After 2000, Thacker wrote for publications such as
The New Republic and
Salon and was a staff writer with
Environmental Science & Technology, a journal of the
American Chemical Society (ACS). Here he published a series of exposés that a senior ACS official claimed showed an anti-industry bias, culminating in an article on the
Weinberg Group that resulted in him being fired by the journal in 2006. In Thacker's Weinberg Group story he wrote about a letter that group sent to
DuPont outlining a plan to protect DuPont from litigation and regulation over
Teflon. The Weinberg Group had done similar work for
Big Tobacco and then began working in Europe to defeat alcohol regulations. ACS editor Rudy Baum called the Weinberg article a "hatchet job". Later that year, Thacker's work was profiled on
Exposé: America's Investigative Reports. In 2007, Thacker joined the
United States Senate Committee on Finance for Republican
Senator Chuck Grassley, investigating
medical research conflicts of interest. Among his work he identified several physicians who had failed to disclose payments from drug and medical companies, including psychiatrist
Charles Nemeroff. He also led the committee's investigation of the drug
Avandia, which included a report that a medical journal had published a
ghostwritten article promoting the drug. He left the committee in 2010 to join the
Project on Government Oversight, a nonprofit watchdog organization. From 2012 to 2014, Thacker completed two fellowships at Harvard University's Safra Center for Ethics. Thacker received the 2021 British Journalism Award for Specialist Journalism for a series of articles in
The BMJ investigating undisclosed financial interests among medical experts advising the US and UK governments on vaccines. The award judges said "[t]his was expertly researched and written journalism on a subject of huge national importance." The Association of British Science Writers chose an article Thacker wrote on Pfizer as a finalist for the Steve Connor Award for Investigative Science Journalism. ==Controversies and False Claims==