Senate lawmakers bristled Friday at a last-minute change to a key cannabis bill during a House vote Thursday — and speculated as to why the Vermont Department of Health abruptly reversed its recommendation to lawmakers on the measure last week.

House lawmakers on Thursday imposed a 60% cap on the level of tetrahydrocannabinol, or THC, in solid cannabis concentrates to be sold at retail establishments when they open in October.

The change to H.548, one of four bills setting up the legal recreational market, was proposed in an amendment offered by Rep. John Gannon, D-Wilmington, and approved by voice vote.

On Friday, senators expressed frustration about the move.

“They held the damn thing for over a week and a half and then come up with this,” said Sen. Dick Sears, D-Bennington, chair of the Senate Committee on Judiciary, at a committee hearing Friday. “There isn’t much time to call for a conference committee. I’m really frustrated by the proposal from Rep. Gannon in the House.”

Still, senators on Friday moved the bill to a conference committee with the House to reconcile their differences over the THC limit.

The change followed a sudden reversal in stance from the Vermont Department of Health late last week.

The department supported eliminating a cap on levels of more than 60 percent THC in solid cannabis concentrates, according to an April 28 message to the chair of the House Committee on Human Services, Rep. Ann Pugh, D-South Burlington, from David Englander, the department’s senior policy and legal adviser. 

It would be more dangerous for people to buy unregulated versions of these products, Englander said, because instituting a cap would require manufacturers to use additives that dilute the product to less than 60 percent.

“You may recall that there were recent illnesses and deaths that appeared to be associated with the ingestion of such additives,” he said.

Then, a day later, Englander sent another message to Pugh, reversing the Department of Health’s position. In the second message, he said that upon further consideration, the department did not concur with lifting the THC limit.

“The risk to users of high levels of THC are significant and we should not risk contributing to the known risks to consumers’ physical and mental health,” Englander said in his second email. “My communication of yesterday to you was based on incomplete information. All errors are mine and please accept my apologies to you and the committee.”

Englander was not available for an interview on Friday, according to Ben Truman, a spokesperson for the Department of Health, and lawmakers said it was not clear why the health department reversed its recommendations.

“It was quite shocking,” said Rep. Taylor Small, D-Winooski, who sits on the House Human Services Committee. “We have gotten no further comment from the department.” 

“It’s very troubling,” said Rep. Sarah Copeland Hanzas, D-Bradford, chair of the House Committee on Government Operations, of the about-face. “But sadly, I don’t have any insight into why it happened.”

In Friday’s hearing, James Pepper, chair of the Cannabis Control Board — which had recommended lifting the cap on THC in solid cannabis concentrates — called leaving it in “a gift to the illicit market.”

“It gives the illicit market a monopoly on supplying the demand for these products,” Pepper told the committee. 

“Somehow a group that opposed legalization from the beginning has taken over,” Sears said. “If we were to accept this, I would want to see some investigation by the Cannabis Control Board of the impact on the black market and the out-of-state sales, because Massachusetts does not have this cap.”

Sears pointed out that Bennington County borders both New York and Massachusetts, which have no caps on THC levels in solid cannabis products. 

“So we’re continuing to invite people to go out of state,” Sears said, calling the House proposal “a stupid decision.”

Pepper said Vermont is the only state besides Connecticut that caps THC levels in solid cannabis products. 

“There is a very broad consensus among regulators that caps are a bad idea,” Pepper told VTDigger on Friday. “A black market will fill this gap. They’ll do so using very dangerous products.”

Sarah Mearhoff contributed reporting.