Late Monday afternoon, employees at O'Hara grocer Giant Eagle Inc. got test results showing some hash brown products sold by the retailer contained a bacterium that can cause a potentially serious infection.

Within hours, an automated system was busy calling more than 300,000 Giant Eagle Advantage Card holders who records showed had purchased the affected product. "We wanted to get the information out as soon as we knew about it," said Michael Sealy, vice president of risk management services.

It was the first large-scale use of the grocer's automated notification system. So far, so good. Officials said many customers have thanked the company for the calls.

Loyalty cards issued by grocers and other retailers have had their critics over the years, as some people worry about how much data the companies gather and others complain they shouldn't have to give up personal information in exchange for supermarket discounts.

But the growing practice of using that data to publicize recalls has generally been well received, even as it serves as a reminder that a company knows about your secret love of beef jerky, Twizzlers, fresh spinach or hash browns.

Warehouse club operator Costco first used its automated phone notification system in November 2007, when a toy with a coating that could make children who swallowed it to "become comatose, develop respiratory depression or have seizures" was recalled.

For years, Costco had been mailing notices to members who'd bought recalled products, said Craig Wilson, assistant vice president of food quality and quality assurance. But the late 2007 case was the first time Costco's computer systems were set up for the robocall notification. The system can make 870,000 calls an hour.

News reports since have cited other chains, such as Wegmans, Price Chopper and Kroger, as implementing similar systems. In February 2009, when tainted peanut butter was making people sick, the Washington, D.C., consumer advocacy organization Center for Science in the Public Interest wrote an open letter urging retailers to get on board.

"Supermarkets enjoy using purchasing data for marketing purposes," said the organization's staff attorney Sarah Klein. "We're calling on supermarkets to also use that information to protect their customers' health by alerting them to identify and return tainted foods."

Giant Eagle found it wasn't easy getting the information from the loyalty card database synchronized with store purchase records. "It sounds simple," Mr. Sealy said. "We've been working on it for a while."

About 10 months ago, the grocer began using the system for pharmacy products assigned Class I recall status, which is the most severe type. Such recalls don't happen often, he said, but it was a good place to start.

The pharmacy data was easier to retrieve than that for general food purchases, and the number of customers affected typically ranges from a few dozen to a few hundred, Mr. Sealy said.

In the case of this week's Giant Eagle and Food Club frozen loose hash browns recall, the grocer felt that the potential health issue was serious enough to pull out its most powerful communications tools, even though Mr. Sealy said the government hasn't yet assigned a status to the case.

An independent manufacturer who makes the hash browns informed the grocer that other products made in the same facility had been discovered to have the bacterium, triggering the tests by Giant Eagle.

In addition to electronically notifying all stores and setting the company's cash registers to block sales of affected merchandise, officials decided to use the automated calling system for the first time on a food item.

It took a couple of hours for the computer system to compile the phone list of affected customers, Mr. Sealy said. Meanwhile, the staff wrote a script for the phone call with a third-party company using "voice talent" to record the message.

They also issued a press release to publicize the recall as widely as possible, as well as putting information on Facebook, Twitter and the company's own Web site. Not everyone who shops at the grocery chain has a Giant Eagle Advantage Card. Usage is high, said Rob Borella, senior director of marketing and corporate communications, but it's "not quite 100 percent."

Even those who have cards don't always update their contact information. Some automated calls may have reached discontinued numbers.

Giant Eagle set up the system not to call after 9:30 p.m. and not to start calling again in the morning before 9 a.m.

Almost as soon as the calls started going out, questions started coming into the toll-free customer care line (800-553-2324). The company reports about 1,000 calls about the recall came in between Monday evening and Tuesday. People wanted to know about things such as the risk involved and how to get refunds.

Now that the first big test is complete, Giant Eagle will look at how it worked. For example, some people said their answering machine messages seemed to cut off the first part of the recorded alert.

The grocer might prefer not to have another opportunity to use the system, since it is intended for only serious product safety issues. "They're not frequent events, and they're not predictable events," said Mr. Sealy, but when they come up Giant Eagle wants to be prepared.

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