Testing of 61 samples bought by AP reporters across the country from the Miley Cyrus line and from the line of charms showed that 59 of the pieces contained at least 5 percent cadmium by weight, with 53 of those measuring 10 percent or higher.
Wal-Mart Stores Inc. received test results in February showing cadmium in these jewelry lines but has continued selling the items.
The chain said last month that it has begun requiring suppliers to prove their products contain little cadmium, or else Wal-Mart would not accept the items. But Wal-Mart said at the time that testing products already on its shelves would be too difficult.
Exactly how many of the items have been sold was unclear. The charms - available exclusively at Walmart stores - were sold under the name "Fashion Accessories." The Miley Cyrus pieces first hit store shelves in December, according to Wal-Mart.
In its only comment for this story, Wal-Mart said the Miley Cyrus jewelry was for "juniors," without defining that age range.
Representatives for Miley Cyrus and BCBGMaxAzria, the designer that developed her brand of jewelry for the "Hannah Montana" star, had no immediate comment.
The items are not known to be dangerous if they are simply worn. Concerns come when youngsters bite or suck on the jewelry, as many children are apt to do.
To judge the availability of pieces that Wal-Mart knew were contaminated, AP dispatched reporters throughout the country last month to search for and buy any of 13 items. Three of those were Miley Cyrus jewelry; the rest were from the line of bracelet charms. The packaging said they were made in China; all were bought for $6 or less.
All but one of the 13 were on store shelves in the eight states where AP reporters looked.
The items were then tested by Professor Jeff Weidenhamer, a chemist at Ashland University in Ohio. He said that the average cadmium content was 16 percent, and that the levels are probably higher.
Weidenhamer's prior research has shown that the testing method he used - an X-ray gun that can roughly tell the amount of cadmium in an item - typically underestimates how much is present.
Representatives of the jewelry industry have argued that the presence of cadmium,, even at high levels, is not by itself proof that an item is dangerous. The important thing, they say, is how much can escape if the item is sucked, bitten or swallowed.
Cadmium in children's jewelry became a public concern in January when the AP published the results of an investigation that showed items at Walmarts and other large chains were as much as 91 percent of the toxic metal by weight. Lab testing conducted by Weidenhamer at AP's request showed that several items easily shed the metal when exposed to a mixture that simulated human stomach acid.
The day after AP's original report, Wal-Mart said it was pulling two of the highlighted items - pendants with themes from the Disney movie "The Princess and the Frog." Within three weeks, the chain had agreed to recall all of the pendants that had already been sold.
Since then, federal regulators have issued two more recalls, for charm bracelets sold at the international jewelry chain Claire's and at a Dollar N More store. Last week, the agency's spokesman said there will be more recalls.
Long-term exposure to cadmium can lead to bone softening and kidney failure. It is also a known carcinogen, and research suggests that it can, like lead, hinder brain development in the very young.
For reasons that are not fully understood, girls ages 6 to 11 - an age range that includes many fans of Cyrus' "Hannah Montana" TV show, movies and CDs - are of particular concern.
Data from a major national study found that girls of that age absorb more cadmium than other children or adults, according to Bruce A. Fowler, a toxicologist with the Centers for Disease Control and Prevention.
The increased absorption could be because those girls typically have iron deficiency and their bodies grab onto cadmium as a substitute, Fowler said, or it could be because they encounter more of the metal in objects such as jewelry.
While AP's January investigation focused on jewelry clearly intended for children, the items tested for AP this time were labeled "not intended for children under 14 years." That is an important legal distinction: Under current law, children's items are defined as for kids 12 and under, and children's products are subject to regulations that others are not.
The importer of the bracelet charms, Cousin Corp. of America, said that earlier this year, it persuaded one of the Chinese factories with which it works to stop using cadmium. The cadmium-heavy jewelry Weidenhamer tested came was produced in 2008 and 2009 at the problem factory, said Roy Gudgeon, vice president of merchandise at Florida-based Cousin.
"Our intention as a company is to never willingly cause harm to a child," he said.
Federal regulators' own research says that kids start becoming interested in making their own jewelry around age 6 or 8. As for products featuring Miley Cyrus, she is 17 and her appeal reaches down to kindergartners.