Google+ users may now see their pictures plastered next to advertisements for a range of products, without compensation.
The company announced on Friday that users' names, profile photos and endorsements may appear on "reviews, advertising and other commercial contexts" by default, under the new terms of its service that kick in on Nov. 11.
The policy changes mean that every time a user over 18 reviews an album or bakery online for example, they may become brand ambassadors for their recommendations, which are then broadcast to others within their Google+ network.
Google explained that "shared endorsements" help people "save time" and improve results.
"We want to give you -- and your friends and connections -- the most useful information. Recommendations from people you know can really help," the company said on its website.
But the new changes to Google's Terms of Service, which follow in the footsteps of recent moves by Facebook, raise growing concerns about consent and privacy on the Internet.
"This demonstrates that Google does not care about their user's privacy," Bradley Shear, a lawyer who specializes in Internet privacy and social media, told ABC News. "This is an absolute abuse of the trust of their customers. We're all essentially now a product. I really think that goes against the grain of what we are as a society."
Previously, when users clicked the "+1" button on products, their endorsements had been used by Google on ads, albeit on a smaller scale. The latest changes mean that comments, reviews, ratings and "follows" can now also be distributed among Google+ users' networks.
Similar moves to employ socially "enhanced" ads were also made by Facebook this year. The social network announced in August its plans to gather users' names, pictures and profile information to use in advertisements and sponsored content without consent.
Unlike Facebook's policy however, Google Plus, which has 390 million active users a month, has granted users the ability to opt out, although they advise against it.
When unchecking the box providing Google with default permission, a pop-up appears asking users "Are you sure?" alongside a message warning that by disabling the setting "your friends will be less likely to benefit from your recommendations."
Google did not immediately respond to ABC News' enquiries. On its policies page, it warns users to "look at the terms regularly."
"If you do not agree to the modified terms for a Service, you should discontinue your use of that Service," the page states.
"Our goal is to be clear about what information we collect, so that you can make meaningful choices about how it is used," the company wrote on its privacy page.
"I think the FTC should investigate whether Google's latest changes to their terms of service violate the consent decree," Shear said. "There needs to be further governmental regulation."
The FTC could not be reached due to the government shutdown.