EASTON — The membership cards that help grocery stores track customers' buying habits and give customers some savings can also make recalls more effective.

Store officials say chains such as Maryland-based Giant and Wegmans are using information from the cards to alert customers who have purchased products affected by recent peanut product recalls.

Spokesman Tracy Pawelski said Giant has used bonus card information to contact about 30,000 customers.

The outbreak has sickened at least 550 people.