The Massachusetts Department of Public Health announced Wednesday the fourth death in the state from a vaping-related lung illness. The victim was an older man from Middlesex County who said he vaped THC, the active ingredient in marijuana.

Dr. Michael Siegel, an expert on e-cigarettes and tobacco from Boston University's School of Public Health, said the Centers for Disease Control concluded that contaminated THC vaping products — mostly black market vapes — are to blame for the national outbreak of vaping-related lung illness that has so far killed 55 people in 27 states, according to the agency's latest update on Dec. 31.

Siegel told WGBH News there are two responses from the state that are overdue.

“The first is to just be honest and to tell the public that this outbreak is being caused by THC vaping products,” Siegel said. “The state has still not made that announcement. … And I think that's inappropriate because we know that Vitamin E acetate oil is the primary, if not only culprit here. And I think that the state needs to be honest and basically just tell the public the truth.”

Vitamin E acetate oil is an additive in some THC-containing products.

In a statement to WGBH News, the Baker administration referred to a CDC press release to caution against pointing to contaminated THC-products as the sole source of the illness.

“While it appears that Vitamin E acetate is associated with EVALI [E-cigarette/Vaping-Associated Lung Injury], there are many different substances and product sources that are being investigated and there may be more than one cause," the CDC said. "Therefore, the best way for people to ensure that they are not at risk while the investigation continues is to consider refraining from the use of all e-cigarette, or vaping, products.”

But the agency's principal deputy director, Dr. Anne Suchat, was more confident in her stance on Vitamin E Acetate with reporters a Dec. 20 teleconference.

“We can conclude that what I call the explosive outbreak of cases of EVALI can be attributed to exposure to THC-containing vaping products that also contained Vitamin E acetate," she said. "I want to stress that this does not mean that there are not other substances in e-cigarette or vaping products that have or are capable of causing lung injury. We know that a persistent small proportion of EVALI cases do not report use of THC-containing vaping products.”

Siegel held to the line that the outbreak was the result of THC vaping products and that the most recent fatality in Mass. only reinforces his argument.

“They [the CDC] found that substance [Vitamin E acetate] in the lungs of just about every patient that was tested" he said. "So, we know that this outbreak is largely, if not entirely, being caused by THC vaping products and this death simply adds to that evidence.”

Siegel also criticized the Baker administration’s initial ban on vaping products as it was put in place last September which encompassed electronic cigarettes that deliver nicotine and not THC, saying there was abundant evidence then that they were safe. And he says that the ban had deleterious health effects.

“I think that there is pretty strong evidence that during the time that this ban was in effect, cigarette consumption actually increased in Massachusetts,” Siegel said. “And that indicates that a lot of ex-smokers, when their vaping products were taken off the shelves, they actually went back to smoking.”

In a statement replying to Siegel’s criticisms, a Baker administration spokesperson said, “In light of the growing health crisis associated with e-cigarettes and vaping, the Baker-Polito Administration implemented a temporary ban on the sale of e-cigarette and vaping products to provide time for legislative and regulatory bodies to better understand what's making people sick and act to protect the health of Massachusetts residents.”