citing instances of the service displaying advertisements for products that they had only spoken about, and had otherwise had no prior interactions with. In August 2019, Facebook admitted that it had been sending anonymized voice data from the Messenger app to third-party contractors for human review in order to improve the quality of its automatic transcription function, but denied that this data was being used for personalized advertising. The company also stated that it had recently suspended human reviews after scrutiny over Amazon, Apple, and Google's use of similar practices for their voice assistant platforms. Platform vulnerabilities Data mining There have been some concerns expressed regarding the use of Facebook as a means of surveillance and data mining. Two Massachusetts Institute of Technology (MIT) students used an automated script to download the publicly posted information of over 70,000 Facebook profiles from four schools (MIT, NYU, the University of Oklahoma, and Harvard University) as part of a research project on Facebook privacy published on December 14, 2005. Since then, Facebook has bolstered security protection for users, responding: "We've built numerous defenses to combat phishing and malware, including complex automated systems that work behind the scenes to detect and flag Facebook accounts that are likely to be compromised (based on anomalous activity like lots of messages sent in a short period of time, or messages with links that are known to be bad)." A second clause that brought criticism from some users allowed Facebook the right to sell users' data to private companies, stating "We may share your information with third parties, including responsible companies with which we have a relationship." This concern was addressed by spokesman Chris Hughes, who said, "Simply put, we have never provided our users' information to third party companies, nor do we intend to." Facebook eventually removed this clause from its privacy policy. In the United Kingdom, the Trades Union Congress (TUC) has encouraged employers to allow their staff to access Facebook and other social-networking sites from work, provided they proceed with caution. In September 2007, Facebook drew criticism after it began allowing search engines to index profile pages, though Facebook's privacy settings allow users to turn this off. Concerns were also raised on the BBC's Watchdog program in October 2007 when Facebook was shown to be an easy way to collect an individual's personal information to facilitate identity theft. However, there is barely any personal information