Public-health officials say there is no evidence that the decorated tableware has caused elevated lead levels in children, which are carefully tracked. But much about lead remains unknown. And the minimum level believed capable of harming a developing brain has been lowered repeatedly.
At the very least, confirmation of the Chinatown findings - the screenings, using a swab intended for home use, indicated only lead's unexpected presence, not its quantity - could suggest another hole in the nation's food-safety system, and one more potential worry for consumers.
"Now, further work needs to be done to identify the magnitude of the hazard," said University of Colorado medical toxicologist Michael Kosnett, who chairs a consumer-products group of the federal Advisory Committee on Childhood Lead Poisoning Prevention. "But the initial screening done by Dr. O'Malley and his colleagues has raised cause for concern."
For millennia, workers have been poisoned by lead. But the devastating impact of far-smaller doses on children was not recognized until the 20th century. Severe disease was routinely seen in children's hospitals in the 1950s.
Since then, three federal bans - on lead in gasoline, residential paint, and soldered food cans - is credited with cutting blood levels more than 90 percent. That has made smaller sources more visible.
Wandering around Chinatown, O'Malley spotted ornately painted cups, spoons, even chopsticks, "the kind of thing you could see that an infant might gnaw on."
He suggested a testing project to the dozen or so students assigned to the ER between their first and second years, and paid for the whole thing himself.
The test, LeadCheck, is very basic. You crush the contents of a tube, swab an item, and watch the color. Pale pink means one part per million. Darker means more.
O'Malley was working in the ER when the students tested the first item. "One of them came running out to me," he recalled, "and she said, 'You're not going to believe this.' It lit up like a Christmas tree - bright red."
The second item tested negative, as did 108 others. Twenty-two of the 27 positives had been bought in Chinatown. Among the five from elsewhere was a Liberty Bell gift-shop mug.
Lead in ceramics meant for food is not illegal. Food and Drug Administration regulations instead limit the amount of "leachable lead," the potential contaminant.
Nearly all tableware is imported, and FDA officials described several levels of enforcement.
The agency's counterpart in China certifies that factories meet U.S. standards. FDA inspectors also conduct spot checks at U.S. ports, focusing mainly on items from noncertified factories.
They use the same LeadCheck swab that the students did, with a twist: They first scratch ceramics with sandpaper, knowing that many of the resulting "false positives" in the field will turn out to be negative after more sophisticated tests at the FDA lab.
Of the 203 FDA field samples from China that were sent to the lab in 2009, the FDA reported four (2 percent) as noncompliant, 163 (80 percent) as compliant, and the rest as other, perhaps damaged or not used on food.
Most of the glazed ceramic ware "is of good quality and complies with FDA requirements," FDA consumer-safety officer Michael E. Kashtock said.
Thomas Gilmore, a Jefferson ER resident who worked with the students, expects within the next few weeks to do the next step, precision atomic analysis, using lab equipment at another university.
"I feel for the merchants," Gilmore said. "I want them to be helped by this project rather than hurt by it."
An attending ER physician who is fluent in Cantonese, Wayne Bond Lau, went back to the stores to explain the initial findings.
"It was my sense that they would do something about it. I thought at the end of the day," Lau said, "that we had gotten through and done some good."
A reporter who visited most of the shops last week found one (Chung May Food Market) had removed all ceramic tableware, some had pulled the items purchased from that store that tested positive, and some had kept all of them on the shelves.
Many stores carried identical items, suggesting that a single distributor or manufacturer might be responsible.
Jennifer L. Engstrand, a corporate spokeswoman for Pier 1 Imports, whose South Philadelphia store sold a "summer stripes" plate that tested positive, said in an e-mail that the company had long used independent labs to conduct tests, including leachable-lead testing, following FDA protocols. "These test efforts verify that Pier 1 Imports' merchandise meets or exceeds U.S. federal and California requirements," she said.
In the United States, children's blood-lead levels typically are tested at ages 1 and 2. The city Health Department gets daily lists of any results that are elevated.
In 2009, the latest year for which figures were available, that was 828 children, or 3 percent of those tested, down from 22 percent 10 years earlier. Two elevated tests within six months trigger a home inspection (553 in 2009) and orders to remove the lead, said Peter Palermo, director of Philadelphia's Childhood Lead Poisoning Prevention Program. The city pays for remediation for families who cannot afford it. Nearly all high-lead-level blood tests are traced to paint that exists in 97 percent of the city's housing stock.
Children 3 and younger, with their small bodies, on-the-ground lifestyle, propensity to lick, and developing central nervous systems, are at greatest risk. As far as lead is concerned, they reach adulthood by age 6.
The test result that now raises concern - 10 micrograms of lead per deciliter of blood - is one-quarter the trigger of 40 years ago.
Some research suggests asymptomatic neurocognitive affects - slightly lower school performance, slightly more attention deficit disorder - even at the current threshold and possibly below, said Fred M. Henretig, director of toxicology at Children's Hospital of Philadelphia.
And he emphasized, "We don't know that it's not causing subtle harm."
At Jefferson, O'Malley worries that language and tradition may make immigrants vulnerable.
In his cluttered office 12 floors above the ER, cardboard boxes overflow with platters, pitchers, and pots. O'Malley rubbed a LeadCheck over a glazed green-and-yellow soupspoon with reddish lettering at the center.
The tip turned bright red, for lead, from swabbing the Chinese character, which means "longevity."
Should You Check for Lead?
Consumer advocates say it may make sense to test certain items used for food, especially if very young children are in the house.
Frequently asked questions
What should I look for? The Food and Drug Administration advises paying particular attention to ceramics and pottery that are brightly painted in orange, red, or yellow; antique, damaged, or worn; handmade with a crude appearance or irregular shape; purchased from flea markets or street vendors; or made by an unknown manufacturer.
How should I test them? Lead-screening kits available
in any hardware store are adequate for home use.
A 10-pack costs $25 to $30.
Are there warning labels? Items intended for decorative use are not regulated for lead. They are supposed to be stamped with warnings such as "Not for food use."
Can I minimize the risk? Heat, acid, and time encourage the leaching of lead, says Jeffrey Ashley, a chemist at Philadelphia University. In other words, avoid repeatedly microwaving a mug of coffee and letting it sit.
For more information
Food and Drug Administration: Go to www.fda.gov and search for lead pottery.
Philadelphia Department of Public Health: Call 215-685-2797 or go to www.phila.gov/health/ChildhoodLead/
Contact staff writer Don Sapatkin at 215-854-2617 or firstname.lastname@example.org.