The U.S. Consumer Product Safety Commission recently denied a petition asking the Commission to ban “any metal toy jewelry containing more than trace amounts of cadmium by weight, which in a foreseeable manner could be ingested by children” as a hazardous substance. The Commission’s engagement with ASTM committees in the development of ASTM standards (ASTM F963-11, which applies to toy jewelry and was made mandatory by the Consumer Product Safety Improvement Act of 2008, and ASTM F2923-11, which applies to children’s jewelry) resulted in restrictions in these standards that reflect the understanding that risk only exists where exposure is possible.
ASTM F963 and ASTM F2923 set “soluble” limits for cadmium and other heavy metals, determined by laboratory testing that simulate ingestion of a metal part: “Although incidental mouthing or handling and touching of products are more reasonable and likely exposure pathways for heavy metals in jewelry, just as it is for toys, accidental ingestion of a product containing an element represents the most health conservative (worst-case) scenario.”
Consequently, the standards require three threshold tests to determine if a laboratory simulation is necessary: 1) is the part accessible during normal use or abuse, 2) are parts small enough to swallow through normal use or abuse – including if breakage occurs, 3) does the material contain more than 300 ppm of cadmium? This last requirement is based on recognition that not all cadmium in the part or coating will release during an exposure event. “Consequently this standard adopts a total content screening limit [300 ppm], with migration testing to be conducted where covered items exceed the screening level.”
The distinction between total cadmium content and soluble content is critical. The assessment of health risks associated with accidental ingestion is based on the amount of cadmium available for absorption which is known to be less than the total amount of cadmium in the part. The scientific work performed by CPSC staff and others supports this interpretation. “CPSC has concluded that ‘soluble cadmium migration is not generally proportional to [total] cadmium content.” One should always be cautious in interpreting a positive laboratory result in assessing potential health concerns. Inherent in the standard testing process is evaluation of the entire ingestible part, which is only directly applicable to total ingestion, not mouthing, licking, or touching – exposure pathways that are considered to be less aggressive.
The standards promulgated by ASTM and supported by the CPSC recognize the scientific understanding that products found to contain heavy metals like cadmium are not necessarily hazardous in and of themselves. Petitioners wanted to ban jewelry that contained any level of cadmium (above a scientifically imprecise “trace” amount) regardless of shape, size, or intended use or age group. Any future modifications of standard limits by CPSC or ASTM will need to consider the detection limits of available analytical methods where the result is never zero but rather less than a detection limit. The ability for manufacturers to prove compliance will have a practical limit. The CPSC should be commended for its restraint.