Wal-Mart Probed on Hazardous Materials

The state is also examining whether Wal-Mart has kept proper records of the hazardous materials it keeps in stores and transports on California roads and freeways, the official said.

"What if they were to get into an accident?" the official asked.

In its SEC filing, Wal-Mart said the company historically had consolidated certain returned merchandise at its return centers and then taken hazardous waste products to a certified waste disposal facility.

Cindy Anderson, a spokeswoman for the Nevada Division of Environmental Protection, said the Las Vegas return center was permitted to dispose of hazardous waste generated there, but wasn't allowed to take such material from elsewhere.

The Nevada investigation stems from unspecified "compliance issues" discovered during the last inspection of the facility, Anderson said.

Although the types of returned merchandise that might be considered hazardous waste might seem relatively benign, an environmental lawyer said regular household products could still be extremely dangerous, especially when mixed, damaged or exposed to pressure or heat.

"It's a legitimate concern, that's why the law exists," said Pat Gallagher, legal director of the Sierra Club. "If there's a car crash and stuff spills on the street, responders need to know what it is so not to create a dangerous fire or pollution situation."

And because federal authorities have the option of resolving such complaints informally or by filing a civil complaint, the fact that they are proceeding with a criminal investigation suggests that they consider it to be a fairly serious matter, Gallagher said.

Wal-Mart in August agreed to pay a $1.2-million settlement with the Connecticut Department of Environmental Protection for alleged violations in that state.

In 2004, Wal-Mart paid $3.1 million in fines to settle allegations that it violated the federal Clean Water Act in nine states, the largest civil penalty ever collected in a storm-water runoff matter.

In 2001, the company paid $1 million to settle claims that it illegally discharged water at construction sites in four states.

Wal-Mart shares fell 36 cents to $48.60 on Tuesday.