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Scrap Tires in Ciudad Juárez and
El Paso: Ranking the Risks
Allen Blackman and Alejandra Palma
September 2002 • Discussion Paper 02–46
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Scrap Tires in Ciudad Juárez and El Paso:
Ranking the Risks Allen Blackman and Alejandra Palma Abstract According to conventional wisdom, rapidly growing stocks of scrap tires on the U.S.–Mexico border pose a variety of health and environmental risks. This article assesses these risks in Paso del Norte, the border’s second-largest metropolis comprised principally of Ciudad Juárez, Chihuahua, and El Paso, Texas. We find that air pollution from tire pile fires poses the greatest threat. Scrap tires in Paso del Norte do not contribute significantly to the propagation of mosquito-borne diseases or to shortages of space in solid waste disposal sites. The burning of scrap tires at industrial facilities is minimal and might not have significant adverse environmental impacts even if it were more common.
Key Words: Scrap tires, U.S.–Mexico border, environment, health, risk assessment JEL Classification Numbers: Q2, O54 Contents
2. Generation, stocks, and end uses
Paso del Norte
3. Mosquito-borne diseases
Scrap tires and mosquitoes
Mosquitoes and infectious disease
4. Scrap tires as solid waste
5. Tire pile fires
Paso del Norte
6. Tire-derived fuel
Scrap Tires in Ciudad Juárez and El Paso:
Ranking the Risks Allen Blackman* and Alejandra Palma
Over the past decade, explosive population growth and a steady demand for used American tires in Mexico have contributed to the proliferation of scrap tires on the U.S.–Mexico border.1 Most of the major border cities host piles containing tens of thousands of tires, and a few of the largest cities—Tijuana, Ciudad Juárez, and Mexicali—are home to piles ten times as large (Blackman et al. 2001). Local and national stakeholders are becoming increasingly concerned about the attendant health and environmental risks. According to conventional wisdom, scrap tires constitute a fire hazard, generate acute air and water pollution when set ablaze, breed disease-carrying mosquitoes, provide dirty fuel for industrial facilities, and contribute to shortages of space in solid waste disposal sites. To mitigate such problems, local governments are developing projects aimed at shrinking stocks of scrap tires. Increasingly, they are turning to federal, state, and international authorities for assistance. For example, the Border Environmental Cooperation Commission, a binational organization that evaluates border infrastructure projects, has received four proposals related to scrap tires since June 1999, including one from Ciudad Juárez (BECC 2001).
Notwithstanding this growing concern, we still know relatively little about the health and environmental risks associated with scrap tires—information needed to inform mitigation * Corresponding author: firstname.lastname@example.org; (202) 328-5073. This research was funded by a U.S. Department of Energy grant administered by Applied Sciences Laboratory, Inc. We are grateful to Alan Krupnick, Richard Jimenez, Eli Maestas, and Jorge Castillo for support and input, and to our interviewees, especially Daniel Chacon and Alma Figueroa. The views expressed in this article do not necessarily reflect those of the above-named individuals or institutions.
1 During the 1990s, annual population growth rates in border cities were well above the national averages for Mexico and the United States. On the Mexican side, the population grew by 53% in Ciudad Juárez, Chihuahua, 68% in Tijuana, Baja California, and 48% in Nogales, Sonora. On the American side, the population grew by 9% in El Paso, Texas, 44% in Laredo, Texas, and 41% in Brownsville, Texas (Economist 2001).
policies. What are the relevant risks? Which are paramount? The answers to such questions are not likely to apply universally: they depend, among other things, on local geography, climate, and demography.
Based on interviews with more than 40 local stakeholders as well as primary and secondary documents, this article assesses health and environmental risks associated with scrap tires in the second-largest urban center on the border: Paso del Norte, the metropolitan area comprised principally of Ciudad Juárez, Chihuahua and El Paso, Texas.2 We focus on four types of risk: (1) the link between tire piles and mosquito-borne diseases, (2) the contribution of scrap tires to municipal solid waste disposal problems, (3) air and water pollution from tire pile fires, and (4) air pollution from the use of tires as fuel. Our analysis is preceded by a discussion of the generation, stocks, and end uses of scrap tires.
