People are being watched as they navigate around pornography sites, experts have warned.
Almost every adult website featured in a new major study is sending details about people's browsing to third parties, according to a new study.
The lack of privacy could cause major problems to anyone who looks at pornography online, the authors warn, with particular dangers posed to people in vulnerable populations.
The confusion about exactly what data is being harvested also makes consent difficult, the authors warn, and websites need to do more to allow users to be sure they are affirmatively consenting to the tracking.
Researchers note that online pornography is one of the primary uses of the internet: it is estimated to account for about 30 per cent of the internet, the biggest websites receive many billions of visits each per year, and they are larger than web giants Amazon, Twitter and Netflix combined.
But the users of those sites know very little about what is actually happening on them. The sites are gathering large amounts of data on the people using them without their knowledge, according to the new study.
The new research looked at 22,484 pornographic websites and found that 93 per cent of them were leaking data out to another company.
Only a tiny proportion of those websites included privacy policies to allow users to understand how their data is being used. The researchers were only able to get that information from a few thousand of the sites, accounting for 17 per cent of the websites studied.
Even those privacy policies that were downloaded were written such that people might need a college education to actually understand what was being done with the information, they warned.
To carry out the study, researchers from Microsoft, Carnegie Mellon, and the University of Pennsylvania assembled a list of adult websites and studied each of them with specialist tools that allow them to understand what data is being sent on to third parties.
They found that 74 per cent of the world's top websites were sending information to Google about what their users were looking at. Vast amounts of data was also being sent to Oracle, Facebook and other companies, they noted.
