Wal-Mart-owned Sam's Club pulled frozen hamburgers made by Cargill from its store shelves over the weekend after Minnesota health officials discovered four cases of E. coli associated with the burgers.

Symptoms of E. coli 0157:H7 illness -- the strain associated with the recall -- include potentially severe stomach cramps and diarrhea.

Cargill learned of the situation on Friday and said in a statement it does not yet know the extent of "any contamination." The investigation, which has been expanded beyond Minnesota, is ongoing.

"We are concerned that some consumers may still have the product sold at retail in their freezers," Bill Rupp, president of Cargill Meat Solutions, said in a statement. "We and Sam's Club are urging customers to return or destroy any American Chef's Selection Angus Beef Patties purchased in any of their stores since August."

Cargill said the hamburgers were manufactured at its plant in Butler, Wisconsin.

All four cases of E. coli being investigated occurred in children, the Minnesota Department of Health said in a statement. The cases are associated with eating ground beef patties purchased from Sam's Club stores in late August and September.

The Topps Meat Co.'s massive frozen hamburger beef recall has many shoppers worried about the safety of their meat, after it may have sickened 25 people in eight states.

"You don't know what's in it," one concerned shopper said. "It makes me feel very scared, and I don't know what to eat."

The recall, which includes 21.7 million pounds of meat, is enough to make a McDonald's regular hamburger for every adult in America.

The meat in question was made in late June and July. The E. coli in the hamburger beef began sickening people in August. It took nearly six weeks before the first recall was issued.

"We don't understand why it took so long to recall this meat. If there was a victim in August, it should have been revealed weeks ago," said Jean Halloran of the Consumers Union.

The U.S. Department of Agriculture, which oversees the industry, said there were no recall delays. However, when the first recall went out Tuesday, only a small amount was recalled. By the weekend, the recall was expanded by more than 600 times.

One victim, who tasted the tainted beef, was 15-year-old Samantha Safranek. She had severe stomach cramps in August after eating it.

"It almost cost my life," Safranek said. "I was just scared the whole time, just thinking, if I was even going to make it. And I didn't want a silly burger just to kill me."

The food recall is the latest in a rash of E. coli-related callbacks this year, including tainted spinach and salad mixes. The USDA said it is unable to explain why there have been so many outbreaks.

However, critics complain that every lot of processed meat should be tested, which is something not required today.

The recall of products distributed to retail grocery stores and food service institutions in the United States was a drastic increase from the 332,000 pounds recalled Tuesday.

The recall represents all Topps products with either a "sell by date" or a "best if used by date" between Sept. 25 this year and Sept. 25, 2008. The Elizabeth-based company said this information is found on a package's back panel.

All recalled products also have a USDA establishment number of EST 9748, which is located on the back panel of the package and-or in the USDA legend, the company said.

The U.S. Department of Agriculture said Friday it had suspended the grinding of raw products at the Topps plant after inspectors found inadequate safety measures at the Topps plant. The USDA declined to detail the inadequate safety measures.

"Because the health and safety of our consumers is our top priority, we are taking these expansive measures," said Geoffrey Livermore, Topps' operations vice president.

He said Topps has augmented its procedures with microbiologists and food safety experts.

"We sincerely regret any inconvenience and concerns this may cause our consumers," Livermore said.

The USDA said three people are confirmed as getting E. Coli from Topps products, with 22 other cases under investigation. Cases were found in Connecticut, Florida, Indiana, Maine, New Jersey, New York, Ohio and Pennsylvania.

E. coli causes intestinal illness that generally clears up within a week for adults but can be deadly for the very young, the elderly and people with compromised immune systems. Symptoms can include severe stomach cramps, bloody diarrhea and, in extreme cases, kidney failure.

Fentora is approved to treat cancer patients whose pain is not sufficiently controlled by conventional painkillers like morphine or other powerful drugs.

The FDA said it is crucial for doctors to precisely follow prescribing instructions to avoid fatal overdoses of the drug, which should not be used for short-term management of migraines or headaches.

"FDA is monitoring this issue very closely," Steven Galson, the head of the agency's Center for Drug Evaluation and Research, said in a statement.

