d-limonene exposure to humans by inhalation: uptake, distribution, elimination, and effects on the pulmonary function

Evaluation of urinary limonene metabolites as biomarkers of exposure to greenness

Exposure to plants is known to improve physical and mental health and living in areas of high vegetation is associated with better health. The addition of quantitative measures of greenness exposure at individual-level to other objective and subjective study measures will help establish cause-and-effect relationships between greenspaces and human health. Because limonene is one of the most abundant biogenic volatile organic compounds emitted by plants, we hypothesized that urinary metabolites of inhaled limonene can serve as biomarkers of exposure to greenness. To test our hypothesis, we analyzed urine samples collected from eight human volunteers after limonene inhalation or after greenness exposure using liquid chromatography-high resolution mass spectrometry-based profiling. Eighteen isomers of nine metabolites were detected in urine after limonene inhalation, and their kinetic parameters were estimated using nonlinear mixed effect models. Urinary levels of most abundant limonene metabolites were elevated after brief exposure to a forested area, and the ratio of urinary limonene metabolites provided evidence of recent exposure. The identities and structures of these metabolites were validated using stable isotope tracing and tandem mass spectral comparison. Together, these data suggest that urinary metabolites of limonene, especially uroterpenol glucuronide and dihydroperillic acid glucuronide, could be used as individualized biomarkers of greenness exposure.

Terpenes and cannabidiol against human corona and influenza viruses-Anti-inflammatory and antiviral in vitro evaluation

The activity of the terpenes and Cannabidiol (CBD) against human coronavirus (HCoV) strain OC43 and influenza A (H1N1) was evaluated in human lung fibroblasts (MRC-5 cells). Also, we examined whether these ingredients inhibit pro-inflammatory cytokines in peripheral blood mononuclear cells (PBMC). The tested preparations exhibited both anti-inflammatory and antiviral effects. The combination of terpenes was effective against both HCoV-OC43 and influenza A (H1N1) virus. The addition of CBD improved the antiviral activity in some, but not all cases. This variation in activity may suggest an antiviral mechanism. In addition, there was a strong correlation between the quantitative results from a cell-viability assay and the cytopathic effect after 72 h, as observed under a microscope. The anti-inflammatory properties of terpenes were demonstrated using a pro-inflammatory cytokine-inhibition assay, which revealed significant cytokine inhibition and enhanced by the addition of CBD.

Essential Oils as Multicomponent Mixtures and Their Potential for Human Health and Well-Being

Essential oils (EOs) and their individual volatile organic constituents have been an inherent part of our civilization for thousands of years. They are widely used as fragrances in perfumes and cosmetics and contribute to a healthy diet, but also act as active ingredients of pharmaceutical products. Their antibacterial, antiviral, and anti-inflammatory properties have qualified EOs early on for both, the causal and symptomatic therapy of a number of diseases, but also for prevention. Obtained from natural, mostly plant materials, EOs constitute a typical example of a multicomponent mixture (more than one constituent substances, MOCS) with up to several hundreds of individual compounds, which in a sophisticated composition make up the property of a particular complete EO. The integrative use of EOs as MOCS will play a major role in human and veterinary medicine now and in the future and is already widely used in some cases, e.g., in aromatherapy for the treatment of psychosomatic complaints, for inhalation in the treatment of respiratory diseases, or topically administered to manage adverse skin diseases. The diversity of molecules with different functionalities exhibits a broad range of multiple physical and chemical properties, which are the base of their multi-target activity as opposed to single isolated compounds. Whether and how such a broad-spectrum effect is reflected in natural mixtures and which kind of pharmacological potential they provide will be considered in the context of ONE Health in more detail in this review.

Ingested versus inhaled limonene in sheep: A pilot study to explore potential different transfer to the mammary gland and effects on milk and Caciotta cheese aroma

Concentration is a key determinant in the overall positive impact of terpenes on milk and cheese aroma; additionally, route of intake may affect the achievable concentrations of dietary terpenes in milk and cheese. In this study, we explored the possibility that the amount of the monoterpene limonene transferred to sheep milk and its corresponding cheese could differ depending on the route of intake and that the aroma profile of these products could also differ. To this aim, 12 lactating dairy ewes were repeatedly exposed to limonene by the oral or respiratory route during a 48-h test period, according to a 3 × 3 Latin square experimental design. Limonene content was measured in individual and bulk milk samples, in 1-d-old and 15-d-old Caciotta cheese obtained from that milk, in the related whey and curd, and in the air inhaled by the ewes in the respiratory treatment group (to obtain an estimate of the dose actually supplied by this route). Bulk milk and fresh (1-d-old) cheese underwent sensory analysis by ortho-olfactory evaluation. Both intake routes demonstrated transfer of limonene to milk, but the respiratory route transferred limonene with greater efficiency than the oral route. Moreover, according to the protocol used in this study, a short period of respiratory exposure induced a slightly higher limonene content in milk compared with oral exposure. As to the fate of limonene during cheesemaking, an important part of it was lost into the whey, perhaps through volatilization. The differences between milk and cheese tended to dissipate in curd and fresh cheese and disappeared completely after 15 d of ripening. Finally, it was possible to distinguish between the 2 routes of limonene intake using sensory analysis, even though no direct relationship was identified between the different aroma profiles of milks and cheeses from the oral and respiratory groups and their respective limonene contents. Overall, our results expand current knowledge on the biological pathways of terpene transfer from feed to sheep milk and cheese, as well as on the role played by terpenes in the formation of aroma in these products. Our observations may contribute to future development of strategies for external control and better standardization of the presence of odor compounds in milk and cheese from dairy ruminants.

