ST. LOUIS — Robert Cole helped a friend learn about his diabetes. Cole of Ferguson, Mo., searched online, printed out some articles from his computer and passed along the information.
About six weeks later, Cole began receiving advertisements in the mail and online for diabetes testing supplies.
He was alarmed by the connection. Cole, 65, who has no history of the disease, launched into a personal investigation several years ago about who owns his identity and personal information and began evangelizing to family and friends about the way individual data is mined and used.
He's not alone in worrying about how his digital moves are being tracked. New efforts are under way to help individuals regain some control of how their information is collected and shared. And new research suggests people are beginning to take steps to protect their privacy online and on cellphones.
Cole called the firm that mailed him brochures to find out how it had obtained his name and address, but he was unable to get an answer. He filed a complaint with the Privacy Rights Clearinghouse in San Diego and tried to contact the American Civil Liberties Union to find out who had the right to access and sell information about him.
"Am I in somebody's database as a diabetic? Because I'm not. I don't even know how to correct that," he said. What if he applies for life insurance and is rejected based on a faulty profile? he asked. Could he be charged higher premiums or be denied credit because of what he types into his emails or into Google searches?
Laura McCarthy Jarman, 30, of St. Louis said she noticed when she was planning her wedding in the spring that most of the ads she saw online were related to weddings. "It was just so bizarre," she said. "You feel like your computer is reading your mind."
She ended up installing an ad blocker, which struck her as ironic, given her own job in public relations and marketing.
An international body, the World Wide Web Consortium, has been working on Do Not Track standards for nearly a year.
The consortium's proposed Do Not Track option would let users choose in their browser preferences a setting that indicates that they do not want websites and ad networks to track their browsing behavior. What businesses would need to do to comply with these standards is still being negotiated.
Microsoft said recently that Internet Explorer 10 will include the antitracking setting as a default, but the Apache Web server, which powers 60 percent of websites worldwide, responded by declaring it would ignore the Do Not Track request.