsbut not to other life; natural predators and parasites; and the release of large numbers of laboratory-sterilized insects, which then mate with normal insects without producing off- spring. While biological control agents usually involve no environmental pollutants and are often highly se- lective, the many complex factors that affect their ac- tion sometimes hinder their effectiveness. U.S. Regulation of Chemical Pesticides The Insecticide Act of 1910 prohibited adulteration of insecticides and fungicides. In 1947, theFederalIn- secticide, Fungicide, and Rodenticide Act (FIFRA) authorized the United States Department of Agricul- ture (USDA) to oversee registration of pesticides and to determine their safety and effectiveness. In Decem- ber, 1970, the newly formed U.S. Environmental Pro - tection Agency (EPA) assumed statutory authority from the USDA over pesticide regulations. Under the 924 • Pesticides and pest control Global Resources An Americanfarmworkertakeshealth precautions whilepreparing pesticides for use on crops. (United States Department of Agriculture) Federal Environmental Pesticide Control Actof 1972, an amendment to FIFRA, manufacturers must regis- ter all marketed pesticides with the EPA before the product isreleased.Before registration, the chemicals must undergo exhaustive trials to assess their poten- tial impact on the environment and human health. The EPA’s decision to grant registration is based on the determination that unreasonable adverse effects on human health or the environment are not antici- pated within the constraints of approved usage. Be- ginning in October, 1977, the EPA has classified all pesticides to which it has granted registration as either a restricted-usage (to be applied only by certified pest control operators) or unclassified (general-usage) pes- ticide. Karen N. Kähler Further Reading Carson, Rachel. Silent Spring. Drawings by Lois and Louis Darling. Boston: Houghton Mifflin, 1962. Cremlyn, R.J.Agrochemicals:PreparationandModeofAc- tion. New York: Wiley, 1991. Levine, Marvin J. Pesticides: A Toxic Time Bomb in Our Midst. Westport, Conn.: Praeger, 2007. Lopez, Andrew. Natural Pest Control: Alternatives to Chemicals for the Home and Garden. Rev. ed. Malibu, Calif.: Invisible Gardener, 2005. Matthews, G. A. Pesticides: Health, Safety, and the Envi- ronment. Ames, Iowa: Blackwell, 2006. Stenersen, Jørgen. Chemical Pesticides: Mode of Action and Toxicology. Boca Raton, Fla.: CRC Press, 2004. Ware, George W. Fundamentals of Pesticides: A Self- Instruction Guide. 3d ed. Fresno, Calif.: Thomson, 1991. Ware, George W., and David M.Whitacre. The Pesticide Book. 6th ed. Willoughby, Ohio: MeisterPro Infor- mation Resources, 2004. Whorton, James. Before “Silent Spring”: Pesticides and Public Health in Pre-DDT America. Princeton, N.J.: Princeton University Press, 1974. Web Site U.S. Environmental Protection Agency About Pesticides http://www.epa.gov/pesticides/about/index.htm See also: Agriculture industry; Carson, Rachel; Envi - ronmental Protection Agency; Food chain; Herbi - cides; Monoculture agriculture. Petrochemical products Category: Products from resources Petrochemicals are organic chemicals derived from petro- leum or natural gas. They are of extreme importance in contemporary life, accounting for the production of al- most all plastics, other synthetic materials, and organic chemicals. Although an enormous variety of organic chemicals can be (and are) made from petroleum or nat- ural gas, usually theterm “petrochemicals” is restricted to those substances produced in very large amounts. Background The origin of the petrochemical industry may be traced to the first production of isopropyl alcohol from propylene in 1920. This effort was originated by the Standard Oil Company in New Jersey. The indus- try grew slowly but steadily during the 1920’s and 1930’s and then received an enormous boost from World War II, with its tremendous demand for syn- thetic materials. By about 1950 theindustry was firmly established in the United States. Ethylene and Polyethylene The most important petrochemical is ethylene. It is manufactured in greater quantity than any other or- ganic chemical. Various raw materials can be used to manufacture ethylene, including ethane, propane, and petroleum distillates such asnaphtha. Regardless of the raw material, the ethylene production process involves thermally driven reactions (so-called crack- ing) in a temperature range between 750° and 900° Celsius. Steam is used to dilute the feed to the ethyl- ene production furnace. The amount of steam used varies, depending on the specific material used to make the ethylene. The annual worldwide produc- tion of ethylene exceeds 100 million metric tons. About half of the ethylene produced is converted to polyethylene. The