Doctors can prescribe drugs for uses outside their approved labeling, a practice known as "off label use." Cephalon is seeking FDA approval for use in a broader group of pain patients.

Last year, a probe by the Connecticut attorney general found that Cephalon promoted some drugs for uses for which they were not approved, a practice that is illegal.

Cephalon earlier this month detailed three deaths of patients on Fentora, which it said were due to inappropriate use of the drug.

The company on Wednesday said it is working with the FDA to finalize a new label to reflect new safety messages about the drug, which comes in pill form.

FASTER ACTING

In its letter to health professionals dated September 10, Cephalon said patient deaths were due to improper patient selection, dosing or product substitution. It also warned that Fentora should not be used as a replacement for a similar painkiller sold by Cephalon called Actiq.

Fentora delivers more medication to the blood than Actiq, and substituting the same dose for Actiq can be fatal, the FDA said.

Dr. Scott Fishman, past president of the American Academy of Pain Medicine and professor at the University of California in Davis, said a big issue is that doctors are not trained in pain management, especially with faster acting painkillers like Actiq and Fentora.

"There are a host of patients out there that need relief quickly. Doctors will feel compelled to use whatever works," Fishman said in an interview.

Fentora is made from fentanyl, which in raw form is 80 times stronger than morphine. Cephalon officials said once it is processed, the difference is much less.

Although the United States has banned the sale of toys made with lead paint since 1978, those products continue to seep into the domestic market.

The CPSC also said China will increase inspections of consumer products destined for the U.S. and assist the agency in tracing hazardous products to the manufacturer, distributor and exporter in China.

"If there is a product recall by a U.S. company that sourced the goods from a Chinese supplier, under the new agreement, China will now let the CPSC know if that supplier also sells its products to other U.S. importers," said Eric Autor, international trade counsel for the National Retail Federation, who attended the summit.

Chinese officials also said China would now require U.S. importers to obtain "export registration" for products that cause concern.

China will also ask importers to provide product designs to Chinese suppliers that are in compliance with U.S. safety standards and that U.S. importers provide reasonable prices to manufacturers to prevent Chinese producers from cutting corners and using cheaper unsafe materials.

Consumers Union, publisher of Consumer Reports magazine, said the agreement between the U.S. and China to eliminate the use of lead paint was "long overdue."

"China faces huge challenges in enforcing adherence to U.S. safety standards in products it exports to this country," Donald Mays, senior director of product safety with Consumers Union, said in a statement. "However, we are encouraged by the fact that U.S. toy manufacturers and retailers have indicated that they want federally mandated third-party testing of children's products."

China moved ahead of Canada as the leading source of imports into the United States, according to the most recent reading from the Commerce Department.

China also accounts for more than 80 percent of the world's toy production, primarily due to its low labor and raw material costs.

This year, Mattel (Charts, Fortune 500), the world's largest toymaker, faced three toy recalls that affected millions of its toys made in China. Mattel said those toys posed lead poisoning and choking risks to small children.

Another toymaker, RC2 Corp., recalled 1.5 million "Thomas & Friends" wooden railway toys in June that were also made in China over concerns that the surface paints on the toys contained lead.

"This is an important signal from the Chinese government that it is serious about working with CPSC to keep dangerous products out of American homes," CPSC's acting chairman, Nancy Nord, said in a statement. "We will be looking for meaningful cooperation on the ground, that means not just with the Chinese government but also with industry at both ends of the supply chain."

For its part, the CPSC has also come under fire from critics who said the agency is not doing enough to ensure that unsafe products do not reach store shelves.

Analysts point out that the CPSC currently doesn't have pre-market jurisdiction, which means that the agency can't test products for safety issues before they hit the market.

In the wake of the recent recalls affecting toys, toothpaste, tainted pet food and other products imported from China, some U.S. lawmakers are taking a closer look at U.S. manufacturers' and the CPSC's role in ensuring product safety.

To that end, on Wednesday, Mattel's CEO Robert Eckert is expected to testify before a Senate Appropriations subcommittee that oversees the Consumer Product Safety Commission about the problem of recalls of products made in China.

Separately, on Tuesday, Sen. Amy Klobuchar, D-Minn., introduced a bill to ban the use of lead in the manufacturing of children's toys, jewelry and other products.

