UC Davis study reveals higher toxicity in disposable e cigarettes Disposable Vapes and Heavy Metal Headaches Grow Strong KC Are e cigarettes really a safer alternative to combustible cigarettes? New study reveals disposable vapes may be more toxic! Learn more about how a University of California, Davis study found that some popular UC Davis study: Disposable vapes may be more toxic than cigarettes WARNING FOR AND Illegal disposable e cigarettes (vapes) may be more dangerous than traditional cigarettes, according to new research from UC Davis. The study found hazardous levels of toxic heavy metals