Emails show that the state did not launch a full review into a Massachusetts lab at the center of a drug testing scandal until seven months after officials learned a chemist had mishandled at least 90 drug samples.

The emails obtained by The Boston Herald show former Department of Public Health Commissioner John Auerbach and his boss, Secretary of Health and Human Services JudyAnn Bigby, didn’t launch a full internal review of the lab, its management and the circumstances that allowed the chemist to allegedly tamper with evidence, until Aug. 31.

That’s seven months after they learned chemist Annie Dookhan had allegedly mishandled drug samples.

A Bigby spokesman said in a statement Tuesday that “the Secretary needed the precise facts to determine how to respond effectively,” to the scandal.