Current voluntary guidelines set forth by the CPSC recommend additional testing of potentially unsafe products rather than an immediate recall of products found to contain lead.

"After a summer of recalls, it's time we make it crystal clear that lead has no place in our children's products. We must keep these unsafe toys off our shores and out of our stores," Klobuchar said in a statement.

The bill provides that lead in any children's product shall be treated as a "banned hazardous substance." It would set a ceiling for a trace level of lead at 0.04 percent per part for children's products, and 0.02 percent for jewelry.

If enacted, this legislation would be the first time standards for lead levels in children's products would be set by federal law.

While current law does not ban lead in toys, the Consumer Product Safety Commission has voluntary guidelines set at 0.06 percent.

Later in the day, the CPSC and Chinese officials held a panel discussion to assess what responsibility, if any, retailers have to ensure that the products they sell comply with U.S. safety standards.

"The CPSC acknowledges that product recalls pose a certain challenge to retailers," said NRF's Autor, adding that the agency said that under Federal statutes, manufacturers, including importers, are responsible for product safety.

"By the time products reach retailers, their best safety enforcement is to do random samplings. That is less than a perfect solution to the problem," Autor said.

Given that retailers generally are unaware of who the Chinese suppliers are to U.S. manufacturers, Autor said he too believes the burden falls on U.S. importers to best maintain product quality and safety controls.

More than 68,000 pounds of bagged fresh spinach are being recalled by a Monterey County grower after routine testing found salmonella in a sample taken from a Watsonville packing plant.

There have been no reports of illness from the spinach, but state and federal health officials said they are working with Metz Fresh of King City to determine the source and scope of contamination.

The recall announced Wednesday comes almost exactly one year after a nationwide outbreak of illness was traced to a batch of bagged California spinach that was tainted with a deadly strain of E. coli bacteria.

Since then, produce growers and distributors say they have taken steps to improve sanitation and testing procedures.

The current recall involves a batch of spinach that was packed on Aug. 22 and distributed late last week to retail and food-service customers, such as restaurants or institutional kitchens, in the United States and Canada.

The salmonella was found during testing at a packing plant that was operating under contract with Metz Fresh, said Greg Larsen, a company spokesman.

In a statement, Metz Fresh said the salmonella was detected in a single sample of spinach at the processing plant. The company said it decided to recall spinach from three processing lines at the plant as a precaution, since all three lines were handling produce from the same field.

Company officials began contacting their customers, asking them not to serve or sell the spinach to consumers, after receiving a preliminary test result on Friday, Larsen said. As of Friday night, he added, "we had corralled and held 90 percent of the expanded lot in question."

The company decided to formally recall the product on Tuesday, after lab analysis confirmed the preliminary finding of salmonella.

Officials are still trying to determine whether any of the spinach was sold or served to consumers.

Salmonella can cause fever, abdominal cramps and diarrhea. It can be life-threatening to children, the elderly and adults with compromised immune systems.

The recall involves only fresh spinach packed under the Metz Fresh label, in packaging marked with tracking code 12208114, 12208214 or 12208314. The spinach was packed in 10- and 16-ounce bags, as well as 4- and 10-pound cartons.

Metz Fresh said consumers should discard the spinach or return it to their retailer for a refund. Consumers with questions can call (831) 386-1018.

Each test, he said, would cost about $50. "The numbers are staggering," he told CNN in a telephone interview. "We need to act fast. The sooner these kids are identified, the better." If a significant number of children were identified as having been poisoned by the heavy metal, Killino said he would consider expanding his suit "to a mass tort action."

He acknowledged, though, that it may not be possible to determine whether the exposure was related to the Mattel products or to another potential source of exposure. The Sarge recall affected toys made between May 2007 and July 2007 that contained lead paint.

That followed the August 1 recall of 976,000 toys from Mattel's Fisher-Price division -- including Dora the Explorer and Sesame Street characters.

Mattel (Charts, Fortune 500) said it subcontracted the work to companies that failed to follow its strict guidelines.

Lead is particularly toxic to the bodies and brains of children under the age of seven. Even small amounts can cause learning disabilities and brain damage that may not be diagnosed until years after the exposure.