Differentiating Cannabis Products: Drugs, Food, and Supplements

“Hemp” refers to non-intoxicating, low delta-9 tetrahydrocannabinol (Δ9-THC) cultivars of Cannabis sativa L. “Marijuana” refers to cultivars with high levels of Δ9-THC, the primary psychoactive cannabinoid found in the plant and a federally controlled substance used for both recreational and therapeutic purposes. Although marijuana and hemp belong to the same genus and species, they differ in terms of chemical and genetic composition, production practices, product uses, and regulatory status. Hemp seed and hemp seed oil have been shown to have valuable nutritional capacity. Cannabidiol (CBD), a non-intoxicating phytocannabinoid with a wide therapeutic index and acceptable side effect profile, has demonstrated high medicinal potential in some conditions. Several countries and states have facilitated the use of THC-dominant medical cannabis for certain conditions, while other countries continue to ban all forms of cannabis regardless of cannabinoid profile or low psychoactive potential. Today, differentiating between hemp and marijuana in the laboratory is no longer a difficult process. Certain thin layer chromatography (TLC) methods can rapidly screen for cannabinoids, and several gas and liquid chromatography techniques have been developed for precise quantification of phytocannabinoids in plant extracts and biological samples. Geographic regulations and testing guidelines for cannabis continue to evolve. As they are improved and clarified, we can better employ the appropriate applications of this uniquely versatile plant from an informed scientific perspective.

Chemical Composition and Antioxidant Activity of Ammi visnaga L. Essential Oil

The present study evaluated the chemical composition and the in vitro and in vivo antioxidant potential of Ammi visnaga L. essential oil to provide a scientific basis for the use of this plant in the traditional pharmacopoeia. Gas chromatography-mass spectrometry was used to identify the volatile constituents present of the oil. The in vitro antioxidant capacity was evaluated by the DPPH and the reducing power assays. For the in vivo tests, oral administration of Ammi visnaga L. oil (600 and 1200 mg/kg body weight) was performed in Swiss albino mice treated with acetaminophen (400 mg/kg). The toxic effect of acetaminophen and the action of the essential oil were measured by determining the levels of lipid peroxidation and antioxidant enzymes in liver and kidneys homogenates. The major components identified were butanoic acid, 2-methyl-, pentyl ester, (Z)-β-ocimene, D-limonene, linalool, pulegone and lavandulyl-butyrate. The in vitro DPPH and reducing power assays showed moderate to low free radical scavenging activity and the antioxidant power was positively correlated with the polyphenols' concentration. In vivo, the Ammi visnaga L. essential oil showed a high antioxidant capacity at both concentrations (600 and 1200 mg/kg), effectively increasing the levels of reduced glutathione, superoxide dismutase, and catalase and significantly reducing the lipid peroxidation. The results obtained from this study suggest that Ammi visnaga L. could represent a source of molecules with antioxidant potential in the prevention of free radical-related diseases.

Analgesic Potential of Terpenes Derived from Cannabis sativa

Pain prevalence among adults in the United States has increased 25% over the past two decades, resulting in high health-care costs and impacts to patient quality of life. In the last 30 years, our understanding of pain circuits and (intra)cellular mechanisms has grown exponentially, but this understanding has not yet resulted in improved therapies. Options for pain management are limited. Many analgesics have poor efficacy and are accompanied by severe side effects such as addiction, resulting in a devastating opioid abuse and overdose epidemic. These problems have encouraged scientists to identify novel molecular targets and develop alternative pain therapeutics. Increasing preclinical and clinical evidence suggests that cannabis has several beneficial pharmacological activities, including pain relief. Cannabis sativa contains more than 500 chemical compounds, with two principle phytocannabinoids, Δ9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD). Beyond phytocannabinoids, more than 150 terpenes have been identified in different cannabis chemovars. Although the predominant cannabinoids, Δ9-THC and CBD, are thought to be the primary medicinal compounds, terpenes including the monoterpenes β-myrcene, α-pinene, limonene, and linalool, as well as the sesquiterpenes β-caryophyllene and α-humulene may contribute to many pharmacological properties of cannabis, including anti-inflammatory and antinociceptive effects. The aim of this review is to summarize our current knowledge about terpene compounds in cannabis and to analyze the available scientific evidence for a role of cannabis-derived terpenes in modern pain management. SIGNIFICANCE STATEMENT: Decades of research have improved our knowledge of cannabis polypharmacy and contributing phytochemicals, including terpenes. Reform of the legal status for cannabis possession and increased availability (medicinal and recreational) have resulted in cannabis use to combat the increasing prevalence of pain and may help to address the opioid crisis. Better understanding of the pharmacological effects of cannabis and its active components, including terpenes, may assist in identifying new therapeutic approaches and optimizing the use of cannabis and/or terpenes as analgesic agents.

