No person is excused from attending and testifying or from producing books, papers, correspondence, memoranda and other records before the secretary or his authorized representative in any cause or proceeding on the ground that testimony or evidence, documentary or otherwise, required of him may tend to incriminate him or subject him to any penalty or forfeiture. No individual may be prosecuted or subjected to any penalty or forfeiture for or on account of any transaction, matter or thing concerning which he is compelled, after claiming his privilege against self-incrimination, to testify or produce evidence, documentary or otherwise, except that such person is not exempt from prosecution and punishment for perjury committed in so testifying.