2. Generation, stocks, and end uses U.S.-Mexico border According to a widely used rule of thumb, the annual generation of scrap tires in the United States is equal to the country’s population. Thus, Americans generate roughly 273 million scrap tires per year—by weight, approximately 2% of the country’s annual output of solid waste.
Unfortunately, consumption does not keep pace with generation: as of 2001, there were an estimated 300 million scrap tires in stockpiles throughout the United States (STMC 2002a).
On the U.S.–Mexico border, scrap tire disposal is a particularly challenging problem.
Mexican demand for American used tires generates a steady flow of used tires from the United States into the border region.3 Most of the cross-border trade in used tires is illegal and informal, since importing such tires into Mexican border states (except Baja California) is prohibited under Mexican law. Although official records show that the United States exported just under 840,000 used tires to Mexico between 1978 and 1985, by all accounts the real figure is much higher (ITA 2001; Reiter and Sprenger 1987). Most American used tires smuggled into Mexico originate outside the border region.
2 Paso del Norte also includes Sunland Park, New Mexico. We confine our attention to Ciudad Juárez and El Paso because Sunland Park contains less than 1% of the metropolitan area’s combined population (approximately 1,800,000), and because we have very few data specific to this city.
3 American scrap tires are often used in Mexico until the tread is completely worn; they are then discarded.
2 Resources for the Future Blackman and Palma Data on stocks of scrap tires in the border region are limited. To our knowledge, reliable studies have been conducted in just two cities: Ciudad Juárez and Mexicali (EcoTechnologías de Mexico 2001; Ramirez et al. 1999). However, interviews with a variety of stakeholders suggest that the tire piles in these two cities are the largest on the border.4
Paso del Norte
Using original survey data along with government figures on vehicle ownership, a 2001 consulting study concluded that Ciudad Juárez generates approximately 828,000 scrap tires per year, or 0.69 tires per person per year (EcoTechnologías de Mexico 2001). However, this estimate omits the flow of American used tires into Ciudad Juárez.
The largest tire pile in Ciudad Juárez is a secured monofill called the Centro de Acopio, located just south of the city. Originally an illegal tire dump, this site has been managed by the city since 1994. This site contains approximately 1,043,000 tires (EcoTechnologías de Mexico 2001).
In addition to Centro de Acopiothere are two large tire piles in Ciudad Juárez, each with over 10,000 tires, and quite a few smaller piles containing from a dozen to two thousand tires.
Estimates of the number of tires in small piles dispersed throughout the city range from two to four million (Chacon 2001; Salmeron 2001).
El Paso City-County generates about 879,000 tires annually (TNRCC 2000). The city of El Paso’s one official secured tire pile, Tres Pesetas, is a privately owned tire collection and transport facility. The site currently contains fewer than 5,000 tires. Although Tres Pesetas accepts almost 2,000 tires per day (730,000 tires a year), it immediately transports them to end users (Perry 2001). Little is known about smaller, informal scrap tires piles in El Paso.
4Matamoras, Tamaulipas, and Nogales, Sonora, probably have fewer than 100,000 scrap tires each, and Tijuana, Baja California, probably has fewer than 1 million tires. By contrast, secured and unsecured piles in Paso del Norte contain well over 1 million tires (Blackman et al. 2001). According to Chacon (2001), the scrap tire disposal problem in Ciudad Juárez is at least as bad as in any other Mexican border city, and it is worse than in the interior of Mexico.
End uses In the United States, most scrap tires are no longer simply consigned to dumps. Rather, they are increasingly used as inputs into a variety of activities. The American market for scrap tires has grown dramatically over the past decade, from about 22% of total generation in 1990 to 72% of total generation in 2000 (Banipal and Mullins 2001). Tire-derived fuel (TDF) remains the most important end use for scrap tires in the United States, accounting for about two-thirds of the total market. TDF is principally used in cement kilns, electric utilities, and pulp and paper mills (Table 1).