Cytotoxicity and Genotoxicity of E-Cigarette Generated Aerosols Containing Diverse Flavoring Products and Nicotine in Oral Epithelial Cell Lines

Electronic cigarettes are the most commonly used nicotine containing product among teenagers. The oral epithelium is the first site of exposure and our recent work revealed considerable diversity among e-liquids for composition and level of chemical constituents that impact nicotine deposition in a human oral-trachea cast and affect the formation of reactive carbonyls. Here, we evaluate the dose response for cytotoxicity and genotoxicity of e-cigarette-generated aerosols from 10 diverse flavored e-liquid products with and without nicotine compared with unflavored in 3 immortalized oral epithelial cell lines. Three e-liquids, Blue Pucker, Love Potion, and Jamestown caused ≥20% cell toxicity assessed by the neutral red uptake assay. Nine products induced significant levels of oxidative stress up to 2.4-fold quantified by the ROS-Glo assay in at least 1 cell line, with dose response seen for Love Potion with and without nicotine across all cell lines. Lipid peroxidation detected by the thiobarbituric acid reactive substances assay was less common among products; however, dose response increases up to 12-fold were seen for individual cell lines. Micronuclei formation indicative of genotoxicity was increased up to 5-fold for some products. Blue Pucker was the most genotoxic e-liquid, inducing micronuclei across all cell lines irrespective of nicotine status. A potency score derived from all assays identified Blue Pucker and Love Potion as the most hazardous e-liquids. These in vitro acute exposure studies provide new insight about the potential for some flavored vaping products to induce significant levels of oxidative stress and genotoxicity.

Human absorption of monoterpenes after a 2-h forest exposure: A field experiment in a Mediterranean holm oak forest

The current body of literature points monoterpenes as one of the determinant factors of the interaction between forests and human health. The present study aims at analyzing the monoterpene absorption by humans during a 2 -hs forest exposure in a Mediterranean holm oak forest focusing on the four most abundant monoterpene compounds: alpha-pinene, beta-pinene, alpha-phellandrene and limonene. Participants' blood samples were collected before and after exposure to forest or urban environment (control). We conducted air and blood sampling using cartridges and head space method and determined the monoterpene compounds through CGMS. We identified the four compounds in forest air during the experimental study being alpha-pinene the monoterpene with the greatest concentration. Results show no significant changes in monoterpene blood concentrations for the forest and control group. However, a negative significant relationship between absorption and baseline blood concentration of the most abundant forest air monoterpenes, alpha-pinene and beta-pinene, was found in individuals visiting the forest, i.e. higher absorption was found the lower the baseline blood concentration was. Although no significant lineal correlation could be spotted between the vital variables and the monoterpene absorption, we found significant correlations between the absorption of the monoterpene compounds. This attempt, first in a Mediterranean holm oak forest, can serve as a starting point and constitute a valuable contribution for further research in regard to experimental design and laboratory analysis.

Essential oils: what is the clinical tolerance in asthmatic patients?

Essential oils in air-spray form are being more and more used for several purposes, even by allergic and asthmatic patients. Available data on the potentially dangerous effects of volatile organic compounds and terpenes contained in essential oils are scarce, and sometimes difficult to compare. Through the present work, we evaluated the clinical tolerance of asthmatic patients exposed to compounds emitted by an essential oils spray, and compared previous and new data available in the scientific literature, focusing on the aspects that may influence clinical results.

Can limonene be a possible candidate for evaluation as an agent or adjuvant against infection, immunity, and inflammation in COVID-19?

Coronavirus disease (COVID-19) caused by novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an ongoing pandemic and presents a public health emergency. It has affected millions of people and continues to affect more, despite the tremendous social preventive measures. The therapeutic strategy relies on suppressing infectivity and inflammation, along with immune modulation. The identification of candidate drugs effective for COVID-19 is crucial, thus many natural products including phytochemicals are also being proposed for repurposing and evaluated for their potential in COVID-19. Among numerous phytochemicals, limonene (LMN), a dietary terpene of natural origin has been recently showed to target viral proteins in the in-silico studies. LMN is one of the main compounds identified in many citrus plants, available and accessible in diets and well-studied for its therapeutic benefits. Due to dietary nature, relative safety and efficacy along with favorable physicochemical properties, LMN has been suggested to be a fascinating candidate for further investigation in COVID-19. LMN showed to modulate numerous signaling pathways and inhibits inflammatory mediators, including cytokines, chemokines, adhesion molecules, prostanoids, and eicosanoids. We hypothesized that given the pathogenesis of COVID-19 involving infection, inflammation, and immunity, LMN may have potential to limit the severity and progression of the disease owing to its immunomodulatory, anti-inflammatory, and antiviral properties. The present article discusses the possibilities of LMN in SARS-CoV-2 infections based on its immunomodulatory, anti-inflammatory, and antiviral properties. Though, the suggestion on the possible use of LMN in COVID-19 remains inconclusive until the in-silico effects confirmed in the experimental studies and further proof of the concept studies. The candidature of LMN in COVID-19 treatment somewhat appear speculative but cannot be overlooked provided favorable physiochemical and druggable properties. The safety and efficacy of LMN are necessary to be established in preclinical and clinical studies before making suggestions for use in humans.

