The black-market battery business is booming across the border.
Exports of used American car batteries have skyrocketed in the past decade up as much as 525 percent, says Iresema Coronado, a UTEP professor and head of the Commission for Environmental Cooperation.
A battery-recycling watchdog group estimated that the amount of used batteries making their way into trucks heading to Mexico in 2011 would have filled nearly 18,000 tractor-trailers.
Although dead batteries are useless to car owners, the lead found inside each battery is like gold to manufacturers. The precious lead found inside can be smelted and reused indefinitely.
Much of the battery exports are legal, where U.S. battery manufacturers opt to ship recycled batteries to Mexico where labor is cheap, worker protection is low, and environmental regulations one tenth as strict as they are in the U.S.
Batteries are broken down in maquiladoras, which are located mostly in Mexico's interior, the largest found outside of Monterrey.
The factories extract the lead, process it in the smelter, then create new batteries with the recycled lead to be sold by the world's biggest retailers in stores throughout the world.
But more and more frequently, the used batteries are making a stop as soon as they get across the border from El Paso.
Mexican environmental regulators cracked down on a stash house in Juarez found to be housing 37 tons of used batteries in January.
In 2011, a truck that had crossed from El Paso was impounded when Mexican agents noticed it was dripping acid. A shipment order showed the 1,800 used batteries were going to a licensed recycler, but the driver confessed he was actually taking the batteries somewhere else.
ABC7 spoke with EPA-regulated battery recyclers in El Paso and New Mexico who say they pay $8-$10 for used batteries to be recycled in regulated smelters in the U.S. They say they are being undercut by black-market buyers who pay up to $14 per battery, then take the batteries across the border.
As you walk the salvage yards of junk-yard row in Juarez, you see the same signs again and again, "Compro Baterias," -- "I buy batteries." But through an ABC7 investigation, battery-business insiders in the borderland and Juarez say what the buyers are really looking for is the pure lead. Buyers pay a higher premium on lead if it is already removed from its battery casing.
They tell us lead dealers and black-market buyers often crack open the car batteries with no protection and no concern for where they are handling the hazardous material.
Scientists say lead exposure can cause heart disease and brain disorders. The C.D.C. has found that even exposure to the material in small quantities can be dangerous.
It is illegal to export batteries to Mexico from the U.S. without having a license. But Mexican customs agents' checks on inbound civilian traffic is sporadic at best.
It is unclear what the hazardous effects of exposing raw lead could have on communities in Juarez. Also unclear are the potential spillover effects that could result from soil and groundwater contamination to residents of El Paso.
"The truth is we really don't know," Diane Cullo, director of battery recycling watchdog group, SLAB Watchdog, said. "We can anticipate what the potential implications are but we really don't know how severe it could become."