Campaigners claim Sheffield Council lets firms track website searches on drug and alcohol abuse
Sheffield Council shared information about its website users - including when they search for help with drug and alcohol abuse - with private companies, it is claimed
More than 25 private firms were given data on visitors to the website - the highest number in the country, campaigners say.
Serious concerns have been raised about how the data is being used, with calls for the council to ban the activity.
Liberal Democrat peer Paul Scriven, who covers IT civil liberties in the House of Lords, said: "It’s a wild west of data where it’s being sold on to companies it cannot police. When they sell it on to a third party it gets sold on to a fourth, fifth, sixth and the council has no idea who they are.
“The legality of this is highly questionable. The Information Commissioner did a report which raises significant questions about the use of this data. In light of that there is only one thing the council can do which is ban this kind of activity until the ICO can determine the legality.
“If they refuse, it’s quite clear they are putting an income stream above the right to privacy of its citizens."
A 17-month study by Brave - a private web browsing service - revealed at least 20 data collection companies received information when visiting Sheffield Council's drug and alcohol support page including eight data brokers and nine advertising auction companies.
It claims that each time users load a web page, private companies receive data from council websites they are embedded on, including: the URL of each page, ID codes, users' location and in most cases, IP address.
This allows them to build a picture of users’ circumstances and tie what they do on one website with what they view across the internet.
The council denies using trackers to sell personal data.
Mark Gannon, director of business change and information solutions at the council, refuted the claims.
“Like the vast majority of websites, cookies are used on our website for site-specific purposes, such as improving customer experience, analytics and advertising through the Council Advertising Network. However, all data gathered via cookies on our website is anonymous, and we would like to make it clear that absolutely no personal details are collected or shared.
Coun Tim Huggan said a lack of action to stop the activity could undermine people's trust in the authority and lead them away from seeking help from its services.
He said: "We want people to be accessing the website and getting information they need but this will make them suspicious.
“Some of the most vulnerable people in Sheffield want to access services to improve their lives and this may cause them to go down other routes."