1.   Scientific studies involving humans have a statistical threshold for causing harm to participants, and if passed they are discontinued.

2.   Scientists conduct several kinds of studies involving humans.

3.   That job falls largely to the patchwork system of ethics boards, bodies that are required by federal law to approve research proposals involving humans.

4.   Until now, the Web has largely involved humans retrieving information from machines.

5.   Zboray agrees, adding that anything involving humans is ultimately vulnerable.

6.   He said he hopes that tests involving humans could begin within two years.