Table 6.

Salient 2018 studies reporting incense-smoke toxicity in distinct in vivo settings

Theme	Analysed/observed	Salient findings	Reference
Study of long-term incense exposure on carotid intima–media thickness (CIMT)	132 adults aged ≥35 years, subdivided into unexposed, non–daily exposed and daily exposed groups. Daily and non–daily exposed were distinguished via <5 or >5 day weekly exposure, collected blood samples assessed for total cholesterol, triglycerides, high- and low-density lipoproteins, HbA1c, and high-sensitivity CRP. Before blood collection, body-mass index was determined. All analysis and measurements were done as per American College of Cardiology and Heart Association guidelines.	Higher combined mean CIMT (0.75±0.2 mm) and combined maximum CIMT (0.93±0.23 mm) of left common carotid artery (LCCA) in daily exposed group than non–daily (mean CIMT 0.68±0.15 mm, maximum CIMT 0.85±0.18 mm) and unexposed groups (mean CIMT 0.64±0.11 mm, maximum CIMT 0.80±0.14 mm). Daily exposed group had 0.74±0.21 mm mean and 0.91±0.25 mm maximum. For non–daily and non-exposed groups, levels were 0.70±0.14, 0.88±0.18, 0.67±0.13, and 0.85±0.16 mm. Despite this, no significant difference was observed amongst the three exposure groups.	[46]
Study of incense-smoke exposure risks in Romanian citizens with respect to living conditions and household design	Self-reported information on respiratory symptoms in 280 elementary schoolchildren. Categorisation amongst allergy, asthma, and flu-like symptoms. Tobacco smoking, cooking (iron stoves), and poorly controlled indoor climate (random incense burning) identified as indoor pollution sources.	Tobacco smoke aggravated asthma and allergy, living near pesticide-sprayed areas and incense-making industries aggravated risk of asthma, incense combustion more popular than using room fresheners in Romania. Incense-smoke indoor air pollution increased the risk of allergy and flu-like symptoms.	[80]
Mechanistic study of aggravated cardiovascular conditions in incense-exposed rats	7- to 8-week-old male albino rats (Rattus norvegicus) procured from Animal Care Center, College of Pharmacy, King Saud University. Kept in ambient temperature with 12 h light–dark cycle, free water and chow diet. Control (8) and bakhur and oud groups (16 each). Exposure to incense for 30 days via whole-body access on a daily basis. Afterwards, rats from each group were anaesthetised, while the remaining 16 from the two incense-exposed groups were kept away from incense smoke for 30 days and killed after monitoring. Physiological markers assessed via plasma analysis.	Enhanced malondialdehyde with balanced SOD and reduced GSH. Endothelial functional markers: NO decreased and ET1 increased in both incense-exposed groups. Enhanced chemokine and inflammatory mediator expressions, including MCP1, granulocyte macrophage GM-CSF), and all endothelial cell– adhesion molecules. Implicit incense-smoke involvement assessed via reversal of symptoms on 30-day cessation of incense exposure.	[63]
Study of incense-smoke exposure on the health of pregnant women, monitored via analysis of hypersensitivity and blood pressure	10,563 pregnant women from Guangzhou cohort study from January 2013 to December 2015. Information on duration and frequency of incense exposure in early and late pregnancy collected using a questionnaire. Details on outcome variables, including diagnosis of hypersensitive disorders and blood-pressure levels, were retrieved from medical records.	Higher hypersensitivity prevalence in women exposed to incense smoke in late pregnancy, with 1.84 as relative risk factor and 95% confidence, similar observations for blood pressure (before delivery, 1.6 mmHg increment in systolic blood pressure (95% CI 0.4–2.8 mmHg), correlations more significant in women with no history of active/passive smoking.	[60]