In Texas, 20.3 million scrap tires, representing 85% of total annual generation, were reused in some way in 2000. Table 2 shows the composition of the Texas scrap tire market.
Again, TDF is the most significant end use.
Of the scrap tires accepted by the Tres Pesetas facility in El Paso, the end use for more than two-thirds is a landfill reclamation project. The remaining tires are used in conjunction with septic tanks, to make toys, to cover piles of agricultural produce, and as TDF in a cement plant in Odessa, Texas (Perry 2001).
Although a small proportion of Ciudad Juárez’s scrap tires is used for fuel by traditional brickmakers (see Section 6 below) and as building materials for informal housing, most are simply stockpiled. According to local stakeholders, however, other end uses are currently envisioned for the city’s scrap tires, including TDF for cement kilns, rubberized asphalt, layering in landfills, rubberized flooring, and blended rubber (Higgs 2001; Chacon 2001; Figueroa 2001;
3. Mosquito-borne diseases Scrap tires and mosquitoes Scrap tire piles are ideal mosquito incubators.5 They absorb heat and trap rainwater, leaf litter, and microorganisms—functions that promote the growth of mosquito larvae (CDC 2001b).
As a result, tire piles can propagate mosquito-borne diseases. Trade in used tires infested with mosquito larvae has contributed significantly to the global dispersion of disease-carrying 5 Rodents also breed in tires piles. However, this does not appear to be a significant problem in Paso del Norte, in part because scrap tires are separated from other solid wastes that attract rodents. There have been no reports of rodent bites in the Centro de Acopio tire pile since the city began managing it in 1994.
5 Resources for the Future Blackman and Palma mosquitoes, most notably Aedes Aegypti and Aedes Albopictus, the two principal vectors of dengue virus.6 Tire piles are typically high-priority targets of efforts to prevent or slow outbreaks of mosquito-borne diseases. Unfortunately, treating them with insecticides is problematic. It is difficult to penetrate tire piles to the depths where mosquitoes breed. Also, mosquitoes are developing resistance to many widely used insecticides. Finally, insecticides used to suppress adult mosquitoes are environmentally hazardous, and those used to suppress larvae are costly.
Thus, mitigating mosquito-borne diseases may require completely removing tire piles (URI 2001).
Mosquitoes and infectious disease
Mosquito-borne diseases include dengue, encephalitis, malaria, and yellow fever.
According to Cortez-Flores (2001), globally, dengue is currently the most important of all vector-borne viral diseases in terms of human morbidity and mortality. Primarily a disease of the urban tropics, dengue can produce a spectrum of clinical illness, ranging from a nonspecific viral syndrome to severe and fatal hemorrhagic disease. People with classic dengue fever are often sick for three to four weeks. Although dengue fever is not usually fatal, dengue hemorrhagic fever (DHF) and dengue shock syndrome can be. On average, 5% of hospitalized cases result in death. The majority of fatalities occur among children younger than 15 years (CDC 2001c).7 Dengue is not uncommon on the U.S.–Mexico border. During a 1995 dengue outbreak, the city of Reynosa, Tamaulipas reported 2,706 cases and Matamoros, Tamaulipas reported 408 cases. In Reynosa, 1% of those infected developed DHF (CDC 1996). Data from the Pan American Health Organization (Table 3) make clear that dengue and DHF are prevalent in all the Mexican border states except Baja California and Chihuahua (where Ciudad Juárez is located).
Dengue fever outbreaks can have serious economic impacts. For example, the cost of a 1981 6 The link between scrap tires and disease-carrying mosquitoes first came to light in 1940s, with the return to the United States of mosquito-infested surplus tires used in Asia during World War II. However, since the mid-1980s, when heavy infestations of Aedes Albopictus in southeastern Texas were traced to scrap tire piles, U.S. law has required all used tires imported from Asia to be certified as dry, clean, and insect-free (Reiter and Sprenger 1987;