Forest Volatile Organic Compounds and Their Effects on Human Health: A State-of-the-Art Review

The aim of this research work is to analyze the chemistry and diversity of forest VOCs (volatile organic compounds) and to outline their evidence-based effects on health. This research work was designed as a narrative overview of the scientific literature. Inhaling forest VOCs like limonene and pinene can result in useful antioxidant and anti-inflammatory effects on the airways, and the pharmacological activity of some terpenes absorbed through inhalation may be also beneficial to promote brain functions by decreasing mental fatigue, inducing relaxation, and improving cognitive performance and mood. The tree composition can markedly influence the concentration of specific VOCs in the forest air, which also exhibits cyclic diurnal variations. Moreover, beneficial psychological and physiological effects of visiting a forest cannot be solely attributed to VOC inhalation but are due to a global and integrated stimulation of the five senses, induced by all specific characteristics of the natural environment, with the visual component probably playing a fundamental role in the overall effect. Globally, these findings can have useful implications for individual wellbeing, public health, and landscape design. Further clinical and environmental studies are advised, since the majority of the existing evidence is derived from laboratory findings.

Effect of Inhaled Lemon Essential Oil on Cognitive Test Anxiety Among Nursing Students

Nursing programs are stressful learning environments, and students are expected to maintain high academic performance to successfully graduate. Cognitive test anxiety has been minimally studied among nursing students, including how to successfully manage. The Cognitive Test Anxiety Scale (CTAS) was administered to 31 students before and after a high-stakes nursing examination. The intervention was inhaled lemon essential oil delivered via a personal nasal device. Neither the control nor the experimental group demonstrated a statistically significant change in the CTAS score from pretest to posttest (P = .19). More quantitative studies are warranted with undergraduate nursing students, the CTAS, and aromatherapy to reduce the burden of cognitive test anxiety.

Chemical profile and in vivo toxicity evaluation of unripe Citrus aurantifolia essential oil

Citrus aurantifolia (Christm.) Swingle (syn. C. MEDICA var. ACIDA Brandis) (family: Rutaceae) essential oil is one of the cheapest oils found in local markets. Although, it is generally accepted as non-toxic to vital organs and cells, majority of people are cynical about it usage. Herein, the present study reports the chemical composition and in vivo oral toxicity study of unripe C. aurantifolia essential oil found in Ghana. The toxicity of C. aurantifolia essential oil extract was investigated via oral administration using two methods: The acute toxicity single dose study (SDS) and the repeated dose method. The oil exhibited no acute toxicity but in the sub-chronic studies, the effects was dose and time-dependent. Chemical profile investigation of the oil showed 9 constituent of phytochemicals (Germacrene isomers (61.2%), Pineen (14%), Linalool dimmer (2.9%), Bornane (11%), Citral (2.9%), Anethole (1.5%), Anisole (1.1%), Safrole (0.3%) and Demitol (0.6%)). Histopathological studies revealed conditions such as necrosis, edema and inflammatory reaction in the liver, spleen and kidneys. Marginal upsurge of biochemical parameters above normal and elevated levels of lymphocytes (35.20-46.40 g/dL) demonstrated mild toxicity among the 100 mg/kg and 500 mg/kg dose groups at the sub-chronic stage. Low levels of hemoglobin (13.60 to 12.70 g/dL), MCV (34.20-24.0 fL), MCH (40.20-36.40 g/dL) along with high levels of liver enzymes confirmed the mild toxicity of the oil at sub-chronic stage. These results demonstrate that, despite consideration of lime essential oil as safe, it can have mild hematotoxic, nephrotoxic and hepatotoxic effects.

Development and evaluation of nanoemulsion and microsuspension formulations of curcuminoids for lung delivery with a novel approach to understanding the aerosol performance of nanoparticles

Extensive research has demonstrated the potential effectiveness of curcumin against various diseases, including asthma and cancers. However, few studies have used liquid-based vehicles in the preparation of curcumin formulations. Therefore, the current study proposed the use of nanoemulsion and microsuspension formulations to prepare nebulised curcuminoid for lung delivery. Furthermore, this work expressed a new approach to understanding the aerosol performance of nanoparticles compared to microsuspension formulations. The genotoxicity of the formulations was also assessed. Curcuminoid nanoemulsion formulations were prepared in three concentrations (100, 250 and 500 µg/ml) using limonene and oleic acid as oil phases, while microsuspension solutions were prepared by suspending curcuminoid particles in isotonic solution (saline solution) of 0.02% Tween 80. The average fine particle fraction (FPF) and mass median aerodynamic diameter (MMAD) of the nebulised microsuspension formulations ranged from 26% and 7.1 µm to 40% and 5.7 µm, for 1000 µg/ml and 100 µg/ml respectively. In a comparison of the low and high drug concentrations of the nebulised nanoemulsion, the average FPF and MMAD of the nebulised nanoemulsion formulations prepared with limonene oil ranged from 50% and 4.6 µm to 45% and 5.6 µm, respectively; whereas the FPF and MMAD of the nebulised nanoemulsion prepared with oleic acid oil ranged from 46% and 4.9 µm to 44% and 5.6 µm, respectively. The aerosol performance of the microsuspension formulations were concentration dependent, while the nanoemulsion formulations did not appear to be dependent on the curcuminoids concentration. The performance and genotoxicity results of the formulations suggest the suitability of these preparations for further inhalation studies in animals.

