The AP has found that while some Mexican producers grow fruits and vegetables under strict sanitary conditions for export to the U.S., many don't—and they can still send their produce across the border easily.This article is informative as far as it goes in explaining what goes on in Mexico and the lack of oversight and inspection.
Neither the U.S. nor the Mexican governments impose any safety requirements on farms and processing plants. That includes those using unsanitary conditions—like those at Agricola Zaragoza—and brokers or packing plants that mix export-grade fruits and vegetables with lower-quality produce.
In fact, the only thing a Mexican company needs to do to sell produce to the United States is to register online. [...]
In the latest contamination case, the U.S. government traced the suspect jalapenos to two farms in the state of Tamaulipas. Both shipped through Agricola Zaragoza in neighboring Nuevo Leon state. Agricola Zaragoza shipped the peppers to its warehouse in McAllen, Texas, where the FDA found the first contaminated jalapeno.
Though usually smaller in scale, such outbreaks are relatively common—at least 3,000 between 1990 and 2006 from FDA-regulated foods, according to the Center for Science in the Public Interest, a nutrition and food safety advocacy group. Those numbers include fruits, vegetables and seafood, and contamination both in the U.S. and abroad.
The cases include a 2004 hepatitis outbreak linked to Mexican green onions that killed four people and sickened 650 in Pennsylvania, and a 2006 nationwide E. coli outbreak that infected about 300 people and killed three and was traced to tainted spinach from California. [Few safeguards for Mexican produce heading north, AP, September 14, 2008]
However, it does not mention country-of-origin labeling which would allow consumers to protect themselves at the grocery store. Congress passed legislation in 2002 that would require that information, but the Bush administration has not allowed it to be implemented because of heavy lobbying from all over.
Here's a clip from Lou Dobbs Tonight from July 2007 on the topic of Country-of-Origin labeling.