Photos: Sniffing out poisons in products

According to this handheld device attached to the XRF machine, one of the two shopping bags being tested contains a whopping 6,974 parts per million of lead, far above the allowable California maximum of 100 parts per million.

When the state finds such a result, it sends the sample for further lab testing. This plastic bag, for instance, would be melted down and analyzed bit by bit.

The state would ask the retailer handing out the bag to respond within 60 days. In a typical scenario, the store would likely prove that the bag supplier did not disclose lead contamination. If the supplier failed to eliminate the lead, the store would have to seek another source for the bags.

Some 60 percent of plastic bags, most made in China, contain high levels of lead, according to the California Department of Toxics Control.