Advertisers are nervous about the do not track technologies being added to many web browsers, saying it can block legitimate business.

Mozilla's Firefox and Google's Chrome joined Microsoft's Internet Explorer as browsers that will implement new features in upcoming versions to prevent people's personal information from getting mined and sold for advertising.

Firefox will allow users to set a browser preference that will broadcast their desire to opt-out of third party, advertising-based tracking. It would do this via a Do Not Track HTTP header with every click or page view in Firefox. Chrome's will be a simple extension called Keep My Opt Out, once downloaded it will prevent data tracking from all sites.

The move, along with a similar new feature from Internet Explorer, could have a profound impact on companies like BrightTag. The Chicago-based company is involved in interactive advertising. It runs a platform where websites and third-party advertisers can collaborate to figure out the best way to create effective ad campaigns.

Marc Niven, founder and chief revenue officer of BrightTag, is not a fan of the Do Not Track add-ons. He said the interactive advertising industry, which may have a bad reputation, drives tremendous value for the biggest companies in the U.S. He says collecting this data isn't necessarily a bad thing as it allows sites to retarget based on behavior exhibited by users.

Data is absolutely necessary. It has been around a long time, even in the offline world. It's a function of how the economy operates. If we were to stop collecting and using data, the economy would freeze up, Niven said.

He doesn't endorse a free for all method, and says it's important for the industry and all the regulatory parties to take time and figure out the best way to deal with the perceived issues. He says giving the control to the browsers, as would be the case with the two add-ons, would be the wrong move.

I get fearful when the control point of data, in essence, would be browsers. If you look at it, three of the four biggest browsers are extensions of a few very large companies: Google, Apple and Microsoft. The fourth, Mozilla, could be as large if it controlled data.That to me is scary. It's not necessarily an improvement to the problem, Niven said.

While the browsers are technically opt out as well, he says their solutions are too black and white. He says some form of opt out, one that's not as all encompassing, would be a better answer.

James Steyer, chief executive of Common Sense, said the browser add-ons don't go far enough.

Although we are pleased that these companies are addressing ways for consumers to protect their privacy and personal information online, it is important to note that these announcements only reflect an 'opt-out' approach. What consumers - and especially kids - really need is an 'opt-in' approach to the collection and use of personal information, Steyer said in a statement.

Common Sense is a non-profit dedicated to improving the lives of kids through informative campaigns on media and technology. Steyer says the organization hopes other players in the industry follow Mozilla and Google's suit and take the online and mobile privacy of consumers, more seriously than they have been.