Human Olfactory Receptors: Novel Cellular Functions Outside of the Nose

Olfactory receptors (ORs) are not exclusively expressed in the olfactory sensory neurons; they are also observed outside of the olfactory system in all other human tissues tested to date, including the testis, lung, intestine, skin, heart, and blood. Within these tissues, certain ORs have been determined to be exclusively expressed in only one tissue, whereas other ORs are more widely distributed in many different tissues throughout the human body. For most of the ectopically expressed ORs, limited data are available for their functional roles. They have been shown to be involved in the modulation of cell-cell recognition, migration, proliferation, the apoptotic cycle, exocytosis, and pathfinding processes. Additionally, there is a growing body of evidence that they have the potential to serve as diagnostic and therapeutic tools, as ORs are highly expressed in different cancer tissues. Interestingly, in addition to the canonical signaling pathways activated by ORs in olfactory sensory neurons, alternative pathways have been demonstrated in nonolfactory tissues. In this review, the existing data concerning the expression, as well as the physiological and pathophysiological functions, of ORs outside of the nose are highlighted to provide insights into future lines of research.

The safety evaluation of food flavouring substances: the role of metabolic studies

The safety assessment of a flavour substance examines several factors, including metabolic and physiological disposition data. The present article provides an overview of the metabolism and disposition of flavour substances by identifying general applicable principles of metabolism to illustrate how information on metabolic fate is taken into account in their safety evaluation. The metabolism of the majority of flavour substances involves a series both of enzymatic and non-enzymatic biotransformation that often results in products that are more hydrophilic and more readily excretable than their precursors. Flavours can undergo metabolic reactions, such as oxidation, reduction, or hydrolysis that alter a functional group relative to the parent compound. The altered functional group may serve as a reaction site for a subsequent metabolic transformation. Metabolic intermediates undergo conjugation with an endogenous agent such as glucuronic acid, sulphate, glutathione, amino acids, or acetate. Such conjugates are typically readily excreted through the kidneys and liver. This paper summarizes the types of metabolic reactions that have been documented for flavour substances that are added to the human food chain, the methodologies available for metabolic studies, and the factors that affect the metabolic fate of a flavour substance.

Cannabis Pharmacology: The Usual Suspects and a Few Promising Leads

The golden age of cannabis pharmacology began in the 1960s as Raphael Mechoulam and his colleagues in Israel isolated and synthesized cannabidiol, tetrahydrocannabinol, and other phytocannabinoids. Initially, THC garnered most research interest with sporadic attention to cannabidiol, which has only rekindled in the last 15 years through a demonstration of its remarkably versatile pharmacology and synergy with THC. Gradually a cognizance of the potential of other phytocannabinoids has developed. Contemporaneous assessment of cannabis pharmacology must be even far more inclusive. Medical and recreational consumers alike have long believed in unique attributes of certain cannabis chemovars despite their similarity in cannabinoid profiles. This has focused additional research on the pharmacological contributions of mono- and sesquiterpenoids to the effects of cannabis flower preparations. Investigation reveals these aromatic compounds to contribute modulatory and therapeutic roles in the cannabis entourage far beyond expectations considering their modest concentrations in the plant. Synergistic relationships of the terpenoids to cannabinoids will be highlighted and include many complementary roles to boost therapeutic efficacy in treatment of pain, psychiatric disorders, cancer, and numerous other areas. Additional parts of the cannabis plant provide a wide and distinct variety of other compounds of pharmacological interest, including the triterpenoid friedelin from the roots, canniprene from the fan leaves, cannabisin from seed coats, and cannflavin A from seed sprouts. This chapter will explore the unique attributes of these agents and demonstrate how cannabis may yet fulfil its potential as Mechoulam's professed "pharmacological treasure trove."

Effects by inhalation of abundant fragrances in indoor air - An overview

Odorous compounds (odors) like fragrances may cause adverse health effects. To assess their importance by inhalation, we have reviewed how the four major abundant and common airborne fragrances (α-pinene (APN), limonene (LIM), linalool (LIL), and eugenol (EUG)) impact the perceived indoor air quality as odor annoyance, sensory irritation and sensitization in the airways. Breathing and cardiovascular effects, and work performance, and the impact in the airways of ozone-initiated gas- and particle phase reactions products have also been assessed. Measured maximum indoor concentrations for APN, LIM and LIL are close to or above their odor thresholds, but far below their thresholds for sensory irritation in the eyes and upper airways; no information could be traced for EUG. Likewise, reported risk values for long-term effects are far above reported indoor concentrations. Human exposure studies with mixtures of APN and LIM and supported by animal inhalation models do not support sensitization of the airways at indoor levels by inhalation that include other selected fragrances. Human exposure studies, in general, indicate that reported lung function effects are likely due to the perception rather than toxic effects of the fragrances. In general, effects on the breathing rate and mood by exposure to the fragrances are inconclusive. The fragrances may increase the high-frequency heart rate variability, but aerosol exposure during cleaning activities may result in a reduction. Distractive effects influencing the work performance by fragrance/odor exposure are consistently reported, but their persistence over time is unknown. Mice inhalation studies indicate that LIM or its reaction mixture may possess anti-inflammatory properties. There is insufficient information that ozone-initiated reactions with APN or LIM at typical indoor levels cause airway effects in humans. Limited experimental information is available on long-term effects of ozone-initiated reaction products of APN and LIM at typical indoor levels.

