The March 17 announcement by Hannaford Brothers that more than 4 million debit and credit card numbers were pilfered over several months forces both the company and consumers to re-examine the brave new worlds of electronic commerce.

The security breach affected 165 Hannaford stores and more than 100 owned by the chain’s parent company was discovered Feb. 27 but not revealed until almost a month later. The span of fraudulent charges on bank and credit card statements victims have discovered has been worldwide.

Locally, banks are spending tens of thousands of dollars replacing cards canceled after the breach was announced and Hannaford Bros. is named in five separate suits filed in federal courts in Maine.

A primary lesson here is that convenience has a cost. According to ConsumerReports.org, debit card purchases topped more than $1 trillion nationally in 2006. Carol Eleazer, a Hannaford vice president, said credit and debit card sales are 50 percent of the company’s business, although she declined to give a dollar figure for the sales.

Convenient, but hackers and cyber villains are adept at staying at least one step ahead of those trying to thwart them. Some have said they will not use debit or credit cards at Hannaford stores again, but there is little reason to believe a simple switch of stores would make consumers less vulnerable to cyber theft.

It can take more time and a trip to the bank to get the cash, and bank records are not invulnerable, but consumers need to be as informed about the potential benefits and dangers of how they buy as well as what they buy.

Those who feel Hannaford Bros. waited too long to reveal the depth of the breach have a case as well. The method of stealing debit and credit card numbers as transactions were processed, rather than from stored files, is a new and frightening addition to the world of cyber crime. Even if the full scope of the breach was not known at first, alerting customers to a potential problem would have been the best course for Hannaford Brothers to take.

One suit accuses the company of not adhering to industry standards for securing card numbers and files, but others are not certain this is the case.

“We’re blazing new ground here,” said Mike Berger of The Griffen Report of Food Marketing, a New England-based trade publication. Eleazer, a Hannaford vice president, said company security is state of the art, and costs millions to maintain and improve. How much is spent to maintain was not revealed.

Credit cards, automated teller machines and debit cards add convenience and mean emergency purchases can be made when buyers could have been left in the lurch 50 years ago.

But the convenience can be taken for granted. Shifting stores is no substitute for taking precautions.

David Harry, editor