**7. Other harms from cannabis**

With the exception of nicotine, smoked cannabis includes many of the same chemicals and carcinogens found in tobacco that can damage lung tissue [82]. Heavy cannabis smoking is associated with chronic bronchitis and inflammation/injury in the larger airways [82]. Findings for other types of lung diseases and cancers are mixed, given high rates of comorbid tobacco use in regular cannabis users. Some of the chronic respiratory effects appear reversible, particularly in those individuals who only smoke cannabis [83, 84]. The impact of cannabis use on lung health may also change, as other methods of intake are gaining popularity, such as vaping or edibles [82].

One of the largest public health concerns with legalization of cannabis use is the effect of the drug on driving. Driving simulation studies show a relationship between blood THC levels and impaired performance, particularly with reaction time and lane position variability (i.e., weaving) [85]. One study had occasional cannabis smokers perform a visuomotor tracking task while undergoing fMRI after taking low-dose THC and found decreased psychomotor skills as well as reduced activity in fronto-parietal areas [86]. After alcohol, cannabis is the most commonly reported drug in driving accidents and fatalities [87]. There is current ongoing research to better understand drug interactions, particularly with alcohol, as psychomotor impairments appear more severe when alcohol and cannabis are combined [85]. Indeed, greater information on the pharmacokinetic effects of cannabis on driving is needed, together with other drug interactions. One difficult problem for roadside testing remains that current cannabis detection through breath, saliva, blood or urine does not provide a reliable measure of recency or potency of use.
