While Amazon's Mechanical Turk (AMT) online workforce has been characterized by many people as being anonymous, we expose an aspect of AMT's system design that can be exploited to reveal a surprising amount of information about many AMT Workers, which may include personally identifying information (PII). This risk of PII exposure may surprise many Workers and Requesters today, as well as impact current institutional review board (IRB) oversight of human subjects research involving AMT Workers as participants.

We assess the potential multi-faceted impact of such PII exposure for each stakeholder group: Workers, Requesters, and AMT itself. We discuss potential remedies each group may explore, as well as the responsibility of each group with regard to privacy protection. This discussion leads us to further situate issues of crowd worker privacy amidst broader ethical, economic, and regulatory issues, and we conclude by offering a set of recommendations to each stakeholder group.