Fumigant and Repellent Activity of Limonene Enantiomers Against Tribolium confusum du Val

The use of pesticides, as carried out in the last 50 years, caused several negative environmental and human health consequences, leading to the development of alternative techniques to control pests, such as the use of compounds of plant origin. In this study, we assessed the fumigant and repellent activity of both the enantiomers of limonene, a monoterpene usually found in many plant species, against Tribolium confusum du Val. We tested both molecules at different doses, air temperatures, and in absence and presence of flour. R-(+)-limonene resulted more effective than S-(-)-limonene; indeed, it was able to reach 100% of efficacy at a concentration of 85 mg/L air when tested at different temperatures without flour. Data showed a positive relationship between efficacy and temperature, and a negative effect of the presence of debris on the bioactivity of limonene. Furthermore, repellency trials reported a higher activity of R-(+)-limonene compared to the other enantiomer.

Noncompetitive Inhibition of 5-HT3 Receptors by Citral, Linalool, and Eucalyptol Revealed by Nonlinear Mixed-Effects Modeling

Citral, eucalyptol, and linalool are widely used as flavorings, fragrances, and cosmetics. Here, we examined their effects on electrophysiological and binding properties of human 5-HT₃ receptors expressed in Xenopus oocytes and human embryonic kidney 293 cells, respectively. Data were analyzed using nonlinear mixed-effects modeling to account for random variance in the peak current response between oocytes. The oils caused an insurmountable inhibition of 5‐HT–evoked currents (citral IC₅₀ = 120 µM; eucalyptol = 258 µM; linalool = 141 µM) and did not compete with fluorescently labeled granisetron, suggesting a noncompetitive mechanism of action. Inhibition was not use‐dependent but required a 30-second preapplication. Compound washout caused a slow (∼180 seconds) but complete recovery. Coapplication of the oils with bilobalide or diltiazem indicated they did not bind at the same locations as these channel blockers. Homology modeling and ligand docking predicted binding to a transmembrane cavity at the interface of adjacent subunits. Liquid chromatography coupled to mass spectrometry showed that an essential oil extracted from Lippia alba contained 75.9% citral. This inhibited expressed 5‐HT₃ receptors (IC₅₀ = 45 µg ml⁻¹) and smooth muscle contractions in rat trachea (IC₅₀ = 200 µg ml⁻¹) and guinea pig ileum (IC₅₀ = 20 µg ml⁻¹), providing a possible mechanistic explanation for why this oil has been used to treat gastrointestinal and respiratory ailments. These results demonstrate that citral, eucalyptol, and linalool inhibit 5-HT₃ receptors, and their binding to a conserved cavity suggests a valuable target for novel allosteric modulators.

EPHECT III: Health risk assessment of exposure to household consumer products

In the framework of the EU EPHECT project (Emissions, Exposure Patterns and Health Effects of Consumer Products in the EU), irritative and respiratory effects were assessed in relation to acute (30-min) and long-term (24-h) inhalation exposure to key and emerging indoor air pollutants emitted during household use of selected consumer products. A detailed Health Risk Assessment (HRA) was performed for five selected pollutants of respiratory health relevance, namely acrolein, formaldehyde, naphthalene, d-limonene and α-pinene. For each pollutant, the Critical Exposure Limit (CEL) was compared to indoor air concentrations and exposure estimates for the use of 15 selected consumer products by two population groups (housekeepers and retired people) in the four geographical regions of Europe (North, West, South, East), which were derived previously based on microenvironmental modelling. For the present HRA, health-based CELs were derived for certain compounds in case indoor air quality guidelines were not available by the World Health Organization for end-points relevant to the current study. For each pollutant, the highest indoor air concentrations in each microenvironment and exposure estimates across home microenvironments during the day were lower than the corresponding acute and long-term CELs. However, considerable contributions, especially to acute exposures, were obtained in some cases, such as formaldehyde emissions resulting from single product use of a floor cleaning agent (82% CEL), a candle (10% CEL) and an electric air freshener (17% CEL). Regarding multiple product use, the case of 30-min formaldehyde exposure reaching 34% CEL when eight product classes were used across home microenvironments, i.e. all-purpose/kitchen/floor cleaning agents, furniture/floor polish, combustible/electric air fresheners, and perfume, needs to be highlighted. Such estimated values should be evaluated with caution, as these may be attributed to the exposure scenarios specifically constructed for the present study, following a 'most-representative worst-case scenario' approach for exposure and health risk assessment.

