Young children who mouth or swallow jewelry containing cadmium may be exposed to as much as 100 times the recommended maximum exposure limit for the toxic metal, according to research published online March 4 ahead of print in the peer-reviewed journal Environmental Health Perspectives (EHP). The study measured bioavailability, or how much cadmium leached out of the jewelry. The research also found that damaged pieces of jewelry in some cases leached up to 30 times more cadmium than undamaged pieces.
"Our hope is that the potential hazards of cadmium-laden jewelry will be taken seriously. While the bioavailability of cadmium from many items was low, the amounts of cadmium obtained from other items were extraordinarily high and clearly dangerous if these items were mouthed or swallowed by children," said study author Jeffrey Weidenhamer of Ashland University in Ohio.
Cadmium, a heavy metal, can cause kidney, bone, lung, and liver disease. Cadmium contamination is a global health concern. Most human exposure comes from food or tobacco grown with cadmium-rich phosphate fertilizer. Health effects typically are not acute but instead result from chronic, long-term exposure. Because cadmium can accumulate in the body, all exposures should be avoided. Agencies around the world, including the World Health Organization, are working to regulate the use and disposal of the heavy metal.
Last year, in testing conducted for an Associated Press (AP) investigative report, Weidenhamer found high concentrations of the soft, whitish metal in inexpensive jewelry imported into the United States from China. The jewelry contamination represented a new avenue of cadmium exposure for children. "It was a complete surprise to find such high amounts of cadmium -- up to 90% by weight -- in some of these jewelry items," Weidenhamer said of the AP investigation. "Given the toxicity of cadmium, information on its bioavailability was needed in order to evaluate the potential risks. That is what motivated [the EHP] study."
Weidenhamer's findings were widely reported, and after multiple recalls of children's jewelry, the U.S. Consumer Product Safety Commission (CPSC) issued recommended limits on cadmium bioavailability. These limits were based on the amount of cadmium leached after an item soaked in a saline solution for 6 hours (to simulate putting the item in one's mouth) or in dilute hydrochloric acid for 24 hours (to simulate ingestion).
For the current study, Weidenhamer's team tested 69 pieces of cadmium-laden jewelry, mostly charms and necklace pendants, many labeled for children and imported primarily from China. Most items sold for less than $5 each and were purchased in 2009 and 2010.
Of 34 pieces of jewelry tested under mouthing conditions, one piece (a football pendant) yielded 2,109 micrograms of cadmium -- more than 100 times the CPSC-recommended limit of 18 micrograms for maximum exposure through mouthing. Eight other pieces exceeded the 18-microgram limit.
Of 92 pieces of jewelry tested under ingestion conditions, two pieces (a football pendant and a heart charm) yielded more than 20,000 micrograms of cadmium, 100 times the CPSC-recommended maximum exposure of 200 micrograms through ingestion. Fourteen samples yielded more than 1,000 micrograms. The researchers found the amount of cadmium released increased linearly, indicating that the longer an item stays in a child's stomach, the greater the potential for harm.
Because normal use, especially by children, can damage jewelry, separate tests were conducted on pieces whose outer coatings were purposefully damaged. Six damaged sandal charms tested in dilute hydrochloric acid for 96 hours yielded a mean of 30,600 micrograms of cadmium, more than 30 times as much cadmium as intact charms, which yielded a mean of 912 micrograms.
"To think there are products on the shelf that you could pull thousands of micrograms of cadmium off by simple extractions like this is very concerning," Weidenhamer said.
The work was supported in part by a grant from the Dr. Scholl Foundation, and the National Science Foundation provided financial support for acquisition of the Varian 220 AA spectrometer.
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