two major types of polyethylene are known as low-density polyethylene (often abbre- viated as LDPE) and high-density polyethylene (HDPE). One of the most important applications of LDPE is in clear plastic wrapping film. HDPE has a wider range of uses by virtue of its superior mechani- cal properties. Familiarapplicationsof HDPE include bottles, such as those used for laundry detergents, and housewares, such as storage crates and home cleaning accessoriessuchasbuckets,pans,andpails. Global Resources Petrochemical products • 925 Vinyl Chloride and Ethylene Glycol A second major use of ethylene is its conversion to vi- nyl chloride. This conversion is effected by a process called oxychlorination: reaction of ethylene with hy- drogen chloride and oxygen. Vinyl chloride is used in the manufacture of polyvinyl chloride, or poly, most commonly known as PVC. Depending on how the PVC is produced (specifically, through the addition of “plasticizers” that alter its physical or mechanical properties), it can have a range of hardness and flexi- bility. Consequently, PVC is a versatile material with many common uses that include floor tile, garden hose, artificial leather, house siding, plastic films, pipe, and toys. In the days when music was recorded on phonograph records, they were usually made of PVC—hence the slang term “vinyl.” The oxidation of ethylene produces ethylene ox- ide, a chemical that easily reacts with water to form ethylene glycol, a useful component of antifreeze. Ethylene glycol is also used in the manufacture of polyethylene terephthalate, commonly known as PET. This polymer is an example of the largest class of syn- thetic textile fibers, the polyesters. PET is also used for both audio and video magnetic recording tapes, in soft drink bottles, and in “microwave-in-a-pouch” food containers. Propylene, Polypropylene, and Propylene glycol Propylene is the second most important of the petro- chemicals. Although ethylenesuperseded it in impor- tance (in terms of tonnage production), propylene was the first significant petrochemical. In the 1920’s and 1930’s, propylene was a by-product of gasoline manufacture. To increase the yield of gasoline from a refinery, other petroleum products of lower value were subjected to intense heating (thermal cracking), which broke the molecules into new, smaller com- pounds, many of which could be used in gasoline. In addition, however, thermal cracking led to some by- products, such as propylene, of molecular size even smaller than gasoline. The beginning of the petro- chemical industry was the use of this by-product pro- pylene for producing isopropyl alcohol. Most people encounter isopropyl alcohol primarilyas the active in- gredient in “rubbing alcohol,” but it has more impor- tant uses as an industrial solvent and as raw material for making acetone, another useful solvent. Today the propylene situation is greatly changed. The thermal cracking process for gasolineisobsolete, so there is no by-product propylene. Instead, propyl- ene is made in much the same way as ethylene, using either propane or naphtha as the raw material. The raw material, mixed with steam, is crackedattempera- tures of 800° to 900° Celsius. The dominant use of propylene is in the production of polypropylene. The properties of polypropylene—and conse- quently its uses—depend heavily on the way the pro- pylene molecules are connected. Special catalysts to control the outcome of the polymerization of poly- propylene were discovered by Karl Ziegler and Giulio Natta, for which achievement they were awarded the 1963 Nobel Prize in Chemistry. A common application for high-qual- ity polypropylene is in microwave- safe dishes and food containers. Some of the lower-strength gradesof polypropylene are useful as flexible, clear plastic films—for example, as food wrap and as the plastic cover- ings on disposable diapers. Poly- propylene and “copolymers” of poly- propylene and polyethylene are widely used as materials in automo- biles. Examples of automotive appli- cations include bumper covers, air ducts, body trim panels,interiortrim and seatcovers,andbatterycasings. Propylene can also be converted to propylene oxide and then to pro - pylene glycol. This material is used 926 • Petrochemical products Global Resources This 1942 display of petrochemical products illustrates the United States’ shift awayfrom cost-prohibitive metals during World War II. Plastic products have became integral in multiple aspects of modern life. (AP/Wide World Photos) directly in antifreeze, brake fluid, and hydraulic fluid. It is also used as a moisturizerinpetfoodsandtobacco products. Propylene glycol is converted to a special family of compounds called urethanes, the basic ma- terials for the production for polyurethane products. Many