Holitzki Hannah, Dowsett Laura E, Spackman Eldon, Noseworthy Tom, Clement Fiona
Affiliation: Department of Community Health Sciences and O'Brien Institute for Public Health, Cumming School of Medicine, University of Calgary, Calgary, Alta.
CMAJ Open. 2017 Nov 24;5(4):E814-E822. doi: 10.9778/cmajo.20170112.
Recreational marijuana has been legalized in 11 jurisdictions; Canada will legalize marijuana by July 2018. With this changing landscape, there is a need to understand the public health risks associated with marijuana to support patient-care provider conversations, harm-reduction measures and evidence-informed policy. The objective of this work was to summarize the health effects of exposure to second- and third-hand marijuana smoke.
In this systematic review, we searched 6 databases from inception to October 2017. Abstract and full-text review was conducted in duplicate. Studies were included if they were human, in vivo or in vitro studies with more than 1 case reported in English or French, and reported original, quantitative data. Three outcomes were extracted: 1) cannabinoids and cannabinoid metabolites in bodily fluids, 2) self-reported psychoactive effects and 3) eye irritation and discomfort.
Of the 1701 abstracts identified, 60 proceeded to full-text review; the final data set contained 15 articles. All of the included studies were of good to poor quality as assessed with the Downs and Black checklist. There is evidence of a direct relation between the tetrahydrocannabinol content of marijuana and effects on those passively exposed. This relation is mediated by several environmental factors including the amount of smoke, ventilation, air volume, number of marijuana cigarettes lit and number of smokers present. No evidence was identified assessing exposure to third-hand marijuana smoke or the health effects of long-term exposure.
Exposure to second-hand marijuana smoke leads to cannabinoid metabolites in bodily fluids, and people experience psychoactive effects after such exposure. Alignment of tobacco and marijuana smoking bylaws may result in the most effective public policies. More research is required to understand the impact of exposure to third-hand smoke and the health effects of long-term exposure to second-hand smoke.
休闲用大麻已在11个司法管辖区合法化；加拿大将于2018年7月将大麻合法化。在这一不断变化的形势下，有必要了解与大麻相关的公共卫生风险，以支持患者与医护人员的沟通、减少危害措施以及基于证据的政策制定。这项工作的目的是总结接触二手和三手大麻烟雾的健康影响。
在这项系统评价中，我们检索了6个数据库，检索时间从数据库创建至2017年10月。摘要和全文审查均由两人独立进行。纳入的研究需为英文或法文报道的、有超过1例病例的人体、体内或体外研究，并报告原始定量数据。提取了三项结果：1）体液中的大麻素和大麻素代谢物，2）自我报告的精神活性作用，3）眼睛刺激和不适。
在检索到的1701篇摘要中，60篇进入全文审查；最终数据集包含15篇文章。根据唐斯和布莱克清单评估，所有纳入研究质量为良至差。有证据表明大麻中的四氢大麻酚含量与对被动接触者的影响之间存在直接关系。这种关系由几个环境因素介导，包括烟雾量、通风、空气量、点燃的大麻卷烟数量和在场吸烟者数量等。未发现评估三手大麻烟雾暴露或长期暴露的健康影响的证据。
接触二手大麻烟雾会导致体液中出现大麻素代谢物，人们在此类接触后会出现精神活性作用。使烟草和大麻吸烟法规保持一致可能会产生最有效的公共政策。需要更多研究来了解三手烟雾暴露的影响以及长期接触二手烟雾的健康影响。
