[Exhibit 16]

June 11, 2024

Securities and Exchange Commission

100 F Street N.E.

Washington, D.C. 20549

We have been furnished with a copy of the response to Item 4.01 of Form 8-K for the event that occurred on June 6, 2024, to be filed by our former client, Psychemedics Corporation. We agree with the statements made in response to that Item insofar as they relate to our Firm.

Very truly yours,

/s/ BDO USA, P.C.