kinds of urethanes can be madefrompropylene glycol, depending on the chemicals chosen for the process. Consequently, the eventual polyurethanes have, as a family, a widerange of properties. Common applications of polyurethanesincludesoundandheat insulation, furniture cushions, automobile bumpers, and plastic flooring and roofing. Acrylics, Polyacrylates, and Polyacrylonitrile A more severe oxidation of propylene leads to acrylic acid, the starting material for acrylic paints. Sodium or ammonium salts of acrylic acid polymerize to the polyacrylates. When polyacrylates are mixed with small amounts of other copolymers, they form polyacrylate “super-absorbing” polymers that have an exceptional capacity for absorbing water or water solutions. The major use of these remarkable materials is in the lin- ing of disposable diapers. The reaction of propylene with ammonia in the presence of oxygen (“ammoxidation”) forms acrylo- nitrile. This is the starting material for polyacryloni- trile, or PAN. Acrylic textiles, such as Acrilan and Or- lon, amount to about 20 percent of all synthetic fibers produced. PAN is also usedto make carbon fibers. Ini- tially, PAN-based carbon fibers were extremely expen- sive (about $100 per kilogram), so they were limited to military and aerospace applications. As an exam- ple, about 10 percent of the weight of an F-18 fighter aircraft is PAN-based materials. Other applications in- clude use inthe space shuttle’s cargo baydoors and in nozzles in the shuttle’s rockets. Improved manufac- turing know-how reducedthecostofcarbonfiberssig- nificantly, and carbon- or graphite-fiber items are in- creasingly available to consumers; among them are graphite tennis rackets and golf clubs. The BTX Compounds and Styrene Catalytic reforming of petroleum, a process used to enhance the octane number of gasoline, produces as by-products the family of compounds benzene, tolu- ene, and xylene, sometimes lumped together and called BTX. They are high-tonnage materials but not as important as ethylene and propylene. Benzene and ethylene react to produce ethylben - zene, which is converted to styrene. Styrene is the raw material for making polystyrene. Polystyrene is an- other example of the petrochemical products that seem ubiquitous in modern life. Applications of poly- styrene include Styrofoam food cartons (such as those used for eggs in supermarkets), cups and food pack- aging at fast food restaurants, plastic utensils, toys, and the foam “peanuts” used as packaging material. Polystyrene and other uses of benzene are so impor- tant that the major use of toluene is conversion to benzene. Xylenes are used as solvents. One particular xylene, para-xylene, is converted to terephthalic acid. This compound, reacted with ethylene glycol (de- scribed above), produces PET. The petrochemical industry has an immense eco- nomic impact, both in the United States and world- wide. In the United States, twenty-nine of the top fifty industrial chemicals are organic (though not all are petrochemicals). Harold H. Schobert Further Reading Burdick, Donald L.,and William L.Leffler. Petrochemi- cals in Nontechnical Language. 3d ed. Tulsa, Okla.: PennWell, 2001. Chang, Raymond, and Wayne Tikkanen. The Top Fifty Industrial Chemicals. New York: Random House, 1988. Chauvel, Alain, and Gilles Lefebvre. Petrochemical Pro- cesses: Technical and Economic Characteristics. Trans- lated by Nissim Marshall. Houston, Tex.: Gulf, 1989. Matar,Sami,andLewisF.Hatch.Chemistry of Petrochem- ical Processes. 2d ed. Boston: Gulf Professional, 2001. Speight, James G. “Petrochemicals.” In The Chemistry and Technology of Petroleum. 4th ed.Boca Raton, Fla.: CRC Press/Taylor & Francis, 2007. Szmant, H. Harry. Organic Building Blocks of the Chemi- cal Industry. New York: Wiley, 1989. Wiseman, P. Petrochemicals. Chichester, England: E. Horwood, 1986. Wittcoff, Harold A., Bryan G. Reuben, and Jeffrey S. Plotkin. “Chemicals from Natural Gas and Petro- leum.” In Industrial Organic Chemicals.2ded. Hoboken, N.J.: Wiley-Interscience, 2004. See also: Gasoline and other petroleum fuels; Oil and natural gas chemistry; Petroleum refining and processing. Global Resources Petrochemical products • 927 . operations are concentrated in the south - 918 • Peru Global Resources Global Resources Peru • 919 Peru: Resources at a Glance Official name: Republic of Peru Government: Constitutional republic Capital. 2009). However, apparent ad- vances can be offset by a number of limiting factors. One of these is the volatility of global silver prices. An example of Peru’s tactical response to down- ward. exploitation of ToquepalaandCuajone.SPCChasundergone a num- ber of major changes, especially between 1968 (when a Peruvian military junta cancelled large parts of its concession) and the conclusion of