“Bummer! We’re still not doing the right thing,” said Shelley Kempner of Queens, who was looking over the produce at Fairway on Broadway at West 74th Street. She prefers a reusable bag, she said, because she “likes the idea of not putting more plastic into the environment.”

Told of the recent lead findings, Ms. Kempner sighed  “It’s still not good enough”  and wondered if she would have to switch to something else. “Are we going to have to start using string?” she asked.

“There’s always something wrong with everything,” said Barry Lebost, standing outside the Trader Joe’s on West 72nd Street with four reusable bags filled with groceries.

But Mr. Lebost, an alternative energy consultant, did not appear fazed by the revelations of lead. He said his home, in Gardiner, N.Y., had been outfitted with a hydroelectric plant that saved the energy equivalent of 200 plastic bags a day. “It may not be a total solution, but this is a step in the right direction,” he said of the suddenly suspect bags at his feet. “The fluorescent bulbs we have now, they’re no good because they have mercury in them. You look at it as a transition.”

But many shoppers said they would continue relying on the bags until more information came out. The bags are usable for years, they said, and any long-term effects of lead may be offset by the environmental benefits gained by not using regular plastic bags.

“I wasn’t planning on throwing it out, so that’s a positive thing,” said Catherine Paykin, standing by the meat counter at Fairway. “As long as I use it and don’t throw it away, that will be my plan.”

Mr. Schumer’s family also shops at Fairway. A spokesman for the senator said the family planned to bring the issue to the attention of the store to see if the bags there were affected.