Lack of heritability of exhaled volatile compound pattern: an electronic nose twin study

Electronic noses can distinguish various disorders by analyzing exhaled volatile organic compound (VOC) pattern; however it is unclear how hereditary and environmental backgrounds affect the exhaled VOC pattern. A twin study enrolling monozygotic (MZ) and dizygotic (DZ) twins is an ideal tool to separate the influence of these factors on the exhaled breath pattern. Exhaled breath samples were collected in duplicates from 28 never smoking twin pairs (in total 112 samples) without lung diseases and processed with an electronic nose (Cyranose 320). Univariate quantitative hereditary modeling (ACE analysis) adjusted for age and gender was performed to decompose the phenotypic variance of the exhaled volatile compound pattern (assessing principal components (PCs) derived from electronic nose data) into hereditary (A), shared (C), and unshared (E) environmental effects. Exhaled VOC pattern showed good intra-subject reproducibility as assessed with the Bland-Altman plot. Significant correlations were found between exhaled VOC patterns of both MZ and DZ twins. The hereditary background did not influence the VOC pattern. The shared environmental effect on PC 1, 2 and 3 was estimated to be 93%, 94% and 54%, respectively. The unshared (unique) environmental influence explained a smaller variance (7%, 6% and 46%). For the first time using the twin design, we have shown that the environmental background largely affects the exhaled volatile compound pattern in never smoking volunteers without respiratory disorders. Further studies should identify these environmental factors and also assess their influence on exhaled breath patterns in patients with lung diseases.

Fragrance materials in asthma: a pilot study using a surrogate aerosol product

OBJECTIVE

Many household products contain fragrances. Little is known about exposure to fragrances on human health, particularly within the airways. This study aimed to evaluate how common household fragrance products (i.e. air fresheners, cleaning products) affect people with asthma, who frequently report sensitivity to these products. Many of these products have volatile organic compounds or semi-volatile organic compounds. This study evaluated nine fragrance materials in an aerosol formulation to assess effects on airway physiology, airway inflammation and symptom perception in normal controls and those with asthma.

METHODS

The effects of fragrances were evaluated in people without asthma, people with mild asthma and people with moderate asthma in a four-way crossover placebo-controlled study. Subjects were exposed twice to a fragranced aerosol and twice to a placebo aerosol (15 and 30 min each). Subjects completed a questionnaire for 29 symptoms during and up to 3 h after each exposure scenario. Spirometry was performed prior to and 3 h post-exposure; sputum induction was conducted 3 h post-exposure.

RESULTS

Nasal symptoms showed the greatest frequency of response in all three subject groups, and moderate asthmatics reported the greatest symptom severity and symptom types. No significant differences were noted in physiology or cellular inflammation.

CONCLUSION

A trend for increased symptoms was noted in moderate asthmatics, suggesting that asthma severity may play a factor in fragrance sensitivity.

Safety evaluation and risk assessment of d-Limonene

d-Limonene, a major constituent of citrus oils, is a monoterpene widely used as a flavor/fragrance additive in cosmetics, foods, and industrial solvents as it possesses a pleasant lemon-like odor. d-Limonene has been designated as a chemical with low toxicity based upon lethal dose (LD50) and repeated-dose toxicity studies when administered orally to animals. However, skin irritation or sensitizing potential was reported following widespread use of this agent in various consumer products. In experimental animals and humans, oxidation products or metabolites of d-limonene were shown to act as skin irritants. Carcinogenic effects have also been observed in male rats, but the mode of action (MOA) is considered irrelevant for humans as the protein α(2u)-globulin responsible for this effect in rodents is absent in humans. Thus, the liver was identified as a critical target organ following oral administration of d-limonene. Other than the adverse dermal effects noted in humans, other notable toxic effects of d-limonene have not been reported. The reference dose (RfD), the no-observed-adverse-effect level (NOAEL), and the systemic exposure dose (SED) were determined and found to be 2.5 mg/kg/d, 250 mg/kg//d, and 1.48 mg/kg/d, respectively. Consequently, the margin of exposure (MOE = NOAEL/SED) of 169 was derived based upon the data, and the hazard index (HI = SED/RfD) for d-limonene is 0.592. Taking into consideration conservative estimation, d-limonene appears to exert no serious risk for human exposure. Based on adverse effects and risk assessments, d-limonene may be regarded as a safe ingredient. However, the potential occurrence of skin irritation necessitates regulation of this chemical as an ingredient in cosmetics. In conclusion, the use of d-limonene in cosmetics is safe under the current regulatory guidelines for cosmetics.

Indoor air pollutants in office environments: assessment of comfort, health, and performance

Concentrations of volatile organic compounds (VOCs) in office environments are generally too low to cause sensory irritation in the eyes and airways on the basis of estimated thresholds for sensory irritation. Furthermore, effects in the lungs, e.g. inflammatory effects, have not been substantiated at indoor relevant concentrations. Some VOCs, including formaldehyde, in combination may under certain environmental and occupational conditions result in reported sensory irritation. The odour thresholds of several VOCs are low enough to influence the perceived air quality that result in a number of acute effects from reported sensory irritation in eyes and airways and deterioration of performance. The odour perception (air quality) depends on a number of factors that may influence the odour impact. There is neither clear indication that office dust particles may cause sensory effects, even not particles spiked with glucans, aldehydes or phthalates, nor lung effects; some inflammatory effects may be observed among asthmatics. Ozone-initiated terpene reaction products may be of concern in ozone-enriched environments (≥0.1mg/m(3)) and elevated limonene concentrations, partly due to the production of formaldehyde. Ambient particles may cause cardio-pulmonary effects, especially in susceptible people (e.g. elderly and sick people); even, short-term effects, e.g. from traffic emission and candle smoke may possibly have modulating and delayed effects on the heart, but otherwise adverse effects in the airways and lung functions have not been observed. Secondary organic aerosols generated in indoor ozone-initiated terpene reactions appear not to cause adverse effects in the airways; rather the gaseous products are relevant. Combined exposure to particles and ozone may evoke effects in subgroups of asthmatics. Based on an analysis of thresholds for odour and sensory irritation selected compounds are recommended for measurements to assess the indoor air quality and to minimize reports of irritation symptoms, deteriorated performance, and cardiovascular and pulmonary effects.

