They might not be the most glamorous imports, but the used U.S. tires that flow into Mexico by the millions have to rank among the most visible.

Private Mexican dealers who sell the tires to budget-conscious consumers have erected huge, troublesome piles of used treads in Tijuana, Mexicali, San Luis Río Colorado, Reynosa, and Matamoros.

In Ciudad Juárez, across the Rio Grande from El Paso, Texas, officials and representatives of used-tire dealers estimate 12 million or more aging treads are stacked at just one site outside the city. In Mexicali, some 5 million tires are piled up.

And imported tires are only part of the problem. Mexico’s Environment and Natural Resources Secretariat estimates that every year the country itself generates 40 million used tires, many of which are disposed of improperly.

The accumulation is causing growing alarm among environmental officials in Mexico and the United States. They fear a catastrophic tire fire could release toxic substances into the air and pollute groundwater. Tire fires can cause pyrolytic oils to seep into the water table. They also emit “criteria” air pollutants such as carbon monoxide and nitrogen oxide as well as “non-criteria” contaminants including dioxins, furans, PCBs and metals, among a host of other compounds.

In 1995, a blaze that engulfed some three million used tires south of Tijuana produced a toxic cloud.

“I think it’s a risk not only for Juárez, but for the entire region that includes the states of Texas, New Mexico and Chihuahua,” says Alma Leticia Figueroa, head of Ciudad Juárez’s municipal ecology department.

In the age of West Nile Virus, Figueroa warns, the tires also are particularly worrisome as potential breeding grounds for mosquitos. Figueroa and other local officials from Mexican border municipalities are working with the U.S. Environmental Protection Agency on ways to prevent tire fires—and to fight them should they occur.

Besides posing an environmental and public-health problem, the mountains of tires in Mexican border cities can cause political conflict, too. In Ciudad Juárez, used-tire dealers have conducted street protests and blockaded government buildings to protest proposed environmental permits and importation fees.

Ernest Chávez, president of the Border Tire Dealers Union, says his group is open to any solutions that involve them and address a tire pile-up that has spiraled out of control.

Searching for answers

As used tires pile higher, officials and representatives from the private sector on both sides of the border are moving on several fronts to tackle the problem.

For instance, the new Mexican-U.S. Border 2012 environmental plan calls for the cleanup of three of the largest tire piles along the border, although the specific sites have not been selected yet.

On a parallel front, efforts are underway to recycle used tires into useful products, including electricity. After undergoing a gasification process, scrap tires have been found to be an efficient energy source for paper mills and cement plants. Mexican cement companies including Cemex and Cementos de Chihuahua are already experimenting with or actively using tire-derived fuel as an energy source.

The incineration of used tires has drawn opposition from Greenpeace and other environmental groups on grounds tire incineration releases dioxins and other pollutants into the air. But advocates insist that with proper pollution-control equipment, tire-fired plants will meet air-quality standards.

Until now, finding investment backing and a sufficient supply of used tires has discouraged a greater use of tire-based fuel, but with tires so abundant, the technology is sparking the interest of the San Antonio-based North American Development Bank (NADB). Launched in 1994 to fund border environmental clean-up projects, the NADB initially focused on financing wastewater systems but now is pursuing a wider variety of environmental projects.

“We’re looking at it as something that has financial viability,” says Suzanne Gallagher, the NADB’S program development director.

While Gallagher acknowledges that significant investment capital is needed, she points out that this cost must be weighed against the damage and expense that could be caused by a large-scale tire fire.

Will the rubber meet the road?

Another tire recycling technology drawing NABD’s interest is the use of shredded tires in the manufacture of crumb-rubber asphalt.

Such asphalt might be used in the latter stages of a five-year program certified by the Border Environment Cooperation Commission (BECC), the body that approves projects for NADB financing, to reduce airborne-dust pollution by paving roads in the Baja California communities of Mexicali, Tijuana, Tecate, Rosarito and Ensenada, Gallagher says.

The BECC already has approved NADB financing for a tire-shredding facility in Ciudad Juárez, where the material will either be landfilled or recycled. Final design of the shredding plant is expected to be complete in the fall.

Meanwhile, Mexican lawmakers are pondering new legislation and binational agreements governing the importation and disposal of used tires in their country.

To fund tire-cleanup, they are considering a variety of possibilities—for instance, requesting a portion of the income from fees U.S. consumers pay when they turn in used tires, piggybacking a tire tax onto the vehicle-plate levy charged to Mexican drivers and assessing Mexican tire dealers a US$1 fee on each tire sold in the country.

Because of the cross-border nature of the tire problem, Mexican lawmakers say U.S. participation in finding solutions is vital. Jeffrey Jones, president of the Mexican Senate’s Border Affairs Commission, expects the tire issue will be discussed at a meeting of U.S. and Mexican legislators scheduled for early August.