Tomatoes are symbolic of many things, chief among them love—the French word for the fruit translates as “apple of love.” In recent years, however, they have come to represent the worst of farm-labor abuse, thanks in large part to the slave-like conditions that long persisted in Florida’s tomato fields and the Coalition of Immokalee Workers' successful efforts at reforming them.

But Florida isn’t the United States’ only supplier of the nightshade—half the tomatoes we eat are imported from Mexico, which is also a leading grower of other fruits and vegetables. In a new investigation published by the Los Angeles Times over the weekend, reporters reveal that working conditions on farms growing produce for the likes of Walmart, Whole Foods, and the Los Angeles Unified School District are less than idyllic. Workers live in labor camps surrounded by barbed-wire fences, depend on the high-priced company store for basic necessities, and go without bathrooms and showers, instead using irrigation dishes for bathing and nearby fields for toilets. All this for just $8 to $12 a day in pay—wages that may be withheld or stolen. While this is happening in Mexico, the trade policies that helped create both the supply and the demand originated in the United States.

“They want us to take such great care of the tomatoes,” Japolina Jaimez, who works at Rene Produce in Sinaloa, one of the farms accused of labor abuses, told the Times, “but they don’t take care of us.”

While Whole Foods promised to stop buying products from Rene Produce, other distributors and retailers were far cagier when asked for comment. “The Mexican government would be the first line of protection for Mexican workers,” said Dan Mandel of SunFed, which used to distribute tomatoes from Agricola San Emilio, one of the suppliers covered in the story, to American supermarkets.

That may be the case, but the squalid conditions of the labor camps, the low wages, and the illegal withholding of pay is largely done in service of American appetites. A full 60 percent of Mexico’s agricultural exports are destined for the United States, amounting to $16 billion worth of tomatoes, sugar, chiles, citrus, and other fruits and vegetables in 2012. Mexico is the United States' No. 1 supplier of imported fruits and vegetables.

While the Times story goes to great lengths to reveal the horrendous conditions on Mexican produce farms—the reporters spent a year and a half working on the four-article series—it has yet to name its primary cause: the North American Free Trade Agreement.

Signed nearly 21 years ago, on New Year's Day 1994, NAFTA promised to create the largest free-trade area in the world, allowing goods to move between Canada, the United States, and Mexico without the hindrance of tariffs or other deterrents. But for Mexican farmers and agricultural workers, the last two decades have been marked by the end of government subsidies, massive consolidation, and an increased focus on growing for export. The country’s chief staple, corn, is now largely supplied by American farmers, thanks to our continued subsidy programs.

NAFTA was not only a historic agreement in terms of size. A parallel deal, the North American Agreement on Labor Cooperation, set standards for workers' rights in all three countries. It marked the first time that a free-trade agreement was tied to labor standards. But the scenes described in the Times stories—backing up long-standing criticism of the NAALC—suggest that those standards are not being upheld. Both the agreement and the Mexican constitution bar children under the age of 14 from working, and yet field hands as young as nine are featured in the story. Employers are also required to provide employees with “comfortable, clean accommodations,” according to NAALC standards, which doesn’t mention rodents, a common presence at the labor camps visited by the Times.

The day that the NAFTA agreement was signed, the Zapatista Army of National Liberation declared war on the Mexican government, taking over areas in the southern state of Chiapas. The group, composed largely of people of Mayan descent, said that NAFTA would be “a death sentence for the indigenous people of Mexico.” As the infographic that accompanies the Times story depicts, Chiapas and other states in the region—which share high rates of poverty and large indigenous populations—are the primary regions where the NAFTA-enabled farms recruit workers, promising fair wages, free meals, and overtime pay, promises that too often are not met.