Taming THC: potential cannabis synergy and phytocannabinoid-terpenoid entourage effects

Tetrahydrocannabinol (THC) has been the primary focus of cannabis research since 1964, when Raphael Mechoulam isolated and synthesized it. More recently, the synergistic contributions of cannabidiol to cannabis pharmacology and analgesia have been scientifically demonstrated. Other phytocannabinoids, including tetrahydrocannabivarin, cannabigerol and cannabichromene, exert additional effects of therapeutic interest. Innovative conventional plant breeding has yielded cannabis chemotypes expressing high titres of each component for future study. This review will explore another echelon of phytotherapeutic agents, the cannabis terpenoids: limonene, myrcene, α-pinene, linalool, β-caryophyllene, caryophyllene oxide, nerolidol and phytol. Terpenoids share a precursor with phytocannabinoids, and are all flavour and fragrance components common to human diets that have been designated Generally Recognized as Safe by the US Food and Drug Administration and other regulatory agencies. Terpenoids are quite potent, and affect animal and even human behaviour when inhaled from ambient air at serum levels in the single digits ng·mL(-1) . They display unique therapeutic effects that may contribute meaningfully to the entourage effects of cannabis-based medicinal extracts. Particular focus will be placed on phytocannabinoid-terpenoid interactions that could produce synergy with respect to treatment of pain, inflammation, depression, anxiety, addiction, epilepsy, cancer, fungal and bacterial infections (including methicillin-resistant Staphylococcus aureus). Scientific evidence is presented for non-cannabinoid plant components as putative antidotes to intoxicating effects of THC that could increase its therapeutic index. Methods for investigating entourage effects in future experiments will be proposed. Phytocannabinoid-terpenoid synergy, if proven, increases the likelihood that an extensive pipeline of new therapeutic products is possible from this venerable plant. http://dx.doi.org/10.1111/bph.2011.163.issue-7.

Chemosensory irritations and pulmonary effects of acute exposure to emissions from oriented strand board

Due to the reduction of air change rates in low-energy houses, the contribution to indoor air quality of volatile organic compounds (VOCs) emitting from oriented strand boards (OSB) has become increasingly important. The aim of this study was to evaluate sensory irritations, pulmonary effects and odor annoyance of emissions from OSB in healthy human volunteers compared to clean air. Twenty-four healthy non-smokers were exposed to clean air and OSB emissions for 2 h under controlled conditions in a 48 m(3) test chamber at three different time points: to fresh OSB panels and to the same panels after open storage for 2 and 8 weeks. Chemosensory irritation, exhaled nitric oxide (NO) concentration, eye blink frequency, lung function and subjective perception of irritation of eyes, nose and throat were examined before, during and after exposure. Additionally, olfactory perception was investigated. Total VOC exposure concentrations reached 8.9 ± 0.8 mg/m(3) for the fresh OSB panels. Emissions consisted predominantly of α-pinene, Δ(3)-carene and hexanal. Two-hour exposure to high VOC concentrations revealed no irritating or pulmonary effects. All the subjective ratings of discomfort were at a low level and the medians did not exceed the expression 'hardly at all.' Only the ratings for smell of emissions increased significantly during exposure in comparison to clean air. In conclusion, exposure of healthy volunteers to OSB emissions did not elicit sensory irritations or pulmonary effects up to a VOC concentration of about 9 mg/m(3). Sensory intensity of OSB emissions in the chamber air was rated as 'neutral to pleasant.'

"Healthy" eye in office-like environments

Eye irritation symptoms, e.g. dry eyes, are common and abundant symptoms reported in office-like environments, e.g. aircraft cabins. To improve the understanding of indoor related eye symptomatology, relevant knowledge from the ophthalmological and indoor environmental science literature has been merged. A number of environmental (relative humidity, temperature, draft), occupational (e.g. visual display unit work), and individual (e.g. gender, use of cosmetics, and medication) risk factors have been identified, which are associated with alteration of the precorneal tear film (PTF); these factors may subsequently exacerbate development of eye irritation symptoms by desiccation. Low relative humidity including reduced atmospheric pressure further increases the water evaporation from an altered PTF; in addition, work with visual display units may destabilize the PTF by lower eye blink frequency and larger ocular surface. Results from epidemiological and clinical studies support that relative humidity >40% is beneficial for the PTF. Only few pollutants reach high enough indoor concentrations to cause sensory irritation of the eyes, while an altered PTF may exacerbate their sensory effect. Sustained low relative humidity causes impairment of the PTF, while its stability, including work performance, is retained by low gaze and intermittent breaks.