Is it a hipaa violation for a Chief to disclose drug screen results to coworkers? Or, anyone other than say, direct supervisors.

No, not unless you work for a medical company.

There are numerous statutory restrictions at the federal level imposed on drug test results. All prohibit disclosure to co-workers. Also, what is commonly referred to as a "drug test" can actually be "medical examination". All depends on what you are were tested for. Any test for other than "illegal drugs" i.e. if the test includes prescription medications, alcohol, unscheduled substances that makes the test a medical examination, the results a medical record, in which case HIPAA would apply.

Drug tests, that is for illegal substances, are not medical records but are nonetheless subject to restrictions, on a need-to-know basis.

Thank you Bill. Very informative.