Lead standard for toys

A new method has been created to detect lead in children’s toys after a rash of recalls in recent years prompted the US Congress to tighten regulations. The Consumer Product Safety Improvement Act, passed in August 2008, slashes the surface lead concentration limit from 600 parts per million to 90 ppm and regulates, for the first time, bulk lead concentration levels; that limit will start at 600 ppm and go down to 100 ppm over three years. Now, ASTM International, an organization that develops technical standards for voluntary adoption by federal regulators, is proposing a method based on energy-dispersive x-ray fluorescence to nondestructively detect lead to below the new limits.

Lead can be detected in seconds with portable EDXRF spectrometers; when bombarded by incident x rays, elements in a sample emit multiple spectral lines that are characteristic of their atomic number. The location of lead—in the bulk or on the surface—can be determined by taking the ratio of two emission intensities. The x-ray measurement is more sensitive than the currently used chemical method, which is based on inductively coupled plasma mass spectroscopy. And ICP is not accurate if metal salts remain trapped when the sample does not completely dissolve, says Stanislaw Piorek, an ASTM committee member and a scientist at Massachusetts-based Thermo Niton Analyzers LLC. “A lot of information is missed when you just scrape one location on a few toys and assume they are all the same,” he says.