The total number of deaths due to e-cigarette or vaping-associated lung illness (EVALI) has reached 55, spread across 27 states, according to the CDC. The agency reported 2,561 total cases of EVALI.

Public health officials say the main culprit is vitamin E acetate, a sticky compound found in some THC vaping products.

The CDC said in early November it was narrowing in on the substance as a “potential toxin of concern” after it was detected in 29 out of 29 lung tissue samples tested by public health officials.