The National Institutes of Health is a government agency but it's pretty complex in nature in terms of who does work (US and Foreign employees/grantees/independents contractors, foreign and local for-profit or non-profit companies/entities/etc.). I'm guessing most require drug testing but not all; e.g. foriegn orgs that don't have to abide by U.S. mandates/laws might not require it).

Find what entity you will work for and look at their website or ask a future co-worker you trust.

https://en.m.wikipedia.org/wiki/National_Institutes_of_Health